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  1. #101
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    Quote Originally Posted by jgrano View Post
    Off chance have you considered integrating some Innegra fabric in your bars? It is supposed to dampen vibrations but does a pretty good job for impact resistance. Hai Velo is using it with some good results it seems.

    innegra
    That's the plan for the near future, yes. I've received mixed recommendations from some acquaintances ("it's great" VS "don't bother at all"). So that pretty much means I must try it and judge for myself.

    As far as suppliers, no one braids it. There are some that say they do, but they steer me in the direction of similar-but-not-identical fabrics. I kinda get it, I've read that it can have a twisting premature failure from improper human handling.

    I suppose it's kinda like buying aramid, you don't literally have to get it from DuPont at this point.
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  2. #102
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    In a previous life I made a ton of test samples for a big bike company. I don't think they ended up using it or anything but some of their now ex-employees have seen a ton of value in it apparently.

    Might be worth doing a non-sleeved layup. If there was a fail safe in carbon handle bars that would be a great thing to bring to market.

  3. #103
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    Testing and re-building of molds continues. What I've changed recently is a slight increase in minimum allowable stem length (70mm, an increase of 10mm), the effect on the mandrel is that the double-S-bend is less extreme. This change helps with sleeve layup and UD layup alike.

    Another change is a more sudden transition from 31.8mm OD to 22.2mm. It used to take all of the length of curvature in the bent portion of the handlebar, now the transition length only takes 30mm. It is subjectively uglier, less flowy, but the first test pull looked mostly fine (which I totally screwed up by using *really old* epoxy that I didn't date check because the canister looked so new, @#$*ing idiot).

    One thing I dislike as an end user about the shorter transition is that it allows less length of a 31.8mm OD, which means less real estate for bolt-on gadgets.

    The purpose of the shorter transition is to create a thicker wall along the outer reaches of the bar, and initiate flex closer to the stem, sorta like a diving board. ALL of the bar failures have happened at the same spot near the grip. This leads me to think the middle of the bar is over-reinforced while the grip areas are insufficiently reinforced.

    It also would appear as though I have wasted months of time on a certain epoxy formula that my current heating device will simply not cure completely enough. I did some tests on some "neat" slabs of epoxy, and just face palmed upon seeing some obvious strength differences. I'd been using ProSet (high temp) for some time now because of its super low viscosity, long gel time, and high post-cure heat deflection temperature (for the sake of people who live in hotter climates than where I live).

    After re-reading the specs on the stuff, it seems that the real cure quality comes from the higher temp cure schedule, which is out of my reach for the time being. See, I'm simply using hot water to cure, so I'm theoretically limited to 212F but practically I'm limited to 160F. And that's not enough to get a strong result out of that particular epoxy. So, in the mean time, it seems I will have to stick with an epoxy that has easier / lower temperature post curing requirements (AdTech 820) before it reaches a strong result, with the trade off being a lower heat deflection temperature. Until I get a proper oven, I'll just have to warn users in very hot climates to be careful about leaving their bike in the car. That part doesn't feel particularly good.

    I've been admonished by my local composites supplier that I am overthinking things with the heat deflection concern. "We have a lot of customers in motorsports, and we haven't heard complaints about this stuff that you consider low temp."

    And I'm like, "I'm not making an aerodynamic fairing, I'm making a structural component..."

    Last few months have been a struggle, but I'm past the point where I see light at the end of the tunnel. I'm nearly outside and the high contrast is starting to morph into details. The bars have become stronger while also becoming lighter, but none have passed the gravity sled yet.
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  4. #104
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    I encountered a sort-of-new kind-of-not way to cause an infusion to fail. What's familiar is the symptom: a blockage in the fast-travel zone around the parting line. The blockage forces epoxy to take the looooooong route through the entire volume of the bar (or, in this case the entire volume starting from the stem area to the end of one grip).

    What is unfamiliar is the root cause of the blockage: a dry gasket that wandered even when it had a registration groove. The gasket grew in width beyond what I expected when it was clamped.

    Note the slightly zoomed in photos that show the flashing. The functional zone has clear resin, indicating an "artery" function. In the incomplete half of the bar, there is no clear resin, because the gasket was pushing directly against it.

    So, now I know why D-profile gaskets sometimes use two Ds. That's what I'm going to switch to, and I will likewise increase the relief area to allow for a wider channel.

    To further highlight just how far the gasket encroached, I had a little tab on the gasket near the end of the bar, which is *meant* to pinch the resin flow at that point, so that the resin doesn't have a reason to just... exit the mold, as opposed to flowing through the laminate.

    It's the same theory as MTI tubes for open-shell vacuum bagging. I simply don't have the room, so I have to emulate it. Kind of a problem when I pinch off one of the tubes, so to speak.

    Show and tell on a... Monday? Milestone: carbon lugs.-far_view_complete.jpgShow and tell on a... Monday? Milestone: carbon lugs.-far_view_incomplete.jpgShow and tell on a... Monday? Milestone: carbon lugs.-close_view_complete.jpgShow and tell on a... Monday? Milestone: carbon lugs.-close_view_incomplete.jpgShow and tell on a... Monday? Milestone: carbon lugs.-excessive_proximity.jpg
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  5. #105
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    Now we're TALKING.

    I'd been out of commission for a little bit because I lightly injured my shoulder. What I'd been doing was dangerous, and I knew it, but ignored it egotistically. It's about a 60 pound load for the mold uppers, and I had been straight-arm supinating them.

