Author Topic: Tube Bender dies  (Read 4681 times)

Offline Mcgyver

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Re: Tube Bender dies
« Reply #15 on: March 07, 2018, 08:43:03 PM »
borrow away....just post pics :)

Offline Mr Moo

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Re: Tube Bender dies
« Reply #16 on: March 22, 2018, 08:03:46 PM »
or you print with carbon fibre filled nylon ......

Offline bruedney

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Re: Tube Bender dies
« Reply #17 on: March 23, 2018, 01:12:50 AM »
So Mcgyver, did you find the plans/article draft?

Cheers
Bruce
‘Results! Why man, I have gotten a lot of results. I know several thousand things that won’t work.’ — Thomas Alva Edison

Offline ddmckee54

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Re: Tube Bender dies
« Reply #18 on: April 11, 2018, 10:42:48 PM »
Okay, I'm getting to the point in my other build where I'm going to be need to bend some tubing - so I'd better get this thing designed.

I've got a question for you guys.  Keeping in mind that this thing will only be asked to bend from 1/16" to 1/4" tubing, probably just aluminum brass and copper tubing, what would you recommend as minimum bend radii for the dies?

What I've got kicking around in the back of my head is a scaled down version of a commercial tubing bender.  I'll try to see if I can convince the idea to get out of my head and into a 3D model so that I can actually do something with it.

Don

Offline ddmckee54

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Re: Tube Bender dies
« Reply #19 on: April 12, 2018, 07:33:30 PM »
I started work on the design for the tubing bender, I've attached a 3D PDF of the Mk. I version along with a screen shot of that PDF.  I've  been debating with myself a couple of different options for clamping the tube in the bender.  No matter how I clamp it I think there is going to be a lot of stress on this clamp so that suggests a big beefy part, at least when 3D printed.

One option would be to clamp one end of the tube to the bender and let the free end be pulled through the bender.  This would mean that the clamp would have to move with the die, making it hard to fit all the required parts into a give volume.  With metal parts this probably isn't that much of an issue, but with 3D printed parts of questionable strength, I think I'd have to start with Ginormous and maybe reduce the size if it worked.

The other option would be to clamp the tube stationary and let the free end do it's own thing.  I think this option will put less stress on the bender parts, but I could be wrong.  I thought I was wrong once, but it turns out I was just mistaken.  The downside to doing it this way is it makes getting the bends in the correct location more difficult.  At least it feels that way right now because you'd need to measure from where the bend ends rather than where it starts.

Anyway, back to the Mk. I Bender.  The dark green object is the Base, I thinking that 2"x2"x1/4" aluminum angle should work just fine.  The red object is the handle.  It's two pieces of 1/8"x1/2" bar, probably Chineseium from Home Despot or whatever's laying around, bolted to a piece of 1/2"x1/2" bar.  All the bolts will be 1/4"-20, I'm not going to be plumbing a NASA project or using titanium tubing.

The dark blue piece is the Tube Clamp, it will be bolted to the base.  I'm expecting this part to see a lot of stress so I will make it beefy.  The light blue piece is the Die, in this case 3/32".  At this point it could rotate if it had to, but I think it will be more or less stationary.  The light green piece is the Die Follower, it will be pressed against the tube by the Die Roller, the magenta colored part.  If everything works like it's supposed to, the Die Roller will press against the back of the Die Follower.  The Die Follower will force the tube against the Die and viola, we're bending a tube.  The Die Follower will support the back side of the free end of the tubing up to the actual tube bend point.

The dimensions either weren't turned on, or they didn't show up in the 3D PDF, the Die is 25.4mm in diameter and the Die Roller is about 40mm in diameter.  I'm planning on keeping the center to center spacing of the Die and Die Roller pivots constant.  As the Die diameter increases or decreases the Die Roller diameter will vary accordingly.  The only thing I have to be careful about is making sure the Clamp location doesn't interfere with any of the various Dies/Die Rollers.

