Tapping units for drilling machines

This topic has 10 replies, 9 voices, and was last updated 2 November 2017 at 13:41 by larry Phelan.

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1 November 2017 at 16:34 #324827
larry Phelan
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@larryphelan54019
I came across a question recently on another forum regarding tapping units.

The question was "how do you keep these things from falling out of the drilling machine when you wish to bring the tap back up out of the hole,since there is no way to lock the tapping head into the spindle ". This is exactly what happens !

I bought one of these units some years ago from "A well known supplier" and found exactly the same problem. There is no way to lock them into the spindle of the drilling machine,so they just fall out as you withdraw the tap. This is nothing more than A-P-I-T-A. !

I solved the problem by making Morse taper holder which fitted my milling machine and using a draw bar. I did have to weld the the end of the tapping head to the holder,since it was not tapped.,but at the end of the day,it worked,

The reason I make this post is to warn other members that these things may not work "out of the box",and that some means of locking them in place should be provided. They will not work on your standard drilling machine.

Has anyone else come across this problem?
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1 November 2017 at 16:34 #30638
larry Phelan
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@larryphelan54019
1 November 2017 at 16:43 #324830
Muzzer
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@muzzer
No idea what sort of tapping unit you are talking about here. Do you mean one of the self-reversing jobbies? Or some sort of tension compression chuck?

You can simply hold the tap directly in a drill chuck if your drill has a slow enough speed. Even better in a milling machine, especially if you have a DRO to line it up.

Murray
1 November 2017 at 16:55 #324832
Brian H
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@brianh50089
The tapping machines I have used, admittedly industrial ones, reverse and unscrew the tap as soon as the drill handle is moved upwards. They are held in by the Morse taper.

Brian
1 November 2017 at 17:01 #324834
David George 1
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@davidgeorge1
Hi I have used these many times and had no problem with them falling out. Maybe the taper in the one you used had a defective taper.

David
1 November 2017 at 17:31 #324839
Emgee
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@emgee
I use a Tapping head from the Tapmatic range and have no problem with the head falling out of the spindle, as said it reverses when spindle moves away from the work.

Emgee
1 November 2017 at 18:29 #324845
Clive Foster
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@clivefoster55965
Autoreverse tapping heads should hold themselves in unless the drill taper is poor. Cleaning up the taper in the spindle of my Pollard 15AY fixed the falling out problem for me. Scary how far the reamer goes up in before an aged, well used taper is clean. Maybe 3/16 deeper on mine. Getting close to the point where I'd have had to make the extractor slot longer.

Got me full set of Pollard tapping heads. Great devices. Need more collets for the baby no 200 but haven't been able to find out what size they are.

Clive.
1 November 2017 at 18:37 #324849
Nick Hulme
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@nickhulme30114
Morse Taper spindle machines have slots for an extractor wedge because when correctly installed and in good condition Morse Tapers tend not to fall out 😀

– Nick
1 November 2017 at 18:56 #324850
Jeff Dayman
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@jeffdayman43397
If I were buying a tapping head I'd get one with R8 mounting – never a problem coming out with that, as it's secured by a drawbar. As others have said Morse taper should not be a problem either unless:

1. taps too large for machine capacity

2. tapdrill hole too small

3. tap dull

4. taper on tapping head badly made (burrs, wrong angles / diameter etc.)

5. taper socket on mill damaged and not making full contact

Of course if you have a mill with Morse tapers AND a drawbar to secure them, that would be secure too.
1 November 2017 at 19:15 #324856
vintagengineer
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@vintagengineer
Slip A fag paper around the shank before you shove it up. This normally works.
2 November 2017 at 13:41 #324994
larry Phelan
Participant
@larryphelan54019
I never had any problem with the actual tapping,just that there was no way to prevent the unit from falling out on the return stroke. The unit in question is a K3MT3,from Chronos,I seem to recall,and just looking again at the instruction sheet which came with it,there is a picture which seems to show a screw fitted to the quill of the drill to prevent what they call "fell down" [their words,not mine ] In fact one is advised to fit such a screw,but I dont think it would be too easy to drill the quill in the first place.. The fact that someone else had the same problem would suggest that it is not unknown.

Regarding wrong hole sizes,blunt taps ect,give me some credit,I,m a bit long in the tooth to make that mistake.

Re the tapers on both my drill and the tapping unit,all I can say about that is that over the last 30 years no MT drill bit or chuck has ever fallen out of the machine ,even 1" drills ,not bad for a cheap end of the market Far East machine !

The taper on the tapping unit was so good that when I fitted an open end sleeve to it,we had great difficulty trying to remove it,so good was the fit. In the end we had to press it out!

Of course,not all tapping heads are the same,some are better than others,like all things,and the fact that I managed to correct mine means that it does the job. It just seems to be overkill to have to use a bigger machine to do such a simple job
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