    We're not meant to pick anything up that way.

    I invested all of $45 into auto-glass movers and a bicycle lift. Healed up mostly, I'm back at it.

    And HOW.

    I trimmed the gaskets by hand with extreme caution, and gave the epoxy fast tracks a bit more volume. It @#$&ing paid off. Look at those clear runners! The resin infusion itself was fast, there was sign of epoxy exit at THREE MINUTES, and it was completed at 20 minutes.

    Also noteworthy is my new vacuum canisters. It's a see-through sandwich of polycarbonate -> polypropylene frame -> polycarbonate. The polycarbonate is insulated from the epoxy with clear packing tape. This arrangement (emptied as pictured) gives me an incredibly clear picture of how much resin has been consumed, and it is easy to place close to the mold for the sake of using a minimal amount of vac tubing.

    Been a good week. It's going to be easier / faster / cheaper to make these bars pretty soon.

    Show and tell on a... Monday? Milestone: carbon lugs.-20170621_170628.jpgShow and tell on a... Monday? Milestone: carbon lugs.-20170622_204911.jpgShow and tell on a... Monday? Milestone: carbon lugs.-20170622_204913.jpgShow and tell on a... Monday? Milestone: carbon lugs.-20170622_025407.jpg
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  6. #106
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    Keep up with those good weeks Drew.....

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    If I don't make an attempt, how will I know if it will work?

  7. #107
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    Kind of a bummer: the latest bar failed testing, due to an insufficient-infusion zone that was so subtle that I didn't really notice it until well after sanding. The watching of water evaporating can occasionally show stuff. The cause was over-compression of fiber in one small zone. All familiar.

    I need to reduce the sensitivity to human error. On the one hand, solid mandrels are great in terms of positive fiber alignment. On the other hand, air pressure membrane (bladder) is more reliable in terms of avoiding over-compression. How to combine best of both worlds?

    It's time I move on to an idea that is similar to how Felt does their frame moldings. They combine a semi-rigid thin jacket that vaguely represents the finished interior shape of the part. Through that, they thread a conventional pressure bladder. The teamwork provided by both tools makes for easy layup and consistent results.

    The way I'm going to do it is to simply make the thin jacket out of carbon, and it'll bond directly into the final product. Two jackets, actually, so that they can be split apart a small amount on compression.

    For some time now, I've wanted to avoid taking this labor-intensive route, in part because of a type of mold that would need to be involved, which would require a lot of roughing time on the CNC mill. Well, I watched my wife catch tiny fish on a river over the weekend, so I had a lot of time to think about how to get around that kind of milling. I think I have a solution that will involve less milling altogether (even compared to my current method, yay).

    Aside from the main goal of avoiding over-compression, I need a compressive element that is easy to remove. The current way I'm doing things with the solid rubber core isn't so friendly given the very small exit diameter at either end of the handlebar.

    EDIT - The failed bar at least showed a friendly failure character. Like trying to break a thin tree branch that is still alive and green, it needed to be forcefully twisted back and forth several times after initial failure.
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  8. #108
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    No pictures for the most recent handlebar because it looks like the previous one (I ACCEPT).

    I stumbled on something neat regarding resin infusion: if you have a mold with an unacceptably high leak rate, and - AND - you have a "moat" around the entire carbon preform (mine is in the form of the epoxy fast-channels), you can suffer a vacuum leak at the edges of the mold, so long as the epoxy injection site is located at the part interior and the injection site has an otherwise acceptable leak rate.

    Basically, if the incoming air flaws going past the outer "moat" seal are given an attractive path out of the mold, that's where the air will go. It'll go around the part.

    I mean, it's not ideal, it's undesired. But it's tolerable, to some extent, provided you have a leak rate that can be compensated by an intermittent vacuum top-off.

    Also, the experiment of imitating Felt with their compound inner compaction tooling, that paid off. Good compaction. (I'm trying to figure out how to photograph this properly.)
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  9. #109
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    "An attempt was made" at shining light from one end of the bar.

    I'm not sure what the black vertical bar is to the left. Otherwise, the bright epoxy indicates the presence of the 0.25mm thick carbon skins that kept the bladder in a bent and reasonably supported shape during layup. Note that they expanded slightly unevenly, which will create some amount of fiber warp.

    Show and tell on a... Monday? Milestone: carbon lugs.-20170702_210019.jpg
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  10. #110
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    Ah wow, I feel good today. A friend came over and gifted me with an armful of donor bars to test. Some reputable, some knock-offs.

    I won't name names out of both (1) respect and (2) fear of liability, but my rig busted a nice handlebar. Oh. Okay. My rig is pretty harsh, perhaps too harsh.

    *wrings hands*

    Going to mod the rig with a high tension impact spring next. Cautiously optimistic about this development.
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  11. #111
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    Briefly: I think I should say that Felt used to do a similar approach to what I'm doing right now. Apparently they are now using the solid core polystyrene thing, which if done right gives crazy good compaction and all the positives that go with that... but as I've learned, is quite difficult to do right.
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  12. #112
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    Quote Originally Posted by Drew Diller View Post
    Briefly: I think I should say that Felt used to do a similar approach to what I'm doing right now. Apparently they are now using the solid core polystyrene thing, which if done right gives crazy good compaction and all the positives that go with that... but as I've learned, is quite difficult to do right.
    You should have said i developed systems like that for the taiwanese and before that the F1 folks

  13. #113
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    Quote Originally Posted by compositepro View Post
    You should have said i developed systems like that for the taiwanese and before that the F1 folks
    My mistake dude. I know that I stand on the shoulders of giants.
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  14. #114
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    Quote Originally Posted by Drew Diller View Post
    My mistake dude. I know that I stand on the shoulders of giants.
    No man I meant if id known this was your preferred method we could have had that running in hours .....hence the history explanation...sorry chap

  15. #115
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    Man, I had another @#$*ing case of what I think is over compression, which doesn't even make any sense. I should be OVER this.

