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Thread: Tube Bending

  1. #1
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    Tube Bending

    Hey folks!
    This is my first post on your site. I hope you don't mind a BMX builder intrude on your knowledge.
    I am looking for a simple way to bend some 4130, 6061 & 7005 tubes to be used for seat and chain stays. Do you have any recommendations? I am very small and need something "in expensive". I just can't afford to pay to have them bent or to buy the ones that are pre bent.

    If you have any recommendations I would appreciate it.

    Thanks!

  2. #2
    Shop Owner/Frame Builder
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    Quote Originally Posted by ggodwin
    Hey folks!
    This is my first post on your site. I hope you don't mind a BMX builder intrude on your knowledge.
    I am looking for a simple way to bend some 4130, 6061 & 7005 tubes to be used for seat and chain stays. Do you have any recommendations? I am very small and need something "in expensive". I just can't afford to pay to have them bent or to buy the ones that are pre bent.

    If you have any recommendations I would appreciate it.

    Thanks!
    Early in our frame building life we bent all of our SS with a conduit bender we bought at Lowe's. It was crude and made identical replications difficult but we make 10-15 bikes this way.

    Later,
    CJB
    www.HammerheadBicycles.com
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  3. #3
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    i use this one with a few modifications to keep the strap part from moving, and to increase its surface area (the stacks of reamed out washers increase the surface area):

    http://cgi.ebay.com/NEW-INDUSTRIAL-T...#ht_809wt_1344

    http://www.pinkbike.com/photo/5762364/

    I had to weld the bolt in to keep the strap part from slipping outward (it takes a lot of force to bend .049 and thicker)
    Last edited by mattty; 04-25-2011 at 10:55 PM.

  4. #4
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    We used this and simply duct tape the tube to the bender so that it would "stay" in place. I told you it was crude....

    www.HammerheadBicycles.com
    Austin's dirty little secret

    www.TrueFabricationBicycles.com
    Texas Born; Texas Bred

  5. #5
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    I made a bender like this one that Walt made:

    http://waltworks.blogspot.com/2008/1...be-bender.html

    The only thing I did differently was I used curved angle iron as the form instead of wood.

    It works great with steel 1/2", 5/8" and 3/4" round tubing, I've never tried to bend aluminum with it though.

  6. #6
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    I am at the early stage of frame building where I use the conduit bender. I mark the point where it goes into the bender with a Sharpie, and a digital angle finder to determine how much I bend the tube.
    May the air be filled with tires!

  7. #7
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    I don't think it needs to be all that complex especially for seat stays.



    I was happy with the result and found that it was not hard to make a uniform bend because I simply made a hash mark on the table so I would know where to pull the stay to. The radius of the plate work great for the stays an a MTB, you might want to use a 35# plate for a BMX bike but that is just a guess. For thicker tubes the extra leverage of a tube bender might be helpful but the seat stays bend fairly easy.
    Mark Farnsworth, Raleigh, NC
    http://farnsworthbikes.com

  8. #8
    shifty
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    Quote Originally Posted by febikes
    I don't think it needs to be all that complex especially for seat stays.
    I like the cut of your jib.

    -b

  9. #9
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    febikes, what stays are those that you're bending?

    I love that threaded plate you have! You don't know how much I want one of those!
    May the air be filled with tires!

  10. #10
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    In the photo, I am bending NOVA stays.

    The index plate is something I took off an old broke down CNC machine.

    Similar stuff can be found at scrap places especially if you go in person.
    http://www.hgrinc.com/

    A shop can also make you one but it would likely be fairly pricey and expensive to ship. Mine is something like 14"x30" and 1.5" thick of steel. The surface on mine is beat up so I can't use it for precision work but for many projects it is really useful.

    At some point I will build something similar to Walt's design...
    http://waltworks.blogspot.com/2008/1...be-bender.html
    Mark Farnsworth, Raleigh, NC
    http://farnsworthbikes.com

  11. #11
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    Quote Originally Posted by ggodwin
    Hey folks!
    This is my first post on your site. I hope you don't mind a BMX builder intrude on your knowledge.
    I am looking for a simple way to bend some 4130, 6061 & 7005 tubes to be used for seat and chain stays. Do you have any recommendations? I am very small and need something "in expensive". I just can't afford to pay to have them bent or to buy the ones that are pre bent.

    If you have any recommendations I would appreciate it.

    Thanks!
    how many do you need to bend? How expensive is your time? How accurate and repeatable do you need them to be?

    I've built my own dies, used a JD2, used various fork blade benders, gone through the whole cerrobend thing and finally an Anvil bender. The Anvil has been one of the biggest time savers to come into my shop. Now that I've had it for about a year and have records of setups and pin stops, bending a set of matching stays is pretty much a no brainer.

    My vote is to suck it up and buy something to do it right the first time.

    edit: I don't want to make it sound like the Anvil is the ONLY way to do it right. There are other (more expensive) options out there. But once you factor in time and all the stuff that doesn't produce a good result, the Anvil is the best value IMO.
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
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  12. #12
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    Quote Originally Posted by smudge
    how many do you need to bend? How expensive is your time? How accurate and repeatable do you need them to be?

