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  1. #1
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    2nd Frame - Wanted to Share

    So I figured I would share what I am doing/have done for my 2nd frame for anyone interested - I have learned a decent amount from this forum and welcome any feedback or criticism you may have.

    Geometry for the frame is shown below here:



    I chose a relatively short chainstay length because the CS of my first was too long for what I liked (I based the first frame off of my name brand FS which didn't work out so good in many aspects). But the 406mm number in the drawing is with the sliding dropouts all of the way forward, so really it can be set between 406 and ~420mm.

    I would have preferred the seat tube angle be a little slacker, but by the time I realized that, I had already bent/mitered the tube and decided to just run it for now, take note of it, and adjust things as needed next time around.

    The tubing in general is on the thicker end (mostly Nova or Vari-Wall 1-.7-1 or 1-.7-.9) with a straight gauge 0.035" ST + Topper and PMW Headtube/BB Shell (thicker option); all which seem to work good for my welding skill. Currently I weld with the pulser set to ~50PPS, 25-30% On Time, 25-30% background current and dab rod as if welding straight current... I don't know if pulsing at this high a frequency actually does anything for me, but in my mind it seems at least a little easier than straight current. I have been playing around with other settings more frequently suggested in these forums (such as 1-2PPS) on scrap/practice tubing and may try things that way the next time around to see how it works for me.

    Because I would like to run 3" tires (actual width measures 2.85"), I decided to make a yoke for the chainstays. These are made from 5mm thick 4130 plate, cut to 36mm tall and bent with a milling vice between an Aluminum round and scrap tubing. In CAD I thought this looked reasonable, was achievable for me to make and, with the bridge/bends thought it would be stiff enough... But it was a nightmare for me to weld up and when I was done, I found that I could move the dropouts around laterally (and plastically) incredibly easily... I am hoping that with the addition of the Seat Stays and SS Bridge the rear end will stiffen this up enough for me to ride without permanent deformation to one side... I guess time will tell.




    The majority of the welds (minus the CS Yoke) turned out pretty decent for me, which I was pretty happy about, and the PMW headtube stayed thoroughly round through my heat input (which was nice, I had problems keeping the straight gauge, 1.25mm HT Stock round). The HT is 125mm long and I will be running a 160mm 27.5+/29 Fork on this. I opted for a 66 degree Head Angle for this bike with a fork sag of 40mm (25%)... I don't really know the best sag point to base this on, nor what Head Angle I really want with this type of bike. My first frame was a 67 Degree Head Angle which I kind of liked, but it was fully rigid and I was intimidated to go any slacker on my first frame. This time around I decided slacker would be nice, and somehow settled on what is shown above.







    At this point in time - the frame is all done with welding. The best method that I have to check alignment is in the 8020 jig that I made, which does show a little bit of HT Twist and mis-alignment of the ST as shown below. I have heard of additional welding passes some people will do to correct this, but I am not sure exactly how to accomplish that without potentially making it worse, and think I have decided to just ride it as it and try and control my heat/improve my welding sequence and mitering as much as I can on the next frame.





    At this point - I really just have smaller details left to finish. Several H20 Bosses to braze into the front triangle (for bottles + cable routing), zip tie cable mounts to braze to the rear triangle, and need to figure out how exactly I want to attack the routing into the ST for the internal dropper post cable (I bought a few a cheap internal cable route cover braze on things from Nova but am thinking I may just cut out a piece of stainless sheet and silver braze on for reinforcing and then drill...). I am not good at brazing and have yet to purchase an OA setup so I have been playing around with MAPP for these small items on scrap (and yes I know that several of you will hate me for saying that) - it seems to works OK I guess for silver and H20 bosses but then again I don't really have a good reference point. Anyway, I will do some more practice brazing and probably finish this frame out with the tools I have on hand currently.

    Oh and I guess for reference, since I mentioned it several times, below is a pic of my first frame. I built this ~ a year ago and have been riding it anytime I ride with the kids or dog (pretty much always except when I go by myself/with friends to faster/more technical trails). It's not amazing by any means but has been really fun to ride and try and learn from.



    -AP
    Attached Thumbnails Attached Thumbnails 2nd Frame - Wanted to Share-yoke.jpg  

    2nd Frame - Wanted to Share-cs.jpg  

    2nd Frame - Wanted to Share-frame-final-welds.jpg  

    2nd Frame - Wanted to Share-ss-bridge.jpg  

    2nd Frame - Wanted to Share-ht-welds.jpg  

    2nd Frame - Wanted to Share-ht-twist.jpg  

    2nd Frame - Wanted to Share-st-twist.jpg  

    2nd Frame - Wanted to Share-frame1.jpg  


  2. #2
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    Hey, Nice Build.