    Vacuum leak-down (or is it leak-up?) was acceptable, 0.3mmHg/hour. Bladder leak-down was acceptable - there's a possibility there's another leak apart from the air compressor quick connection naturally leaking down because that's what they do.

    See the blue specks? Part of the wax mold was damaged. This screams over compression. I'm just not sure how to process that because I'm using a sort of "soft mandrel". It's squishy before layup specifically to avoid over compression.

    I kept the bladder air pressure below what I've learned is a threshold for over compression. After infusion was done, I increased pressure slightly, still below threshold.

    The stuff coming out of the exhaust tubes looked the way it should.

    Curiously, I heard a familiar noise, but in an unfamiliar context: the high pitched whoosh of a small volume of vacuum being refilled by atmospheric pressure, while demolding. Uhhhh... what?

    I've done some solid gains in process control of late, and this has me utterly baffled. I'm so pissed off that I'm considering making my own room-temp prepregs and side stepping infusion entirely.

    Show and tell on a... Monday? Milestone: carbon lugs.-dry-spot.jpg
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  16. #116
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    My best friend has a saying when someone makes a claim about the accuracy of their actions:

    "DID YOU?..."

    I have learned to repeat it back to myself after I assert some claim, whether said claim is directed at someone, or if I'm trying to convince myself in order to grapple with uncertainty.

    After inspection of the damage, I found "print-through" of twill carbon fabric on the surface of the mold flange juuuuuust outside of the damaged mold area. This means stuff not meant for the flange got in the flange. This means that the fabric thickness was just too much for the bend zone. (It also means I should increase the flange thickness to prevent mold damage in case of future human error, which is likely based on evidence.)

    "But, brain, I swear I checked all the major spots with a caliper and subtracted by 1mm. I checked the bend."

    DID YOU?...

    ...

    Maybe I didn't, and just think I did.

    ...Crap. Time for a plain ol' redo.
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  17. #117
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    I love these little mantras - I have some for teaching which I say to students every time they have a question about their work. Eventually, they come to realise that if they ask themselves the mantras first, they can usually proceed without needing me to come and pander to them. My private mantras are far more detrimental and only said within inner-monologue... they probably do more harm than good

  18. #118
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    The unsaturated zone was indeed over-compressed. I made another bar and it infused fully.

    Show and tell on a... Monday? Milestone: carbon lugs.-20170830_145053.jpgShow and tell on a... Monday? Milestone: carbon lugs.-20170830_145931.jpg

    Some funny stuff happened with this one. I took (what I thought was) an extreme aversion to over compressing the layup. This was effective, too effective in the stem area, to the extreme that the outermost fiber didn't reach the mold surface all the way (even though the pressure bladder DID cause the laminate to grow slightly).

    This one-time result is that the epoxy injection had a huge amount of room to play with, and I had to inject a lot. This (presumably) caused the interlaminar lubricity to increase, causing the fiber stack to expand, displacing a LOT of resin. Overnight, as the epoxy was gelling, the vacuum tubes were forcefully expelled. Weird.

    Even with that bit of drama at the stem area, the bend zone over compression persists in being a problem. This time I got a clearer look at why. It has to do with avoiding warp in the fiber as it is being laid down. Not only does a thicker fiber stack result in that area overall, but it is not 100% as orderly as wrapping around a completely straight cylinder. It stands to reason that this small amount of chaos increases the fiber thickness further in that area.

    As temporary relief before finding some better solution, I'm going to change the guide-skin-mandrel-things such that they have an inner diameter reduction in this problem zone.
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  19. #119
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    I was wrong about the leak rates I quoted of my various canisters and the molds in particular.

    I'm at something more like 0.9mmHg/min rather than 0.3mmHg/min. So I'm not quite at NASA spec yet for leak rate, while previous I thought I was. Dang.

    I spent some time doing isolation tests, as finite as testing a solitary short bit of vac tubing with a gauge on the end. I learned to apply mastic tape to the gauge itself (you get what you pay for, they're cheap gauges).

    It's all well and good if I test the mold cavity by itself, but supposing I make a mistake in sealant *after* disconnecting those isolated test tube fittings, or while fitting in the replacement hoses that are going to be doing the actual infusion?

    No thanks. I'd rather just leak test while the functional system is in place. Even if that means accepting a higher leak because there are more joints to manage.

    That in mind, here's my current preferred vacuum catch can. It is sealed with a rubber gasket (I cast one) and a thru-bolt. There are rubber gaskets around the thru-bolt, and the huge washers have a thirty degree cone surface on the clamping/business surface. It seems to do a good job of smooshing the gasket inward toward the thru-bolt.

    They're otherwise made of PVC cap and polycarbonate, and are tiny and easy to evacuate in two seconds.

    The polycarbonate looks a bit chopped up because that's what I did to it. Used to be a large rectangular plate. I did the math, and I could get a slight boost in surface area while shedding five clamping bolts.

    In the future, the only mod I'm going to do is having them held together WITH MAGNETS.

