# Shop Outfitters Bending Die Review



## RCP FAB (Jun 15, 2011)

I finally broke down and ordered a 3/4" die set from shop outfitters. This is all an attempt to bend chain and set stays for my trials frames, but I have seen people ask about the dies in the past, so here is some information on them.

As of right now I have no idea if this set up is going to bend thin wall chromoly without damaging it (to the point where I need it bent anyway).

Price: $169.58 to my door
CLR: super tight, around 2.5"
Die finish: Very smooth, much better than I was expecting

The main reason I chose this over any other die set, was the roller, vs a drag block. Also, it has a really nice stop block, vs a strap with other dies like JD Squared.

Here are some pictures. Once the metal comes in to make the actual bender I will post the results. The bender I drew up is going to be wall mounted.


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## shandcycles (Jan 15, 2008)

The problem I see with that wall mount bender is that you're only going to be able to start your bend near the end of the tube. So you won't be able to do s-bends or anything else funky.

(unless you've got a void in the wall behind the bender?)

Steven


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## RCP FAB (Jun 15, 2011)

I am not sure that I would attempt any s bends with this small of a CLR. This was planned to be a bender specific to doing a super tight bend in 3/4 x .049 and .058 for trials chain stays and possibly .035 seat stays if it doesn't ruin the tube.

Though if it is possible to do nice s bends with it I am sure that I will regret not having it designed to do so at some point in its life.

Thanks for the heads up, I will look into it.


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## RCP FAB (Jun 15, 2011)

These are what I have been using. I am trying to replicate them from some heavier, straight tubing.


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## smudge (Jan 12, 2004)

RCP FAB said:


>


If you fabricate the bender exactly as shown in the drawing, you might not get what you're after.

For your best chances at bending without buckling, your two round dies are going to have to practically sit on one another (as in your drawing) to fully encapsulate the tube. Your clamp block, if setup as in your drawing, wouldn't allow you to put an axle through the roller when it's positioned at the beginning of the bend. You'll have to move the clamp block back (toward the wall)

One more thing...that roller is going to leave a sweet dent at the end of the bend. If you want to avoid that dent in your frame, you'd best pull the roller toward the BB end of the tube so you can cut the dent off with the BB miter. You obviously can't do that if your rig is mounted to a wall as shown.


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## RCP FAB (Jun 15, 2011)

Thanks for the tips Sean.

The stop block has that radius on the roller side of it, and the hole is off center in it. It allows a piece of tubing to be inserted into the bender, even with the die, roller and stop block all in place.

As far as the denting, I didn't even think of that. On mild steel these dies are supposed to work for flawless 180* bends in .049 and thicker. I guess I will see how the chromoly fares.

Thanks again


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## j-ro (Feb 21, 2009)

Havent checked in here for a bit but here's what I know about what you got going.

The stop block while good will still need to be backed up by some form of clamp to keep it from pulling thru. Sacrifice a pair of vise grips and run a 3/4 end mill thru the jaws to make a perfect clamp for the back of the block.

second, your follow die needs to be able to be advanced towards the main die to tighten the tolerance or it will crinkle the tube.

alternately, if you drill the hole for the follow die in the right place you can drive the whole shitteree together around the tube with a tapered pin to draw it tight

I think you may want to rethink the mounting, it looks kludgie to me and if you do get it working right you will be wanting to use it for more than just one thing.

You may be better served to construct it to bend 180* and then cut out the pieces that you need.

Let me know if none of that makes sense and i'll try to clarify.

jake


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## teatreetim (Nov 14, 2011)

The clamp should hold the piece. It's no different in principle to the attached pic. It will give a flaw at this point though because the wheel wont get right up to the clamp. I would do one bend per piece and cut away the beginning bit for a nicer finish.


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## j-ro (Feb 21, 2009)

the clamp won't hold the piece. It would hold if you were bending the mild steel that it was designed for but the harder 4130 fights back and will slip.

My point about bending 180 was more to have him think about alternate anchoring setups and how the bender actually loaded.

My comment about the slipping was from direct experience with the bender as was the comments about how to set it up. I've bent more than just a little tubing with mine.


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## mickuk (Jul 6, 2007)

teatreetim - I've got a version of the bender in your pic (the same bender is badged to lots of different companies).

