Jig for hand tapping

Hi Guys,

In theory hand tapping is easy. Trouble is keeping things upright.

So again in theory take the typical hand tapper, remove the tommy bar and extend the upper tube before replacing the tommy bar. If this extended tube is fitted to an upright stand with suitable tubing that is a sliding fit to the extended tommy bar you have a basic hand tapping jig.

My question is there a suitable jig out there cheap and easily converted, or a pre made jig? Any thoughts

Chris

I rarely tap with conventional tap wrench.

You probably already have a 'suitable jig' in your workshop. Mine is my pillar drill (for work not in the mill or on the lathe). Depending on thread size either hold the tap in the chuck or make a tubular extension for you tap wrench.

Turn the tap by gripping the chuck.

I would say that 80% of holes I tap (M2 to M12) in the drill chuck are under power or more correctly power assistance. VFD at lowest frequency and lowest torque.

Ian P

Search for "Who has one of these tapping fixture tools ?" in the Search this Site box at the top right.

I can't remember who originally designed this but I have made two from LIDL drill stands and they work fine and are cheap to make.

EdH

Chris,

For years now I have used the drill chuck that made the tapping hole to grip the tap, taper version [ #1 first of course]

Insert the tap into the hole, apply pressure on the quill and rotate the tap using the chuck key to feed it into the hole, keeping the pressure up to help it.. After a few turns, I lock the quill, undo the chuck and now, as the tap has started truly vertical, transfer the job to the bench vice and complete the tapping in the normal way.

A wooden wedge placed strategically in a table slot will stop the job or vice it is mounted in spinning while the first few engagement turns for the tap are being made

Simple, low tech, quick and effective

Regards Brian

Edit. Ian beat me to it, he clearly types faster than I do

Edited By Brian Wood on 16/07/2020 18:13:33

I have a short piece of 3/4" square bat, drilled to suit tapping sized drills for 5mm,6mm 8mm 10mm and another block for 12mm.

To use I simply clamp the block over the hole to be tapped, thus keeping the tap upright.

Nothing fancy, but it works, so gammy threads are now a thing of the past.

I might add that there are very few situations where this "Jig" cannot be used.

It,s simple and cheap.

You can just lightly close the drill huck around the tap shank imediately after drilling so the spindle is still directly above the hole. This will guide the tap with teh tap wrench part way down it's shank.

Or make a simple guide to go in the chuck with a 60deg point on one end and drilled with a ctr drill at the other, this can then be used to guide both male and female ended taps.

Correction, I should have said drill the holes to suit the outer dia of the tap so that the block supports it.

Larry your idea seems relatively novel. (Thank you to everyone who posted so I can reflect on my approach). Bare with me but can you clarify what bat is in engineering terms. Also are these holes threaded as you know the tapping drill is less than the thread size so the holes in the jig surely would need tapping before using it. Can you put me right on this.

Chris

Edited By Chris TickTock on 17/07/2020 11:57:29

R is next to T on the keyboard

I made a Tapping Fixture out of an old Pistol Drill stand. The arm was just a piece of box section with two sleeves welded into place and reamed so that they were parallel.

The Tap is held in a small (3/8" capacity ) drill chuck. The T handle is about 4 inches long, to limit the torque that can be applied. This can still be enough to break a small Tap if handled carelessly.

This enables the tap to be kept square to the work, reduces the number of hands needed for the task.

AS a clock maker, working mostly in brass, lubrication won't be required, but for Steel Rocol RTD is my choice, with white spirit or WD40 for Aluminium and its alloys.

HTH

Howard

Why make this complicated?

All you need is a hole that is perpendicular to one surface and is a slip fit for the tap. Measure the diameter of your tap, and drill a hole slightly bigger. If you do this in the lathe and part off at 2 to 3 times the diameter of the tap, you'll know that the requirements are met. Stamp the size, and keep each with the associated tap just like tap and clearance drills.

This is a good use for some of the stub ends of small diameter material that accumulate; you could knock up a set for all your taps while your coffee cools.

Oops yes ..wasn't being funny didn't think of the obvious...bar intended not bat. I make many typos so hope Larry takes it as genuine question.

Chris

Sounds good. Never though about it but will a 3 jaw drill chuck hold square tappers well and in its centre. I suppose it must or the posts here would be redundant. However on a lathe 3 jars do not hold a square stock usually. So I think I must ask.

Chris

A drill chuck will hold the shank of the tap, and if the Tap jams, will slip, preventing breakage.

The essential thing is to prevent applying any bending moment to the tap. That is a sure way of breaking a Tap.

A drill chuck covers a variety of Tap sizes. A Tapping block will hold the tap square to the work, but you need one for every size of Tap. And being short, because some taps have a larger shank that the actual cutting portion of the Tap, any clearance between Tap and Block risks the thread being out of square..

Recently, I had to counterbore to admit a 8-32 UNC Tap to cut the thread at the bottom.of a deep hole, which effectively provided guidance for the tap.

Howard

Home made tapping blocks work well on flat material as said. if you've drilled the hole on a curved surface the blocks won't be any help. This setup uses a spring loaded centre that fits in the rear of the tap, or in this case the rear of the tap wrench.

Yes, a spring loaded centre is useful way of holding the Tap in line, and minimising bending.

Some time ago, in MEW, there was an article on making a Tap holder that seemed to cater for operations to produce a tapped hole. Ir used a drill chuck that could be extended from Centre drilling, through tapping drill to holding the Tap and rotating it by fitting handles, for use as a Tap Wrench; or could also be used as a sensitive tapping device, by removing the driving pin and holding a knurled ring containing a ball race.

Howard

Several years ago I bought a dedicated cast iron tapping jig. I'll try to find it and take a photo. It has never been used for its proper purpose.

rgds

Bill

I've got a George Thomas Tapping and Staking tool which does the job, but I rarely use it. If I hadn't got it cheap I wouldn't have bothered.

**LINK**

A hazardous venture into the workshop undergrowth eventually found the hand tapper. It seems to be made by 'ROFMILL' and the photos below showit with the drill chuck key fitted in the tap holder. The handle is adjustable for swing.

rgds

Bill

I would think for Chris's application (clocks) a tapping and staking tool would be the go to tool. However with the general trend in these threads to buck traditional methods in favour of more modern approaches there are loads of alternates. Really depends how many holes you need to tap, the tapmatic or similar auto tapping head in the drill press or mill is a pretty good way of dealing with multiple holes or bigger threads. Pay your money and take your choice.

Paul.