Introduction: Make a Wood Tap From a Bolt

Picture of Make a Wood Tap From a Bolt

The ability to cut threads in wood can be useful for many projects. Often the needed tap can be expensive and a car ride away. For many applications, a tap can be made from a spare bolt. This simple tap can be made in less than 5 minutes with amazing results.

Step 1: Tools and Materials

Picture of Tools and Materials

Tools:

  • Angle Grinder
  • Bench Grinder
  • Drill

Materials:

  • Bolt or screw the size of the desired threads

Step 2: Shape Tap

Picture of Shape Tap

If using a bolt, cut off the hex head. Create a slight taper on one end of the thread using a bench grinder. You can rotate it by hand or by using a drill to ensure an even taper. This will center your tap when using it.

Step 3: Clamp Tap and Cut Flutes

Picture of Clamp Tap and Cut Flutes

Clamp your tap on a work bench or in a vice and cut 3 or 4 flutes along the tap. This will give somewhere for the wood chips being cut from your threads to go.

Step 4: Clean Up Threads

Picture of Clean Up Threads

Using a nut, run it up and down your tap. This will clean up any burs developed from cutting the flutes.

Chuck the tap in a drill and verify that it runs true. I haven't noticed any damage to my chuck from clamping directly on the threads. If you are concerned about possible damage, grind the threads away with a bench grinder.

Step 5: Tap Hole

Picture of Tap Hole

Drill a clearance hole just smaller than the minor diameter of the threads. When tapping the hole go slowly and back out after every other revolution or so to clear out the wood chips. These threads will not be as strong as a threaded insert or a t-nut, but they are very useful for some applications.

What other shop tricks do you have up your sleeve? Let me know in the comments.

Comments

gizmologist (author)2017-11-04

I'd leave the head on the bolt so that I could tap holes using a wrench. Thread a nut all the way onto the bolt FIRST, before doing any grinding. Then when done grinding, thread the nut off to clean up the threads. This trick also works very well whenever you have to shorten a bolt.

tomatoskins (author)gizmologist2017-11-04

I completely agree when cutting a bolt that you need to put a nut on first. And I thought it would be the same with the tap. However with the slight taper placed on it at the beginning, the threads don't get misaligned as much as cutting the bolt off completely would.

If you try to use a standard wrench on a tap it won't thread completely straight and it will wobble out the hole. That is unless you use two handles like a traditional tap and die set. I also noticed that the small amount of play between the hex head and the wrench or socket being used can cause the threads to not be perfectly straight.

I used a tap made from a bolt to thread the end of a rolling pin (instructable will come after Christmas) and it was just slightly out of square. The tap needed to have the hex head on it so it could freely change depth opposed to being firmly held in place with my tailstock like this tap would be. So the hex head definitely is useful is some situations, however the threads may be slightly out of square.

Poppy Ann (author)tomatoskins2017-11-06

Hi, you said

"If you try to use a standard wrench on a tap it won't thread completely straight and it will wobble out the hole."

this all depends on who is doing the tapping I have tapped many holes without a tap wrench and never had one not straight as long as you take the time and keep watching the tap to make sure it is still straight you will not have a problem, having to use a bolt or some threaded rod to cut the thread just needs a little more concentration, also on large diameter holes it would be better to leave on the head of the bolt or to put two nuts on a piece of threaded rod and lock them together makes it much easier to apply the higher torque required to cut the thread.

tomatoskins (author)Poppy Ann2017-11-06

You are correct. As long as you can apply a 100% moment with no lateral forces you will be fine. However this can be difficut. Which is why standard tap and die sets have two handles on them. When you apply a couple monent there will be no lateral forces to wobble out the hole. Both are possible, one is just more likely.

bpark1000 (author)tomatoskins2017-11-05

Simple way to get thread square is to drill a clearance hole in scrap piece of wood. Slide the tap through that, and while holding the scrap firmly against the item being tapped, start the tapping a few turns. Then remove tap and scrap, and continue tapping.

Poppy Ann (author)bpark10002017-11-06

A great idea.

thaddaeus (author)bpark10002017-11-05

Great advise. And poetic, too!

kreidence (author)2017-11-05

This is a great way to reuse bolts with burred heads. Something which would otherwise end up on landfill.

jimofoz (author)2017-11-05

Nice idea that I've used before. A couple of comments:
Yes, standard taps will work fine on wood.
If you want want to toughen up the threads a bit, soak with some CA (superglue).
Lee Valley Tools did some testing awhile ago and found that especially in the smaller sizes (screw sizes 4 & 6) a tapped machine screw held better than a standard wood screw.

rejenk3 (author)2017-11-05

I’ve used the technique where I didn’t have a tap the right size (speciality or metric). Works fine in aluminum too. We tap wood in building radio control planes frequently and it works fine. An additional trick is to tap the wood, apply thin CA glue to soak in the threads, retap after glue sets.

john043 (author)2017-11-26

For sure your idea would work quick & easy. before I read it I was thinking that if I needed the threaded hole, spot on 90 degrees, I'd chuck the tap in the drill press and hand turn it in (Press turns way too fast to turn on the power!!!).

