Tapping head on CNC

Just acquired a tapping head, the basics of which I understand. The unit functions nicely on a pillar drill. But when wishing to try it on the CNC mill, there are some ponderables.
The unit does not have an adjustable friction clutch and I am concerned that if I simply programme the feed rate/speed ratio. What happens at the bottom of the thread when the unit is switched from down feed to retract and auto reverses. With a pillar drill the Z axis quill is quite free to absorb the change. But under driven feed on the CNC, during that small moment of change, the Z axis feed must be momentarily static before it reverses. I am assuming, bang goes the tap?
Is there any contingency normally built in the these units that mitigates this problem. I am completely new to this and probably missing something obvious. But if you have knowledge of the process and would share I would be most grateful.

Why not just rigid tap?

Because I have the damn thing, including the spiral taps and I just have to learn how to use it on the CNC.
Have machine sub-table project coming up with lots of M8 holes. Could put in as many as I really wanted as opposed to the number I felt like hand tapping.

I've seen companies without rigid tapping capability drill the hole pattern on a CNC then use a mill drill, pillar drill or tapping arm to bung the threads in.

Have a tapping arm but far too light for this head. But just read a good thread on the other site, hope this is permitted :- http://www.cnczone.com/forums/tormac...c_tapping.html

Answered a lot of questions that I had. If you have an interest in the subject, it may be worth a look?

It would help if you up a pic of the exact head you have. Tapping heads come in different guises. To make sure people are barking up the right tree put up an image so people are double sure what they are dealing with.

It's not common to use the type of head you are describing on a cnc as it appears to be a self reversing head more akin to Manual tapping operation with the head.. these types of unit need the spindle to rotate in one direction only and not reverse..... so how you are programming here is key factor. It will mean you will need spindle rotate clockwise Z- x amount (sometimes a small dwell is needed at the Z - position) then spindle does not change rotation then Z + to a z up position..

Normally on cnc you will either rigid tap which is full synchronous (rotation to Z feed) I'm not a massive fan of ridged as machines can go out of calibration and there is absolutely no leeway if there is any pitch errors, either machine or tap.. The other standard method is a tension and compression tapping head. This relies on the machine reversing direction at the full Z - position.. so clockwise rotation Z- (feed tap) dwell reverse spindle, feed tap (out of the part) Z + to a safe z up height.

I much prefer tension and compression as it gives soft start and exit and gives adjustment for any pitch error with no breakages.

I hope that info is helpful

Thanks for reply. I am familiar with rigid tapping. - However I am really enthusiastic to try this head out. Some details follow :-
The head is an obscure Yamatokoki Manf. Co. unit with the prefix NEWS. It is well engineered and the auto reverse functions more or less perfectly on a pillar drill. - Axial retraction about 20mm. Forward and reverse are geared 1:1. Fitted with a stop rod beside the quill. It resembles a Procunier. Have assumed it is a cone type unit.

I've got 3 tapmatic tapping heads, they work a treat.

I'll have to see if I can dig out the code as one of them doesn't have a clutch, but taps M3 like a dream

Andy - Thanks I would be most grateful to read your code if it could be available.

Hi! Did you get the tapping head working on CNC?

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Originally Posted by toomast

Hi! Did you get the tapping head working on CNC?

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Yes, got one of my tapping heads for sale if your interested?

toormast - I have only really played with it. - Need to find a brain slot to have a good go at it.
Andy above would probably be more helpful than me, until I manage to get my head round it.

One of mine in action

https://youtu.be/jR26gs1tvtM