cutting holes for outlets in plywood

Motomeister13 · Feb 16, 2013

Morning all,

I am building a new detached garage.

I am hoping to wrap up my rough in wiring today. After inspection, I will insulate, and then put up 1/2 inch plywood on all walls and ceiling.

I have used heavy duty plastic boxes. I thik there will be about 30 when I am all done.

Does anyone have any luck using a rotary tool with 1/2" plwood? I am thinking that i will burn through the wall of the box before I cut the plywood.

Measuring the palcement of each box on the plywood will take an eternity.

My other thought was to cut a sponge to fit into the box. Wet the sponge with food coloring, and fit the plywood. Then pull the plywood down, and use the color to jig saw out the box.

Any other thoughts?

THANK YOU!

Tim The Tool Man · Feb 16, 2013

I have always taken the measure and cut eternity method for plywood (which must mean I'm still measuring and cutting???). Rotary tool is for drywall, won't work well with plywood as you suspect. Your sponge idea sounds like a neat trick. How about instead, either paint the rim of the boxes and press the plywood against them before they dry or cut finish nails slightly longer than the outlet screw mounting holes and then insert the nails pointed end out, then this time kinda punch the plywood where you think the outlets are located and cut measuring off the dimple marks... Wow that is a nice run-on sentence! I think I'll leave it as is.

kngelv · Feb 16, 2013

I did the exact same thing a year and a half ago. I put most of my outlets at 49" from the floor. This way you can lay a sheet of plywood sideways about a half inch above the floor and be below the boxes. This saves a lot of cutting. I also put six outlets at the top of the walls for a heater, and a few fans. This also saves on the cutting. I used the measure, and cut method, but your sponge idea should work. I believe there is some type of tape made specifically for this purpose. If I was doing this today I would use either a router, or a good multi-tool like a Bosch or Fein to do the cutouts. Good luck.

James

Gary S · Feb 16, 2013

I'm with Tim. I measure the hole with the plywood on sawhorses and cut it before installing.

nkachur · Feb 16, 2013

I have been using a rotozip to cut OSB and it works like a hot knife thru butter.

Way quicker than a jig saw. I would be careful with the plasic boxes thou.

Just one other point the rotozip will cut the screw tabs off of a steel box if not careful

Big-Foot · Feb 16, 2013

I put tape over the outlet boxes and then I use a large Crayola Crayon to draw the outline of the box on the tape. Then push the drywall or wood up into place and give it a few love taps on the front right over the spot where the outlets are. Works like a champ every time. If no crayola, use the wife's old lipstick.

Use a jig saw to cut your holes through that wood as the spiral saw will take forever and probably burn up a few bits in the process.

BigMoneySteve · Feb 16, 2013

Just one other point the rotozip will cut the screw tabs off of a steel box if not careful .....[/QUOTE said:
We're not gonna ask how you know that....

Speedy Petey · Feb 16, 2013

Some of you guys must not be very adept at using a Rotozip. Like nkachur, my Roto with a Sabre bit in 1/2" ply or osb is nearly as easy as drywall, and much steadier. The Rotozip is almost up there with the battery drill as far as greatest inventions go IMO.

That said....no way I'd use it to cut out plywood with nail-on plastic boxes. You will not feel any difference in resistance with plastic boxes and cut right thru them.
Measure and cut is the ONLY way to go.

nkachur · Feb 16, 2013

BigMoneySteve said:
We're not gonna ask how you know that....

First time I used it on the shop had the blade misadjusted and noticed the feed rate go down. Finshe the hole and noticed that I could no longer mount the recepticle as there was no where to place the screw. :lol_hitti

Oh well I had to replace the box.

ptgb · Feb 16, 2013

Just spent 3 days putting 3/4" plywood on my walls. 52 total outlets, about 22 single, double, and triple boxes. They are the adjustable ones that allows you to turn the screw to make them come in or out to be flush with your sheeting thickness.

I found, especially with the 3/4" ply, to just do it the old fashioned way; measure and cut with a jigsaw for all the openings. Had a helper, so made it much easier to measure and transfer the measurements to the plywood on saw horses.

...I only was way off on a few :dunno:

Sometimes just need to do it the hard way.

Tim The Tool Man · Feb 16, 2013

Speedy Petey said:
Some of you guys must not be very adept at using a Rotozip. Like nkachur, my Roto with a Sabre bit in 1/2" ply or osb is nearly as easy as drywall, and much steadier. The Rotozip is almost up there with the battery drill as far as greatest inventions go IMO...

I don't think anyone here is inept with the Rotozip. You are correct, with the right bit it will cut wood fairly well. However you are not going to feel any resistance if you are using it to reverse trace an outlet box through a sheet of plywood or even OSB. You will end up with a very sloppy cut and the bit will probably eat right through your outlet box. It is just not the right tool for the OP's job.

You can give me either a jig or an oscillating saw and a tape measure over a spiral saw for this job any day!

zmaxmotorsports · Feb 16, 2013

Talk to your inspector to see if he will let you run the wire first and get a partial rough in inspection then have him come back once the plywood is up and you cut in boxes,before devices are installed.
That would save you lots of scratching.

p_mori7 · Feb 16, 2013

zmaxmotorsports said:
Talk to your inspector to see if he will let you run the wire first and get a partial rough in inspection then have him come back once the plywood is up and you cut in boxes,before devices are installed.
That would save you lots of scratching.

