How to Tap/Thread Wood

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Introduction: How to Tap/Thread Wood

About: Huge geek who loves trying new things. This generally gets me into some weird projects. Figured it was time to start sharing them!

When working with or designing metal parts, being able to have threaded holes for bolts is something that is great, and often taken for granted. It allows pieces to be attached together and detached easily. This is more of a challenge and often not considered for woodworking projects because wood isn't as strong as metal.

Luckily, tapping wood is actually pretty easy, and can be strong with some minor additions, giving your wood projects more flexibility.

What You'll Need

Step 1: Drill

For making a threaded hole, you first need to make a main hole that removes most of the material, except for the threaded area. To know what size you need for your pilot hole, here is a link to a convenient chart. If possible, use a drill-press so your hole doesn't wobble around. It should be as straight and consistent as possible so your threads have lots to grab onto. Using a hand drill is more likely to make a little bit sloppier hole, but would work if you are careful.

Step 2: Tap

If you have a proper tap, you can tap the pilot hole the same way you would any other material, but you won't need any oil. Since wood is really soft, you can likely "tap" the hole using just the bolt you want to put in it. Getting it threaded at the start can be a little tricky. Make sure you push the bolt into the hole while turning it so the threads catch.

As you are turning the bolt into the hole, watch out as the bolt can get hot with all the friction. Take your time. Also, don't tighten the bolt all the way down as this can strip the new threads you made.

Step 3: Reinforce the Threads

This really is the trick to the whole thing. Thin CA glue flows really well and will soak into the pores of the wood and around the threads, reinforcing the entire thread. Once it dries, you have the strength of the wood, and the glue, which will hold your bolts tight.

Put a few drops in the hole so it runs down the side. Make sure to cover as much of the thread as possible. For a small hole, 2-3 should be enough, but a bigger/deeper/wider hole may need more drops.

When you put the glue in, you may see a little puff of smoke come out of the hole, Not to worry, this is common.

Step 4: Done

Leave the glue to dry for a few hours. Once it's dry, take your bolt and re-screw it into the now completed hole. It may be a little tight at the beginning as the bolt needs to push/cut the glue away, but once it's been put in once, it should be smoother from then on.

Now that the hole is threaded and sealed, you can disassemble and reassemble your projects really easily, and attach parts together in ways that you usually can't with woodworking.

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    16 Discussions

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    raphan

    4 months ago

    I never made taps in wood because I didn't know this trick with cyanolicrat glue to strengthen the hole. Thanks for the tip !

    3 replies

    I'm glad you mentioned the full name of the glue for I never knew it.I find a lot of people use initials and it leaves me clueless,being from the over 65 folk,thank you.Thanks also for the tips on how to tap into wood now all I need to know is how to make a wooden bolt!

    I've always known this as cyanoacrylate. I don' know if this is the same thing as raphan's cyanolicrat or not. They could be just a molecule or two different. Great Instructable! Good photos, easy to follow. One thing I'd add is that when doing this sort of project I always use thick scrap wood under the wood I am tapping/drilling just to avoid holes in a surface where they are not desired. I then make sure to firmly clamp down the being-worked-upon wood (with a spacer block between the project and the clamp to avoid unsightly circle marks!) so that the project doesn't start spinning around and possibly whack someone or something! In ten+ years teaching intermediate/high school art with a lot of woodworking, I never had a single shop accident that required so much as a BandAid! I am an absolute stickler for shop safety and my kids have always learned a lot, had a great deal of fun, and turned out admirable projects. Thanks for sharing this project.

    A small tip, but hopefully it helps you make even cooler things :)

    One more tip that I have read about (but never tested myself) is to cut a slot lengthwise across the threads of the bolt with an angle grinder. This will make the cutting of the threads easier since it will help cutting the wood and moving the wood shards away. This works best with bigger holes and bolts. Nice tip about the cyanoacrylate glue!

    2 replies

    A method used by engineers to recover a damaged thread when they don't have the right tap. An angle grinder might be a bit fierce for that - generally, cutting the slot across the threads is best done with a hacksaw

    Depends on the size of the bolt! :-D

    OK for hobby projects, but please don't do this for anything that needs any real structural integrity. Either use a screw designed for wood, or drill right through and put a nut on the other side.

    1 reply

    Absolutely agree. Bolts that are loaded sideways should be Ok, but anything that has force pulling the bolt "out" should use a more secure method like a nut and washer on the back

    Would it be good to tap the hole again after gluing it?

    1 reply

    That would probably work, just be careful not to cross-thread the hole and wreck the threads you already have there. Using just a bolt is possibly safer for your threads

    I had no idea! Thank you for this well written instructable.

    I have been doing this for a number of years, it's a great way to mount stuff on wood, preferable in some ways to wood screws.

    I do this using a tap, and doing that in pine I am able to put the tap in a drill for a quick tapping.

    Another method comes to mind which is to use repair "springs"

    They are generally used to screw into a larger damaged thread, then screw in a smaller thread size. If pushed into a hole drilled into the wood, the spring would expand and give you a metal rather than wood thread surface.

    "T" nuts are designed for wood, but work best when on the opposite side of the timber.

    Yes! -Never tried tapping soft wood (thanks for CA glue Info.) but I commonly use dimension oak, drilled and tapped from 4-40 to 10-32 for both electronics bench breadboard mounting and small cabinet back plane mounts. (Got a cheap box for a project? - Cut a back plane of oak to fix the back of the box then drill and tap component and PC board screws into it to hold the parts.) Almost any hardware or home improvement store has a handy supply of pre-cut pieces of white oak.

    Oak pieces should be thoroughly dry before sanding and being sealed lightly with spray polyurethane, and the poly should be dry before drilling (use drill size for metal) and tapping. Corners can be chamfered with sandpaper or even routed to look nicer.

    Burn-through resistance of oak for electronics is substantial, and much better than thin plastics. Using oak, one can make all kinds of mistakes and burn resistors, transistors, I.C.s and caps without torching their work bench. (-Assuming that there's a power supply fuse in there somewhere.) The projects are nicer to work on than metal or plastic, don't slide around while being put together, secure heavy and light parts well, they are fairly insulated from the bench and they look nice.

    One difference from the softer wood the author shows is that after tapping, i.e. a screw into 3/4" thick oak, I lightly spray each screw with silicone lube before it goes into the tapped hole the first time. The glue trick isn't needed in white oak.

    So thanks for your post - now I'll try soft woods when the need arises.

    Or you could use a tapped fitting (left of picture) to save using any glue and give a strong bond. If you need an anchor for a bolt you can use a fitting such as that on the right.

    a tapping fitting and a bolt fitting small.jpg