Ronald Reagan (author)2017-11-05

Would a stardard tap for tapping metal work in wood? I'vs never tried it.

MartinG40 (author)Ronald Reagan2017-11-12

"Would a stardard [sic] tap for tapping metal work in wood? I'vs never tried it."

Yes, but wood tapping is easiest using a cordless drill. Standard taps have square shanks which won't fit the drill chuck. If you don't want to make your own there's a YouTube creator (The Wood Whisperer) who's selling an excellent set of round shank wood taps... https://www.youtube.com/watch?v=QC6p5SSUSW4

Poppy Ann (author)Ronald Reagan2017-11-06

yes as long as it is a course thread, you can get away with one not so course when using very hard wood.

Yes. It just gets the tap crusty with wood. The relief in the tap isn't designed to self clean very soft chips. Just brush it out with a toothbrush or it'll rust.

alc38 (author)2017-11-06

Coat the threads you cut with 2 applications of superglue to harden them.

MartinG40 (author)alc382017-11-12

"Coat the threads you cut with 2 applications of superglue to harden them."

Was just about to comment the same thing. For best results fill the initial hole with low-viscosity cyanoacrylate glue, then tap the hole when completely dry. Refill threads with glue and tap again. The resulting threads are almost as hard as metal ones.

PROJECTILE PRO (author)2017-11-09

pretty cool

deluges (author)2017-11-04

Nice tip that I have been using for a while, nice to see it documented with such good pictures.

Yet I find the last image confusing - it looks like you're tapping with a drill, but I guess you're simply using the drill press to keep the tap straight? It can be confusing to a beginner who could try to tap with a drill.

Irritable_Badger (author)deluges2017-11-05

Tapping a hole in wood using a drill or drill press isn't a problem unless you're using very small screws (smaller than #4) or high speeds.
The wood is softer than non-rigid "flex" tapping collets. In naturally oily woods you don't even need to predrill the hole. You can make the hole and cut the threads simultaneously with the tap.

In rigid tapping operations in metal it's a different story because chips and heat are the enemy. Insufficient coolant, misalignment of the tool with the hole or simply excess speed will lead to broken taps almost immediately.

deluges (author)Irritable_Badger2017-11-08

Don't you have a problem with the feeding rate of the wood, especially in a drill press ? I guess once the tap catches on it might be able to "drag" itself through the wood but I feel like it might split the beginning of the thread if it has'nt caught on enough.. I don't know if I'm being clear ^^

deluges (author)deluges2017-11-08

hasn't*

Irritable_Badger (author)deluges2017-11-08

Assuming an appropriately slow speed, tapping soft materials, like wood, the problem with the drill press is the spindle return spring trying to pull the tap out. Letting the tap "self feed" isn't an issue.

On consumer drill presses the return spring is usually a flat wound coil inside a housing on the feed handle shaft on the opposite side of the head than the handle. Just take it off.

If you can't slow your drill speed enough use a ratchet and socket to turn the spindle manually using the nut that holds the forward pulley.

It doesn't need to be perfect. With few exceptions, wood has enough movement to cover the entire range of thread tolerances in any given 24 hour period. You don't actually want it to be too perfect. If you make it too tight the wood will end up splitting around the fastener as it moves throughout the seasons.

deluges (author)Irritable_Badger2017-11-08

Unless you make a die out of a nut to thread a dowel and make a whole wooden bolt ;)

I do see you point though, and it is a valid one.

ChrisC203 (author)2017-11-06

After you make the threads put a few drops of cyanoacrylic (super glue) in the hole. It will harden the threads. Run the tap again after the glue hardens to clean up the threads. Repeat a couple of times and you will have good threads in wood.

Yonatan24 (author)2017-11-04

I've been wanting to do this for a project. I have to see if I'll be able to do this with a Dremel. Has anyone tried this?

PerP2 (author)Yonatan242017-11-05

Yes I have

Yonatan24 (author)PerP22017-11-05

How did it go? Did it work ok? I'm just thinking it will take me so much time to remove all of the material with a 1mm cutting disk...