^^^
This.

or maybe remove the boxes, drill a 1" hole in the approximate location, install the plywood, fish wire thru the hole, then install a surface mount box.

terry603 · Feb 16, 2013

ben told lipstick does a great job for outlets. thick enough to stay in place,bright enough to see, plus cheap and easy to find

Speedy Petey · Feb 16, 2013

Tim The Tool Man said:
I don't think anyone here is inept with the Rotozip. You are correct, with the right bit it will cut wood fairly well. However you are not going to feel any resistance if you are using it to reverse trace an outlet box through a sheet of plywood or even OSB. You will end up with a very sloppy cut and the bit will probably eat right through your outlet box. It is just not the right tool for the OP's job.

You can give me either a jig or an oscillating saw and a tape measure over a spiral saw for this job any day!

You forgot to quote my second paragraph. :see:

Speedy Petey said:
That said....no way I'd use it to cut out plywood with nail-on plastic boxes. You will not feel any difference in resistance with plastic boxes and cut right thru them.
Measure and cut is the ONLY way to go.

Norcal · Feb 16, 2013

My preferred way is to cut out openings from the back using a Mag 77 SkilSaw for square or rectangular openings & a hole saw for round holes, but I must repeat this: It must be back cut to do it this way, & ones thinking must be correct or all the cutouts will be bass ackwards, plus if whoever sets the boxes is sloppy or inept & they do not mount the boxes at all the same height it makes the cutouts all that harder.

Proper preperation will make any job go smoother.

Notch1988 · Feb 16, 2013

I don't see how putting some form of transfer liquid on the outlet boxes, hanging the plywood on the wall to get the transfer, then taking it down to make cuts is any easier or faster than taking two measurements per box and using a template to make the layout.
I did my last shop in 1/2" ply, including the ceiling with 30 recessed lights to cut out, and used my rotozip for the whole thing and it worked awesome. I killed a number of their cheaper blades but so be it, it was super quick and easy. Just wear ear plugs.

eljefino · Feb 16, 2013

Just get an overhead projector and lock it down a few feet from your wall. Trace the boxes with a vis a vis marker then it'll be projected on your plywood. The only flaw there is the repetitive motion of raising the wood, tracing the lines, then lowering it for cutting.

If you really want to nerd it up you can shoot every unfinished wall with slide film then project the slides on the finished wall. Developing time will slow your project though.

Ch3No2 · Feb 17, 2013

Norcal said:
My preferred way is to cut out openings from the back using a Mag 77 SkilSaw for square or rectangular openings & a hole saw for round holes, but I must repeat this: It must be back cut to do it this way, & ones thinking must be correct or all the cutouts will be bass ackwards, plus if whoever sets the boxes is sloppy or inept & they do not mount the boxes at all the same height it makes the cutouts all that harder.

Proper preperation will make any job go smoother.

^^^^^^ What he said!

rockchucker · Feb 17, 2013

Really?

Measure and cut the Plywood. This is not Rocket Surgery.

Install the Boxes at 48 1/2" from the floor to the bottom of the box since it is in the shop. This way you can always lay a 4x8 sheet of anything on the wall and still have access to the outlet. This will also make cutting the holes for the Boxes a snap. Remember to raise the Plywood off of the floor ~1/2".

KPSquared · Feb 17, 2013

This ^^^^

This is not a difficult task. Tape, pencil, saw. Get off the internet and get at it!

Tim The Tool Man · Feb 17, 2013

Speedy Petey said:
You forgot to quote my second paragraph.

I know I did. Didn't mean to mislead anyone. When I first got my rotozip I plowed right through metal boxes, romex protection plates, and nails while it was equipped with a saber saw bit. (it smoked a lot as well!) Sure I can do the job just fine now by feel, though I think it is quite slow going and the bits don't last all that long. Regardless, I should have said "metal" work boxes -sorry if I offended.

Not saying your method is wrong, if it works for you then have at it! I'm just thinking of the OP, it sounds like he is asking for advice because he has not done this before and doesn't want to screw up his job. That is why I gave him my opinion and advice.

Motomeister13 · Feb 17, 2013

Awesome responses all. Thank you.

Where I can get a quick transfer with something like lipstick I will on low vertical panels I will. On the ceiling where getting the plywood up and down is time consuming, I will measure. A jig and pilot bearing with a laminate trimmer will be my cutting method either way.

I have pulled 90% of my wire already, and tucked the wire into the boxes. I will calll in my inspector for a rough in, so I can insulate, and plywood, then call him agan later for a final.

Thank you again.

Great stuff.

Rich

Speedy Petey · Feb 17, 2013

Tim The Tool Man said:
Not saying your method is wrong, if it works for you then have at it!

For the record, my preferred and suggested method was to measure and pre-cut. I never implied that routing like sheetrock would work well here, in fact to the contrary.
That's what the second paragraph said.

roche · Feb 18, 2013

I just finished putting 1/2" plywood and used the measure and precut method for ~30 boxes. Having a helper helps a lot.

cutting holes for outlets in plywood

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