    Show and tell on a... Monday? Milestone: carbon lugs.-20170911_004133.jpg
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  20. #120
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    Did I say 0.9mmHg a minute? Cripes. I meant 0.9mmHg an hour.

    Still not perfect, but perfect isn't achievable with polymer based vac equipment.
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  21. #121
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    Quote Originally Posted by compositepro View Post
    No man I meant if id known this was your preferred method we could have had that running in hours .....hence the history explanation...sorry chap
    You do not owe me any apology, nor did *I* really know that the expanding split mandrel was my preferred method.

    Turns out, it isn't. I had more consistent success with the solid mandrel method (despite my habit of damaging mold edges using that method). The issue I've been having with the split mandrel is seam misalignment, which has often resulted in severe under compression.

    So -- how to return to the solid mandrel stuff, while avoiding some of the pitfalls that I experienced with solid mandrel.

    I pondered some alternative cores - different waxes for instance, but that would involve a machinery addition I cannot yet justify.

    What I really need is a zero-day fill-in element for a solid mandrel.

    HELLO, why not just one of my already functional pressure bladders, except just... don't treat it like a bladder in terms of compaction. Rather, just treat it as a large physical volume where epoxy isn't allowed to travel.

    I've been trying to poke holes in the logic for a few days. None found, so I'm going to push out a few in this manner.
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  22. #122
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    Tested some of the more recent bars vs some older bars vs some donor bars.

    I did break some eBay carbon bars -- yikes that was scary how thoroughly and suddenly they snapped.

    I broke some of my older bars, wasn't surprising, though they were a step up.

    Happily, my most recent iteration of bars reflected the following falling object setup many times:

    1 meter drop, payload ~9 kg, spring tension ~109 N/mm (spring spec by manufacturer 62.4 lb per 0.1"), spring travel limited to 19 mm. This is the first time I've had the necessary values available, I *hope* I did the math correctly.

    I increased the drop a few cm such that the spring bottomed audibly (I do not have sensitive equipment for measuring this but I know what I heard). The bars survived this. I increased a few more cm and that was met with failure.

    Testing isn't close to done (is it ever?), especially since none of the above informs me of what has happened inside the laminate, but I am finally getting near acceptable peak strength values.

    Which is good because I have debts to pay.
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  23. #123
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    Quote Originally Posted by Drew Diller View Post
    You do not owe me any apology, nor did *I* really know that the expanding split mandrel was my preferred method.

    Turns out, it isn't. I had more consistent success with the solid mandrel method (despite my habit of damaging mold edges using that method). The issue I've been having with the split mandrel is seam misalignment, which has often resulted in severe under compression.

    So -- how to return to the solid mandrel stuff, while avoiding some of the pitfalls that I experienced with solid mandrel.

    I pondered some alternative cores - different waxes for instance, but that would involve a machinery addition I cannot yet justify.

    What I really need is a zero-day fill-in element for a solid mandrel.

    HELLO, why not just one of my already functional pressure bladders, except just... don't treat it like a bladder in terms of compaction. Rather, just treat it as a large physical volume where epoxy isn't allowed to travel.

    I've been trying to poke holes in the logic for a few days. None found, so I'm going to push out a few in this manner.
    this one falls into the realms of advanced stuff we use to use to make turboprop blades , one of these methods was to fill the bladder with low melt alloy , effectively meaning you have a solid mandrel at wrapping and a liquid one that you could pump air into to remove the alloy through a valve when you were at ramp temperature, we did try using the fact bismuth expands as it cools but it didn't provide enough compaction on thicker laminates though was very good at thin ones ,the alloy also meant it had a very good temperature gradient inside the part as well as the tool side

  24. #124
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    Hey compositepro, I had another idea and I'd like you to shoot some holes in the logic.

    It's been ... well I lost count, almost 20 bladder cycles since I've had a positive air pressure rupture. The other day, I had a slow-flow but high-pressure leak. The way I had set up the closed mold was a bit different so I had no way to gauge this. (Mea culpa.) I was leaking 90 psi through a pin hole. The infusion went pretty well, and my goal at the time was to up my game with respect to waste material, by cycling acetone through the exit epoxy lines, which happen to be the longest lines.

    I learned a lesson the hard way about applying TWO clamps on either side of a cut before cutting a line with liquid in it. Highly pressurized epoxy sprayed all over the place, thankfully away from me, generously skinning a brand new aquarium dosing pump with a glittery pattern of epoxy dots. The pin hole positive air pressure leak happened to be located outside of the part (why the infusion went ok), but inside of the vacuum seal (why this did NOT affect the initial pressure rise test is currently confusing me). Once a free escape was made, the flash/runners were the path of least resistance.

    So, in the vein of simplicity - I'm trying to make these bars inexpensively because that's what I want to buy - what if I had *nothing* inside the mandrel of the bar? What if it was just an enclosed envelope of nominal atmosphere pressure? Cap the ends with fast epoxy sort of thing, to be later snipped off during finishing work.

    The risk is that absolutely capping the ends precludes me from measuring the air pressure inside to ensure that it is not messing with the partial vacuum environment of the infusion process.

    An alternative question: is it possible to do a mock infusion to measure the volume of, say, water actually absorbed during the flow process, and then be able to get ALL of that water OUT of the mold before infusing epoxy / some other resin? Doing so would bypass the need to check the mandrel interior pressure.

    I realize I'm obsessing over this a bit and I should just accept the occasional 5% defect like any other manufacturer. But that ticks me off and I want 99% reliability damn it.
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  25. #125
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    I love hobbies.

