Cutting brass sheet for wagon floors

[JimG]

I've been watching this discussion about the brass wagon floors and I think I would go for cutting them on a milling machine - either vertical or horizontal. This means that the sizes can be accurate and repeatable especially if the machine is CNC controlled. I would also use engraving brass which is flat. I get my brass sheet from Ian Cobb and it is flat. Ian Cobb cuts his sheets with a bandsaw so no distortions from guillotining.

Ian Cobb Brass Sheet

Unfortunately he is out of 1mm sheet at the moment.

I also note that you can also get laser cutting of brass - e.g....

Laser Cutting

...although I don't know what the finish of the edges might be compared to the machined quality from a milling machine.

Jim.

 

[markjj]

When I built a batch of ABS iron ore wagons a few years back I was lucky to have a Proxxon KS230 table saw in my tool kit. I had a very fine toothed blade that was perfect for cutting floors from brass about 0.5- 0.8 cm thick. These saws are about £140 new or you can pick them up for around £50-£70 on Ebay in good condition. I think a fine tooth blade was around £10-15.

 

[simond]

Does this process give a right angle edge on 1mm sheet?

a guillotine will cause some distortion, it’ll cause a fine “smear” of the very edge, in the cut direction, so there will be a fine burr on the underside of the stock, and the top of the stock will have a slight radius on the edge. Logically these will appear in mirror image on the cut off piece.

The edge itself should be square, assuming the guillotine is sharp and well adjusted, and the burr will disappear with a moment’s filing, or even a touch on an emery sheet stuck to a bit of heavy MDF.

 

[adrian]

Do you think that 0.75mm plastic is going to warp/distort when stuck to 1mm brass?

Not particularly - reticence was more how they'd be glued together, treating only one side of thin sheets plastic or metal never seems a good idea to me.

Ply was my initial thought... and then I was reminded by others that the original, full thickness floor had details on the curb rail / end rail, such not being possible with a wood floor.

Sorry I can't visualise the issue without knowing the prototype. Now I'm probably the least qualified modeller in the world to make this statement but I just wonder if you are overcomplicating the issue.

 

[adrian]

When I built a batch of ABS iron ore wagons a few years back I was lucky to have a Proxxon KS230 table saw in my tool kit. I had a very fine toothed blade that was perfect for cutting floors from brass about 0.5- 0.8 cm thick. These saws are about £140 new or you can pick them up for around £50-£70 on Ebay in good condition. I think a fine tooth blade was around £10-15.

Good point I have a little table saw for which I also got a little "diamond" grit slitting disc. I got it for another job but I'll have to try it on some thin sheet.

 

[Dog Star]

Not particularly - reticence was more how they'd be glued together, treating only one side of thin sheets plastic or metal never seems a good idea to me.

If we follow the direction as noted here then we shall (a) find out and (b) tell all.

I just wonder if you are overcomplicating the issue.

Maybe, probably...

A characteristic of CAD and 3DP seems to be knowing when to stop. Drawing a 3D model of the detail on the prototype is easy and a regular activity; 3D printing that detail as part of a bigger picture often presents a result that is not achievable with other manufacturing processes, such as injection moulding or lost wax casting or etching. In the case of the current project we have a 3DP for the wagon body and for the floor and those parts have details included as surface features - having got such details with a 3DP then we are reticent to change processes/construction if that means loss of fidelity.

Wooden body (prototype) wagons often had cleats or reeves for tying the sheets of tarpaulins and (at least) the GWR put such rope-off points on the outer, vertical, face of the curb / end rails. We have those rope-off points in our 3D CAD and we have included that detail on the vetical edge of the 3DP for the wagon floor. We shall lose such detail if we replace the 3DP floor with a single layer such as plywood or brass... hence the idea of placing a brass sheet within a recess in the bottom of a 3DP floor.

regards, Graham

 

[OzzyO]

Hello Graham,

how about this bench top shear from Chronos


Or this one?

Just look them up at Chronos.

ATB

OzzyO.

Edit for spelling mistake.

 

[simond]

The shear will definitely leave the cut off parts curved and maybe twisted.

