Re-casting LG2/Colphos 90 into plate form

Hello all.

I was recently trying to get hold of some LG2 (or Colphos 90) but in plate form. It soon became clear that these materials are more widely available in hex or bar and that I'd find it nigh on impossible to buy as plate.

My question is, if I absolutely needed LG2 in plate, how feasible would it be to get a foundry to melt a bunch of ingots and re-cast 'em into plate? Would it dramatically change the free-cutting/weather-resistant properties? Would it end up looking like the inside of an Aero bar?

This is just an idle question from someone who doesn't know all that much - I'll likely go with Naval Brass (CZ112) - not as aesthetically pleasing, but available in plate and meets the hard wearing / good in a marine environment requirements. Not as free cutting, but should be OK - there are a lot of letterforms which will need to be machined using end-mills down to 0.5mm, as in the pic.

Many thanks for your advice, excogitation etc.

Wal.

Would PB102 do? if so M-machine do that in sheet form as well as flat strip

Hi Jason,

I looked at PB102 - with a machinability rating of 20% (poor) and requiring copious flood (of which I have but a meagre trickle) I get the feeling that I'd be fighting a losing battle using the tiny end-mills.

Wal.

What size & thickness pieces do you need?

Edited By JasonB on 09/02/2022 16:26:27

One off - 582 x 98 x 6mm (thickness can be greater, up to 10mm)

Admittedly an odd size.

Wal.

Edited By Wal Werbel on 09/02/2022 16:30:35

They do LG2 block 11mm thick and price by teh 25mm x 25mm square, may be worth e-mailing lynn to see if the blocks are big enough to suit your needs.

Hi Wal,

They shouldn't have a problem casting that, and you won't get any loss of machinability or corrosion resistance (in fact the machinability will be better). If the surface area is large compared to the volume you unlikely to get draw holes, as is the case with your plate. Plates are easy to cast when compared to large volume - small surface area components like cylinders or bars. This is of course assuming the foundry is even remotely competent. Cost is of course another matter.

Hope this helps...

Cool, well spotted Jason.

I'll drop 'em a line to see what's available.

Cheers!

Wal.

Many thanks for that info. Hehe - ah yes, it's always the cost that decides..!

Wal.

I don't think they will cast plate as you know it. Plate is rolled to get the nice smooth finish either side. Casting will be rough and need machining down flat both sides.

Or could you machine those individual letters out of slices of round or square bar of suitable size?

These stock Leaded Bronze sheet/plate and flat bar :- S&D Non-Ferrous

Might be worth giving them a call.

Edited By Nick Hughes on 09/02/2022 22:15:54

I see what you're saying - although I wouldn't mind facing off both sides, as long as the thickness is there. Machining the letters individually wouldn't work for this job - imagine a long flat bar that gets inlaid into a paving slab - kind of a heritage way-marker.

Thanks Nick - Yep, I dropped them an email last week - the closest they can do is PB102 or CZ112.

Hi Wal, is this a commercial (paid-for) job? There is another option that may be worth considering.

If you are going the cast route then why bother with getting a flat bar cast.

CNC the whole thing including letters from some pattern board and have it cast with the letters as most nameplates are be it with pattern makers letters or these days a CNC pattern. I'm just doing one for a friend.

Edited By JasonB on 10/02/2022 07:17:09

Casting that in high definition is easy ! Gun metal or brass ? Serifed letters in a size of your choice from 1/2" to a 4" in plain. Flat background or raised border ? Noel.

Thank you fellas,

Yes, of course - that's the straightforward approach, just make the pattern and get it cast. So the next part of my question is how much detail can I expect to lose? As mentioned, I know bugger all about casting and what can be done nowadays. Some of the letterforms get quite small (5-6mm in height, occasionally with serifs) and my customer would be after a specific background 'texture' which may or may not be problematic - I'll post a couple of example pics of bits and pieces I've done for him below.

But of course - if bronze is absolutely what's required then casting it is the way to go, I think that in his mind's eye my customer is seeing a rougher, pitted finish and a greater loss of detail than he'd perhaps want - CNC machining it takes away some of those perils of casting.

Noel would be better places to say for sure but I would say you will loose some fine detail with sand casting particularly your textured backgrounds, if the part were smaller than investment casting would be a possible option.

You would also need to machine some draft angle onto the sides if the letters which either means a 3D toolpath with many fine step downs or using the edge of a tapered engraving tool with single flute, both options considerably add to machine time.

A woven background as in old AA badges is copied - every thread ! A showmans loco 3"long in relief, even the lettering round the canopy can be read - if your eyes are good enough. Using mansfield sand you will loose almost nothing BUT it will look cast. Check out any shot of the Fred Dibnahs MADE IN BRITAIN . Look closely and you will see 2 tiny dot marks for drilling, cast in ! Foundry lettering has a good draft as part of it's design. There are 3 standard fonts, flat face serif, 1/2" up, Flat face 1/4" to 4" and sharp face 1/8" up. The bevel gear illustrates the detail that can be achieved ! The 2nd image show the edges rounded due to polishing. Noel

PS this is over 20 years old and was done for OLD reeves ! N

Edited By noel shelley on 10/02/2022 23:57:05

Hi Wal,

If this is for a specific job with only one letter size, it might be easier to find the minimum size circle which will fully circumscribe the biggest letter and buy a length of round bar of that diameter. LG2 is easily parted off so if you faced the end of the bar and parted off a 6mm length you could then loctite the faced side onto a piece of aluminium as shown in your photo. Repeat until you have the number required and face them off using a fly cutter. Then it's just a case of milling out the letters.

Regards,

Alan C.