  26. #126
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    Quote Originally Posted by Drew Diller View Post
    I realize I'm obsessing over this a bit and I should just accept the occasional 5% defect like any other manufacturer. But that ticks me off and I want 99% reliability damn it.
    I did an isolation test the other day. I reproduced a problem that I suspected, but sounded too crazy to be real.

    It's real.

    My inflation bladders are produced with a very soft silicone rubber with a 1,000% elongation-at-break rating. In reality I subject them to 200%. Like other silicone rubbers, they will run if a small tear is started. Supposing a partial pinhole gouge was made in the surface. Then suppose 100 psi air pressure was directed at the surface for the purpose of cleaning particulate so a good vacuum seal would take to the surface. Could the high air pressure create a pocket or tunneling effect in the surface, enough to pry open the hole and create the runaway tearing condition?

    Yyyyyyyyyep.

    Behavior change: I now clean the ends of the bladders with packing tape. The same idea behind using those little tape strips on a roll when you need to clean pet hairs off your clothing when leaving the house. This is a win, as the tape is faster / more complete to clean with anyway.
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  27. #127
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    Quote Originally Posted by Drew Diller View Post
    ...Like other silicone rubbers, they will run if a small tear is started. Supposing a partial pinhole gouge was made in the surface. Then suppose 100 psi air pressure was directed at the surface for the purpose of cleaning particulate so a good vacuum seal would take to the surface. Could the high air pressure create a pocket or tunneling effect in the surface, enough to pry open the hole and create the runaway tearing condition?...
    It's always the details, the little things that you don't know that you don't know that get you.

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    What follows will probably be the most useful thing I've posted in this thread specific to handlebars or other quasi-single-tube inflation design, assuming any other CF newb ever reads this and wants to retrace my steps.

    Tygon 3350. It's a pre-fab silicone tubing that has been cured to extremely high purity, and I'm assuming used for medical purposes. A farming scientist buddy of mine uses it for making tight bends in vacuum lines. Unlike the vast majority of pre-fab silicone tubing I found out there, this one has a usefully high ultimate elongation at failure (how far did it stretch when it ruptures) of 770%. This is a downgrade from the stuff I was making (1,000%), however, it's good enough.

    As a bonus, the slightly higher durometer makes for easier insertion of inflator fittings. Once inserted, they sort of hold themselves in temporarily while awaiting a retention device prior to full inflation.

    I made some mandrels with it, at close to road bike tire pressures.

    Caveat: it's expensive. (On the other hand, it's durable.) #worthit

    https://www.usplastic.com/catalog/fi...Tygon-3350.pdf
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

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    Feels like I should update. Latter half of December and all of January sucked. I made a few bars and they were nice, except for when they weren't. If I look at the data, the reliability ratio is CRAP (less than 50% keep).

    Then had some multiple computer equipment failure. Then spent a few weeks being sick. All better now, boots on the ground. The bed time gave me some non trivial hours to think.

    I suspected that the small bladder inlet diameter coupled with the inlet being a boring ol' cylinder shape made for a leaky combination - occasionally a leak that would blow bubbles directly into an infusion.

    ...At a slow enough rate to be considered part of the natural leak rate.

    So I was like SCREW IT. If the use of a bladder only nets me a small % bump in fiber volume fraction, for parts of this size why even use a bladder at this juncture? I've had that thought before, and have also thought of using just a filler for the mandrel during layup and epoxy transfer.

    Now... now I just had a lot more motivation. Just remove the chance for air intrusion entirely, and circle back later on with a revised custom inflator that is suitable to the small inlet diameter. So the problem is then WHAT filler specifically to use, something that I'm sorting presently. This filler nonsense is a step I'd rather not have to take, and will remove down the road, but right now I'm into the "extreme circumstances" line of thought.

    I also determined that the use of mastic tape in a hard-mold-against-hard-mold situation is not a good idea. Mastic tape really should only be used for its intended application, with a hard mold on one side and a film membrane on the other. The deformation of the membrane prevents the tape from liquefying and migrating as it had been doing for me. A vacuum seal needs to be good for potentially unlimited hours, not just "very good for four hours and then suddenly not good at all".

    So I did a vac drop test with a revised mold with nothing in it, using only rubber gaskets at a prescribed loss in thickness upon compression. Yeah... yeah that'll do. Hardly a noticeable pressure rise in a 48 hour period! Are you KIDDING me? How long have I been blowing bubbles into otherwise perfectly good-- you know what, NEVER MIND, I don't want to know, let's just move on!

    So hopefully the next few bars will be "lit" as the kids say these days and I can move onto the gearboxes already because I don't even give a 57!t about these handlebars beyond their value as a litmus test as a single-point-of-failure manufacturing exercise.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  30. #130
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    Man, it's going to be fun watching you do a drop test on a lug. Remember, you started doing lugs? Ha. When are you going to do 'that' bike Drew?

    Eric
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  31. #131
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    Quote Originally Posted by Eric Malcolm View Post
    Man, it's going to be fun watching you do a drop test on a lug. Remember, you started doing lugs? Ha. When are you going to do 'that' bike Drew?

    Eric
    I think I could take what I've learned and make a better lug, though, at this point, I could either take it or leave it with respect to lugs. I remember WHY I started with lugs, and that still makes sense, but I have less motivation to make stuff from bamboo. "Less" is not to conflated with "no motivation".

