Author Topic: My Tubing Bender (Read 22362 times)

snub · « **on:** June 15, 2011, 12:06:52 AM »

I've never used one of these nor seen one except in pictures. I decided to build one using ideas from others, but throwing my own ideas in as well. I built 3 rollers and 3 'follow blocks' for 3/16", 1/4" and 3/8" tubing. They are 1" high so that in the future I might be able to bend 1/2" and 3/4" tubing. Here is a pic of it without the follow block in place. You can see the roller bearing that is encased in a block that has 8 pins for guiding it in fore and aft movement, depending on the diameter of the roller. The threaded handle pushes on the block and hence the bearing.

A couple of pics of the block and bearing:

Here are all the pieces:

All set up and ready to bend:

As you can see below, at 90˚ I have run out of follow block. The only insight I had into the length I should make it was from DiAcro, which said the length of the follow block should be 3 1/2 times the radius of the roller for a 180˚ bend. Perhaps my math is wrong. Anyways, I just backed off on the handle and reset the block.

And finished:

BarryG41 · « **Reply #1 on:** June 15, 2011, 03:28:16 AM »

A nice job and very well designed. I made a bender years ago for a production application. Only for 5/16 tube, in comparison mine looked like it was gnawed out of steel by steel eating rats.

Barry G

Bogstandard · « **Reply #2 on:** June 15, 2011, 05:02:47 AM »

Snub,

The way to get around the follower block problem is to use another roller with a groove cut in it, it works like an infinite length follower block.

John

Bernd · « **Reply #3 on:** June 15, 2011, 07:45:50 AM »

Snub,

Nice piece of tooling you've made. Really does a nice job of bending.

Bernd

DaveH · « **Reply #4 on:** June 15, 2011, 08:39:51 AM »

Snub,

Nicely made and a useful bit of kit.

DaveH

djc · « **Reply #5 on:** June 16, 2011, 04:22:16 AM »

Quote from: snub on June 15, 2011, 12:06:52 AM

As you can see below, at 90˚ I have run out of follow block. The only insight I had into the length I should make it was from DiAcro, which said the length of the follow block should be 3 1/2 times the radius of the roller for a 180˚ bend.

Technically, that is correct. When you do a 180 degree bend, you are going half of the circumference of the grooved roller i.e. pi x R. However, for it to work in practice with exactly this length, the end of the follow block would have to start directly opposite the bearing centre and it would finish similarly. If you want to start the follower with its end flush with the machine's frame and have it end this way, you need to add the frame width to the 3 1/2 R dimension.

I wonder if you should replace the dead end clamping screws with studs and wing nuts, one with a spring under it and slot the top cover on the other one. Enables quick-release and is more long-term durable than screwing into and out of aluminium.

John Stevenson · « **Reply #6 on:** June 16, 2011, 04:48:04 AM »

I'm more intrigued by the square headed countersink screws in the third picture?

John S.

Bluechip · « **Reply #7 on:** June 16, 2011, 02:55:27 PM »

JS

Never seen machine screws with square socket drive, but 'coach-bolty' things, yes.

Slung a lot out about 3 years ago. Only square drive key I had was 1/4" AF, the ones I had were 5/16" drive, or maybe 8mm ??

linky ...

http://www.squarescrews.co.uk/

Not that I suppose mine were from there.

Dave BC

Blade · « **Reply #8 on:** June 17, 2011, 10:58:29 AM »

Nice work, looks like it functions well and makes a great bend.

No1_sonuk · « **Reply #9 on:** June 17, 2011, 01:42:09 PM »

Quote from: John Stevenson on June 16, 2011, 04:48:04 AM

I'm more intrigued by the square headed countersink screws in the third picture?

They're "Robertson" drives. Popular in Canada.

dickda1 · « **Reply #10 on:** June 17, 2011, 03:06:03 PM »

Beautiful job.

I am adding this to my project list (derived mostly from these forums).

Dick

allanchrister · « **Reply #11 on:** June 18, 2011, 04:49:52 AM »

Looked at the square drive listing for the UK. Doesn't show Robertson square drive machine screws. Are they made??

Davo J · « **Reply #12 on:** June 18, 2011, 05:25:38 AM »

Nice job and looks like it works great.

Dave

snub · « **Reply #13 on:** June 18, 2011, 10:18:42 PM »

Thanks to all for your compliments and comments. It is much appreciated.
Regarding the length of the follow block, I found this old picture from DiAcro. Judging by the size of the guys hand in comparison to the size of the tubing, I would guess the tubing to be about 1/4" in diameter. Yet look at the length of the follow block. 6" or so? I'm just guessing.

Hobby-Machinist · « **Reply #14 on:** June 19, 2011, 09:52:03 AM »

You did a great job on that- it looks a lot more sturdy than what you can buy!

Congratulations!

Nelson

snub · « **Reply #15 on:** June 19, 2011, 02:04:10 PM »

Quote from: allanchrister on June 18, 2011, 04:49:52 AM

Looked at the square drive listing for the UK. Doesn't show Robertson square drive machine screws. Are they made??

You can get them at any hardware store in Canada. I can't believe the rest of the world isn't using them.

Here is one of the Robertsons best attributes. A quality driver has a slightly tapered business end. Just push the screw onto it and it will stay there all day long.

Available in 4 sizes:

Bernd · « **Reply #16 on:** June 19, 2011, 07:06:13 PM »

Never liked those square drive screws. Saw them the first time on a mobile home I lived in.

They seem to strip out to easy, even with the right size driver.

Bernd

PTsideshow · « **Reply #17 on:** June 20, 2011, 07:58:56 AM »

Great job on the bender, Have to second the no vote on the square drive heads as only have had bad luck with them as they seem to strip out much faster than others.
In my current edition of the handyman in your pocket Industrial maintenance edition my review of the books

They have 28 common head styles listed and pictured, both security (tamper proof) and regular. I prefer the Torx head internals for a better screw head for use with a drive bit,drill motor in wood work. They strip out a lot less.

MadModder

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