Landing Page

Make a SQUARE hole with a ROUND forstner drill bit!

in woodworking a square hole is called a mortise and it's half of the strongest joint in the craft the mortise and Tenon joint if you want to build furniture that will last you have to know how to make square holes and perhaps the simplest way to do it is with a browned forstner bit that's what I'll show you today including some really handy tips that few others seem to mention in fact this video is going to be different right from the get-go because I'm not going to use a drill press like everybody else seems to show we're going to do it quick and easy with just basic tools so imagine you want to connect this piece to this one with a 90 degree angle I'll use a pencil to Mark the width of my connecting work piece on the edge of the other one of course I don't want my Tenon to be the full width of the connecting board so I'll come in about half an inch from each side of my mortise that'll be its length the width of the mortise will be determined by the forstner bit I use so I'm only going to need one layout line for that right down the center a quick way to find the center is to angle my rule so that I have an inch mark on each Edge in this case the one and the three this positions the two Mark in the exact center of the edge now having marked that I can carry the line the full length of the mortise with the end of my combination Square now I could just use that pencil line as my guide but here's another trick that will really help you to bore your holes accurately I'm using an awl to create a shallow Groove over my Center Line now the tip of the forstner bit can slip into that Groove and it will make sure that I'm always drilling right on my line as I said the width of my mortise is determined by the forstner bit I use I'm fortunate enough to have a full set of beautiful fish forstner bits these are made in Austria with an old world foraging process and I use them exclusively in half for years I highly recommend you just try one of them maybe just a three-quarter inch since that's a great size for mortising this inch and a half thick material you're never going to go back to your cheat bits again after you try this I'll put a link below this video if you want to check them out now I'm using a piece of tape to Mark the depth of my mortise on the shaft of my forstner bit then I place the point of the bit in that Center Groove and position it so that the edge of the bit will cut just beside my layout line on one of the mortises ends I like a variable speed drill so I can spin it slowly good bits cut really fast and there's no need to go nuts here I stop when my tape begins brushing the top of the work piece then I move to the other end of the mortise be sure you hold the drill as straight as possible I find it easier if I get the work piece close to me so I can then look down from the top just be sure it's not so close that you snag any loose clothing if I'm boring a particularly deep hole I might pull the bit back out every now and then so the chips can clear that'll help keep the bit cool and it'll prevent it from getting stuck inside now that the two ends are finished I can use overlapping holes to remove the remaining waste in the center as long as the point of the bit finds a place in the wood the guide Rim doesn't have to be fully engaged if your bid is sharp and of high quality it should bore straight downward even if it's overlapping an existing hole if it does slip to the side halfway into the mortise don't worry about it you can just clean it up with the Chisel speaking of a chisel with the bulk of the waste bored out I can now use this to turn my row of circles into a single square there's no need to do this all in a single chop pair it back a little at a time and concentrate on keeping your chisel straight up and down as you did with your drill here's another tip that'll help with that try clamping a piece of wood that has a square Edge right on your pencil line you can then use it to support and guide your chisel straight downward another way to gauge how Square the sides of the mortise will be is to take note of the hollow marks that are left by the edge of your round forstner bit when those are all shaved away the sides should be relatively straight now that you have a mortise you can cut the Tenon to fit inside it's best to do it this way creating the mortise first because it's far easier to make a Tenon smaller so it fits into the square hole than to make the hole bigger so it fits around the Tenon if you need some help with the Tenon I have videos on that too I'll link to them below see you next time

Related Articles

Back to top button