    THAT frame, are you referring to the one I wanted to make that is the same tack as how Zerode started with the Alfine jackshaft, before they moved on to the Pinion design? If so... that ship has sailed, for a very specific reason. Shimano. They were a contributing reason to my favorite bike shop deciding to close down. It was a unique shop where you could walk in with a cheap bike or an expensive bike and the owner would take you seriously. My blood pressure always lowered.

    So emotionally, screw Shimano. Objectively, also, screw the Alfine design. I took one apart in the intervening time and I was like WHAT, this is what's on the inside?? How do these go anywhere at all? Some of the small torque transfer cogs were toys to my eyes and not in the good way.

    I decided I want to make my own gearbox instead because I'm a control freak. An affordable one. I've been told - by someone indeed, who would know - that what I have in mind is going to be high budget. Personally I took it as a challenge even though I'm sure he did not intend for that. The way I see it, the gearbox market is still very very young, and you have these extremes of almost ineffective range at a quasi-affordable price (Patterson 2 speed, Efneo 3 speed) VS amazing performance at absurd price (Pinion). Must there really be NO middle ground? Really?

    Rrrrrrrrrreeeeeeaaaally? I REJECT THIS. I want a gearbox bike that can get stolen and it won't break my heart if it does because the 'box only cost a few hundred bucks.

    I've been told by nearly all industry folks "Well Drew you're not going to make money that way". @#$**@&%&@#* if I wanted to make money and only make money, I'd go back to writing software for manipulative information merchants. On the other hand, when I find one of "my people" and make my elevator pitch, not only are the keen on the idea, but they start describing the idea to me in fine detail. Clearly it is wanted, and clearly it does not have a great profit potential, but I'm focusing on the "clearly it is wanted" part. I can make money from bikes in other ways (such as refining custom handlebar production to a degree where they are easy to make and can be pumped out in quantity).

    Sorry for vent.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  32. #132
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    Gee, I was just hoping to see some interesting Carbon and Bamboo put together in a very innovative way...Lol.

    Anyway, I am enjoying the thread, just wondered where the bike thing was going for you.

    Eric
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  33. #133
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    Quote Originally Posted by Eric Malcolm View Post
    Gee, I was just hoping to see some interesting Carbon and Bamboo put together in a very innovative way...Lol.

    Anyway, I am enjoying the thread, just wondered where the bike thing was going for you.

    Eric
    It's going places, just with these long standing pauses to deal with the occasional, I don't know, fundamental processing flaw. Sorry if I'm making this out to be a catastrophe, I walked past the pile of "good enough to drop test" bar and it was not exactly empty:
    Show and tell on a... Monday? Milestone: carbon lugs.-some_progress_i_guess.jpg

    I'm dissatisfied because that's the kind of output I'd like to see in one week. ...Not the better part of a friggin year.

    Regarding the bamboo stuff, I'd like to keep those to either of two extremes: (A) high-fashion "finish carpentry" type build where the carbon lugs would be minimal or invisible (underneath with an overwrap of nearly invisible fiberglass) and mini slabs of bamboo would be glued and turned and polished and lacquered and all that shiny BS, vs (B) low-fashion intentionally hippie these-were-some-plants-that-came-out-of-ground-and-made-into-a-frame-and-it-looks-exactly-like-that. Specifically on the notion of a (B) build, I have a down tube in mind that weighs five pounds for the down tube only, and that takes a certain kind of customer.

    Is that innovative, though? Ehhhhhhhh.... *shrug* depends on the viewer.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  34. #134
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    Finishing up a nearly week long melt cycle. The last job of melt / pour iterations is less picky about having things crunched up into tiny chunks because the large volume of not-quite-drained molten wax makes for a quick re-congeal and melt compared to starting when cold. Sometimes I like to play puzzle while waiting impatiently for the heated spigot to unclog.

    At some point I'd like the "gun" like accessory where the wax is moved along by a fairly strong pump, instead of currently having to rely on gravity loading from a very full vat in order to achieve a fast pouring rate. It's inefficient to wait for the *entire* vat to become molten. But those guns ain't exactly cheap soooooo it's on the back burner.

    EDIT: I've figured out how to keep my hands free and clear of a hammer-and-chisel arrangement, but sometimes the pieces come apart at high speed, slip off the table, and hit me in the knee. At some point I'll have a coarse grinder bin to remove the risk - I would make sure that it is analog / human powered.

    Show and tell on a... Monday? Milestone: carbon lugs.-20180214_000020.jpg
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

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    Some good news.

    I have established with some degree of certainty that my bladder-related vacuum leak-up rates are small but significant. Tiny but intolerable.

    After much hand wringing, I did my first infusion of a fully solid filled mandrel with the new vac gasket design. It's pretty easy to put together, the leak-up is very slow. Critically, the epoxy fast travel zone on the inlet side came out as pure epoxy.

    I also tried to employ an external resin brake - it kind of worked. Epoxy didn't quite reach the exit / recirculator zone, but a small amount of did come out of the mold.

    Unfortunately, the filler still needs some tuning. All the fillers I have tested so far experience volumetric shrink or warp or porosity. The result is extra resin ingestion, such that the fiber volume fraction is 48% rather than the desired 60%. I thought that it is about time to try compositepro's suggestion of using a low-melt alloy what with its neutral or backwards CTE. ...Unfortunately, with the large amount of indium present in Field's Metal, and with indium being more expensive than silver, it's not something I can quite justify at the moment.

