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Seeking slim-nosed spring tapping guide/follower

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Bill Phinn17/06/2021 20:49:15
559 forum posts
86 photos

I have the ubiquitous spring tapping guides [the one with the 3/8" pointed nose and the other with the reversible 3/16" pin], and find them satisfactory if a little sloppily made.

However, a real limitation is that when using taps whose square end is less than 3/16" from corner to corner, the tap is usually quite deep within the jaws of even my smallest tap wrench [Eclipse E240] and neither tapping guide's nose/pin can reach below the tap wrench jaws to engage with the hole or point at the top of the tap.

Does anyone know of a commercially available tapping guide that has a thinner nose/pin than 3/16" and is double ended?

I would make the tool myself if I was in a position to house the lathe I've been planning to buy but not been able to for far too long.

Thanks in advance for any suggestions.

JasonB17/06/2021 20:54:31
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Moderator
21300 forum posts
2419 photos
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I just tighten the tap wrench onto the shank of the tap then any guide will reach, also if tap get stoo tight the wrench will hopefully slip before the tap breaks.

Brian G17/06/2021 21:05:07
776 forum posts
34 photos

I've found that if the tap is too small the point of the guide centres itself in the jaws of the tap wrench which seems to do the job. If the point on the end of the tap gets in the way of this I just hold it a bit further down in the wrench.

Incidentally, if you have a big enough chuck an automatic centre punch is a pretty good makeshift tapping guide for taps with hollow ends.

Brian G

peak417/06/2021 22:48:29
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1466 forum posts
159 photos

I assume that one end of your tapping guide has a concave end to suit pointed taps.
The small tap will effectively be recessed down a small square hole in the tap wrench, which is why you can't reach it, so maybe use a ball bearing across the top of that hole and the concave end of the tapping guide; it should all self centre.
Maybe a bit of grease to save losing the ball.

Bill

DC31k18/06/2021 07:31:47
554 forum posts
1 photos

Make a pin with an end that is less than 3/16".

Buy 3/16" silver steel. Cut off suitable length with hacksaw. Chuck up in drill (press, pistol, cordless - Bradson-type might be a little tedious). Switch on. Use file to reduce to desired diameter. Loctite on suitable retaining collar.

There are innumerable round things that can be made without a lathe.

Bill Phinn18/06/2021 12:10:38
559 forum posts
86 photos

Thanks to everyone for your helpful replies.

Jason, that's a simple solution and arguably better anyway than the wrench jaws holding the flats of a tiny tap in only a portion of their vees. The only potential disadvantage I can think of is whether holding a round shaft between the two vees and repeatedly turning the tap against resistance would mar the jaws eventually - presumably not on properly hardened jaws.

Bill, the ball bearing idea is a good one, with numerous applications, presumably. I'll have to see what ball bearings I've currently got.

Brian, I gave away my auto centre punch so I'm not sure what the body diameter is on most commercially available ones. I do, however, have a 16mm drill chuck and an ER32 collet chuck with all the collets.

DC31k, I was tempted to do what you suggest; I do have two of the knurled type tapping guides, so one can be adapted or sacrificed, as the case may be. Presumably I'd be best off reducing just the tip to a taper [like on auto centre punches], rather than trying to reduce the whole piece of 3/16, otherwise the resulting pin won't be supported laterally by the opening in the tap guide as it slides in and out.

DC31k18/06/2021 13:30:41
554 forum posts
1 photos
Posted by Bill Phinn on 18/06/2021 12:10:38:

Presumably I'd be best off reducing just the tip to a taper [like on auto centre punches], rather than trying to reduce the whole piece of 3/16

Yes. Only 'machine' the minimum amount you need to fit inside the tap wrench. The reason I suggested silver steel is that its diameter and roundness is better than cold rolled. I do not know if a standard tap guide pin is hard: if it is, you could chuck it up in a cordless drill and give it a gentle introduction to a 4 1/2" Makita.

Howard Lewis18/06/2021 15:45:46
5228 forum posts
13 photos

Spring loaded tapping guides are, or were, available, in various sizes, (I have three different sized ones, and with Pointed or Concave ends. )

Am a firm believer in supporting and guiding the Tap. Many Taps break because of being bent.

They go into a drill chuck, and I lower the chuck until the pin is just against the back end of the slot inn the body.

If the tapping is long enough to bring the pin to return to the outer end of the slot, I just move the drill chuck down again, so that the Tap is supported.

The concave ones just fit over the pointed end of the Tap, and just clear a small Eclipse Tap Wrench on the flats of the Tap.

My alternative method is to use a Tapping fixture. Basically a drill chuck that can slide through an arm on the column of what used to the the stand for a pistol drill. This holds the Tap perpendicular to the work, protects it from bending, and slips if there is any sign of the Tap jamming. The length of the tommy bar prevents excessive torque being applied.

Howard

John Reese19/06/2021 23:25:25
961 forum posts

Joe Pie (You Tube) makes knurled knobs that fit the shank of the tap and are held on with a grub screw.

Bill Phinn20/06/2021 12:47:45
559 forum posts
86 photos

Thank you for the further replies.

I had a look at the video, John. I might well have a go at something similar, though with two short screw-in handles rather than a knurled wheel to turn the tap. I can drill down the centre of round stock on my wood lathe reasonably accurately.

Simon Williams 321/06/2021 12:50:38
605 forum posts
81 photos

Adapting Jason's suggestion of tightening the tap wrench onto the shank of the tap, grind two flats at right angles (or thereabouts) on the round shank of the tap. Now slip a bar type tap wrench over the shank, and tighten the screw handle so that the two ground surfaces nestle cosily in the jaws of the tap wrench. One of those little Eclipse bar type tap wrenches is ideal. This gives you a positive drive to the tap.

It will still work if the flats are not exactly at 90 degrees, though one would like to make a tidy job of it, of course.

With a little bit of luck only grinding two flats on the shank of the tap wrench means you can leave the engraving showing the tap size, pitch etc, intact.

The standard size (1/2 shank?) female tap guide can now engage the male taper on the top of the tap as this pokes out of the tap wrench with plenty of spare room.

Best rgds Simon

Bo'sun21/06/2021 13:13:01
495 forum posts
Posted by JasonB on 17/06/2021 20:54:31:

I just tighten the tap wrench onto the shank of the tap then any guide will reach, also if tap get stoo tight the wrench will hopefully slip before the tap breaks.

Just be careful. I managed to snap a 5BA tap using this method. I considered grinding a small flat on the tap shank, but thought that might exacerbate the problem.

John Reese22/06/2021 22:20:30
961 forum posts

Chuck the spindle of the tapping guide in an electric drill. While spinning t in the drill use your bench grinder to reduce the OD.

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