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Howdy fellers,
I'm considering having some various laser-cut Acrylic templates made.
I'm concerned about a router bit grazing the edge of the Acrylic and causing mayhem.
How do you safely cut the work piece using an Acrylic template?
Thanks,
Dan

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So far the only acrylic template I've used is the StewMac neck pocket. I use their router bit with three bearing bushings on the router bit shaft. For the first cut I raise the template using spacers about 3/8 inch thick using double side tape to stick it all together and attach to blank. After the first pass or two you can take out the spacers. Just be sure to make sure that the router depth is deep enough that only the bearings touch the template edges. StewMac actually has a video showing this process on their website/youtube channel. Like I said, just double check to be sure bit doesn't touch template, (ask me how I know).
Good luck and watch the video

I us acrylic templates all the time.
Wood ones too.
Definitely less worry with the wooden ones.
Make sure your bearing is oiled to prevent it getting hot and exploding if you're using a 3/8ths pattern bit.
Route close to the template without touching it, I make 1/8th inch passes.
For the final route to the template, don't let the bearing touch the template for more than a few seconds at a time just to be sure the acrylic doesn't melt.
Once you get below the template onto the wood, as long as you oiled the bearing you'll be fine.

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Old growth, shmold growth!

A side note about acrylic, don't run a router with an acrylic base on top of an acrylic template unless you cover one of the pieces with tape or something.

I bought an acrylic base for my Bosch Colt so that I could use Porter Cable guide bushings then I tried to run that on top of an acrylic template. The vibrations would cause little tiny spots of contact between the 2 pieces of acrylic to melt & weld to each other. They were very tiny spots that could easily be separated but it made it impossible to template route.

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Thanks for the great advice!
I've been using 1/2" MDF, but the edges don't hold up well.
It sound's like using Acrylic can be risky.
I could attach an MDF spacer to the underside of the acrylic so I have a gap between the router bearing and the work surface.
I may just go with plywood with CA hardened edges - easy and safer.
Dan

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I've had some of my acrylic templates for almost 15 years.

Just gotta be more careful with them or the bearing can melt them.

The bearings you need to oil anyway, especially smaller ones, as they'll destroy a wooden template too if they blow up.

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Old growth, shmold growth!

Are balls really stable?

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Old growth, shmold growth!

I guess I am just not patient enough to limit my passes. In addition to the above advice and not necessarily against any of it I highly recommend using offset bushings. For this to work you do need to plan thing out by making your templates also offset. But you can use spiral bits and longer ones without fear of bending the bit since the bushing rides rather than the bearing connected to the bit.


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Ken

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Ken

I only use it now for routing pickups at an angle and for f holes now as I have a CNC. For outside cuts on guitar shapes a pattern spiral bit is ok, if the blank is ha sawn near to shape. But it still gets dicey taking a full thickness pass. Trying to nibble away at it first before the bearing touches the pattern is dangerous or nerve racking at best. If you had an offset pattern that a bushing rides on, you can use a plunge router an take reliable cuts at 3/16 or so depths always riding on the bushing.

Let me see if I have a photo.


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Ken

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Ken

I can't find one.
Try routing a Humbucker rout from an angled pattern above with a pattern bit on an arched top guitar with a pattern bit. I use a template bushing and a 5 inch long quarter inch spiral end mill for this. It kind of simulates what a pin router can do.


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Ken

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Ken

Yep, routing end grain is a scary thing. I usually sand it rather than route.
All of my electrics have a thick (1/2-3/4") drop top. What I've been doing is cutting the top close to the line and then route with a template. After I glue the top to the back, I use the edge of the top as a guide to route the back.
I'm just too chicken to attempt to route the entire body height.
I'm getting ready to start an LP flat-top (Junior?)
I'm going to take my time making the templates and hardening the edges as Mr. Morelli suggested.
Thank for the great tips.
Dan

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I looks like a case where I will have to do a little video of this. Next time I use a bushing I will try to remember.


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Ken

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Ken