Here's a query that's a bit different... and I know that I'll get an answer on this forum...

I am planning to make a 'Polar Sundial' for the garden, like this one (but made of metal, not cardboard!):



Having recovered from seeing the cost of a suitable bit of engraving-grade brass ( ) I am now thinking of using a length of 'dull polished' stainless steel. This is affordable, weatherproof and strong. The trouble is - I will need to put lines and numerals on to show the time. I could try to engrave them - a skill I'd love to learn - but from previous experience I know that it's tough to work stainless steel.

Can anyone suggest an alternative method for marking out the metal that will be durable and weatherproof? I was thinking of etching the design, but I can't think of anything that would eat stainless steel (or, at least, anything I would be able to buy).

The only other alternative would be to get the engraving done professionally, but I'm sure that would be expensive...

Black enamal paint ?

Or some nice acid etching ?

how about spark erosion? might be a bit exciting, but I am sure that there is scope for the adventurous DIYer,...

:

Etch by sandblasting, the same way they do car windows?

I'll ask the wife, you should see the state of our 3 month old sink!

punches? I made a guide plate when I did my vin plate which was essentially a length of metal with very accurately drilled holes at set intervals and the letter punch is positioned using this. With a bit of practice on scrap reckon it could be made to be quite tidy.

or print out the numerals onto tracing paper and use a center punch to dot around the image??

Just an idea

Cheers

Rich

[Edited on 26/6/11 by RichardK]

For stainless etching chemicals, see these guys.
http://www.megauk.com/metal_etching_kit.php
The prices on this page are steep because they include a load of kit you don't need for a one-off design. However, the parts numbers for the individual components (such as the etchant) are listed so you could give them a call. Plus, I've got a UV exposure unit you can borrow if you need one as I'm only up the road from you.

If you wanted to go down the aluminium route, these guys are absolutely superb for front panels.
http://www.schaeffer-ag.de/index.php?id=97&L=1

Good luck!

Ed.

Any engraving company will lay you out a waterproof sheet.

Hydroflouric Acid

But DO NOT get it on your skin.

Don't look if you're squeemish !!

http://firegeezer.com/2009/08/11/whats-the-hf/

We have a stainless etching system at work that uses an electrical current applied through a sponge pad that is wetted with an etching solution.You make a screen print stencil using a special printer and then position it over the work , the chemical soaked pad is then applied and used to pass a low voltage current through the stencil and work piece leaving a nice dark brown to black imprint of the stencil depending on current and time used.
I don't know what the chemical is but it is not particularly dangerous, just normal basic chemical safety is required ie wash hands well afterwards.
A Google search for electro chemical etching should bring something up.
Paul

You can etch using a cotton bud and salt solution and a PP9 battery similar to the electrolysis process. Example here.

quote:

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Originally posted by Peteff
You can etch using a cotton bud and salt solution and a PP9 battery similar to the electrolysis process. Example here.

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Pete - that looks ideal! That page is now bookmarked. I knew this forum would come up with something.

As for hydrofluoric acid - a few years back I was talking with a bloke who had spent most of his life in the chemical industry (went from lab technician up to senior manager of research) working with some 'interesting' chemicals. He reckoned that he never lost his fear of that stuff...

I will investigate all of the other links though...

Thanks to all!

Laser marking would do it, lots of stailness (and other metal) parts are marked this way these days. Most systems are CAD or True Type Font driven so you could create the layout/text you want and supply to a suitable company along with your sheet of stainless.

ETA....once the laser system is programmed the work part is done (same as a CNC set-up). You could probably get a batch of 5 done for the same price as 1 and be left with 4 to give away as gifts to family etc.

Also, water jet cutting might be an option. Use a very thin sheet of stainless and have the patterns cut right through it, then bond it to a thicker back plate (maybe in contrasting material).

[Edited on 27/6/11 by nick205]

Hi David,

Laser etching is quite good, but not locost.

I have badges made by this method. (see pic)


laser etched badge


However, with number and letter stamps you could do something like:-


l
1
l

(The dashes are a capital I)

First you would mark out lines with a scriber & square.
Then you would clamp box section across the plate to act as a guide and keep the stampings in line
and square, holding the stamp against the box.

By moving the letter "I" sideways you can feel it drop into the scribe line.

The trick when stamping is how hard you hit it. A number "1" requires less force than a "4" to get the same depth.


To finish you need to polish out the scriber marks with a flap wheel in a die grinder.

(Note. No chemicals. I know you just love chemicals. )

HTH
Paul G

quote:

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Originally posted by a4gom
I'll ask the wife, you should see the state of our 3 month old sink!

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Paul,

Those badges have the sort of finish I would like on my sundial... but I dread to think how much a pattern 18" x 4" would cost to get done...