Tapping Fixture for a Drill Press

A tapping fixture allows more precise cutting of threads with a tap than can be done by hand. I adapted a drill press so the quill can be used as the heart of a tapping fixture. Here is a commercial tapping fixture. The photo shows my tapping fixture ready to use. My attachment handle gives me leverage for turning the quill. The arms on the quill allows me to keep some downward pressure on the quill. This helps the tap bite into the metal when cutting.

Materials

• 1 1/2 inch black iron pipe
• 5/16 x 3/4 inch bolt
• 1/2 inch black iron pipe

Tools

• Metal cutting bandsaw
• Center punch (spring loaded)
• Drill and bits
• 5/16 x 18 inch thread tap
• Metal lathe
• MIG welder
• Digital caliper
• Spring clamp

Step 1: Size the Tube or Pipe

1 1/2 inch black pipe has an internal diameter very near to the diameter of the lower part of the drill chuck on my drill press.

I cut a piece from the pipe about 3/4 inch wide. See the second photo.

Step 2: Enlarge the Internal Diameter to Fit the Chuck

I am thankful to have an old Atlas metal lathe I could use to enlarge the internal diameter of the pipe until it fit over the lower part of the drill chuck. A digital caliper was very handy for checking progress. I also smoothed the saw cuts with the lathe. The second photo shows the piece of black pipe enlarged enough to slip over the end of the drill chuck.

Without a lathe, it would be possible to use a file or a grinder (with a cylindrical stone) to enlarge the internal diameter, but some patience would be required.

Step 3: Attachment Locking Mechanism

Something needs to lock the pipe collar to the drill chuck and provide leverage for turning the drill press quill when cutting threads. I chose something very simple.

The holes in the chuck for the chuck wrench are 5/16 inch in diameter. I used the end of a drill bit to determine the size. See the first photo.

I used a digital caliper to determine the distance between the bottom of the part of the chuck turned with the chuck wrench and the center of the holes for the chuck wrench. The second photo shows a faint line scratched into the outer surface of the black pipe collar. I used a spring loaded center punch for drilling exactly on that line.

I began with a very small drill bit and worked up to larger bits until I had drilled a hole about right for tapping to make threads for a 5/16 inch bolt. I tapped the threads. See the third photo.

Test the fit with a 5/16 inch bolt. See the fourth photo. The end of the bolt screws into the hole for the chuck wrench.

Step 4: Weld the Bolt Into the Handle

I used a spring clamp to hold the pipe collar to a piece of aluminum angle in a vise. I slipped 1/2 inch black iron pipe over the head of the bolt and tack welded the 1/2 inch pipe to the bolt.

I finished welding the bolt inside the 1/2 inch pipe. See the second photo.

Cut the pipe handle to length. See the third photo.

The fourth photo shows my attachment ready to use.

Step 5: Use

A drill press vise clamped to the drill press table is handy. Add a little downward pressure on the quill arms as if you are drilling a hole. Use the fixture handle to turn the quill and begin cutting threads. Because the chuck has three jaws but the tap is made for a four sided holder, it is difficult to keep the chuck from slipping on the tap. I could carefully grind three flats on the tap, or I could use the tapping fixture to start threads and then finish in a vise.

Update: This Instructable shows how I made an adapter to interface between the 3-jaw drill press chuck and the 4-sided end of the tap.

Comments

[gadjetramjet]

I like it!!!

[Phil B]

Thanks. I have not needed to use it much, yet. I think it will be very helpful when I need it.

[charlessenf-gm]

Why not simply tap one of the three holes the check key fits into?
If you have the pipe, and the welder, but no lathe - split the collar and stretch it a bit to fit over the chuck, then close the split with a nut positioned over one of the chuck key holes.
Or what sbelectrics said! ;)
PS Thanks for introducing me to Micro Mark!

