Author Topic: Tube Bender dies  (Read 4556 times)

Offline ddmckee54

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Tube Bender dies
« on: February 07, 2018, 10:38:33 PM »
Just had a brain fart.

With a 70% infill, or greater, do you think a 3D printed part would make a viable die for a small tubing bender?  It almost feels like it's a silly enough idea that it should work.  Interchangable dies for different sized tubing and different bend radii would be a snap.  The biggest problem that I can foresee would be delamination of the dies due to the stresses involved, but if the infill percentage is big enough that might not be an issue?

I'm not saying these would be suitable for heavy walled SS hydraulic tubing, but for the thin walled tubing we normally use it just might work.


Don

Online b.lindsey

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Re: Tube Bender dies
« Reply #1 on: February 07, 2018, 11:05:23 PM »
For a one off job on thin walled tubing it might work, but I don't see it lasting long. In the time it takes to print, you could probably make a permanent steel die. Just my 2 cents.

Bill

Offline crueby

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Re: Tube Bender dies
« Reply #2 on: February 07, 2018, 11:19:12 PM »
I don't know much about 3d printing, what is the infill you mention?

Online b.lindsey

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Re: Tube Bender dies
« Reply #3 on: February 07, 2018, 11:25:05 PM »
Chris, it's common to use honeycombing on the interior areas of printed parts to save weight, material, and build time. This can be varied depending on requirements, even up to 100% ( a solid part).

Bill

Online zeeprogrammer

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Re: Tube Bender dies
« Reply #4 on: February 08, 2018, 12:19:24 AM »
Go for it. Find out when you try it.
Make them large enough to have sufficient surface between layers.

I 3D printed a spindle stop for my mill. I don't know if the stresses compare...but I'm happy with it.
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Offline AussieRoy

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Re: Tube Bender dies
« Reply #5 on: February 08, 2018, 12:25:59 AM »
It really does depend on what size tube bender you're talking about., and what material you're planning to bend.     For a small tube bender (say one for 3 to 4 mm tubing, which is what I have), and copper tubing, you will probably get away with using a 3D Printed part made using PLA Filament.  A larger tube bender will have much higher forces on the die.   I'd recommend PLA filament  because it is fairly hard  (as plastics go) and is not as brittle as some other 3D Printing plastics.  I'd also make sure to anneal the copper tubing before bending, to reduce the forces on the die even further. 

On my small tube bender, the forces required on the hand grips to bend annealed 4mm copper tubing are quite low, so I imagine that a 3D Printed Die should work for a while.   You may even find that less infill (say 30 or 40%) might work better, as it may allow the plastic die to be slightly more flexible, possibly overcoming PLA's tendency towards being a little brittle.    Even if the 3D Printed Die is fragile and only lasts a few bends, it'll only cost you a few cents of filament and a little time to print a new die.   I guess it all depends on how frequently you use your tube bender.

Offline Mcgyver

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Re: Tube Bender dies
« Reply #6 on: February 08, 2018, 02:05:18 AM »
based on the 3D items i've seen, I doubt it'll stand up....but would be pleased to proven wrong.  Please post if you do an experiment. 

Here's some shots of one I made the old fashioned way many years ago; maybe you'll get an idea or two from it.  Two features I was pleased with - the outer die as a straight section then follows the tube around - this eliminates the bulge you can get in the copper that is pushed ahead of a round die.  Secondly the straight die in contact with the shoe is on a cam so you can tight the show to press tightly against the round die












Offline Xldevil

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Re: Tube Bender dies
« Reply #7 on: February 08, 2018, 04:00:32 AM »
Your tube bender looks like very versatile and well thought tool.
Do you have any plans for it and would you mind me asking for them?
Anyway,great craftsmanship.
Cheers,Ralph

Offline Zephyrin

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Re: Tube Bender dies
« Reply #8 on: February 08, 2018, 09:30:34 AM »
I guess that the plastic dies will not stand the efforts needed during bending, tube easily collapses as soon as the forming dies are not tightly joined.
I did some tests here :

Beautiful set of dies you have McGyver !

