V bit engraving in Acrylic.

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ca.280
Posts: 5
Joined: Sat Mar 06, 2021 8:31 pm
Model of CNC Machine: Generic 3018

V bit engraving in Acrylic.

Post by ca.280 »

Have been using a diamond drag bit to etch (mostly text) on cast acrylic in the LED, base lit signs I make and
would like to go even deeper so the engraving is more prominent even without lighting. Have purchased a 30deg, 2 flute
V bit designed for plastic and could use some starting parameters (spindle speed, feed rate, depth of cut etc.) that have
worked for you. I realize that all machines are different, I just need a starting point. Max RPM is 12K. Have tried
with that RPM, 900mm/M feed rate and .5 depth of cut and it melts the Acrylic, no chips. Any info appreciated
befor I waste any more plastic.
Thanks

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Xxray
Vectric Wizard
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Model of CNC Machine: CAMaster Stinger 1
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Re: V bit engraving in Acrylic.

Post by Xxray »

.5 is crazy deep for an etch, would say you would need at least 3 passes to possibly avoid melting, and really don't see any benefit or purpose going that deep for lettering - But for sure it will be a mess if you just try to hog it out in one pass no matter what bit and settings you use.
Generally, you want high feed rate and low RPM, which reduces the dynamics [friction] which causes melting - Higher the RPM's and slower the feed rate, the more friction/heat will be created, and acrylic as you know has a very low flash point, and there is no return once it starts. Whatever bit you use has got to be sharp, dull bits don't stand a chance.
Also, consider trying a TBN, I know some guys have had success using vbits but I think TBN are better optimized for deeper plexi cuts - I have done tons of intricate 3D in plexi over the years with great results, but have never had the need to 2D etch very deep
3.jpg
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Doug

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