tube benders

[zank]

Question for those bendings chainstays, seatstays or tubing for racks...

What's your weapon of choice? Are you simply using forms and dies and muscle or is anyone using an automated bender? For multiple bends, how are you keeping the bends in-plane? Pics?

[Tom Kellogg]

For our stainless racks, we used to use standard hand benders that you can get at any cheap tool place like Harbor Tool Freight. They actually work pretty well, but like any hand bender, they will NOT make perfectly symmetrical bends. Last year, Jeff and I made our own bender for the major bend at the front of our racks so that we could match the width of a Brevet crown with the radius of the bend. It turned out to be much more difficult to figure out the spool radius and groove depth than we thought. We got it after four tries. For our blades, we just use a split pulley sheave. We don't bend chain stays, so that is easy.

Keeping stuff in plane? practice and care. Jeff has gotten pretty good at it. You don't want me anywhere near a tube bender. I can bend fork blades pretty well and we keep them in line with the oval by eye. Works pretty well.

I have heard that Ron at King cage used to use the cheap benders like we do, but as his production went up he eventually made his own stuff.

Merlin does all of its stay bending with dies. Very expensive, but it seems that when it comes to tissue paper thin Ti tubing, it is the only way that can be reliably made to work. They do have CNC benders down there, but they can only use them when bending somewhat thicker stuff. I have seen them work, amazing. I saw a batch of triple bend heavy MTB chain stays bent. The bender accomplished all of the bends exactly to spec. and in plain in about six seconds each. Pretty cool.

[steve garro]

For our stainless racks, we used to use standard hand benders that you can get at any cheap tool place like Harbor Tool Freight. They actually work pretty well, but like any hand bender, they will NOT make perfectly symmetrical bends.

Keeping stuff in plane? practice and care. Jeff has gotten pretty good at it. You don't want me anywhere near a tube bender. I can bend fork blades pretty well and we keep them in line with the oval by eye. Works pretty well.

I have heard that Ron at King cage used to use the cheap benders like we do, but as his production went up he eventually made his own stuff.

i agree with all the above. for racks {i've only done 4 - they take more time then you would think} i bend 3/16th 4130 with a bender from aircraft spruce. for the bending on the sit-ski we made the bender, there's a pic of it in the flicker stream with my buddy doug. we started with cast pulleys, but had one explode so we have milled ones. for SS's i have an arbor press with a "shoe" and "rockers" i'm doing some S-bend SS's tomorrow, i'l post some pics. i reckon that for what i assume you are doing {light cross stays, maybe?} that you would want a simple wood radius bender {drew has some really cool ones} you need less bensd then you would think to get a good S-bend stay, esp. if the SS is 400mm+ in length........allot of bending is developing feel and still you end up chucking one {or two} into the recycle bin now & then.......Ron at king cage has a way cool dedicated widget to bend cages, i'll see if i can get the video. my buddy welds them, he says ron can bend a cage faster then he can weld them...he has a 6' tall cage in his yard!........steve.

[Curt Goodrich]

The only bending I do other than fork blades is for racks. Like Tom, I just use a cheap hand bender, pulley and a Wilton vise. I don't bend stays. The hand bender works great and since each rack is different I don't see that it makes sense to tool up more than that. Phase isn't that difficult and let's face it it's a rack! So if it's a little off a little gentle persuasion and all is fixed.

I think Garro has something a little more sophisticated given all of those droopy (I'm teasing) top tubes.

[steve garro]

I think Garro has something a little more sophisticated given all of those droopy (I'm teasing) top tubes.

those are their whole own animal, but i'll go into them if you really want......steve.

[suspectdevice]

I borrow an Ercolina numeric control rotary die bender...



It made all that stuff a lot easier...

[EnginCycles]

I am working on some new bender stuff this week during my "i will never have time for this" projects. Dedicated this week and next for shop improvements.

I use wood and aluminum dies. I have rollers that follow the tube in all the applications. I also pack all my stays with sand before bending.

more after the holiday.

Cheers and Happy New Year.
-Drew

[hampco]

we use swagelok tubing benders here for most racks, a rigid for the 3/8" stuff. swagelok is worth the money

dave levy/ti cycles has a hydraulic muffler bender for his big stuff - that's the tits

[Roman]

dave levy/ti cycles has a hydraulic muffler bender for his big stuff - that's the tits

Yeah, baybee.

[maunahaole]

those are their whole own animal, but i'll go into them if you really want......steve.

If there ever was a place to discuss such things, I think you are there. I'd like to hear about it...I may not totally understand it, but fire away.