    This means I need to revise the small-diameter bladder inlets such that they do not exhibit blow-by. I think this also means I should soon invest in a very fine resolution vacuum gauge, something that can tell me within minutes of a fine vacuum leak instead of having to wait several hours for a leak-up to show some tangible pressure rise.

    In the immediate time frame, I'm going to try a multi-phase approach to a paraffin wax filler. The hope is that gravity fed castings will bleed around the small gaps left over from the shrinkage of the previous gravity casting.

    I'm over the moon freaking happy to know that my vacuum integrity problem has been diagnosed, and that a solution is around the corner.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  36. #136
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    Quote Originally Posted by Drew Diller View Post
    This means I need to revise the small-diameter bladder inlets such that they do not exhibit blow-by.
    I think I've accomplished this in an isolated test mold with a super tiny vacuum envelope volume. Finally. The solution's shape is kinda like the wine-cork design of the larger bladder inlets, but in the form of a press-in rubber washer - well, two of them, of different hardness - with a bit of mastic underneath where the gasket cord pokes out.

    The compression force is enough to nearly close the bladder inlet such that the bladder hesitates to inflate until some significant pressure is introduced. Cripes. Now to mill some new molds with this change in mind and move on.
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    A "Sad Trombone" moment.

    So I've been having this recurring issue lately with continuous profile gasket cord where they exert what appears to be a pressure hot spot, causing the relatively soft wax mold material to fracture.

    This fits with some of my intentional fracturing of the mold, where once the tiniest crack begins, I can just sit there with even torque on a chisel, and the crack will just spider, and spider, and spider...

    Anyway, the cracks unsurprisingly let air in. This particular version of mold fracture is relatively new, and didn't happen in this way with the older flat gaskets.

    So, back to flat gaskets. Found a faster way of makin' em. Yay. Leak-up rate tested out okay. Yay. Started an infusion job last night, and it was good until suddenly it wasn't.

    It appears as though an inlet tube liner (present because it eases the removal of epoxy from the inlet and outlet tube sites) got sucked too far into the mold, and bent into an L shape, cutting off inlet flow. The epoxy inlet side channel was almost pure epoxy, indicating very low vacuum blow-by. And the epoxy seemed to spread evenly across the inlet flashing. However, the infusion just... stopped halfway. I was unable to extract the tube liner on the fly, and I could not blame things on a sudden spike in epoxy viscosity from premature polymerization. It was just... jammed.

    I might need to make a custom liner that has a little butt at the end with a C shape to let the epoxy through while also not traveling with the epoxy.

    Whomp whomp. I tried to validate what I could of the revised gasket design - there were no visible traces of epoxy blow-by.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  38. #138
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    When you get all this sorted you may be better off building for the aerospace industry than the bicycle.
    As little bike as possible, as silent as possible.
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  39. #139
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    Quote Originally Posted by Velobike View Post
    When you get all this sorted you may be better off building for the aerospace industry than the bicycle.
    If the bike industry pisses me off I'd probably gravitate toward motorsport or boating firmware.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  40. #140
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    @Velobike: also, this latest flub is probably why other molding outfits use a side-entry injection port. During clean up, you just pull two halves apart. Easy peasy. I'm doing the top-down approach because it makes my particular assembly easier and the feed lines much shorter. And my way *appears* to have a slower vac leak rate, except for the part where it gets, ah, overzealous like this.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  41. #141
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    Quote Originally Posted by Velobike View Post
    When you get all this sorted you may be better off building for the aerospace industry than the bicycle.
    that is the best advice anyone has ever given on a forum related to bikes.....

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    Woo!!!

    YEAH.

    Show and tell on a... Monday? Milestone: carbon lugs.-20180330_053946.jpg

    YEAH!!!

    This bar worked by the thinnest of margins! Literally - the gasket wandered and almost occluded the fast track again. Damn thing needs a retention channel.

    Now I get to move on to the next thing.

    EDIT for some stats:

    - Resin content ~42%
    - Pulled the deepest and most stable vac I've yet seen
    - Gaskets migrated SEVERAL millimeters
    - Infused without explicit degassing at the start (???)
    - All surface features intact across entire bar
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  43. #143
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    More good news: pulled three bars in a row with identical cosmetics. 99% free of surface blemishes, all within a few grams of each other. I managed to stuff a few extra grams of carbon into one of them, which resulted in a 1% lowering of resin content.

    Next step: make this sort of consistency old hat.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  44. #144
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    Five in a row. Three of them in an every-other-day pattern.

    At present, the only thing keeping me from one-a-day is how fast the mandrels cure. I'm using Kwik Kick epoxy for that task, as it advertises one hour cure. Unfortunately, with the 0.3mm wall thickness of the mandrel, the exothermic reaction of the epoxy doesn't really stand a chance because there's no volume to work with. So it takes six hours.

    So, I basically need to find a very fast cure epoxy that is longer than the handful-of-minutes epoxy one can find at the hardware store. It seems I'm having trouble finding that happy in-between.

    I am feeling pretty jazzed up at the moment. Five in a row!!! They all weigh within a few grams of each other. I'm estimating cut and trimmed mass will be around 260 grams.

    Show and tell on a... Monday? Milestone: carbon lugs.-20180409_175458.jpg
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  45. #145
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    Dozen+ in a row

    My standards are shifting a bit. I've made a bunch in a row, so that's no longer a neat trick.

    What's next? Can I make them:

    - stronger/lighter?
    - cheaper?
    - faster?

