Rolling brass sheet

I have a small manual bending rolls....the sort you can buy for about £100... so fairly lightweight and nothing too sophisticated. When rolling some 28 gauge brass sheet to make a loco cleading sheet the other day, the edges of the brass were distorted into what I can only describe as a sort of frilled edge. The rolls were tightened down to pretty much maximum. I got the impression that the outer edges of the brass were being squeezed more than the centre part thus causing the "frilling". The brass sheet seems to be of a "hard" variety and I did not anneal it before rolling. The size of the brass sheet was 6" x 8" with the 6" dimension being fed into the rollers. Before I waste any more brass, the questions that I would like answered are:-

1. would annealing have made any difference, and

2. is this the sort of result I might expect from a cheapo rolling machine.

Mick

Hi you had the rollers too tight causing the edge.to frill too tight causes the roll to bend.We used to roll polished stainless with cardboard both sides to prevent marking the sheet.

It does sound as though the brass was being squeezed between two rollers, rather than just bent around three. This is a 'standard' technique for reducing sheet thickness, but it puts a big load on the rollers etc, and if they are not man enough they will be forced apart - and more apart in the middle than at the edges. Hence your frilliness.

'Pretty much maximum' with any modest tool is likely to show its limitations.

Cheers, Tim

Michael/Tim. I think that you have pretty much summed up what has occurred here and where I have gone wrong. I had a nasty suspicion that it was "operator error" ! I shall give it another go tomorrow although I would appreciate an opinion on annealing. The diameter I am trying to roll to is approx 2".

Mick

Brass does work harden but also air hardens over time so it will ease the rolling process if you anneal it first.

The rolls should only be tightened enough to grip the sheet sufficiently to feed it through the rolls. Don't try to roll it to tightly on one pass, do it in several rolls and increase the amount gradually. You may have to anneal it more than once to get a clean roll.

Are your feed rolls geared together? If so you shouldn't need excessive pressure to allow successful feeding.

hi mick,

the brass should be ok with rolling. 28 swg isnt much. ive never had the crimping effect on my home made rollers. dont anneal the brass especially 28 swg. there is something else wrong that i cant fathom out with your results.

cheers,

julian

My first thought is -28 sgw is pretty thin so shouldn't put a big load on any set of rollers.

Second thought is, you can always roll it in more than one pass, which might make it less likely to distort.

Neil

Thanks for the input gents.......I have now completed the task and I am now wondering how I made such a dog's breakfast out of what proved to be a simple procedure. Quite simply, I had tightened the rollers down far too much. Still, it is good to know that your excellent advice is so readily available.

Mick

I have a set of geared rollers made to the GHT design, and have experienced the same effect as Mick has described. The solution here is to remove one of the gears, hence disabling the gear train and reducing the pressure.

Roger

Oops, yes I'd somehow misread the gauge of the plate, agree 28SWG is light enough not to need annealing.

Roger, not sure how you perceive that removing the gearing on the rolls reduces the pressure. The whole point of the gears is to ensure the top and bottom rolls turn in sync and in my experience reduce the need to tighten down the top roll so much. I also have the GHT style rolls albeit in a scaled up version. Happy to be enlightened

Graeme W - interesting thought, but I can only comment on my own experience.

In his workshop manual book (p 213), GHT says "An interesting feature of the proposed gear drive is that any increase in the resistance to movement of the work through the rolls is accompanied by an automatic increase in the pressure between the driving rolls" I can only think that in my case I started off with too much pressure and that the resulting resistance further increased the pressure between the rolls and resulted in deformed edges.

You have probably avoided the problem by reducing the pressure from the top roll, whereas I've not increased the pressure by removing a gear - same result.

Hi

I have a set of bending rollers which I purchased second hand and I'm using for the first time. I have been trying to bend the 'wing' flanges for a Rainhill tender. I'm using 20SWG brass sheet about 8 inches long and 2 inch wide tapered to 1 inch. I am trying to bend along the 8 inch length. The problem I have is that I cannot get the rollers to move the sheet. The rollers go round but the brass just slips.

It may be that the size of brass that I am using is just not suitable for putting through rollers.

Any thoughts would be appreciated any alternative ideas on how to form these flanges other than bending would be really helpful.

Thanks

Mike

Mike, I did something similar by cutting strips from a suitable size tube 1 piece of tube would provide all you need. when the piece is cut and cleaned up, I can be soldered to the tender side.

Chris Gunn

Hi Chris

Many thanks for your reply. I have ordered a length of 2" dia 20SWG brass tube. Any thoughts on how to cut it? I don't have a band saw but do have various jig saws and Dremells....and of course a hacksaw!

Mike

Mike,

You could insert a piece of suitable wood inside the tube, then cut with either a tubing cutter or fine tooth hacksaw.

The wooden insert prevents the tube deforming......

Rolling thin sheet can be over engineered. As a past builder in O to G3 locos a pile of newspapers a hefty lump of round bar longer than the sheet as a rolling pin adopt a known position facing Mecca and burn of a few calories. Remember to check the bar surface for 'dings' and place paper between roller and sheet. Should the tyros in our midst be unfamiliar with the term 'rolling pin ' MIchael G of this Parish. Has been placed on alert😜