sstein Posted May 4, 2012 Report Share Posted May 4, 2012 hey guys, i am gonna be building a couple of frames for myself at home and I am after a bit of advice from anyone who has experience. Basically I am after advice on bending and crimping the chainstays for tyre clearance. I am going to be sand bending the tubes, would it be better to crimp first and bend after or the other way around? Quote Link to comment Share on other sites More sharing options...
Rob Leech Posted May 4, 2012 Report Share Posted May 4, 2012 How do chap, I take it this is steel? What are you using to bend the tubing? Something similar to this? >> http://www.google.co.uk/imgres?q=hydraulic+tube+bender&hl=en&client=firefox-a&hs=3gR&rls=org.mozilla:en-GB:official&biw=1680&bih=887&tbm=isch&tbnid=20QiJd7yzB7qjM:&imgrefurl=http://www.germes-online.com/catalog/17/20/782/15109/sell_hydraulic_pipe_bender.html&docid=p7Dey2CrD-cXNM&imgurl=http://www.germes-online.com/direct/dbimage/50114317/Hydraulic_Pipe_Bender.jpg&w=360&h=360&ei=KlGkT7nyHtGbOvmr3JcD&zoom=1&iact=rc&dur=521&sig=101563258154059085097&page=2&tbnh=161&tbnw=161&start=30&ndsp=38&ved=1t:429,r:15,s:30,i:168&tx=73&ty=111 You can just get the clearance by bending, but it is difficult to get and may well take you a few times to get it. It also depends on your dies, what CLR (centerline bend radius) the die is giving, how close a fit the die is to the tube, ect. Would definately say bend then crimp, if you were to try bending a crimped tube, it would simple crumple at the center of the die . Hope thats of some help chap, Josh. Also, pretty sure you already know this, but thought i'd add it anyways, when you pack the sand make sure it is packed TIGHT. If there's any space for it to move into, the tube will buckle . What we used to do was to blank the end of the tube, fill it with water, then add the sand. Worked a treat, just took a little longer . Quote Link to comment Share on other sites More sharing options...
sstein Posted May 4, 2012 Author Report Share Posted May 4, 2012 actually gonna try doing it without a bending machine and instead use a wooden guide (I know this is possible with sand bending). Also whether or not it requires crimping depends on the chainstay length and tyre width, pretty sure that I wont get clearance with a standard bend (no crimp) with the measurements i want. Quote Link to comment Share on other sites More sharing options...
Rob Leech Posted May 4, 2012 Report Share Posted May 4, 2012 Ritey o, not a bad plan. You'll probably be looking at quite a shallow bend then, with simply the crimp giving the clearance. Maybe look at more than one bend profile, like the speed race fans use. Best way to find out is just give it a try with some smaller sections, draw out the bb and the distances you need and get it to match, can't go wrong with that . Cheers, Josh. Quote Link to comment Share on other sites More sharing options...
sstein Posted May 5, 2012 Author Report Share Posted May 5, 2012 cheers for the advice dude. Do you reckon that a conduit bender would be strong enough to bend reynolds chainstays? The average cheapy conduit bender has the right size die and I am not mass producing frames. If it could work it would be a much easier option Quote Link to comment Share on other sites More sharing options...
Rob Leech Posted May 5, 2012 Report Share Posted May 5, 2012 I'd of thought so, yeah. What diameter is the tube your using? 22/25mm? And the wall thickness? 1.6? If it's either of those, or smaller, it wouldnt be a problem for it . Cheers, Josh. Quote Link to comment Share on other sites More sharing options...
sstein Posted May 5, 2012 Author Report Share Posted May 5, 2012 Yeah 22*1.6 (when i make the first few out of hi-ten) and then that will go down to 22*1.2 when I go to reynolds Quote Link to comment Share on other sites More sharing options...
FamilyBiker Posted May 5, 2012 Report Share Posted May 5, 2012 are you gonna sell one of those to me when finished?i supported marino wit many of his problems bending fork tubes,maybe youll have one or another thing i can help with if this thread is gonna be lasting a while Quote Link to comment Share on other sites More sharing options...
sstein Posted May 5, 2012 Author Report Share Posted May 5, 2012 Not really planning to sell any, more just because I enjoy making stuff. Might give 1 or 2 away for testing purposes but I already know who is gonna get them Quote Link to comment Share on other sites More sharing options...
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