[Phil B]

The chuck holes are relatively shallow. Taps I have seen require some extra depth beyond the threads to be utilized. The chuck body may be hardened. I am not sure. The chuck wrench holes are already 5/16 inch in diameter. I would probably have to tap for 3/8 inch and would probably have to drill the holes out a little so the tap works and makes threads, but then the hole for the chuck wrench would not fit the chuck wrench, which is what I need most often. Sizing and shaping the collar would be a heroic effort that might be possible if it could be brought to a little above red hot so the metal is very malleable. If by MicroMark yiu mean the little spring loaded punch, those are very helpful and not expensive at all.

[sbelectrics]

Nice use of a drill press to avoid 'drunken threads' as our metalwork teacher used to call them. However, unscrewing the handle each time to move it around the chuck must be a bit of a chore? Could you not spring-load the handle so that it simply pulls out to move it around and the spring holds it into the hole in the chuck when released? (Or even just make the handle telescope in and out by about 5mm to enable pull-to-rotate and push-to-tap operation?)

[Phil B]

Once in place for use, there is no need to remove the handle until finished tapping threads. I should have made it a little shorter so it clears the arms that lower the quill, but I can easily and quickly remove the control arm in my way and use one of the other two arms.

[sbelectrics]

Sorry about that; it's just that in the photograph it doesn't appear that the handle will pass the drill pillar. However, using your idea as the basis, I have now found a spare adjustable side handle from an old SDS drill which clamps nicely onto the knurled part of my pedestal drill chuck so that I can use that to do the same job in future. (The advantage of turning the outer section of the chuck is that it tends to increase the clamping force on the tap or drill as it is turned.)

[Phil B]

I hope it works out well for you. A great thing about projects on this site is readers can adapt according to materials, tools, and skills available.

[jwzumwalt]

Really nice tip! It makes you wonder why this isn't included when you buy a drill press, or why they are not sold as an accessory... though, I think haveing 3 or 4 handles (or even a continious ring and spokes) would be an improvment.
I'll be making one for myself next weekend!

[Phil B]

I poked around on the Internet before posting this and found using a drill press as the foundation for a tapping fixture is not at all uncommon. If I were to make a free standing tapping fixture, there would be a number of challenges already resolved by the makers of the drill press. My biggest problem is the tap slipping in the chuck before I can tap more than a couple of turns. But, that does give the start of a straight set of threads easy to finish well by hand. I find the one arm for turning the quill is very adequate.

[jdhoff_comcast]

There are also commercially made socket-type tap holders available although these require more space between chuck and piece to be tapped.

[tonyfoale]

I use those on a tapping head that I made, they can be seen at https://www.instructables.com/id/Manual-Thread-Tap...
If you get one of those hex to 3/8" square drive adapters which are made to use sockets with battery screwdrivers with hex fittings then the hex will fit in the drill chuck and not slip, the socket-type tap holder will not allow the tap to slip.

[efoster6]

Looks great but the idea of the bar with the screw doing the turning and 5/16 is only a small thread I would be more inclined to weld the handle on and put the locking and drive screw on the other side and use a larger size with the end turned down to make a good fit into the chuck and weld a nut on the other side so that your not pushing on the thread if you can follow what I mean

[tonyfoale]

I was thinking the same as I read the post.

[Phil B]

I wanted to keep this as simple as possible.

[lemondropkid]

Thanks, certainly helps me out, always have difficulty starting a thread. The idea from Syncubus below is also a big help.

[Syncubus]

While this is interesting and I liked your clever mounting method, I've often seen people chuck a short, pointed tool in a drill press (or milling machine) and use that in the indentation in the back of the tap (nearly all taps have this indentation) to 'steer straight and provide quill pressure' while using a regular tap wrench on the tap. This avoids the 'square peg in a hexagonal chuck' problem and requires a lot less storage space.

Here's an example: https://www.instructables.com/id/tapping-a-straight-hole-with-the-aid-of-a-drill-pr/

[lemondropkid]

Great idea, why didn't I think of that ! Thanks for the example too.

[Phil B]

Interesting idea. Thank you for the link.

[AlyssonR2]

I did something similar a good few years ago using a defunct hand drill with a 5/16 chuck and a simple drill-press attachment.
Perfect for those small tapped holes in sheet metal and small parts.