William

On blind holes, especially ones that small you need a head with a well behaved and sensitive clutch so that tapping goes to depth each time and stops before the tap hits the end of the hole. Any deficiencies in the clutch will leave you with either a goodly proportion of incompletely threaded holes, a pile of broken taps or both.

Asking a lot of a lower end one I think. If doing one or two its easy to adjust the pull to cope with inconsistant clutch action. With 500 it needs to be "pull and go, lift and reverse" every time the same.

I have a set of Pollard tapping heads bought used via the usual sources which are excellent.

When used in conjunction with a drill travel stop tapping depth is very repeatable with the drive clutches disengaging cleanly ready to reverse when the drill feed handle is lifted. They are also sensitive enough to feel when a tap is becoming blunt as more pressure is needed to keep the drive going. Tapping also stops a little earlier with a blunted tap as it can't pull as far away from the clutch before drive is lost.

Absolutelly don't skimp on taps, the good ones are expensive for a reason, and lubrication.

I broke a few taps before I got the technique nailed down. Including an M12 fine in a monumental fit of inattention! Only one to do so I didn't set the drill stop. Ooops, bad move. Just because I'd gotten away with it before …

Clive

Hi William. I managed to get myself a SPV , which i believe was an expensive item. Picked up 2nd hand at auction for £30. Had to make some collets for different taps ,. Not sure of the cheaper versions but this one has a full adjustable torque setup. I have not seen the cheaper ones in operation but have seen the better ones being demonstrated on youtube. Tapmatic etc. Pic of mine below. Hope you find the right one.

Steve.

If you go with Tapmatic it seems the best head for your use will be the 30TC/TD model that has a clutch and tapping depth stop adjustment.
Manual at this link: **LINK**

Used models are available on many auction sites to reduce the cost but beware of thrashed to near death tooling.

You don't mention the grade of stainless you will be drilling and tapping, some grades are easier to work with which may influence your choice of drills, taps and tapping head.

Emgee

Having read the instructions the Tapmatic seems too clever by half to me with its clutch torque adjustment and, apparently considerable self feed after the stop depth.

My Pollard heads have simple double cone clutches, one forward & one reverse. Takes about 1 mm, often less, for the tap to pull the feed clutch out of engagement and stop. No springs, no clutch torque adjustment or other complications. Torque control is just down to the operator not pulling the drill handle so hard that the clutch engagement is sufficient to transmit enough power to break a temporarily stuck tap.

As David says quality taps and a good lubricant makes all the difference.

I'd trust a used Pollard far more than a used Tapmatic simply because there is so little to go wrong. So long as the clutches grip adequately and the reset spring that switches the thing back to forward drive is still strong a Pollard pretty much has to work unless te bearings are totally, and obviously, trashed.

A Tapmatic is something you pretty much have to buy new to ensure fully functional quality. Unless you know its history.

Clive