Using Drill Bushings in Your Projects
George VondriskaDescription
I love building jigs and fixtures for my shop. When I’m building jigs that work in conjunction with a drilling operation, I find it’s best to add drill guide bushings to the jig so the jig holds up and stays accurate. If I’m investing my time, after all, I want the jig to last.
What’s a drill guide bushing?
A drill guide bushing is a chunk of hardened steel with a very specific inside diameter. Match the inside diameter of the bushing to the outside diameter of drill bit you’ll be using. See Sources.. The outside of the bushing is threaded so you can screw it into your jig.
What’s the benefit?
If you simply make your drilling jigs from plywood or hardwood and then run the drill through the locating hole over and over, you’re going to elongate the hole and the jig will quickly lose it’s accuracy. By using a guide bushing instead, the drill bit will be running inside the hardened guide bushing, and you’ll never lose accuracy.
Installing the guide bushing
Most guide bushings have ½”-20 threads, so a ½”-20 tap will give you the threads you need in order to screw the bushing into your jig. Drill the hole for the tap slightly undersized
The best bit
There are lots of types of drill bits available. Understanding different drill bits will help you choose the best one for the job.
Lots to learn
There are so many tips and tricks like this in woodworking. Have a look at our great woodworking tips to see what else we have available to make your woodworking easier to do.
Sources: Drill Guide Bushings
If you like making your own jigs in your shop and they're gonna be jigs that require that you use a drill bit you're gonna love this 'cause here's the thing. I am making a jig here that I'm gonna use to locate holes in another project. So, it's 1/4 inch holes that I need for a 1/4 inch drill bit. If I drill holes into this plywood and then I follow them with a drill bit once I do that probably five times this jig is gonna very quickly lose its accuracy because the metal bit is rubbing up against the plywood and it's gonna elongate the hole and it's gonna move the hole and all sorts of bad stuff is gonna happen. That's where these guys are so cool. You need to know about these. These are called drill bushings. You can get them in a variety of sizes. These are 1/4 inch but you can get whatever inside diameter you need. And here's how this works. I have already laid out the hole locations I need for my project. I'm gonna go to the drill press and do a little pre-drill here and then I'll come back and we'll look at what we have to do as our next step. Got my holes drill. But to understand this better, let's look at this again. The bushings are threaded and in this case they're 1/2 inch 20. So, that's 1/2 inch diameter 20 threads per inch. You need to know that because we wanna drill a hole that's slightly under size slightly under size because our next step is gonna be to tap the hole. And the way we're gonna do this is just with a 1/2, 20 tap, run that in. So, the deal with the hole is that depending on what size tap you're using that dictates how much under size the hole can be. Now, this is pretty forgiving because we're cutting threads in wood. So, it's a different deal than when you're doing this in metal and you have to be uber, uber precise but still we wanna get this, right. I just have my hand underneath. I'm feeling the tap coming through the bottom of the board there. And then back that out. And once we have that out, come out it'll accept our insert. Cool, that's just kind of a neat thing drilling and tapping the wood. And once the inserts are in here then we got that, we got that, we got that. And no matter how many billions of times we use that bushing we're not gonna lose our accuracy because that's steel hardened and it's not gonna wear out from the drill but riding up against it. So, if you're into making jigs in your shop these drill bushings are really, really good thing to know about and available on Amazon available from a wide variety of sources. Good thing to have in your shop in a just in case perspective so that when you need them, you got them.
I use taps quite often in my plumbing job.... I feel like I should have had this idea but, totally missed it. I went to the hardware store the other day and bought a bunch of T-nuts to thread some bolts into a honing guide I was making. After watching this, it dawned on me that I already have the exact tap that I would have needed. Oh well. At least now I have some T-nuts. Haha
If I use my drill in reverse while in the bushing, will it unscrew it?
You have some great ideas and techniques. Add that to a magical delivery, and I am always entertained and educated. Thank you!
Hi George, If you put the tap in the chuck of the drill press and turn it by hand to start the tap it will guarantee the thread is exactly true to the face of the jig. Cheers Norman.
U must tap the hole sraight