[steve garro]

If there ever was a place to discuss such things, I think you are there. I'd like to hear about it...I may not totally understand it, but fire away.

sure - but i'll wait until Zank responds so maybe we can focus on his project. there's always more to learn when it comes to bending........steve.

[zank]

thanks, gang. Yes, you saw right through me. I am mostly interested in S-bend seatstays at the moment. I want to bend the stays on cross bikes to be spot-on 8 cm between the centerlines of stays where the canti-bosses go. I have been getting bosses from Mark with no miter and then mitering them myself to be as close to 8 cm apart as possible for the different sized bikes. If I do some sweet S-bends and draw them up for each bike, I can nail that 8 cm width for each individual bike. And the S-bends will give some more mud room too. I'm thnking keeping the lower bend the same for each bike and then adjust the upper bend depending on size.

Steve, I love to see all kinds of metal work. Please post away!

[Saab2000]

S-Bend seatstays kick ass. At least they do if the bend is subtle and elegant. I like the look.

[Tom Kellogg]

If you look at the Merlin road seat stays, that is exactly why we did it that way. The lower radius is the same for all sizes, but we move the upper radius to fit the seat tube. That way, the transitions between the two radii are always parallel and all of the brake bridges are exactly the same length. I would recommend that you draw up a rear elevation where your radius start point and tangent point are the seat stay tabs on the rear drops and your standard canti boss location. Then decide what radius you want and locate it. That way it will reach perpendicular (parallel) at the the bosses. If you make a tool to make the radius, you will still need to custom bend the upper radius for each frame, but the lower radius will give you the look and fit you want.

[zank]

Thanks for the advice, Tom! It's a fantastic bonus that the bridges end up being the same. Sweet!

[EnginCycles]

thanks, gang. Yes, you saw right through me. I am mostly interested in S-bend seatstays at the moment. I want to bend the stays on cross bikes to be spot-on 8 cm between the centerlines of stays where the canti-bosses go. I have been getting bosses from Mark with no miter and then mitering them myself to be as close to 8 cm apart as possible for the different sized bikes. If I do some sweet S-bends and draw them up for each bike, I can nail that 8 cm width for each individual bike. And the S-bends will give some more mud room too. I'm thnking keeping the lower bend the same for each bike and then adjust the upper bend depending on size.

Steve, I love to see all kinds of metal work. Please post away!

Mike,
I was trying to get the 80mm centreline* and found the effort needed in either math or making stuff was not going to offset the 3 minutes it takes to miter a canti stud (i do this on the mill and just offset the needed amount).

I adjust the distance i start the lower bend according to the dropout used (meaning some have longer tangs than others). The amount of bend depends on 1) style bike i.e. cross, or mtb (no s-bend road bikes here) 2) drop outs used i.e sliders start out wider than standard drop outs. The upper bend has the same issue with drop out style but the location of the 2nd bend depends on size of the frame, size of the wheel and how much tire clearance is going to be achieved. My main goal is matching the clearance at the chainstays. Keeping them in phase takes patience and as i said before i use a scribed line. measuring the amount of bend is the hard part. I use a system that could never be explain in print. It would need a photo. Not sure if that helps or is just rambling??

Cheers,
Drew

*That was my little addition of coolness for Richard!

[zank]

It all helps, Drew! Much obliged.

[Dave Kirk]

I do all my stay and blade bending on a wooden ramp that I designed and built a number of years ago. Dead simple and repeatable.

Back in my Serotta days I had a Di-Acro bender that I liked very much. Pretty cool tool. I'd like one now just for the fun of it. Don't know what I'd do with it but I still wouldn't mind having one.

A few years back I needed to make a new SCCA approved roll bar for my race car and I must tell you that bending 2"OD DOM tube ain't easy. I borrowed a friends bender and it was seriously hard to pull that lever! 2.000" tube with an .095" wall is pretty stiff stuff.

dave

[steve garro]

i don't have any standard measurements, as i use everything from Dazza's sockets to the almost 4" long paragon integral disc mounts.......i figure the "tire bend" and then asthetically for me the "2nd bend" fall around 2/3rds of the way between that and the end.......i just have some hash marks on the arbor press and i know the springback rate - see the chart below the fixture........i did allot of bending corners for custom frames for white water rafts for all over the world.....for the grand canyon and natl' geographic - up to 2" Al. stuff so got some licks in there. i'll do flicker set when i do my next set of SS's.........steve.

[VertigoCycles]

I made my own aluminum dies for bending 7/8" and 3/4" stays and have another die for 7/8" stays for MTBs. As others have already written, patience and practice are needed to keep them in plane. It shouldn't be terribly difficult to set up a stop to get repeatable bends.

I saw Ron from UBI up in Portland a few weeks ago and he was singing the praises of the Diacro bender as well.