Poppy Ann (author)Yonatan242017-11-06

I have done it using the 1mm cutting disk to cut the slots but used a file to cut the taper with the bolt held in a power drill

PerP2 (author)Yonatan242017-11-05

I was using a smaller bolt and it was hardened but still worked fine. I was able to tap all I needed

tomatoskins (author)Yonatan242017-11-04

It should work just fine with a cut off wheel in a Dremel. Be sure to share a picture when you're done!

foxpup (author)2017-11-05

Great instructable!! I'll bet a similar path could be followed to make your own custom die and put threads on a dowel. Cutting slots out of the inside threading of a steel nut or tapped hole would be doable with a metal cutting jig saw blade. If you got that working you could screw wooden bolts or threaded rods into the nice tapped holes you make with this method. :-)

johnny3h (author)foxpup2017-11-05

I've done this in years past, even on small nuts, by using very small 'Warding' files. The triangular ones seem to work best; just make sure that the 'cutting face' of the flute gap you're creating is PERPENDICULAR to its direction of travel when tapping!

Poppy Ann (author)johnny3h2017-11-06

if not perpendicular then it should slope away from the direction of thread just like most machine taps.

mickbakos (author)2017-11-05

"Create a slight taper on one end of the thread."... Could you please explain how to do this?
Thanks a million
Mick

Poppy Ann (author)mickbakos2017-11-06

if you are using a bolt with the head cut off then just mount it in a electric drill get it either mounted to a bench or held solid by someone else then power up the drill and use either a file or grinder on the end to be tapered it is easy to cut a taper on the end "it is much harder to cut a flat than a taper"

spielbass (author)2017-11-06

Couldn't your make threads in wood using just a bolt, the way you would use a forming tap in metal. It compresses the wood instead of cutting it away, which may be stronger. Any opinions on this?

PhuketAussie1973 (author)2017-11-05

that’s great eat thanks, but what about a die for cutting threads on wood dowel? I would want to be able to do both.

skylane (author)PhuketAussie19732017-11-05

Use a nut held in a vice to thread a dowel.

Taper the dowel a little bit first.

cavalier19 (author)2017-11-05

Neat idea .

mrwonton (author)2017-11-05

smart!

Irritable_Badger (author)2017-11-05

Use a hacksaw to cut the bolt. Cut between two threads and you not only don't beat up the threads, you're left with a nice sharp "tooth" that makes initial alignment much easier when you start taping and it leads in much easier.

Put paraffin wax on the tap to lubricate the tool. Just rub the block across the threads. It's about $3 for a box of 4 blocks of wax and you'll lose it before you ever run out. It's in every grocery store and in the US it's usually sold under the "Gulf" brand. You can also use it on drawer runners in furniture if you've got sticky drawers.

ErnieGant (author)2017-11-05

If you apply some CA Glue to the threads after forming them they are a lot more robust.

Time_and_Turning (author)2017-11-05

I have done this, and similar things. But perhaps I misunderstand: If the hole to be threaded is drilled just smaller than the minor diameter of the threads, it isn't a clearance hole. You want a hole sized to produce a 50% thread in hard materials, and a 75% thread in soft materials. Tables for easy fit clearance, tight fit clearance, and tap holes are readily available for various standard thread sizes. Practically speaking, in wood anything between 50% and 75% would work. Aim for the larger hole if you intend to use glue on the threads, especially if the selected glue expands as it cures.

Whenever possible, use a drill press, or a lathe as a horizontal boring machine. You turn the spindle by hand; the machinery keeps it all aligned properly. You may have to give the forward feed a little assist if the threads are not sufficient to feed the work by themselves. It wouldn't be a bad idea to use those machines to aid in grinding threads off leaving a smooth shank.

For tiny screws, such as in scake model building, sizes #2 & #4 and possibly even #1 use a fine tooth jeweler's saw with the screw held confined in the soft jaws of a small vise or machinist parallel clamps.

Another point on repairing a damaged hole in wood. Wood dowels work nicely for repair plugs. Hardwood dowel stock is available from suppliers to craftsman wood workers. Or hunt up the right tree, like a maple, collect a few fallen branches from it and allow some small pieces of the right diameter time to dry.

groundcontrol (author)2017-11-05

Matthias Wandel did it

Hehe, was wondering how far I would have to read down till someone mentioned Matthias' method. Helpful way of keeping the flutes straight too.

ThomY2 (author)2017-11-05

done that 30 years ago working as a mechanic

chrissnyder12345 (author)2017-11-05

Never thought much about tapping wood, but once this is done, and if the threads wear out or strip, I guess you could insert a heli-coil (maybe a bit of epoxy to hold it in place).

Or go up a size

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Bio: My name is Troy. I'm a Mechatronics graduate studying Mechanical Engineering. I love making things and doing anything outdoors (especially SCUBA diving). I am ... More »
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