Homemade tube bender problems

[armalites]

It's about now I would be on the phone to Stakesys with my credit card

 

[Jedamere]

On the one with the yellow jack it looks to me like the right hand side of the slot is in line with the right hand side of the pin holes and as they are a different size it means the roller is offset to the right.

I think we need to be careful saying the jack needs to move, I would say the postion of the slot the roller moves in is more important.

The holes and slots are all marked on centre on the plans.

I have tried positioning the jack further forward and back and still didn't have any luck

 

[Jedamere]

Looks like the test pipe is too short. A longer pipe would give you more leverage. The bend starts because the front clamp lifts up one end of the pipe so that it is not parallel to the bed of the straight die. As the die comes up straight and in line with all the pivot points yadda yadda, because of the slight angle of the pipe, it begins to bend around the upper die.

I also tried a longer test piece and again no succes, really running out of ideas haha

 

[Jedamere]

It's about now I would be on the phone to Stakesys with my credit card

I'm getting very tempted haha

 

[Jedamere]

Have you tried pulling the tube so the die is already pivoting before enagaging the jack to see it makes any difference?

If I pull the tube up, as soon as the jack pushes on the follower it clamps the tube flat between then and then locks out there

 

[addjunkie]

It's about now I would be on the phone to Stakesys with my credit card

Ive been tempted for a long time. Maybe my next big purchase before I retire. (Only excuse i can think of at the minute)

 

[Jedamere]

Ive been tempted for a long time. Maybe my next big purchase before I retire. (Only excuse i can think of at the minute)

Any excuse is a good excuse I'm regretting not just buying one now

 

[Dee J]

I might have a bit of the answer... I think it relies on the u-clamp holding the tube tight to the top die at the very end. So that where the jack applies pressure the tube is slightly clear of the top die - giving a start to the bending action. If that clamp is loose or the tube fractionally undersize then the tube will just tilt a bit and the whole thing lock up solid..... Does that happen? Does the tube tilt from horizontal as you crank up the jack?

 

[Wallace]

Is the tubing the correct diameter for the die and follower? Are the dies Imperial and the tubing Metric? There must be some triangulation offset between the roller pivot and the die pivot where the force is applied for the bending action to start. The triangulation offset would be the contact area on the tube between the die and follower. Tightening the bolt against the tube with the clamp hoop fitted sets the triangulation offset by taking up all the slack in the pivots and effectively starting the bend, the tube should now be sitting at a slight angle to the bender and the die rotated a few degrees. Pumping the jack then squeezes the tube out around the die as something has to give way and the tube should be the weakest link. If the tube is smaller than the die and follower the triangulation offset will be reduced needing more force and may crush the tube. Did the clamp hoop come with the die set or did you make it? Everything I can see in your photo is very well made and I'm wondering if the tolerances may be a bit too good! If the clamp hoop pivot is spot on so the tube is almost flat with the die the triangulation will be reduced. Moving the clamp hoop pivot a little further out should increase the triangulation angle as the die will be rotated further with the bolt.

(The joys of using a mobile phone to post, Dee J posted while I was writing)

 

[Revs1972]

Haven't a clue how to make it work, but after watching the guys video , if ever something needed bolting down to the ground or to a sturdy table then that would be it !

 

[Jedamere]

I might have a bit of the answer... I think it relies on the u-clamp holding the tube tight to the top die at the very end. So that where the jack applies pressure the tube is slightly clear of the top die - giving a start to the bending action. If that clamp is loose or the tube fractionally undersize then the tube will just tilt a bit and the whole thing lock up solid..... Does that happen? Does the tube tilt from horizontal as you crank up the jack?

The tube doesn't seem to move, as you crank up the jack it applies pressure between the two but the tube is held square against the follower. I'll have a look when I'm at the workshop though cheers

 

[Jedamere]

Is the tubing the correct diameter for the die and follower? Are the dies Imperial and the tubing Metric? There must be some triangulation offset between the roller pivot and the die pivot where the force is applied for the bending action to start. The triangulation offset would be the contact area on the tube between the die and follower. Tightening the bolt against the tube with the clamp hoop fitted sets the triangulation offset by taking up all the slack in the pivots and effectively starting the bend, the tube should now be sitting at a slight angle to the bender and the die rotated a few degrees. Pumping the jack then squeezes the tube out around the die as something has to give way and the tube should be the weakest link. If the tube is smaller than the die and follower the triangulation offset will be reduced needing more force and may crush the tube. Did the clamp hoop come with the die set or did you make it? Everything I can see in your photo is very well made and I'm wondering if the tolerances may be a bit too good! If the clamp hoop pivot is spot on so the tube is almost flat with the die the triangulation will be reduced. Moving the clamp hoop pivot a little further out should increase the triangulation angle as the die will be rotated further with the bolt.

(The joys of using a mobile phone to post, Dee J posted while I was writing)

All the tube and dies are the correct sizes, I've made sure of that The clamp hoop came with the die set, but if needed I can make another one

 

[Wallace]

Dee J and I seem to be thinking on the same lines except his explanation was shorter! I think the jack location should be central, and I'm going to presume the roller and die pivots are well greased as that would help.

 

[gaz1]

I might have a bit of the answer... I think it relies on the u-clamp holding the tube tight to the top die at the very end. So that where the jack applies pressure the tube is slightly clear of the top die - giving a start to the bending action. If that clamp is loose or the tube fractionally undersize then the tube will just tilt a bit and the whole thing lock up solid..... Does that happen? Does the tube tilt from horizontal as you crank up the jack?

the jacking action is behind horizontal of the pipe therefore when you do jack it up the action forces the the die to roll forward therefore bending your tube if its in line all it will do is lock up instead of allowing the former to roll forward as the die turns

 

[J1nx]

Can you encourage it by popping something like a ratchet strap from frame around end of tube and back to frame and putting some tension there?

 

[Screwdriver]

Well if that's the correct (curved) die for that setup, it has to shift. The pivot is offset from the centre of the radius so the bottom die can come straight up, in line with the (offset) pivot and the top die has to rotate out of the way. It just has to so;

Your frame isn't strong enough
or
Your jack isn't powerful enough
or
the pipe is too strong for the design capacity

 

[Jedamere]

Hi guys, incase anyone wondered how this turned out. I turned up a spreader plate to go ontop of the bottle jack and added some gusset plates to the design. I've tested it on some smaller tube and I'm working my way up wall thicknesses to find its max

 

[johnny max]

Were did you purchase the die set from

 

[addjunkie]

This is a bender design I like, as it takes up far less space than the horizontal type....shame the dies are so expensive

Sure these plans were a free download on the pro tools site a few years ago

 

[Jedamere]

Were did you purchase the die set from

I got the die set from Stakesys mate