upgrading my opinion on the JD2 Bender

[smudge]

I haven't had much nice to say about the JD2 Bender...ever. With some manipulation, it's possible to make it usefulish. I've been struggling to bend seat tubes for a while now, having sent out hundreds of $$ of material only to have half of it come back useful. Now I have a bit more hope.

Basically, all you need is a "follow" block and something that puts pressure on it. As a quick and easy proof of concept I turned down a 7/8" bar and popped some bushings into the JD2 frame. I used a crappy harbor freight hydraulic ram and the SWAG offroad holder to make it easier...mostly to prevent the backlash normally present when using the ratchet mechanism.


what's also needed by VertigoCycles, on Flickr


What's needed by VertigoCycles, on Flickr


1 3/8" tube bent by VertigoCycles, on Flickr

I'm going to machine a new, larger radius die over the weekend and will sell this one. I've also started designing a "roller carriage" that uses a screw to jack it into the follow block to eliminate all of the slop...that will hopefully eliminate the slight denting, but even if it doesn't this is the most functional this bender has ever been for me.

[edoz]

Is that block in place of the follower that comes with the bender?

[smudge]

Is that block in place of the follower that comes with the bender?

it's not, I made that.

[TrailMaker]

Hey;

My Pro Tools 105 has a tension maintainer included in all of the smaller radius die sets. I'm not sure at what point they are added, but it is offered. My .75" die set came with it. It consists of an extra full length chassis pin with a flat on one side to be set in the main frame. The follow shoe has a tab welded on it that a large bolt threads through and into this pin, pushing the follow die forward and into the material, with variable tension based on how hard you crank the tension bolt. I'd be glad to snap a photo for you of it in use if you'd like. It looks like this in the catalogue;



There is no spring back with that tensioner tightened, and you cannot release the tube until that tensioner is relaxed. I suspect that this is a mandatory item for all thin wall tubing, all of which within our interest is exceeding the recomendations for minimum wall thickness. I have never had any problem with thick stuff like .095 -.120, but have had failures at as thick as .063 without the tensioner. I can very easily bend .035 wall tubing using the ratchet with no kinks and only the usual compression distortion.

I don't think you will ever eliminate that compression distortion using a draw through bender. Not that it isn't worth a try. The tension adjuster may help that.

[edoz]

it's not, I made that.

Ok, let me rephrase that. Is the block that you made used as a replacement for the stock follower?

[smudge]

Yes. Instead of being fixed on a pin with the tube slipping through, it stays fixed to the tube and rides on a roller.

[todwil]

Yes. Instead of being fixed on a pin with the tube slipping through, it stays fixed to the tube and rides on a roller.

So you turn it into a greenlee bender?