The basic setup is sort of OK - the bit that bolts to the bench and the arm / adjustable roller position so you can take out slack.

But beyond that it needs lots of rework to make even homebuild quality bends.

The holder / stop for the tube is the very worst bit. I've not had trouble with the tube slipping or pulling through, but it is far too narrow and puts in nasty dents. I've had to make new holders for every tube size, with a long contact area and radius edge.

The rollers also only touch about 1/4 of the tube diameter - so they leave 2 grooves, and the cast quadrants have an awful profile. Both of these issues can be improved by tidying them up in a lathe.

Rcp's setup addresses most of these problems (long holding block, all parts with a good quality full tube profile). But I still think adjustment of the roller might be needed.

I also find that the point loading from the roller can still be bad for putting dents into thin wall tubes. I've had much more success using a drag block and running a plain roller or ballrace along the back of the block - it still only contacts the tube at a single point, but it does tend to spread the load more as the tube deforms.


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## teatreetim (Nov 14, 2011)

I have 3 benders, one similar to the pic but a different brand. My point wasn't that the example I showed gives perfect bends. Using that drawn system the pull out force is a vector of the total force so the smaller the bend radius, the greater it will be held in by the clamp. I've modified my bender too but no matter what that system wont give a perfect result. The other 2 benders I own use drag blocks but cost a few thousand each with dies.

Notice theres already a clamp bolt in the OP's pictures.


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## RCP FAB (Jun 15, 2011)

Here's the new design. I am still working on something to tighten up the roller, but this should get it going. I ordered the materials over the weekend, they may be here for Friday.

Still has the option to be wall mounted, or bench, or floor with a longer tube.


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## RCP FAB (Jun 15, 2011)

I got the bender made today. Came out as designed, so thats a plus. Drilling a 13/16" hole though a 3" piece of 1.5x1.5" cold roll was... well... intersting. So was welding this with my diversion only plugged into 110v (can you say multi pass?)

Anyway, the (probably very much overbuilt) bender is built. I clamped it in the mill vise today to give it a test (until I get it mounted on the wall). There is definatly a learning curve, the accidental jerk of the handle will ripple the tube.

.035 takes a mild amount of force to bend with the nearly 5 foot handle. I bent a test piece to 55*, the inside came out very smooth when even force is applied, the outside flattened out some, but not in a way that looked too bad. I also highly doubt that I would be using any 55* bends on a bike frame.

.049 and .058 will get tested when my chromo order shows up, for some reason it didnt get shipped with the rest of the order.

The biggest issue that I am running into is the tube slipping, as Jake said. I am thinking about getting a few of these McMaster-Carr to clamp on the tube and wedge up against the block.

The vise grips were and epic pain to blow an end mill though, and when all said and done still left marks in the tube making s bends impossible.

I may try freezing a tube once I get it mounted on the wall, I would really like to bend some .028 for seat stays, but currently I dont think it will do that thin.

Also forgot to take pics today, so I will get some tomorrow or over the weekend.


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## edoz (Jan 16, 2004)

RCP FAB said:


> The biggest issue that I am running into is the tube slipping, as Jake said. I am thinking about getting a few of these McMaster-Carr to clamp on the tube and wedge up against the block.


Those would probably work well, but I was kinda thinking of the tube blocks from Paragon Machine Works. Either way, thanks for the report.


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## j-ro (Feb 21, 2009)

RCP FAB said:


> I got the bender made today. Came out as designed, so thats a plus. Drilling a 13/16" hole though a 3" piece of 1.5x1.5" cold roll was... well... intersting. So was welding this with my diversion only plugged into 110v (can you say multi pass?)
> 
> Anyway, the (probably very much overbuilt) bender is built. I clamped it in the mill vise today to give it a test (until I get it mounted on the wall). There is definatly a learning curve, the accidental jerk of the handle will ripple the tube.
> 
> ...


If you have a paragon tube block that will work to clamp as well but yeah, split collars are the way to go.

The thicker tubing will bend like a dream if you are getting it to work on the .035 all ready.
.028 is a big ask. I've always said that one day when I run out of projects I will buckle down and make it work but i've never had much luck on those smaller dies. It rolls great but bends like crap.

The slight ripple you are getting means the follow die still needs to move closer yet.
The fact that the follow die is out past the bend point means that it is breaking the tubing over the fulcrum and making the crinkle.