By the time I got to this point I decided that I'd been at it long enough and went to bed.

I'm planning on plenty of overkill when I print these things.  Right now I'm planning on 10 layers top and bottom, 10 perimeters, and 75%-80% fill.  That should give me approximately 2mm walls on all sides and an almost solid plastic part.

Updates will follow.

Don


Online crueby

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Re: Tube Bender dies
« Reply #20 on: April 12, 2018, 09:02:52 PM »
The die roller will see a lot of stress too, you could extend its axle up higher, and have an inverted L shape piece come over the side from the base plate to support it, otherwise it might want to twist as you move the lever.

 :popcorn:

Offline Mcgyver

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Re: Tube Bender dies
« Reply #21 on: April 12, 2018, 10:07:55 PM »
So Mcgyver, did you find the plans/article draft?

Cheers
Bruce

sorry for missing this earlier Bruce, no progress yet

Offline ddmckee54

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Re: Tube Bender dies
« Reply #22 on: April 12, 2018, 10:36:35 PM »
I can see that the handle pivot would be a weak point now that you mention it.  If I do this right I could probably rotate the Tube Clamp 180°, then bolt the Tube clamp and the handle pivot support bracket that you are suggesting together into one unit.  United we stand - divided we fall, and all that.

I was pretty sure that I needed to move the location of the Tube Clamp anyway.  I think if put in a 2" diameter die in the handle, the die would interfere with the clamp in its' present location.  But it was latte last night when I decided that I'd had enough fun for one day.

Ummmm.... tube bend radius, is that measured on the tube centerline , or where is it measured?  I'm assuming that it is measured on the tube centerline, until I'm convinced that I should be doing it differently.

Just had a brain fart, if I do this right I can lengthen the 1/8"x1/2" bars and then replace the 1/2"x1/2" bar with a printed part.  That way the only parts on this thing that weren't printed would bed the 1/8"x1/2" bars, the bolts, and the base.

The Mk. II is on its' way,

Don

Offline ddmckee54

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Re: Tube Bender dies
« Reply #23 on: April 13, 2018, 04:26:40 PM »
OK, I did some work on the Mk. II.  BUT, while I was sitting here typing this I just had an epiffinie, epiphiny, brain fart.

I thought that I was being "Oh so clever" by maintaining a constant spacing between the Die and Die Roller pivot holes.  Within reason. no matter what the bend radius that spacing would remain constant.  I thought that would keep the mounting holes for everything constant.  What I just realized is that the tube position does not remain constant.  The tube centerline will remain in the same plane above the Base, but its' location on that plane will vary.  So, the clamp design will change with every different bend radius.

Hmmmm..... Maybe a universal clamp holder with a unique clamp insert for a specific tube size and bend radius.  Then I could probably get away with a constant mounting location for everything.

A screen shot of the Mk. II and its' 3D PDF are attached.  Now if I can just convince the voices in my head to quit hoarding the Mk. III idea we'll see if I can develop it a little more.

Don

Offline ddmckee54

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Re: Tube Bender dies
« Reply #24 on: April 19, 2018, 07:32:34 PM »
While I was cleaning the shop over the weekend I found a piece of 1/8" x 1/2" hot rolled Chineseium from Home Despot.  After holding it in my hands and considering it carefully, I'm now of the opinion that there really won't be a lot of meat left in the bars of the handle after drilling 1/4" holes through them.  They might just turn into pretzels under stress.  I'm thinking that 1/8" x 3/4" would be better and that 1/4" x 3/4" would be more better yet.  I'll re-design the handle to be a pair of 1/4" x 3/4" bars and I should be able to start printing parts in a couple of days, got get that stinkin' solder feed drive working first.  The only printed parts that this will affect will be a spacer and the hand grip.

I'm just about to the point in my other build, "A fix for the shakes.", where I need to stop by the hobby shop and get a piece of 3/32" aluminum tubing to bend for a solder feed tube.  I'll need to build the tubing bender first I guess.

