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Smokedaddy
11-08-2004, 12:35 PM
I know this subject has been discussed before because I’ve read the archives. However I need some clarification from those of you that actually have hands on tubing bending experience, with a particular bender. I’ve personally bent a butt-load of small (1/4” O.D. to 1” O.D.) stainless steel semi-conductor electro-polished tubing and pipe, with extreme accuracy over the years but I can’t afford a high end bender. I’m looking for a bender for ¾” to 2” tubing.

Do you know of a somewhat inexpensive bender, say under $1,200, including at least 3 dies, that doesn’t scratch or mar the tubing noticeably, or most importantly, doesn't visually distort the physical diameter of the pipe or tubing in the radius of the bend?

Also, HOW do you calculate bending parameters? Does the bender you’re familiar with use setback and arc length formulas for bending calculations (end to center, center to center etc.)?

-SD:

torker
11-08-2004, 12:53 PM
SD...I built a bender years ago...patterned after a Pro Tools or JD2 bender. With the m/s dies is is really easy to get galling with this type of bender. If the tubing isn't spotless and the die/tubing well greased you will get galling. My next bender will be the type where the outer shoe rolls on rollers and doesn't drag on the tubing. As for distortion....while you may be able to control it somewhat with good dies etc.....you also have to think about what you are doing. You are stretching the snot out of the outer radius and forcing or mashing if you will, the inner radius. There has to be some sort of deformation no matter what. If you can't see it on the outside then it must be on the inside. I've cut a few perfect looking bends apart and measured the wall thickness to determine this. Just a few things to keep in mind.
Russ

ibewgypsie
11-08-2004, 01:03 PM
My model 3 Hossfield type bender bends 1/8 wall 1" tubing with no flattening or marking of the lightly wd40'ed tubing.

It is clean unrusted tubing.

The roller type benders are better. Mucho more expensive.

I am on the linux machine or I'd post the link.

JD3 is what I remember the site being, About 245 for bender, shoes are pricy about 200 a pop.. Degree ring, pedestal, and other parts are more. I made my own handle. Have a hydraulic powerpack to adapt to it as soon as I find the "happy" cylinder.. I just can't justify putting a 24"x2" cylinder on it.

Using instrument tubing benders, a roller bender you can put the screw flange on the tubing after you bend it. THIS bender does not do that good of a job.

It is cheap, works well but not perfect is what I am saying. You won't buy a better bender for $3k.


David

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David Cofer, Of:
Tunnel Hill, North Georgia

Ries
11-08-2004, 08:46 PM
Bending tubing is like fast cars- a direct relationship between cost and quality, and high quality means high cost.
I think David is right that the best low cost tubing bender is the JD2 hossfeld copy. http://www.jd2.com/
You need dedicated dies for each size tubing, which are pricy. And you cant do real thin wall stuff. And you still may get a little distortion- the metal has to go somewhere.
The really nice benders, like a 35,000$ Pines bender, use an internal mandrel to support the tubing, which is custom for each size of tube and radius of bend, and tooling can cost upwards of a grand per size. So when you see perfectly bent stuff, that is often what is used.
One thing you could try, especially for smaller diameter stuff, is a low melting point metal filler, like cerromet, which is available from MSC or Mcmaster Carr- costs around 25 bucks a pound, but is reusuable, and can be melted in a double boiler. You fill the tube with it, bend it, then melt it back out again with hot water.

Smokedaddy
11-09-2004, 01:59 PM
To clarify, I'm not looking for perfectly bent semi-conductor grade precision from a particle generator perspective, or NASA quality control, rather an accurate, consistent bender that doesn’t visually distort the tubing or pipe radii. I’m not doing production work but do only quality symmetrical work. I want my own machine. Mostly design and fabricate motorcycle, streamliner frames and custom bicycle type frames.

BTW, to ask again, HOW do those of you that bend, calculate the bending parameters, like center-to-center bends etc.? Do the Hossfield type benders use setback and arc length calculations? Do you bend by eye balling it? Bend by a protractor wheel? In other words, if I gave you an isometric drawing with dimensions, HOW to you calculate and setup for bending the project?

Thanks for your time,
-SD:


[This message has been edited by Smokedaddy (edited 11-09-2004).]

ibewgypsie
11-09-2004, 04:08 PM
There is bender software on the site.
http://www.vansantent.com/model_3_bender.htm
I use center of bends since I was trained that way in INST apprenticeship. I have not even read the instructions that came with my bender. Slippage of the shoe is what really ticks you off.. all benders do it..

NOW Particle accellerators.. WHO ARE YOU? DO they know you escaped from the Cylons yet? (battlestar galactica).. SORRY.. just had to ask..

I can post a picture of a bender shoe I made here.. I wanted a closer radius than the bender shoes I have.. I made the shoe on the lathe. It has a 3" radius, and no I have not tried it out yet.

Too bad you are not my neighbor, Sounds like we could have some fun together.. thou it must be terrible to live close to me.

I had a 3/4" bore hydrogen peroxide rocket turned nozzle up to test the thrust. Police/neighbors have been unhappy since. They thought it was some kind of steam whistle and I let them continue thinking. STill looking for that right piece of metal to make a Real one. Gonna strap it on the harley and take a ride. I plan on putting a cpu in charge of throttling to stop from overspeeding tires past ratings.
Be much better than nitrous..

