1. #1
    Is it a viable proposition to do light relief engraving on old slate tiles?
    I guess one would use solid carbide. If by chance you have any experience of this technique. I would be grateful for any advice. Speeds and feeds etc. for max. 1mm. "z" depth.

  2. #2
    You may have already looked into this but laser etchers/cutters do a great job of engraving into slate and granite. It just barely scratches the surface though, so im not sure it will get down as far as 1mm.
    CNC routing and prototyping services www.cncscotland.co.uk


  3. #3
    Yes it is possible to cut slate with carbide but the cutting edge has to be ground to a different angle to give a small back relief to preserve the cutting edge, in reality you are grinding the stone not cutting it, If you want 1mm deep you would do this in 1 pass.

    Your cnc machine also needs to be very rugged with water flood.

    The image below shows a 2.5d relief that is 8mm high for the flower and 6mm high for the text all the stone between is ground out with 2mm roughing passes then change to a V cutter to do the relief in 2mm passes.
    as regards feeds you need to test cut on each type of stone, on old stone that has oxidised/hardened you will find it is slow.


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  4. #4
    Gentlemen - Thank you.
    I posted prematurely before discovering the extensive amount of web info available.

    My router is a small light piece of kit purchased specifically for this to avoid the obvious corrosion/ erosion to the main mill. So unfortunately will only be capable of light cuts and small step overs. Currently working out the screw protection for it and perhaps machining in a fabricated plastic bath??
    As to coolant, assume tap water is OK or are there any obvious additives?
    Will trial with existing single flute D bit carbide bits. But saw some 4 square unfluted 60 and 45 deg. cutters being used. Which would be easily ground and resharpened from broken stubs. Any info on that appreciated.

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