Cutting thin plywood vaneer

preserved_killick · Post by **preserved_killick** » Tue Mar 10, 2009 8:03 am

I'm building a small cabinet for my electrical panel and battery switch.

http://picasaweb.google.com/fongemie/Sp ... directlink

The Blue Sea switch will be panel mounted to the front of this cabinet, except I'm having a heck of time cutting a clean 3 5/8 inch hole in the plywood for the face of the switch to poke through, which has a micron thin vaneer on the surface. I've tried scoring the plywood with a razor, then cutting with a fine tooth jigsaw blade pointed down and the vaneer chipped. A fine tooth coping saw does a little better, except I'm finding it difficult to accurately follow my line, the hole ends up sloppy.

My next try I'm thinking a 3 5/8 hole saw, perhaps score the line first, might try running the hole saw in reverse to start?

Any tips? Something I've not tried?

-thanks..

Post by **Tim** » Tue Mar 10, 2009 8:20 am

Cover the area with masking tape, and use a 3-5/8" Forstner bit. It's the best way to make a really clean hole. (You might find other sources for this bit; this link is just one for illustration and comparison.)

You can surely come up with other ways, like a hole saw, but they may not provide such a clean hole.

Whatever you choose, tape over the plywood in the area where you'll be cutting.

Post by **Tim** » Tue Mar 10, 2009 8:36 am

Another option would be to create a perfect template of the hole you need, and use a router with the template to cut the actual hole in the plywood.

Quetzalsailor · Post by **Quetzalsailor** » Tue Mar 10, 2009 9:18 am

Yup, truly a pain particularly for brittle woods and veneers bonded with insufficient glue.

My skills usually result in the tape lifting the chips of veneer off when I've tried it. Cutting towards the veneer or face to be preserved and lifting the blade away from the work on the return stroke seems to work but is slower than the usual hacking away. Cutting well undersize and sanding out to the required shape is my usual method; I have a small collection of spindle sanders, and I chuck them up in the drill press. (Like these, but don't buy the junky ones, they get hot and slide: http://www.rockler.com/product.cfm?page=1268 ) Cutting tools that are new, razor sharp and fast tip speeds work better, too. Tim's suggestion for the router fits that last category when using a nice new bit.

Jigs are always an interesting proposition - balancing between 'perfect', fast and good enough. A trick I came up with to use a router for a circular hole was to use a clipped finishing nail for a centering pin in the center of the proposed hole and drill a corresponding pin hole in the base of the router. A router base has lots of room for pin holes - useful for circular or radiused openings whose radius is between 1" and 2.75" (and depending on your router) - and they'll not impair the router. I have bolted special homemade bases onto my router for occasional but intensive use (I think for hinge mortices on a slug of shutters). I have bolted a stick onto the router base to extend the center out to larger circles and for a four-center ellipse.

preserved_killick · Post by **preserved_killick** » Tue Mar 10, 2009 10:02 am

Thanks for the suggestions guys.

Tim, I like your Forstner Bit suggestion, I didn't know they were available that large. I did play around with the masking tape suggestion, but like Quetzsailer it just lifts the vaneer. I would have thought the router would tear it up. I'll try it on a sample today. Quetzal..the centering pin idea sounds interesting, the distance from the outside cutting edge of the bit to the pin in the base would need to be the radius of my circle..correct?

I must say, I hate this plywood vaneer. Not enjoyable at all to work with. I'll play with this for a couple more days and If I can't get it right I'll just build a the cabinet face out of solid wood.

Quetzalsailor · Post by **Quetzalsailor** » Tue Mar 10, 2009 11:58 am

Yup. Measure several times and drill once. It's sort'a backwards; 'outside' is the side opposite the bit from your pin.

Note that the centering will drop out when the cut is complete. Beware or take steps to control it.

I'm perfectly capable of chipping the face of solids, too.

kendall · Post by **kendall** » Tue Mar 10, 2009 1:11 pm

A method I use is to tightly clamp another peice of wood to it, then drill through both. That way it doesn't have the room to splinter, it's just like drilling the center layers of plywood.

Also, when it comes to hole saws, the best ones for general use are the cup and arbor type sold at better hardware stores, but the cheap home-owner kits with the removeable concentic rings for different sizes normally have much finer teeth and leave a smoother cut on finished surfaces.

Ken.

preserved_killick · Post by **preserved_killick** » Tue Mar 10, 2009 7:01 pm

Kendall,

Your suggestion worked perfectly. I clamped a scrap piece of 1/2 thick plywood to it, then buzzed through it with a cheap aggressive tooth 1 inch hole saw. It worked perfectly..clean straight edges. I also tested it with a jig saw and the chop saw with success.

I also tried cutting it with a router (no clamped wood) and it still chipped.

I just need to go out and buy a 3 5/8 hole saw.