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

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

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

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

  6. #106
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    Keep up with those good weeks Drew.....

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

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

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

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

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

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

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

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

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

  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.
    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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