Don
« Last Edit: April 19, 2018, 07:37:16 PM by ddmckee54 »

Offline ddmckee54

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Re: Tube Bender dies
« Reply #25 on: April 23, 2018, 10:21:33 PM »
OK, I was busy printing stuff over the weekend, photos attached.

The first attachment is the Bender family photo.  This is all of the printed parts required to bend 3/32" OD tubing, I think.  With the exception of the hand grip, the largest part. everything was printed at a 0.25mm layer height, 3 perimeters, and 75% fill.  I chose the 0.25mm layer height because my Z axis lead screws move 8mm in one revolution.  At 200 steps per revolution, 0.25mm is the thinnest layer I can print - without the software having to play games with the numbers.  I was thinking about adding more perimeters for a greater wall thickness, but the 75% fill gives me an almost solid part.  We'll see how it preforms.

The second attachment is the parts for the actual business end of the bender.   The back row is the pivot bolt support arm and the clamp holder top and bottom.  These will be universal parts that are used for all tubing sizes.  The actual tube clamp parts are setting in front of the clamp holders.  The front row, from left to right, is the 1/2" bend radius 3/32" tube die, the 3/32" die follower, and the 3/32" die roller.  These parts are a unique set for each tubing size and bend radius.

I'm going to have to get some metal for the rest of the parts.  I'll go to a steel supplier and get some drops, need about 3 feet of 3/4" x 1/4" bar stock and about 6" of 3" x 3" x 1/4" angle.  I thought I had some 3 x 3 angle, but it was 2 x 2 and too small.

While typing this I just realized that the only thing keeping the tube clamps in the clamp holders, other than friction, is an itty-bitty 1mm radius half-pipe that I included to register the clamp parts in the clamp holders.  I've got a feeling that those registration half-pipes aren't going to survive much stress.  The layer laminations are running parallel to the forces.  So I either need to find a better method to ensure that the clamps remain in the clamp holders, despite the forces involved in bending the tubing, or I need to re-design the entire clamp/clamp holder set-up.

Don

Offline ddmckee54

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Re: Tube Bender dies
« Reply #26 on: June 11, 2018, 08:49:06 PM »
Been a while since I updated this thread.  I haven't forgotten about this project or abandoned it, been a little busy.  My brothers and I are co-executors of our mother's estate and that has kept us busy for a while.  Then there's that pesky 4 letter word that starts in W and ends in K.  Lastly, I got this idea for a 3D printed rubber band gun with all the bells and whistles that's been kicking around in my head - full sized replica of a Walther PPK, 6 shot, semi-automatic, magazine fed, etc... 

I did get the steel bar and the aluminum angle I needed to build the tube bender.  Once I get the rubber band gun debugged and out of my head, I'll get back to this project.

Don

Offline ddmckee54

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Re: Tube Bender dies
« Reply #27 on: August 08, 2018, 05:06:31 PM »
Once again it has been quite some time since I updated this thread.  I'm gonna plead work and laziness.  With my job July 4th and Christmas are our busiest times of the year.  It seems like I'm either scrambling with last minute project details before a plant shutdown, working through the plant shutdowns to get the project installed, getting the project running to hand over to production, or working on a project for the next shutdown.

In my abundant spare time I have come to the conclusion my idea for the tube bender won't work very well, at least not as designed.  Don't get me wrong, I still think that 3D printed dies will work just fine - especially for the smaller sized that I have in mind.  In my original design the tube is clamped stationary and the dies move along the tube.  To layout where you wanted to bend a tube you would need to know where you wanted the bend to end.  For a single bend this will work OK, but for multiple bends my method means that you need to know where each bend ends.  This always felt a little bassackwards, because when you're bending a tube to fit you usually know where you want the bend to start not where it's going to end.

I think I'm going to try the more traditional approach of clamping the tube stationary to the die, and the pulling the tube around with the die.  The original method I designed would clamp the tube stationary in the bender and pull the dies around the tube.

Don