    I've built my own dies, used a JD2, used various fork blade benders, gone through the whole cerrobend thing and finally an Anvil bender. The Anvil has been one of the biggest time savers to come into my shop. Now that I've had it for about a year and have records of setups and pin stops, bending a set of matching stays is pretty much a no brainer.

    My vote is to suck it up and buy something to do it right the first time.

    edit: I don't want to make it sound like the Anvil is the ONLY way to do it right. There are other (more expensive) options out there. But once you factor in time and all the stuff that doesn't produce a good result, the Anvil is the best value IMO.
    Thanks, Smudge, I'm glad your digging it. Need to get yours updated to the new alignment arm stuff.
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

  13. #13
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    Hang on.

    Set-up fees for mandrel bending is like 60 bucks per bend, and then each bend is about 4-6 bucks.

    That's expensive?
    No longer member of the bike industry nor society, so don't hassle me.

  14. #14
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    Quote Originally Posted by Thylacine
    Hang on.

    Set-up fees for mandrel bending is like 60 bucks per bend, and then each bend is about 4-6 bucks.

    That's expensive?
    isn't it? It depends on the production schedule, whether or not you want to carry inventory, frame size differentiation, tube diameter differentiation.

    FWIW, I use two different radius dies per stay, different diameters between CS and SS. That's four setups and $240 in setup fees. If you're the builder, how many trips to the bender do you need to make before you slap yourself in the forehead?

    I'm going through this again right now with 34.9mm tubing. I could keep sending them out to the bender that ruins 80% of what I send him or I could spend a few hundred $$ paying a local CNC shop to make me dies and blocks and then at least three days of my own time designing and fabricating a hydraulic press. For the expense, risk and time it takes me to send it out, I'm better off doing as much as I can and bringing the operation "in house".
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
    flickr :: www.vertigocycles.com

  15. #15
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    Quote Originally Posted by DWF
    Thanks, Smudge, I'm glad your digging it. Need to get yours updated to the new alignment arm stuff.
    It looks like the new dies have a doodad machined into them that mine don't. Looks sweet though, I like your take on it.

    I got the 2-bolt SS tube blocks BTW. Thanks!
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
    flickr :: www.vertigocycles.com

  16. #16
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    Quote Originally Posted by smudge
    It looks like the new dies have a doodad machined into them that mine don't. Looks sweet though, I like your take on it.

    I got the 2-bolt SS tube blocks BTW. Thanks!
    New mandrels do but we have a retrofit system too. You can either send yours to us and we'll retrofit it or you can do it yourself (two .188 pin locations and d&t for 1/4-20 or M6x1 hole).
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

  17. #17
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    word. I'll give you a call on Monday. Looks like I need to buy a 0.188 reamer.
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
    flickr :: www.vertigocycles.com

  18. #18
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    Funny stuff here...
    Today I am googling tube benders again and I come across my two year old thread. Since making the original post nothing has changed in terms of my bending. I am still sending them out to a shop and wasting money. I don't do many frames, but with a magazine article coming out and one of my frames 1 of 4 discussed I figure things may pick up.

    Some of the posters at Practical Machinist pointed me in the direction of the Di-Acro benders. These are a much more expensive but I have been told that they are well worth the price. I have found a couple on craigslist that I am looking into. Do any of you know much about them? Specifically the ones linked below.

    The first one seems to have a lot more components on it. I don't know if all that is needed or not. The one below is much closer to me but I don't know what is missing on it.

    Do any of you know much about these?

    Diacro 1 Bender

    No 1 DIACRO Hand Bender 2" Radius Cap 3 16" Steel Round Bar Cap 24607 | eBay

  19. #19
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    #1 is too small, you really want a #2. #3 will work.

    The quikloc on the craigslist ad is worth the money, not having it is a pain.

  20. #20
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    Tube Bending

    Will the #1 work for Aluminum tubing? That's pretty much all that I'm making now.

  21. #21
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    Tube Bending

    Let me also add. I'm just bending 1/2" seat and chain stays on small BMX race bikes for 3-6 year olds.

    Crazy I know, but I found a nitch market.

  22. #22
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    Hey;

    Think outside your current little box and look for something that will do what you need to now, and more. Having something for one immediate need is not very useful when something more in depth comes along. Versatility pays in the end.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
    - John Hajny, a.k.a. TrailMaker

  23. #23
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    problem with a diAcro #1 is the diameter of the largest die you can put on it and the leverage you have. I would jump on that #1 for racks or other small stuff if it were near me, but I think you will be pushing it to do 1/2" stays.

    A diAcro is what you want, but you have to recognize that it's a pretty big investment. People make their own dies, but there is a pretty big investment required to do that too.

  24. #24
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    Tube Bending

    Well, I made a decision that I am thrilled with. I didn't buy a tube bender. Instead I save major money and made a tube bender out of Oak. Basically, I made something that bends both right and left seat stay and secures it while I make my mitre cut for the seat post.

    Here are a couple pictures.

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    Tube Bending



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