Homemade tube bender problems

[Jedamere]

Hi guys, I've recently built a tube bender from plans I bought from 'engineered to slide' it's a vertical bottle jack style bender that uses pro tools Portabender dies. But when I try and use it it gets to the point just before the bend should begin and locks out. If I push it further it bends the plate under the die follower.

I was hoping someone on here might have built something similar or had a problem like it.
I've made sure the pivot points are greased, I machined all the pins to the right sizes (triple checked that lol)

Any help is appreciated, I've been a long time lurker and seen a lot of people helped out on here so I thought it was worth an ask

Kind regards, Jed

 

[123hotchef]

Hi Jed sorry I can not answer your question but welcome to the forum mate

 

[123hotchef]

is the die straight like on a plumbing bender?

 

[Jedamere]

No it's a curved die, very similar to a conventional tube bender but it has a large aluminium follower

 

[Jedamere]

 

[slim_boy_fat]

Hi Jed sorry I can not answer your question but welcome to the forum mate

Ditto

Lot of nicely finished bits there, hope someone can sort the 'design' problem easily for you.

 

[Woody.v8]

It looks like the jack is directly below the pivot pin of the die?
If that's the case it will never work, it needs to be offset to give a lead

 

[armalites]

I'm intrigued how the rotation is created, the jack is in the same line as the centre of the die so as you say as soon as the jock makes contact it's just going to press the tube against the die

 

[Jedamere]

This is a video of the guy I got the plans off using his if that helps guys

http://engineeredtoslide.com/2014/03/ets-bender-action/

I think the idea is the pivot on the die is offset so as you jack the bottle jack up the tube is dragged round, but I've tried moving the jack back and forth and still no luck.

 

[pedrobedro]

Have a look on blind chicken see if you can spot anything you might be doing wrong. They encourage free thinking and adaptation. Is your jack strong enough ?

 

[Jedamere]

Thanks Pedro I'll have a look on there

 

[armalites]

Just watched overload's vid link, it does look like you need quite a bit of pressure to start it moving

 

[overload]

 

[overload]

>Jedamere Looks to me you need to beef yours up more.

 

[Woody.v8]

Haha he's got a lot of faith in it, he hides in his car while its running!

 

[armalites]

I suspect it may be a bit chilly there

 

[Jedamere]

>Jedamere Looks to me you need to beef yours up more.

The design I built mine too should work as the guy I got it from uses his frequently, I did reinforce the clevis plate with a bit of 12mm plate but it still doesn't want to work

 

[8ob]

I am looking at this and wondering if the U strap was made longer under the tube ( pinch bolt also) whether the former may have a better chance of starting the bend, thinking along the lines that the former was swung out a little may give the ram a fighting chance of a start/lead . Just thoughts.

Bob

 

[WorkshopChris]

I am looking at this and wondering if the U strap was made longer under the tube ( pinch bolt also) whether the former may have a better chance of starting the bend, thinking along the lines that the former was swung out a little may give the ram a fighting chance of a start/lead . Just thoughts.

Bob

The same thing was going through my mind, at the moment everything is directly in line above the ram, its as if the the arc on the former needs to be under the ram at the the moment it looks to be at the flat on the end, once it starts it should follow the arc on the former through.

 

[daedalusminos]

This type of bender is designed so there is minimum offset between pivot and force input - thus it needs lots of force but little travel, exactly what a bottle jack provides. Unfortunately this means it's also horribly inefficient with most of the force being exerted on the frame. Look at your design and you'll see most of the forces are in compression or tensions through the steel, except that lower plate that contacts the jack - it's the weakest link. Try welding some 'fillet' plates in a 'V' from jack contact out to top edge.