Official Luthiers Forum!

Hey guys, I want to start cutting pickguards with my CNC. I'd be pretty happy to find out at what speed you guys cut yours and how deep the depth of the cut is per pass. I'd really like to avoid melting or burning pastic on my first try, especially at the price tort and pearl sheets cost

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www.MaillouxBasses.com
www.OzBassForum.com

Cut as fast as you can, one pass through and maybe one finish pass. If it's melting, you're cutting too slow or your spindle speed is too high for your feed rate.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I also find plastic prefers a conventionally cut finish pass. Climbcutting leaves burrs.

My machine's a stepper so doesn't have a fine enough resolution to do pickguards. We drill, pocket and rough out on the CNC but bevel and profile on table routers.

Excellent, thanks for the tips guys

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www.MaillouxBasses.com
www.OzBassForum.com

It would be good to open a discussion on bits for pickguards.

I've found the most success with 1/4" single flute O-flute straight bits. I run the router at about 10K RPM.

I'd like to hear what others are having success with.

I use these - 1/4" bit, conventional cut, full depth pass, 10000rpm, 80"/min. Works for me

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www.morganguitarworks.com
www.morgancustomguitars.com

Is there is any way you can run a lubricant/coolant on the cutter while it is cutting? you could just brush it on ahead of the cutter.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

You shouldn't need to use coolant or lube on plastic. If your process is off, then the coolant won't help much and if your settings are right then you won't need it.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I haven't cut pick guards yet, but when cutting other plastics I have found that compressed air works well to clear chips and to keep everything cool. You would want to make sure you don't spray air under the guard while you're cutting though. I have had 1/8" Plexiglas lift when the air blast got under it. I'm planning on making a vacuum jig to hold the piece while cut out the guard with a hardboard or plexi board holding the edge down while cutting. I'll let you know how that goes.

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Josh Garrett
Galloup Guitars CNC

Haven't been on in a while but thought I'd chime in. First off coolant will only do good if it's a constant stream or spray a dab here and there is really only for metal to keep it from ruining the bit, a dab won't cool just lubricate. Plus you don't want any solvents near your cnc that you're going to be cutting wood on.

Next get the correct bit. A single flute is more traditional for cutting plastic. Melting during cutting isn't always the feeds and speeds. Some plastic is meant to be machined and won't melt unless you're way off base. I would cut as fast as possible, 10,000 RPM and two passes (rough and finish) at full depth. I would also go to Tap Plastics or order online a bit designed specifically for cutting plastic.

You can also sandwich the pick guard between some MDF to help keep it cool by way of the sawdust.

@Sheldon Dingwall, what kind of machine are you using and what kind of equipment (steppers and drivers). Stepper and Servos both have resolutions so high it's not even conceivable that you're having a problem because of steppers. If you're having a problem cutting pick guards because of the resolution it could be a number of things, the worst being machine design, but that's almost NEVER the case. The next link in the chain is looking how you have your stepper drivers and Mach 3 (if you're using Mach 3 as your CNC software) set up. They should be setup for micro-stepping bi-polar with somewhere in the neighborhood of 10,000 steps per inch assuming you have 5 Turns Per Inch. Next would be making sure you have the resolution in your CAD program set correctly. If you want some help with your machine PM me and I'd be happy to help.

Hi Cartierusm,

Mine's a rack and pinion machine so <1 turn per inch. This gets me a little over .001" step resolution but 1200"/min rapids. Saving for a VMC.