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Discussion Starter #1 (Edited)
I am currently getting a job ready in a locker room. I am applying 3/4" maple plywood to an existing painted plywood surface. The issue, I need to cut 25 round-4.75" holes for air vents that will have aluminum vents over them into approx. 1 1/4" total depth material. I have 1/2" error margin on the holes with the vent flanges. Anyone have suggestions. I was thinking a hole saw.
 

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John
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I am currently getting a job ready in a locker room. I am applying 3/4" maple plywood to an existing painted plywood surface. The issue, I need to cut 25 round-4.75" holes for air vents that will have aluminum vents over them into approx. 1 1/4" total depth material. I have 1/2" error margin on the holes with the vent flanges. Anyone have suggestions. I was thinking a hole saw.
That's the way I'd go. Hole saw that size isn't cheap but is likely the fastest way to do it,
DEWALT D180076 4 3/4-Inch Hole Saw - Amazon.com
:smile:
 

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I assume the holes don't have to be perfectly round. I think I could cut 25 holes with a jig saw before someone could go to the store and get a hole saw.
 

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Discussion Starter #5
Well not perfect but I would need a jig to make sure the holes are within tolerance and in a straight line for aesthetics. I always wanted to but a good laser level that would shoot a line across a long field, that would help immensely. Any thoughts
 

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I think just the first cut out would be good enough for a pattern. You could put lines from center at 90 degrees from each other to help line it up. As far as laying out a straight line won't a caulk line work or are you spanning too far?
 

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Discussion Starter #7
I'm 19 feet long on 1 span with 11 holes in white maple plywood clear finished with 3 coats polyurethane. Spaced approx 20 inches apart.
 

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I'm 19 feet long on 1 span with 11 holes in white maple plywood clear finished with 3 coats polyurethane. Spaced approx 20 inches apart.
Well 19' isn't too long of a span for a chalk line however I didn't know you were working with finished plywood. That would be harder to cut with a jig saw without damaging the finish. You would probably have to cut a round hole in a piece of masonite to run the saw on so the base of the saw would scar the finish.
 

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Discussion Starter #9
Good idea on the scratching:thumbsup:. Never crossed my mind. I'm going to try a hole saw first. A contracting friend said they use a hammer drill when they use hole saws. Keeps the teeth clean as its cutting
 

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Discussion Starter #12
I would make a template as Steve suggests and use a jigsaw and a good quality blade, most hole saws don,t stay sharp that long under ideal conditions even at correct speed in a drill press, that is a lot of material and a big hole to cut with a hand drill.
These holes for the vents will be cut after the maple is installed. Here is a picture of the before install. It's the bottom of the stalls in a locker room. Each vent hole has to be drilled after install since no 2 benches are the same width. Total depth of cut will be 1 1/4".
 

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Master firewood maker
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a jigsaw would probably be the easiest thing to work with. but it could be a pain to get them all within the tolerances.

for more certainty about the tolerances, i would make a template for a router and make the holes with a router with a 1/4" bit.
 

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Discussion Starter #14
Yep:thumbsup: I am looking for my sleeve collar and will make a template out of MDF and then clamp it to the area as i move along
 

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If the hole locations make it practical make a t-square type jig that will index to the edge of the plywood.

Then just slide it to your center lines and clamp.

Much faster.

:)
 

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Discussion Starter #17
a jigsaw would probably be the easiest thing to work with. but it could be a pain to get them all within the tolerances.

for more certainty about the tolerances, i would make a template for a router and make the holes with a router with a 1/4" bit.
Another issue the plunge cut on my router with a straight cut bit is only 3/4" max with the sleeve collar. I need a longer bit to router out to 1 3/8" depth in 3 passes to get to the bottom.:thumbdown:
 

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where's my table saw?
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perfect

I'm a mind reader. T jig was exactly what I was thinking.:thumbsup:
Hole saw the jig cross plate, then adjust it to the centerline, screw it down on the "T" and you're good to go. Any other way is too time consumming..... however removing the plug may prove to be difficult. :furious: That's always been my bugaboo when sawing through 2X material. A hole saw with two holes on the top side, if they make one, will make punching out the plug real easy.
 

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Discussion Starter #19
Thing is going through approx. 1.5 " of material. I had the router jig made out of 1/2" MDF ready to go sleeve collar and all. Then realized I can't get the depth of cut I need. I was figuring 3 passes with the router and success! I have been told that with a hole saw I will use at least 2 maybe 3 bits as they won't hold up. That's 120 smackeroos for 20 holes minimum.
 

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where's my table saw?
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