How to Drill and Tap Threads on a Drill Press

How to tap threads on a drill press along with layout tips and tricks. This can be done by using the power of the drill press, but I’ll be doing this by hand instead and I’ll be sharing some tips along the way. #metalworking #stainlesssteel

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Instead of using nuts with washers, I wanted a more rigid setup. I used a couple of stainless steel plates in behind instead. For marking these out, I took measurements from the clamps to determine the positions of the fastener holes. Go over the area with a marker. Sometimes any scriber lines can be hard to see, so the high contrast between the black marker and silver from the scriber lines makes it easy to see. The caliper is used to mark out the basic location and then the lines are finished up with a square and scriber.

The hole center points are marked out with a center punch. This creates a dimple in the material, a spot where a drill bit can lock onto and it prevents it from wandering.

I’ll be using is a 10-32. If you are unsure of the fastener type, a great way to verify this is using a tap and die set. These sets will come with a thread gauge, which measures the pitch of a fastener or threaded hole. There are two versions, SAE and metric, here I’m using SAE. A thread gauge is made up of various leaves, some have more than others. Each of these leaves has its own thread pitch which has a number stamped on the side.

Look for the matching die nut. We’ll be looking for a 32 in the size, the die should fit like a nut. It should thread on easily, haven’t proper contact with no binding if it’s a clean fastener. Stamped on the die is the size, just like the fastener, it’s a 10-32.

Look for the matching tap. I’ll be threading a through a hole so a tapered tape will do just fine here. If you were working with a blind hole, you’ll want to start with a tapered or plug tap first, then finish up with a bottoming tap so that blind hole is almost fully threaded.

On the side of the tap will be the size, it’ll either be etched or stamped.

Referring to drill and tap index. Based on the tap size, this would be a number 10. We have two different thread types to pick from under number 10, this is 24 and 32. We’re working with 32, going over to the column, it requires a #21 drill bit which is 0.159”. Not all drill bit sets have specific sizes available, = this chart also lists an alternative metric which is 4.1mm. I don’t have a #21 or 4.1mm drill bit, but I do have a 4mm drill bit which is about 0.002” smaller than a #21.

A center drill will be used first to prevent the drill bit from wandering. You can lower the chuck and spin it on the center punch mark, this will help with alignment. Then clamp the part in place. Apply some cutting oil and then drill the part.

Making a pilot hole, this creates a path for the final sized bit to follow and helps reduce drilling force. Apply cutting oil, this too will aid in drilling and helps reduce the bit of overheating which can shorten its life. The bit I’m using for a pilot hole is a 3mm. Peaking when drilling instead of one a constant push also helps with keeping the bit cooler.

Using a 4mm drill bit for the final hole. Cutting oil is also recommended.

Remove the bit and clean away any chips.

Then install the tap. The plate has kept the same position the whole time, maintaining the accuracy of the threaded hole. Power tapping is an option where you’re using the power from the drill, however I prefer to do this by hand especially with harder materials. Apply cutting oil to the tap.

Ensure the tap is tight in the chuck, then lower it into place.

Rotate the chuck by hand while providing light downward pressure pushing down the chuck. The tap will thread into the material, take your time. If you feel binding, back out the tap slightly to break up any chips and then continue to thread it into the material.

While holding the chuck in place, loosen the chuck and retract it. You can then remove the tap by hand. You may be required to remove the part and clean away any chips from the backside as they can create binding when removing the tap.

You maybe have some burrs leftover on the outer edges of the holes, a large drill bit can be used by hand. Rotate the bit and it should be able to clean away any burrs. You should be left with a clean pointed thread profile, when a faster is installed, there should be minimal play. If you plan on using any thread locker, the holes will need to be cleaned with a solvent first.