Offline ddmckee54

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Re: Tube Bender dies
« Reply #9 on: February 08, 2018, 02:51:06 PM »
Thanks for the replies.

As far as what to bend and how big will it be?  I don't think this would be a viable die for any tubing larger than 6mm or 1/4".  I was thinking of tubing more in the 1/16" to 3/16" range, that would be what about 1.5mm to 4mm-ish.

You might be able to print nylon dies that would work for larger tubing, but I think the under 6mm to 1/4" range might be doable in PLA with enough infill.  You'd also want to print a LOT of perimeters to get the majority of the plastic where the stress is going to be.

What type of tubing?  I would think that these dies should be able to handle thin-walled brass and aluminum K&S hobby shop type tubing.(Aluminium if you're on the other side of the pond, not my fault you guys don't know how to spell.  Said with tongue firmly in cheek.)  Copper tubing for steam lines - maybe, after annealing.  Stainless steel or steel tubing?  I think that would be one of those YouTube "Good luck Chuck, let's see how many bends we can make before this thing breaks" type of deal.

Don

Online Tennessee Whiskey

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Re: Tube Bender dies
« Reply #10 on: February 08, 2018, 07:29:20 PM »
The YouTube machinist, Tubal Cain, AKA Mr. Pete 222, just did a video where he printed change gears for an Atlas lathe. During his “destructive testing” the belt slipped or the motor stalled before any teeth were broken on the gears. In the size range you are proposing, I’d be willing to bet a cold soda pop, that the printed dies would be superior to metal for no other reason than friction between the die and bending stock. If time and materials aren’t an issue, I would print at a high fill rate, just cause it can’t hurt and it might give you some peace of mind.

Cletus

Offline Zephyrin

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Re: Tube Bender dies
« Reply #11 on: February 09, 2018, 07:46:03 AM »
In the video, the printed gears at 100%filling looks indeed very dense and hefty ; maybe a bender die could do it, if it don't flex upon load.

many small lathes use plastic gears without troubles, my X2 mill also had plastic gears, before I put steel ones...after breakage !

Offline Mcgyver

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Re: Tube Bender dies
« Reply #12 on: February 09, 2018, 01:31:11 PM »
many small lathes use plastic gears without troubles, my X2 mill also had plastic gears, before I put steel ones...after breakage !

are the 3D plastic printing results now as tough the what you can get from resin and injection molding?  I know its rapidly changing, but they weren't anywhere close to it a year ago.

Ralph, let me have a look.  i built that a long time ago, I was going to do it as an article in home shop machinist, will have to dig through some old files




Offline jadge

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Re: Tube Bender dies
« Reply #13 on: February 09, 2018, 02:33:08 PM »
I don't see why a 3D printed die wouldn't work. Some years ago I made some PLA press tooling with the idea of forming the fluted cones in brass sheet, as seen on the top of traction engine lamps. This worked after a fashion, although were not capable of forming the sharp internal detail in the flutes that I wanted. However, I couldn't break the tooling using the vice; I had to use the flypress for that! I can't remember what fill I used. I may even have stuck with the standard 20%.

Andrew

Offline ddmckee54

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Re: Tube Bender dies
« Reply #14 on: March 07, 2018, 07:28:45 PM »
I'll need to do a little bit of tube bending for the solder guide tube in my "Fix for the shakes" thread, at least I will when that project gets that far.  I plan on stealing borrowing as many ideas from Mcgyver's tube bending set-up as the law will allow, so in a week or three I'll print up a die and try it out.  Using some of his ideas will be a good starting point and I won't be totally re-inventing the wheel.  It will only be 3/32" OD (0.014" wall) K&S aluminum tubing, but I've got to start somewhere and I might as well do something useful with the die instead of just making it for funsies.

That would be aluminium tubing for you people living on the side of the pond that doesn't know how to properly spell aluminum.

Don