Suggestions for engraving a coin

Need suggestions from the group. I am trying to engrave challenge coin for a group that I am apart of. The blanks in the pic are 14ga .0623, 2" round alum blanks. I am using the 90 degree MC Etcher. The quality is not great.

Should I just invest in a laser? I am looking at thicker blanks.

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I suspect that @KevBarn14 might have some tips since he’s spent a lot of time drag engraving.

Unless that’s really soft aluminum, it looks very different than the samples I’ve seen in the shop. Can you share your C2D file?

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I will have to update the file when I get home.

I’ve found that the 90° can get too aggressive when there are lots of small details. Because you are not cutting material, but rather displacing it, the top edges of the engraving lines can muddle your finished design. The 120° tends to do a better job with those tight detailed areas. With the 120° I’ll run the paths twice to get super clean lines. In my experience, less displacement tends to equal a better look.

Send a few more closeup photos as well as the file and I’ll take a look.

One other thing about metals, I find the use of full crosshatching produces an almost mind bending set of reflective surfaces. For brass jewelry I use 30° linear lines. You can manipulate the coverage by reducing the step over of those lines.

I’m happy to look further at your project when you get back to your shop.

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Thank you @KevBarn14

I have been thinking about getting the 120 degree etcher

It’s my preferred engraver 90% of the time.

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Should have bought the 120 also

I would recommend getting thicker blanks (3/16" or 1/4" thick) and v-carving the details on the obverse and reverse sides with a 30-60 degree v-bit instead of DDE.

I am looking at thicker blanks, didnt think about using a vbit.

@KevBarn14

Will a 120 deg be able to engrave this kind of coin. Do light passes and going over it twice.

I am at work but will post the C2D file when I get home in a few hours.

@KevBarn14

Here is the C2D file for the coin.

Busby Valiant Coin.c2d (790.5 KB)

Do you have anything to take the burr off?
I was doing some tiny engraving on aluminum. I tried the 90 and 120 drag bits as well as some V bits from dremel. The spinning v bit lets you get deeper than the drag bits. All of them leave a raised burr that makes the work look rough. If you’ve already machined the entire top of the coin, you can run a surfacing pass again a couple thou higher than the surface to catch the burrs.
I had decent results running the toolpath twice. The second pass cleaned up some of the crap leftover from the first.
And if you’ve ever cleaned a piece of glass with a razor blade, I use that same motion using a razor blade across the top of the aluminum to shave off any material thats sitting proud of the surface. Its a little harder with aluminum than glass, because the aluminum is softer and easier for you to gouge if you dont do it right.

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Here are a couple more up close pics. And a pic of one I did just by outlining.


It is leaving a slit burr. I need to do a second pass. Next test to see how that turns out.

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I’ve been using these: https://www.amazon.com/gp/product/B08FSZVL1D/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 with decent success. I haven’t tried as fine of detail as what you are doing, but I’m pretty sure these could handle it. I went REALLY slow and had a really shallow depth (0.01 in per pass). I used a lot of wd40 (probably not the right stuff to use, but it worked)… I added a texture to the coin on the lower left of the pic. For Aluminum, I just used a cheap 1/8in sheet and let the shapeoko cut it them out…

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@Chengdu28

Did you use an endmill or what to do those coins.

Yeah, I used it this end mill: https://www.amazon.com/gp/product/B08FSZVL1D/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

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@Chengdu28

What kind of feeds and speeds did you use.

These were my settings
Screen Shot 2022-04-07 at 8.00.55 AM

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