A proper straight blade guillotine does not seem to do that, but I guess it depends on the angle of the moving blade to the fixed one.

 

[Dog Star]

If a guillotine is top of the way forward then I shall certainly look for outside, maybe commercial, help.

 

[Mikemill]

Graham

I would echo the recommendation of the Warco 3 in 1 sheet metal tool, a good investment.

I have had one for many years and use it all the time, a good shear, excellent for boiler rolling, and bending.

Instead of using to back fence I clamp a fence to the front plate that way the piece you want stays flat, plus it is easier to see and adjust.


Mike

 

[Paul Tomlinson]

7'6" is 52.5mm in 7mm/ft, which translates to 2.07". 2" wide brass strip is readily available in a number of thicknesses, which would mean you'd be half way there?

Or club together and buy the Mini Formit.

 

[Lancastrian]

I should have thought a guillotine [as were sold by Metalsmith in days of old] if repeatability is the name of the game.

I saw eight of them, brand new, last Tuesday just waiting completion to then go out to customers!

 

[GrahamMc]

OK, so the S7 modellers in B'stoke are a tad mad, just pushing boundaries, just pushing.

On eBay now, one mini Formit, it's in Frome.
Starting at £75, on for a couple of days. Grab it quick?
I'm glad I checked, I'm sure someone here will want it if it's a bit far for you, Graham, or you can't arrange a courier.

Or go back to the hacksaw/scrawker ideas and use a bench disc sander, as below, to clean up the edges and get the dimensions accurate, unless you have access to a milling machine which would be better.

 

[OzzyO]

Hello Graham,

if you've got the space and money this would be a good buy and it's delivered.

www.ebay.co.uk/itm/394205964863?_trkparm

ATB

OzzyO.

 

[David Waite]

The Bench top Shear that OzzyO displayed is for cropping lengths of solid material only
not normally used for cutting sheet material, guillotines are used for sheets, when a burr is formed on the lower edge of the sheet that is on the guillotine after the cut, is normally due to a worn blade or flex from cutting thick material that the machine wasn’t designed to do but mainly just too much movement in the blade this is adjusted by tightening the line of bolts that push on the rear slides these are normally tightened to a maximum friction that almost stops the blade from moving and well oiled, bear in mind this is for full size machines not models but i would assume they would have the same characteristics and full size machines have a full set of spring loaded clamps that press down on the sheet before the blade contacts the sheet this stop’s distortion and movement and prevents the sheet from trying to roll over the edge and follow the blade down, different materials can act differently in a guillotine some will come out perfect some not so good.
David.

 

[Dog Star]

Thank you to all those who have contributed to this topic, there is more than enough information to keep the discussion active at our next local modelling "T&C get-together".

 

[OzzyO]

T & C ???????

 

[Dog Star]

tea and cake

 

[Brian McKenzie]

if you've got the space and money this would be a good buy and it's delivered.
www.ebay.co.uk/itm/394205964863?_trkparm

Like other WT'ers, I've been happy with the performance of one of these '3 in 1' machines, for guillotining thin brass and nickel silver sheet that we typically use for our models.

I'd not previously cut anything thicker than 0.55mm n/s - and as that took a good couple of chomps with the handle to cut 300mm wide sheet, I suspected that anything much thicker would start straining the machine. And so it proved:

The piece of 1mm brass guillotined is approx. 215 x 58mm. The edge of the cut requires minimal cleaning up, but about 3mm of curvature was introduced over the length. Should Graham wish to advise exact dimensions for a wagon floor (and PM's a delivery address), I'll finish mill to size and pop it in the post for his experimentation.

-Brian McK.

 

[Dog Star]

Some progress of a sort...

Guillotine sheet into the required sizes is an option although sources tell me that the plate may become curved / twisted in the cutting process.

Laser cutting from Brass sheet is possible, a quote from PPD is 24 parts at £4.50 per inclusive of VAT and delivery.

Photo etch of brass sheet is possible, costings on PPD website indicate that 24 parts are going to be in the region of £5 per inc. VAT and delivery.

Summary? still looking.