60 - 6-1/8" Holes in 3/4" plywood

[Jim Bills]

I have a friend in Denver who needs to cut 60 - 6-1/8" holes in a piece of 3/4" plywood. The plywood is 48"x 85". Looking for suggestions. This would seem to be an ideal application for a computer operated router. This is a one time deal, so any suggestions will be appreciated.

Thanks, Jim

[Jim Becker]

I agree about the computer controlled routing system...you might want to post in that forum here to see if there is anyone in the Denver area with a ShopBot or similar that will do the work...and also contact ShopBot directly for a reference.

[Julio Navarro]

how far apart do they need to be?

[Ralph Barhorst]

I just did something similar to this, just not as many holes and my holes were only 3-1/2" diameter.

I made a plywood base for my router and drilled an extra 1/4" dowel hole in the base that was spaced the correct distance from the router bit. This hole is used as a pivot point for the router. I was using a 1/4" spiral bit so the center of the hole was 1-5/8" from the center of the router bit. I then clamped the plywood that needed the hole to a sacrificial piece of plywood and drilled a hole for the 1/4" dowel through both pieces of plywood. Insert a dowel that goes through both pieces of plywood and then slide the router onto the dowel using the extra hole in the router base. Route the circle in the top piece of plywood making sure that you only go deep enough to complete the cut in the top piece. The bottom piece of plywood keeps the router centered when the hole is complete making the edges of the hole nice and neat.

This works well and really doesn't take too much time.

[Barry O'Mahony]

Maybe make a 6 1/8" hole in a template, and use a template bit.

[Jack Diemer]

How about a 6 1/8" Hole Saw. :D

[Ken Fitzgerald]

I'm with Barry............make a template and either use a flush cutting bit with a bearing to follow the template or use a guide bushing and a straight cutting bit....otherwise...CNC time!

[Don Baer]

I'd vote for Barry's method. Circle guide for the router. Drill all of the center holes at the correct spacing and then just move the router from hole to hole quick and easy.

[Chris Giles]

This may seem rather bizarre, but depending on how clean the holes need to be, you might be able to make a small circle cutting jig for a sabre saw that would only require a pilot hole for the blade to be bored thru and the jig to be screwed at the center point. Veneer core plywood can be hard on router bits as it tends to dull them at the glue lines, so a nice jigsaw blade would be preferable for cutting through this type of material.