    I don't really think I can make them cheaper. This is about as low investment as I can figure. I started it that way.

    Stronger it is, then. I paid attention to some advice given elsewhere by compositepro, and I implemented it in the form of additional fibers wrapped around the bar circumference rather than along its length. An analogy to how human skin restricts and focuses the force of human muscles.

    Wow, yes, that is very strong, and buckling upon failure is reduced, all without special materials. I built a stupid little "pre-test" test that is nothing more than a lumber-platform with a hole in it, into which I place a sawed-off 1-1/8" steer tube, to which a stem and anti-rotation blocks are attached. I had a 210 lb guy stand on a handlebar so I could watch the deflection. Fascinating, easily more than an inch deflection at the ends.

    I wanted to try some specialty materials (boron) that can reduce buckling by handling compression loads (and reduce the amount of carbon needed, thus, lighter). Yiiiiiiikes. That looks like an exclusive club to be in. Shelving that for a later date out of raw lack of influence and investment cash.

    So I guess the next most approachable thing to do is start putting CNTs in my resin. And I don't think I'm yet tooled up for that in terms of air flow management - important not just for my health but also because the stuff costs $30 a gram.

    With the undesirable notions in mind, I suppose my only option for improvement right now is to make them faster. Indeed, with the practice of so many failed bars, I and the inclusion of some very high areal weight UD fiber that has a friendly warping character (or, as friendly as it gets...), I can now do layup in just less than an hour.

    It takes me longer to align, close, connect, and pressure test the mold components. That'll need some work. I think this means I have to (grumble) yield on some previous held notions regarding mold-cavities-per-volume-for-milling-efficiency. The driving force is that this latest mold set didn't get killed by anything and has done dozens of pulls, which means the milling-time-per-part is no longer a lead factor of the economy.

    ...Which means I'll need a new mold to test some of the fast mold assembly things I have in mind.

    Been playing with polishing a little bit too. Almost out the door with this stuff.

    Show and tell on a... Monday? Milestone: carbon lugs.-%5Bmp%5D-1500-grit-buff-vs-brillo-pad.jpg
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  46. #146
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    Thats looking pretty good.

    Are you selling these now?

    Eric
    If I don't make an attempt, how will I know if it will work?

  47. #147
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    Looks fantastic Drew! This has been my favorite thread to follow along.

    Are you still infusing? I was under the impression that CNTs don't work with resin infusion.

  48. #148
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    @Eric: very close now. The last safety check I wanna do is send it out for someone to X-ray. Just how bubbly is it on the inside? 2%? 10%? Inquiring minds wanna know.

    @octanejake you know that doesn't surprise me to hear - the epoxy barely makes it through on its own, why would thickening it make it any easier? I've been thinking of moving to DIY prepregs. Been thinking that a while, honestly, but was encouraged privately to avoid it on the notion of "you keep moving little pieces around, just perfect this one thing first".

    Bearing in mind I must keep the room temp cure for the extremely CTE-fickle wax mold material, DIY prepregs have some things going for it:

    1) I get to skip all the vac setup and validation nonsense, this is currently the biggest pain to me
    2) Reduction of waste epoxy
    3) Lack of the liner film waste that keeps mass-manufactured prepreg from sticking to itself

    Another practical limitation that made me choose to avoid testing DIY prepregs was my table space. A single layer of 150g/m^2 carbon takes up a lot of freaking area just to make a handlebar. However, with the recent inclusion of the 373g/m^2 stuff, that number changes to a figure that can fit on my existing layup table.

    Perhaps the time is right. Vacuum infusion sucks (haha whomp whomp).
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

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    Moar

    Been keeping my head down lately, and have come up with a reasonably consistent routine. I had fun taking this picture, my apologies to the handful of you who've already seen it.

    I made a bunch of friggin bars so far in July. Zero count of total rejects. WHOOOOP.

    Show and tell on a... Monday? Milestone: carbon lugs.-%5Bmp%5D-then-there-were-many.jpg

    Also, I have a question for anyone willing. First, I need to detail something about my infusion setup. I'm using a cheap peristalsis pump meant for aquariums. This completely forgoes the catch pot on the pull side of the infusion mold, whatever comes out goes back into the injection source pot. The peri pump is three-headed so it holds vacuum (relatively, depending on the age and quality of the tubing) even when not rotating.

    The thing here is that I do not have a vacuum gauge that can withstand direct contact with epoxy, and then separate after epoxy has cured, and have the gauge continue to function. So what I've been doing is verifying vacuum holding with a temporary gauge directly on the inlet tube, then clamping the line and removing the gauge. This effectively means that during the actual infusion, I'm running with no gauge at all. Today I noticed something, after verifying an unusually good seal (for once). After letting the peri pump run a while, there was - what looked like - kind of a fog on the inside of the exit tubing on the exit side of the peri pump.

    My question is: does this happen to be water content that has boiled off from the dry laminate preform, and then condensed in the tubing once the water vapor was confronted with atmospheric pressure again?

    I ask because the peri pump does not hold a particularly deep vacuum, I assume because of the distance between the impeller cylinders letting in at least a smidgen of atmosphere every seal / unseal event.

    In the photo below, you'll see two opaque silicone lines crossing each other - that's what goes in the peri pump - the exit PVC tubing is heading south or towards the camera. What I'm guessing is the condensate is just a small puff leading from the silicone-to-PVC black coupler.

    Show and tell on a... Monday? Milestone: carbon lugs.-possible-water-exhaust-condensate.jpg
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

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