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David Cofer, Of:
Tunnel Hill, North Georgia

Oh yeah, it was before I put the motor on my indexer, but it is perfect for figuring inclinations and making repeatable bends angle to angle/degree rotation relationship. I have the measurements on a softtail frame I designed.. it comes out within a few degrees.. you still have to tune the bends with a torch because of the difference in springback from piece to piece. Chrome moly needs to be annealed anyways.


[This message has been edited by ibewgypsie (edited 11-09-2004).]

Smokedaddy
11-09-2004, 05:29 PM
Thanks Dave,

Nope ... I'm not a spaceman. In the semi-conductor industry, partical generation is a major problem. Bending radii protocol is critical. It prevents partical generation inside the electro-polished tubing. For example, the 1/4" tubing spec requires 10r bends or a 2 1/2" radius.

I was just interested in how someone calculates their bending layout, via thier particular benders. You shouldn't need software to bend tubing or pipe. One simply uses a the setback forumula and arc lenght formula. Set zero on the begining of the arc and bend to the end of the arc. Pretty simple and extremely accurate. You don't need a protractor or degree finder physically made on a machine if you bend by arc length.

Setback = bender radius (times) the tangent of 1/2 the angle of bend

Arc Length = desired degree (times) .01745 (times) bender radius

I did find the bender below too (see the link) from RMD. It runs about $1,800. Sure wish I knew someone locally that has something like we're talking about. What'z your opinion about this bender. Check the video out on the site if you have time.

http://www.rmdbender.com/products/m100.htm

-SD:

ibewgypsie
11-09-2004, 06:07 PM
M100.avi played a song for about 45 seconds. Not sure what all that is about but I didn't like it. It was supposed to be a video for the bender.
Jimmi-Hendrix style graphics, colors washing screen.. yeah.. I don't think I'd buy a goat from them if I was hungry..

THE misspelling on the main page. Watch yourself.. Probably someone with a garage and a ideal..

For a instrument tubing bender that bender will probably be okay.

I'd still drive down and test drive one, take a bundle of tubing with you. Look around before you write that check.

David

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David Cofer, Of:
Tunnel Hill, North Georgia

GunnySnow
11-09-2004, 06:12 PM
Hello There,

Check out these two links for benders. I have tried neither of them but wish I knew someone that has before I drop the cash.

Gunny

http://mtechsupply.com/view_page.php3?getcategory=Benders&prodid=184

http://www.mtechsales.com/products/Benders/smallbenders.shtml

ibewgypsie
11-09-2004, 06:27 PM
Click on the VanSant link I posted above.. same bender.. cheaper..

I am a cheap rascal..

I own one of the Model 3 benders.. bring you some pieces of 1" tubing/pipe and play with it. I like cold beer.. lemme know ahead of time so I can empty out the fridge.

*I have not used mine for a year now. It is still not for sale. It works.. and I have this small sideshaft motor, clutch, and wheels to make my daughter a mini-bike.. soon.. hopefully before christmas..



David

[This message has been edited by ibewgypsie (edited 11-09-2004).]

HTRN
11-09-2004, 06:35 PM
Dave, the reason for the weird graphics is because you don't have a DIVX codec... Lemme guess Windows media player, right? When Media player gets a file it can't completely decode because it doesn't have the proper codec, it plays a "visualization" instead.... I could see the video just fine.

What misspelling on the main page?

On that note, Lindsay Technical books sells a book on how to make a primative bender.

HTRN

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This Old Shed (http://http:thisoldshed.tripod.com/enter.htm)

Smokedaddy
11-09-2004, 06:37 PM
Gunny,

Thanks .... I looked at those sites already. I did write a couple too, asking a few questions. I'm leaning towards something like the JD2 Model 4 bender but I need a few questions asked.

Cheers,
-SD:

torker
11-09-2004, 09:06 PM
SD...I use the arc length/leg length method for the roll cages etc. that I build. I've always found this to work well, to the point where, when doing multiple door bars, etc. for stock car cages, that I can notch the tubing before it is bent (much easier). And yes I have buggered up some tubing trying to show off like that! As for determining angles...etc, well...kind of hillbilly but I lay out what I need to build on the floor in actual size then copy the angle with a 2 1/2' long deal I made out of 1/2"x1/8" flat bar (2 pieces) with both pieces rivetted at on end. I just spread the two legs out til they copy the angle I need for tubing. As I bend I check the angle (releasing the spring back of course) until it's right. Then I use the ratchet tooth count to copy the rest of the bends. This is as accurate as I need. I've stacked 10 door bars up and all are identicle so that's what I go with.
Russ

[This message has been edited by torker (edited 11-09-2004).]

dsergison
11-10-2004, 12:42 AM
JD2 + stainless tubing.... I've been bending .065 wall 1" stainless with a 4.5" CLR. it looks really good. it is about .020 skinnier in the arc, but it's really almost impossible to see. I grease the follower (which has aluminum wiping pads) and I don't have any problem with galling. I'm happy.

[This message has been edited by dsergison (edited 11-09-2004).]