# round holes required for vents



## gowings (Jun 17, 2013)

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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## Gary Beasley (Jan 21, 2009)

If you can find one that size you are good to go.


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## jschaben (Apr 1, 2010)

gowings said:


> 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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## Steve Neul (Sep 2, 2011)

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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## gowings (Jun 17, 2013)

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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## Steve Neul (Sep 2, 2011)

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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## gowings (Jun 17, 2013)

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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## Steve Neul (Sep 2, 2011)

gowings said:


> 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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## gowings (Jun 17, 2013)

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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## FrankC (Aug 24, 2012)

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.


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## TimPa (Jan 27, 2010)

+1 on the hole saw - lennox.


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## gowings (Jun 17, 2013)

FrankC said:


> 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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## Chris Curl (Jan 1, 2013)

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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## gowings (Jun 17, 2013)

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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## jharris2 (Jul 9, 2012)

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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## gowings (Jun 17, 2013)

I'm a mind reader. T jig was exactly what I was thinking.:thumbsup:


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## gowings (Jun 17, 2013)

Chris Curl said:


> 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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## woodnthings (Jan 24, 2009)

*perfect*



gowings said:


> 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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## gowings (Jun 17, 2013)

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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## woodnthings (Jan 24, 2009)

*This will work*

Cheaper than you'd think...by several.
http://www.ebay.com/itm/4-3-4-Hole-...308?pt=LH_DefaultDomain_0&hash=item35a020885c


http://www.ebay.com/itm/Black-Decke...473?pt=LH_DefaultDomain_0&hash=item4ced995129


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## gowings (Jun 17, 2013)

Yea and 37.00 shipping. I checked it out. Thanks for the link:thumbsup:


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## woodnthings (Jan 24, 2009)

*whacu talkin' 'bout Willis?*

$37.00 for shipping? HUH?

http://www.ebay.com/itm/Black-Decker...item4ced995129
Item condition:
New
Quantity:
101 available / 70 sold 
Price:
US $8.00 +$7.00 shipping


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## jharris2 (Jul 9, 2012)

woodnthings said:


> Cheaper than you'd think...by several.
> http://www.ebay.com/itm/4-3-4-Hole-Saw-Bit-Bi-Metal-One-Piece-1-3-4-Depth-/230319753308?pt=LH_DefaultDomain_0&hash=item35a020885c
> 
> http://www.ebay.com/itm/Black-Decker-4-3-4-Holesaw-USA-Made-SO76-/330403762473?pt=LH_DefaultDomain_0&hash=item4ced995129


Voila!

PS. The T-jig is still a viable option when using a hole saw as Bill suggests.


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## Sleeper (Mar 24, 2009)

I can’t even believe anybody would even consider a jigsaw for that many holes Wow. :blink:
The hole saw is the only way to go. I have cut thousands of holes with a hole saw and wouldn’t do it any other way. Making a jig is a must especially if you not skilled with that size of hole. The saw can wobble if you don’t have a good hold of it.


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## gowings (Jun 17, 2013)

I will either use the hole saw or my router with collar sleeve and straight bit. T Jig:thumbsup: is definitely the way to go. My experiences with the hole saw in the past is I usually get 4 or 5 holes at 1.5" deep in spruce and the teeth are getting dull.


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## Sleeper (Mar 24, 2009)

They do wear out especially the cheaper ones. I have a box full of worn down hole saws that I keep for those nasty holes or holes where I suspect nails. I also use the used ones for gypsum board. I’ve used a lot of different brands from B&D to Skil and Milwaukee, but lately I’ve been using Lennox because they seem to last a little longer. I started out using Milwaukee on Cedar Logs and the cedar would eat them up, so the material deepens on how long they will last. I just figured the cost of hole saws per job and didn’t depend on them to last long.


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## jharris2 (Jul 9, 2012)

Or you can adhere old sanding belts to them, and use them in your drill press as sanding drums.


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## Sleeper (Mar 24, 2009)

jharris2 said:


> Or you can adhere old sanding belts to them, and use them in your drill press as sanding drums.


Umm, I like it :thumbsup:


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## woodnthings (Jan 24, 2009)

*two things will dull a saw*



gowings said:


> I will either use the hole saw or my router with collar sleeve and straight bit. T Jig:thumbsup: is definitely the way to go. My experiences with the hole saw in the past is I usually get 4 or 5 holes at 1.5" deep in spruce and the teeth are getting dull.


Heat and abrasives. You could try cooling the saw with a water gun or spray bottle as you pull it our to clear the chips. Don't think you can power through a 1 1/2" board in one pass. 

The cedar may have some abrasive quality to it, but usually around any knots. I sided my entire house, shop and garage in Cedar, so I've cut my share of it without dulling my saw blades to any extent.


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## gowings (Jun 17, 2013)

Remember, this is not cedar. This is Maple plywood.


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## mics_54 (Oct 28, 2008)

hole saw


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## Smith Brother (Dec 9, 2012)

Be CAREFUL using a drill press as a drum sander. It is easier than you think to bend the arbor shaft, and then you don't have a GOOD DRILL PRESS..

I did that many many years ago, and believe me it can happen. If you do us it for anything that requires side pressure, be sure and NOT put to much pressure on such. 

Dale in Indy


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## mics_54 (Oct 28, 2008)

Holesaws clog with sawdust quickly with no route of escape for the cuttings. Clean the cuttings out every few seconds and the saw will cut much better and reduce heat.


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## gowings (Jun 17, 2013)

You got that right. I just finished cutting 21- 4 3/4" holes in 3/4" mdf. Painfully slow on the drill press. Man that new bit was smoking by the time I hit 15.


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## Smith Brother (Dec 9, 2012)

Did you apply very LITTLE pressure, and back off OFTEN? Need to let the bit work, and keep it cool, IMO. Also if teeth get clogged, then hit gently to knock dust off. 

Glad you are finished.

Dale in Indy


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## gowings (Jun 17, 2013)

Very little, in fact I could read the writing on the bit as it was turning at times. This is only part 1, now I have to router out 1 1/4" deep holes 4.75" wide, out of stationary plywood benches.


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## against_the_grain (Aug 15, 2010)

I would not attempt this cut with a hole saw bit. The router idea with the template is probably the way to go. 

If you have a spiral saw or Rotozip with a circle cutting jig . They do well for circles with the jig.But not sure these would be capable of cutting through that thickness. Probably not.


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## gowings (Jun 17, 2013)

*Final pics*

Thought I'd post the outcome.
I used a flush trim bit with a sleeve collar in a Porta Cable plunge router. 
All that's left is to silicone in, the vents:thumbsup:


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## jharris2 (Jul 9, 2012)

Nice work! Thanks for the update.


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