CaseyWilson Posted April 4, 2014 Report Share Posted April 4, 2014 I need to drill holes from 1 to 3 inches through three layers of 3/4 plywood. I'd like to minimize chip out and drill through all the layers at once. Smooth inside edges of the hole is a plus. I'm drowning in options. What should I get for the drill press? Hole saw, spade/paddle, brad point, Fortsner? Quote Link to comment Share on other sites More sharing options...
Tpt life Posted April 4, 2014 Report Share Posted April 4, 2014 Smooth edges is difficult with ply. It can take forcefully clamped zero clearance starting and finishing blocks. As a rule I would stay far away from a paddle/spade. Hole saws will friction heat but can burnish with that heat. Forstners are a great option but I have no experience with a bit of that type in those sizes. Quote Link to comment Share on other sites More sharing options...
Freddie Posted April 5, 2014 Report Share Posted April 5, 2014 I go forstner bit with a backer board under the ply. If you can't find a bit large enough the a router, circle guide and template guide bushing in the router. 1 Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 5, 2014 Report Share Posted April 5, 2014 Forstner all the way...a good, new, sharp forstner. Like Carus said, it's not only essential to back up the hole, but you need to CLAMP down the workpiece and the backer, or you'll still get tearout...the bit just lifts the workpiece off the backer as it exits otherwise. I find it less necessary to use a backer at entry. Start your hole very slowly and let the spurs of the forstner cut a clean perimeter before you start to plunge. Clear your chips frequently but don't back completely out of the hole in case your spindle is not perfectly straight. And that's a great idea from Freddie...Rockler sells patterns of all kinds. I have a couple templates with a bunch of different hole sizes. You can get very clean results like that. It's probably a better idea (and cheaper than buying a huge 3" forstner). Quote Link to comment Share on other sites More sharing options...
EdgewaterWW Posted April 5, 2014 Report Share Posted April 5, 2014 Hole Saws ($) are only about 2" deep for a 3" round bit, you need 2 1/4" and then you have to get hole saw plug that is stuck on arbor out. Forstners bits ($$) are great clean holes, if you use a junk board under the boards you are drilling that will help with the chip out. Also with a 3" bit you will have to drill at a slow speed. Quote Link to comment Share on other sites More sharing options...
..Kev Posted April 5, 2014 Report Share Posted April 5, 2014 I'm going against the grain here and saying the hole saw. Drill most of the way thru, flip the piece, and finish the cut. Perfect hole every time. Quote Link to comment Share on other sites More sharing options...
EdgewaterWW Posted April 5, 2014 Report Share Posted April 5, 2014 I'm going against the grain here and saying the hole saw. Drill most of the way thru, flip the piece, and finish the cut. Perfect hole every time. That will work! stop the tearout and the wood plug stuck in the bit. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted April 5, 2014 Report Share Posted April 5, 2014 I'm going against the grain here and saying the hole saw. Drill most of the way thru, flip the piece, and finish the cut. Perfect hole every time. That will only work if the pilot bit can reach all the way through, creating a hole to guide the second cut. Even then, if your press has any slop, there is a risk of offsetting the two holes. I would choose the forstner bit, making sure it is sharp. Go slow, keep the hole cleared of chips. Use backers on top and bottom, although a sharp bit should not be causing tearout on entry. Quote Link to comment Share on other sites More sharing options...
Freddie Posted April 5, 2014 Report Share Posted April 5, 2014 The forstner bit is really your only solid option as far as tooling chucked in a drill press. You can't beat the perfect clean hole that you get from the bit, and if it is going to be seen, I would not reach for any other bit. Quote Link to comment Share on other sites More sharing options...
Jfitz Posted April 5, 2014 Report Share Posted April 5, 2014 I also would use a forstner, with sacrificial backer board. What's the travel on your drill press - will it go the full 3"? Quote Link to comment Share on other sites More sharing options...
Nestor Posted April 5, 2014 Report Share Posted April 5, 2014 Clamp all pieces together and drill pilot hole. Separate boards and use hole saw. Sent from my iPad using Tapatalk Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 5, 2014 Report Share Posted April 5, 2014 Hole saw is more suited for construction...not nearly as clean of a cut as a forstner. It'll work, just not as well. Sorry fellas. Quote Link to comment Share on other sites More sharing options...
Slick218 Posted April 5, 2014 Report Share Posted April 5, 2014 Hole saw and drill from either side. The pilot bit will prevent the hole from being offsetSent from my SGH-I727R using Tapatalk Quote Link to comment Share on other sites More sharing options...
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