Author Topic: Bending rolls  (Read 244 times)

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Offline Nick

Bending rolls
« on: Jul 21 2020 09:26 »
As a diversion from the T3 project, I built a set of bending rolls. At some point I would have to roll a boiler, firebox, cab roof, and various other bits and pieces, and the idea of using a selection of rods and tubes seemed a bit hit and miss. I know it can be done, but I liked the idea of using the proper tool for the job. I had made a smaller set for the smaller gauges years ago but something bigger was called for.

The starting point was George Thomas's design, published in ME some time in the 1970s and republished in Model Engineers Workshop Manual. I redrew it, converting dimensions to metric because that is what I use, changing some dimensions to suit available stock, and generally simplifying some of GHT's elaborations such as using stock hex bolts instead of his turned and knurled screws with optional tommy bars. I chose the de luxe version with a gear drive between the driving and pinch rollers.

Yes, I know I could have bought one but this way I have just the tool I want. Besides, I like machining!

Nick






Offline 753

Re: Bending rolls
« Reply #1 on: Jul 21 2020 09:47 »
Nick
You have made a very nice job of the rolls, they are most useful.
I bought one of these universal sheet metal forming tools a few years ago, now used all the time especially the shears, would not be without it, sold by many tool suppliers.
 https://www.machinemart.co.uk/p/clarke-sbr305-3-in-1-universal-305mm-sheet-me/

Mike

Offline IanT

Re: Bending rolls
« Reply #2 on: Jul 21 2020 11:03 »
305mm?

They used to call that 12" when I were a Lad   ;)

IanT
Nothing's ever Easy - At least the first time around.

Offline cabbage

Re: Bending rolls
« Reply #3 on: Jul 21 2020 11:18 »
My clone is from Axminster tools - they call it a fabricator. The only thing I can complain about is the fact that it only has one crank handle... This either left (yay!) or right fitting, but for an even "pull" I would love a second crank handle.

Regards

Ralph

Offline Nick

Re: Bending rolls
« Reply #4 on: Jul 21 2020 19:21 »
Mike,

Shears - the ones I've used have always left a little bit of distortion at the cut edge. I haven't had to do much platework in G3 yet but what I have done, I have managed well with my trusty piercing saw. But we'll see how it goes.

Ralph,

Congratulations for spotting that I'm left handed! The gear drive avoids the need for a second handle.

Nick

Offline cabbage

Re: Bending rolls
« Reply #5 on: Jul 21 2020 19:44 »
Nick, being a sinister person as well... It is easy to spot!!!

Regards

Ralph

Online John Branch

Re: Bending rolls
« Reply #6 on: Jul 21 2020 19:56 »
And here was me thinking the photo was back to front!

John

Offline 753

Re: Bending rolls
« Reply #7 on: Jul 22 2020 09:43 »
Nick
One area were the shears are very useful is cutting narrow strips boiler bands etc, if you use the shear in the conventional way the strips are distorted, but if you reverse the stop i.e. clamp a fence in front of the shear, the cutting force is against the bed thus the strips stays flat.
As we used to say instead of raising the bridge, lower the river!

Mike

Offline Nick

Re: Bending rolls
« Reply #8 on: Jul 24 2020 08:56 »
That's a good thought. I was thinking to use commercial brass strip available in 3.0 x 0.15 mm section, which is very close to scale, but I'll keep it in mind. I won't have to decide for some time yet!

Nick