Plaque material

I have (perhaps unwisely) agreed to make an engraved plaque for a tree planted to celebrate the Jubilee. Obviously this will spend its time outdoors, any suggestions for material please? My initial thought is to use ali as I have some 10 mm plate to hand, with a mounting post of stainless steel tube, with stainless fixings. Site is well inland and rural so salt and pollution level is low. Will engrave on my CNC mill and if possible do an intaglio job with a black wax or resin in-fill. If possible will also use some kind of passivating coat or laquer on exposed metal surface. If it all works at a later date I might do a brass version but that sounds pricey! Questions:

• Any reason why ali should not be used? Will it just corrode too quickly (especially with stainless fixings)?
• Could anyone recommend a protective coating?
• Is there a source for some kind of engraving wax or resin (I know I can get black epoxy from Maplins, and one can even use Araldite mixed with lamp-black!)?

Any suggestions or ideas gratefully received!

Thanks, John.

John,

I too was approached to make such a plaque but as my engraving skills are somewhat lacking I chose to decline.

I have a sad feeling the preponderance of non ferrous metal plaques in Jubilee and memorial woods is likely attract the wrong kind of visitors and I would therefore be inclined to consider a non metallic alternative such the plastic laminate of the type that has been engraved by sign makers for many years now. Such a plaque would perhaps not be as attractive as a polished metal one but at least the material would not deteriorate in the elements and would have little attraction to thieves.

On the subject of protective laquer I have in the past protected unpainted metal with the clear acrylic top coat from two part car paints, this is very easily available, seems to adhere well to most materials, has a high gloss and is very hard wearing.

Ian.

Get an offcut of some Corian (or equivalent) from somewhere that makes kitchen worktops. Nice to machine, easily shaped, many colours and doesn't need protecting from the weather.

Martin.

Thanks for the lacquer suggestion Ian! Round here we don't seem to get much criminal activity and they would get better pickings off the church roof...probablt famous last words!

I wondered about Corian, will look into that, thanks Martin.

You can get engraving wax from Meadows and Passemore.

Russell.

Most engraved plates here are done in stainless, bonded on to what ever and screwed as well, but bronze/ brass, even attached that way seem to disappear, and thats in a rural area. The Corian sounds like a good wat to go, anything with no scrap value. Ian S C

John,

PM sent, see my messages box, top left.

John S.

John, as a long time engraver I would recommend the Coriann sheet as a base and to fill the lettering use cellulose paint in whatever colour you want.

Then I would spray all over with an Acryilic spray that they use on circuit boards.

There are Laminates wwith various interleaved colours that can be engraved through to the one underneath, for instance Black sheet with a white underlay that shows when engraved through.

I found Hindleys.com and their price for coloured laminate is good.

Clive

Edited By Clive Hartland on 24/05/2012 15:21:12

If you do want to use aluminium, note that lots of anodised alloy doors and windows are about that have lasted many, many years.

Personally, I prefer a wooden plaque that can slowly degrade away as the tree grows - the tree should be the lasting monument to human whimsy, not the plaque.

Neil

Folks, thanks for all the ideas and suggestions. A local joinery has kindly supplied a metre square bit of white Corian gratis, so I'm going to have a go with that and filling in the letters with paint.

Yes this wood sounds perfect and at least the pikies cannot sell it for scrap.

Wood ? Corrian is plastic

Well, I went the Corian route and the result is OK but not as good as I would have liked. Blowlamp, what speed do you run the cutter at for engraving Corian please? I used a 30 degree taper engraver cutter running at 5000 rpm, fastest my mill would go, but the letters are not cut all that cleanly. Anyway a good learning experience...

BTW if anyone is interested, I used a free open-source program called F-Engrave to generate the G-code. It's very easy to use though a limited set of fonts and you have to use the same font size and style throughout.

From what I can find out acutting speed from 12000 to19000 rpm, with a feed rateof 1.5 to 3 inch per sec. If getting things wet is no problem, a spray of soapy waterwill help, or keep the nozzel of the vaccuum cleaner close to the cutter. The warning is to make chips, not dust. Wear a dust mask.

Ian S C