Believe me, when you get a clean bend they will hear the 'woo-hoo' two blocks away.

don't forget pictures !


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## RCP FAB (Jun 15, 2011)

As of right now, the only way to get the roller closer is to spin it, or the main die down (which isn't out of the question).

I will need to do some s bends and see how they come out. If those come out nice I wont touch the layout.


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## j-ro (Feb 21, 2009)

RCP FAB said:


> As of right now, the only way to get the roller closer is to spin it, or the main die down (which isn't out of the question).
> 
> I will need to do some s bends and see how they come out. If those come out nice I wont touch the layout.


Not being a pain here but really trying to help.

If the dies are so close that they are touching and you can still slip the tubing thru them to load the bender with the whole thing assembled then you will probabally need to adjust them somehow. They must've changed them somewhat when they went from the the 20/20 model to the 20/40 model.

I do remember buying a set of closeout 1/2" dies when they had them up on the site so maybe they're not interchangeable.

When mine is loaded without the clamp block tightened I can just barely tap the tube back and forth with a hammer, it's tight. Once it's bent there is play to move things around and take the tube out but not before.


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## RCP FAB (Jun 15, 2011)

pics finally


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## RCP FAB (Jun 15, 2011)

Bent up some chain stays today. .058" wall. The heavy stuff comes out perfectly, I haven't tried .049" yet.

I will say, even with the 5 foot bar, .058 takes a HUGE amount of effort to bend. I am going to have to order some 5/8" cold rolled bar to slip in the handle. The 7/8" x .120 DOM is very very flexy.


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## TrailMaker (Sep 16, 2007)

Encouraging stuff, Ryan;

Nicely rendered machine. Seems to be a habit of yours! :thumbsup:

I'm days from entering my own bending odyssey. I've bent miles of tubing over the years, but never anything nearly this thin/resistant. I'm told by a very reliable source that it comes very much down to the quality of the material, but also the bender, and the proper procedure. I've got the first two, and hope to find the third! Although I can't stand wasting material, I'll probably try and blast some long bends just to see what I can get away with, but in reality I only need about 26* for the CS on #1.

Another thing that interests me is in continuing the ovalized profile at the bend toward the node end of that tube; where it would attach to the BB housing. I'm not sure that rendering it the old fashioned way with a mallet on a semi soft surface would yield an acceptable result. I'm wondering if a slip roller or something similar might work?

Keep the reports & pics coming!


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## RCP FAB (Jun 15, 2011)

Thanks. What size material are you using for the chainstays, 3/4x.035?

The .035 stuff that I bent as a test piece worked really well with the flattening on the outside for the trials frames because I notch them into the bend.

I want to make the roller adjustable (closer and further from the die) so I will actually be able to fine tune the flattening on the outside.


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## TrailMaker (Sep 16, 2007)

Notching right at the bend?

Oh, that's perfect. Look really sano! It not only looks right but gives you a little more room at the housing besides. I agree the adjustable roller will be crucial in controlling the stretch of the outside of the radius. Being able to control the bend apex environment right down to the exact diameter of the tube will allow maximum flexibility in the profile you can achieve.

When I see a tube that has ovalization at the bend, and has a straight section to either side of the bend, it looks moderately "amateurish" and less than aesthetically pleasing to me. It does not give me as good a structural feeling either. If I had a straight section from bend-to-BB housing, I would want the oval profile to continue on the straight section past the bend, just like one of the highly manipulated stay tubes you can buy.

Yes I will be using .75 x .035 CroMo and trying for s-bend stays. I will be trying this in my ProTools 105. However, I am not relying on the crude saddle and pinch bolt. I am going to try to make my own saddle employing a milled tube clamp arrangement to hold the tube from slipping. Waiting on the .75" ball end cutter and the tubing.....


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## RCP FAB (Jun 15, 2011)

Yeah, it works well for this. (2.8 tire clearance, 380mm chainstays and clearance for an 18T front cog)

I am going to work on the adjustable roller set up this weekend.

I would try to convert your bender into a non ratcheting type for this stuff. Even the slightest hesitation in the bend from start to finish kinked the tube when I was playing the the thin stuff.

Also, a 2 piece shaft clamp worked perfectly for holding the tube, it also only takes up about 1/2" of space between the bends, which was beneficial to my set up because the holding block takes up about 2.5" before the bend starts.


