Thread: WWTP028: Seat Stay Bending

I had a couple of hours this weekend, so I dragged out all the WWing stuff and made a new bender: The posts are 7/8 x 0.035 4130 that I had laying around. This worked way better than the last one as the pushers can pivot. The mandrel (not pictured) was supposed to be 8" radius but after sanding it on the belt sander (the band saw made a mess out of the MDF, I should have changed blades but was lazy) then it ended up being more like a...

Quote: Originally Posted by zipzit I sometimes wonder if less is more.. er... not so fancy. I remember seeing this very simple jig for an S-bend chainstay. I noticed it on the very impressive Wolfhound Cycles 29er split wishbone build (Customer = Jay Carpenter) See http://wolfhoundcycles.blogspot.com/...ers-build.html Comment from the blog: [font=Verdana] Photo of chainstay bender is at http://2.bp.blogspot.com/_cRA2LWYSP8...s1600-h/33.jpg...

Quote: Originally Posted by pvd Fill the whole stay. Cap with electrical tape (best I've found) and freeze it solid. The colder the better. Give it plenty of time, semi solid is not good at all. You have to work quick. Handle the stay with a rag to avoid heating it up any. Have all your markings in place ahead of time so you go from freezer to bend as quick as you can. I've only had one stay split. It's a good thing when it...

Hydraulic tubing is a lot softer than and more ductile than Cro-moly. It is also much heavier wall. .049 is a lot different than 3/4" x .035.

Quote: Originally Posted by pvd The bike I'm working on right now will hopefully have a double bent ovalized stay around the chainring and tire using a 4" radius. 5.25" radius was too big to make the design come together. In general, I prefer tighter bends to lazy bends. I'm bending out of need rather than astetics and I need all the space I can get usually. I just haven't had that problem. On a 29er, unless I do a...

I've been looking at this one going at ebay: http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT - But was thinking that I could as well just make one myself based on the same design but with an adjustable following die that kept the tube close to the mandrel, then Steven (Shand) showed me this: http://www.lindsaybks.com/dgjp/djgbk/pipe/index.html So when I have time I will make something like the latter from scrap in the shop. Truls

You gotta know there's about 20 more products you could sell the hell out of......what a tease. -Schmitty-

Quote: Originally Posted by DWF In my experience, it is very rare in bike building that you need a radius smaller than 11". The bike I'm working on right now will hopefully have a double bent ovalized stay around the chainring and tire using a 4" radius. 5.25" radius was too big to make the design come together. In general, I prefer tighter bends to lazy bends. I'm bending out of need rather than astetics and I need...

The reason the tube crushed that way is because there is no support inside the tube. you are trying to stretch the skin on the outside of the bend whilst shrinking the skin on the inside of the bend all at the same time, something quite literally has to give In the absence of a tube bender or a mandrel, filling the tube with sand is an excellent way of doing this. we have a cnc tube bender here and i still use sand bending sometimes for one...

I sometimes wonder if less is more.. er... not so fancy. I remember seeing this very simple jig for an S-bend chainstay. I noticed it on the very impressive Wolfhound Cycles 29er split wishbone build (Customer = Jay Carpenter) See http://wolfhoundcycles.blogspot.com/...ers-build.html Comment from the blog: Quote: It has taken many attempts and a lot of sacrificed material to develop these chainstay forms, even though they look pretty cowboy,...