    Does the HT to ST remain in plane, and the rear drop-outs perpendicular? This the critical area where the wheels follow each other.
    Doing Silver only requires a heat source capable of getting the steel up to red heat. Anything will do, high tech is ideal but not necessary for braze-on work.

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

  3. #3
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    The HT and ST are closer relative to each other in plane than relative to the BB shell, but still not perfect. Either way I decided to call it done, got the braze-ons attached and painted it up this morning. It's the first frame that I have painted personally but turned out pretty decently so I'm happy with it - at least at this point without riding it.

    I used to live near a frame-builder who would let me pay him a little to use his facing/chasing/reaming tools but I moved recently to the Seattle area. At this point I'm curious if there is anyone up here willing to do the same? If not, I'll either need to find a shop that actually has a 44mm setup or consider finally needing to spend a decent amount of money for these tools...

    2nd Frame - Wanted to Share-capture.jpg

  4. #4
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    Darn, I was hoping you'd just clear coat it!
    This post is a natural product. Variances in spelling & grammar should be appreciated as part of its character & beauty.

  5. #5
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    Are there problems with just a clear coat sticking to the raw frame? That is what I heard from the guy at work teaching me to spray - but he has never painted anything like this... Anyway, I used the same acid etch primer and single stage paint I bought to learn how to paint with and keep fixtures/tables from rusting.

  6. #6
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    Quote Originally Posted by a_j_p View Post
    Are there problems with just a clear coat sticking to the raw frame? That is what I heard from the guy at work teaching me to spray - but he has never painted anything like this... Anyway, I used the same acid etch primer and single stage paint I bought to learn how to paint with and keep fixtures/tables from rusting.
    Sorry, I don't know how it's done. Your frame just looked really pretty as it was. It's nice in black as well.
    This post is a natural product. Variances in spelling & grammar should be appreciated as part of its character & beauty.

  7. #7
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    That looks really good, I'm looking forward to the ride report!

  8. #8
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    Quote Originally Posted by a_j_p View Post
    but I moved recently to the Seattle area.
    How "Seattle" is that? I'm in Southeast Tacoma...

  9. #9
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    I'm in NE Seattle.

    I had a T47 BB chased and faced at a local shop and it was $100 - I called Paragon and bought the taps for $300 the next day. The tools are expensive and inexperienced builders get more distortion than experienced ones so they wear the tools faster. I'd do it for a fee.

  10. #10
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    Thanks duandr and briderdt for the offer... Sorry for not getting back, I had gotten so used to receiving an email when someone replied that when I didn't get anymore emails I just assumed nobody had responded... I am closer to Renton than anything.

    I did end up finding a local shop willing to chase/face the BB and ream/face the HT for ~$50 - though after they finished the PMW headtube of mine, I am not sure they'd want to do it again...

    As for the bike itself, I have about 10 rides on it now and it's better than I was expecting so I am happy. I did have to dish the rear wheel slightly to the left to center it within the yoke that I made, but even between that and the other mis-alignment I showed earlier, I don't notice anything riding. It even tracks fine in a straight line with no hands at most any speed.

    Because the chainstay yokes were so easy to cold-set when I was building the frame - the first 5 or so rides I kept checking that the rear end hadn't moved after cornering hard, etc. but so far so good. I am not the lightest rider around and I've pushed it reasonably hard to somewhat test it out so I'm now assuming it will probably be OK unless I do something really dumb.

    It has been a very long time since I have ridden a hard tail. I've spent the last year or so riding the fully rigid bike I built previously where I could, and a 6" trail bike everywhere else (which is what I am most used to these days). Anyway, I am surprised how much of an improvement this is over my last frame - and very happy that this time around I can actually manual and pick my front end up over things easily. I will need some more time on the bike to know for sure, but so far I think the locations/times where I feel the need to pull out the trail bike are going to be significantly less frequent.

    I do have a question though: do you guys typically drill a drain hole in the bottom of the BB Shell? Where I came from was so dry that I didn't think much of it - but many of my rides these days are pretty wet, and as I do have somewhat of a gap around the seatpost cable routing... I am starting to think I should flip the bike over and drill a small hole in there now.

  11. #11
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    Quote Originally Posted by a_j_p View Post
    Thanks duandr and briderdt for the offer... Sorry for not getting back, I had gotten so used to receiving an email when someone replied that when I didn't get anymore emails I just assumed nobody had responded... I am closer to Renton than anything.

    I did end up finding a local shop willing to chase/face the BB and ream/face the HT for ~$50 - though after they finished the PMW headtube of mine, I am not sure they'd want to do it again...
    That's great it all worked out! When chasing and facing, the bike shop (in my experience) typically just removes paint or some corrosion and maybe a skim cut on the faces. Framebuilding requires we remove the material caused by distortion before paint (and then again after). Minimizing distortion doesn't just make a better bike, it saves effort and minimizes tool wear.

    Enjoy your bike and welcome to the best part of the country (if not the world)!

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