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## TrailMaker (Sep 16, 2007)

Yep;

I'm all over it. I've developed a contact (now friend) _in the industry_ and he has a ton of 
experience with all manner of building techniques, bending among them. He schooled me on 
the technique for my bender (he has one also) and this tubing. 'Like pulling an oar 
through calm waters" is how he put it. Smooth, solid, one deliberate motion. To that end, I've 
already adapted my bender.










Of course I've wanted to convert it to hydraulic for years, which might likely work well for this thin stuff. Now I just wish I could find the bend stop for this thing. Never needed it till now!


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## RCP FAB (Jun 15, 2011)

mmmmm s bends


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## Clockwork Bikes (Jun 17, 2006)

Very nice looking!


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## TrailMaker (Sep 16, 2007)

Wow;

Great results, Ryan. Really sweet. Now, let's see them in .035 !  (for inspiration!)

My 3/4-.035 tubing should arrive in the next few days.


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## RCP FAB (Jun 15, 2011)

Thanks guys. .035 will be happening soon, without too much issue I feel.

I started on the adjustable roller position today, more to come.



















And the new bench, which is now securely mounted to the wall.


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## RCP FAB (Jun 15, 2011)

I got the adjuster done today. Now I just need to get the dies turned down to the proper sizes.


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## j-ro (Feb 21, 2009)

You know what's wrong with that?

Absolutely nothing!

looks great, I've got bender envy now.


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## TrailMaker (Sep 16, 2007)

Hey;

Sweet, but that may be redundant.  Are the die profiles too deep?


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## RCP FAB (Jun 15, 2011)

Yeah, the die is the correct size, they just have a U shape more than half a circle


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## TrailMaker (Sep 16, 2007)

RCP FAB said:


> Yeah, the die is the correct size, they just have a U shape more than half a circle


Hey;

That is typical.

I'm going to hypothesize a bit here regarding what depth might be ideal. You have noted the rolling wave of material on the inside of the bends in the Di Acro thread? I'm going to guess that an extremely tight fit will exacerbate that phenomenon (as well as the "type" of bending being done - draw, roll, etc), while a loose fit will promote ovalization. I'm going to theorize that somewhere between the two extremes you will find the optimal compromise. All this by way of saying that you may have to sneak up on the right dimension for the rollers.

You may also be able to control the same aspects with your adjustable tension scheme. Now, this begs the question, do you want a perfect OD dimension in those rollers, or slightly less? Without the tension adjustment, I might assume you want a "perfect" OD fit. With the tension adjustment, you might want it somewhat under sized. in the end, the tension adjustment may only be necessary to take into account differences in OD or material properties with different batches of tube.

It's all a bit theoretical, and might not even play out that way at all. More testing required!

My 3/4 x .035 tube arrived yesterday..........


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## TLKD (Mar 29, 2010)

Wow that's pretty much the best looking bends I've seen from a 2 roller bender like this so far.

The very first one I made was very similar to yours and didn't do half as good so I went away from this design and made this one right there. "Pulling" the tube from the center round die seem to work better than pushing the tube onto a round die. On top of this I've added some sort of a mandrel attachment, which is basically just a bullet threaded onto a piece of 1/2-13 threaded rod that I can adjust with locknuts at the end. If the bullet is perfectly located at the tangential point of the bend, I can produce a 1" x .035" wall 4130 tubing on a 3" center radius die with less than .020" of ovalness. First sight it looks round, you really gotta get close to see it. I don't know if you could add something like this to yours but this might be a good way for some other guys still on the drawing board... Also, what I've noticed from a couple of tries is that the die's measurments (to match 1/2 the tube) seem to be very important, if they're U shaped, you will only be able to obtain a certain roundness. What I got now is perfectly half the tube but .005" deeper. (so 1.000" wide by .505" deep). I would assume staying within these proportions for bigger or smaller die would produce similar results to what I've got.

Cool thread by the way !

Cheers !


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## RCP FAB (Jun 15, 2011)

I finally got around to spinning the dies down to the proper size today. I left them slightly big, its always easier to go smaller. Right now with the 2 dies touching each other the hole left between them is about .005-.008 bigger than the .750 tubing is (which varies some). The bad part is I am out of .035 wall tubing, and I forgot the camera at home.


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