Engraving Copper Bracelet Blanks


I’d really appreciate any advice on how to engrave copper bracelets with various designs.

I use C101 grade copper blanks 170 mm long x 10 mm wide x 2 mm thick with a 5 mm y radius at each end. I have these cut by a laser firm and order them by the 100’s. These arrive as flat blanks and they are bent to shape later on in the manufacturing process.

I’m no milling expert and my workflow is currently inkscape/svg --> carbide create --> carbide motion. I only need a 0.2 mm to 0.3 mm engrave depth so I find a 101 ball does the job just fine if I reduce the stepover to 0.35. To keep the blanks held securely in place during the engrave I had a ply jig made that is screwed on top of the nomad 883 mdf table. The jig holds 8 blanks. The jig is 3.2 mm thick so each blank rests slightly underneath the ply.

When it works the results are excellent. However there are imperfections in the blanks, e.g, small bends and warps. Even when carefully checked these may be hard to see with the naked eye. For blanks with imperfections they vibrate slightly during engraving which ruins the design resolution and leads to a distinct variability in engraving depth. As things stand, the error rate is too high to make the machine commercially viable.

If anyone has any suggestions on how to solve my problem I’d be very grateful.



How are the blanks attached to the jig? Are they just resting on top, or is there a top clamp holding them down?

If you don’t need to go to the very edge of the blank, I’d use a fixture that holds the blanks down. For a 2mm part, Id go with 3.2mm (1/8") material, aluminum or even acrylic, and cut through at 9mm by 169mm with 4.5mm radius, and on one side, cut a 1.5mm deep lip the full blank size plus about 0.2mm clearance. A plate goes under it to support the blanks with matching flat bottom pockets about 0.3mm deep for location of the blanks, and both are drilled for holding screws, the bottom threaded holes, the top clearance. The extra 0.2mm leaves a gap between the plates so they can squeeze the edges off the blanks and bring them into flat. A pair of precision pins to line the plates up will help.

This could be done on the Nomad with a little setup.

Unless you “contour compensate” for the imperfections in your blanks, are you not faced with this inconsistency regardless of the engraving machine? It sounds like “truing” your stock is a fundamental piece of your consistency puzzle.


Use a touch probe to digitize the blanks, then adapt the flat paths to them — bCNC and a few other apps do this and it’s a typical part of the workflow for PCBs:

Many thanks for all your suggestions it’s really appreciated.

Some days I need to engrave over 100 blanks, so I think the best approach is to make the stock as true as possible using a jig that can ‘flatten’ them.

The jig I’m using at the moment was cut from 3.2 mm thickness ply using my laser cutter (a 60 watt CO2 Trotec machine). The jig is just a series of thru-material cuts in the shape and size of the blanks. The centre of each cut has a 2 mm OD semi circular hole at one side to allow the blank to be easily prized out after being engraved. The reasoning behind all this is that the engraving process has to be time efficient and simply slotting blanks in and out allows a large number to be engraved in a single day.

It’s clear this doesn’t work consistently however and some sort of vice and base mechanism needs to be incorporated into the jig design in order to flatten the blanks.

Typically I only need to engrave the central 6 mm width up to 10 mm from either end of each blank so I have quite a bit of material to use with a vice mechanism, if that’s the way forward.

I’m convinced there must be a straightforward to do this. It would be a shame otherwise as I may end up upgrading my laser to include a fibre source to engrave instead (which also works, even using a 20 watt but is far slower).

Thanks again for your kind help.



Heres a fixture made using HDPE-

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I’d recommend just a cover for the jig that clamps the tags into the jig you have. This might be enough to even out the differences for you.