The hole was there to hold the tap while it was being ground during manufacture; nothing to do with using a guide when tapping. Changes in manufacture mean that the hole is no longer needed.

I’ve never used a spring loaded guide for tapping. If I’ve just drilled the hole on the mill then I hold the tap in the drill chuck and turn it by hand to get the tap started, then finish off by hand. Alternatively I just tap by hand using a standard tap wrench and align the tap by eye.

Andrew

I use one of the 3 sizes of eclipse chuck type tap wrenches and put the centre (dead or live) in the tailstock or spindle  and use the hole in the end of the tap wrench. Even the small BA sized one has a hole.  Noel.

I have some small taps I have ground a couple of flats on at 90° to each other so that when using a tap handle on the shank they are less likely to slip. I find that when applying pressure downwards on the handle when starting the thread that any slip makes the tap handle move down the shank.

Martin C

The series of Tap Tru tap guides includes spring loaded guides / supports with both concave and convex ends.

Using chuck type tap holder (In the spindle provides support) or in a chuck type holder which can have a centre drilling for location, will maintain support and location.

Support is important; Taps don’t withstand being bent!

Howard

To get run of the mill tapped holes square, I have a couple of short pieces of aluminium L section cut square, and of lengths for various taps to be guided against . The tap is merely squared up in the corner with the L held in contact against the surface. Once running orthogonal, the guide is removed and the thread completed. The technique can also be used for drilling. With moderate skill it is quite adequate for many purposes.

Funny you should mention that as I was going to say that it would be almost impossible to have a “one guide suits all” setup. Taps not only vary in diameter but the amount of chamfer can be different from one make to another as well as the length of the square section.

The same applies to tap wrenches some are thinner than others, if you look at the two images I posted earlier the first small tapwrench on th eM4 tap is actually thicker than the larger Eclipse one in the second image on a M6 tap so won’t clash with a guide so easily. So find some thin ones or modify what you have.

I to remove the guide once the tap has started but can appreciate that as you may not be able to use two hands on the tapwrench the risk of pulling things offline by just rotating with one half of the wrench will require the guide to be used for a lot longer, more so on the larger taps that need more effort.

On 6 December 2023 at 20:00 JasonB Said:

 

EDIT, Found a better pic in a book! Pointy end gets used for taps with a ctr hole in them

Being the owner of a dire set of metric carbon taps more useful for cleaning threads than actual tapping, I tried a cheap 11 quid set of the spiral taps as Jason’s borrowed photo above.

Having used them they start very easily and follow the hole, they don’t need backing and they act like a drill bit with swarf coming out of the hole at 60 odd rpm which makes me wonder why there’s a tap wrench in use at all in that photo.

Hi, “tapping guides” almost twelve years ago during my day job back then, my workmate and myself had to unexpectedly drill and tap eight holes in a steel structure on a river, in the middle of somewhere near Cambridge, and we hadn’t taken any tapping gear with us, as the original plan was to use nuts and bolts. We were too far away to return to the workshop and back again, as the first stage of the job had to be finished on day one. We managed to come up with an improvised solution with what we found in our toolboxes, which I posted about here at the time, https://www.model-engineer.co.uk/forums/topic/metric-taps/page/3/#post-88451

Needless to say no tapping guide was available either. The phrase, “When the going gets tough, the tough get going” springs to mind, as you just can’t go back and say you couldn’t do the job. I will add the customer passed the whole job without any fault.

Regards Nick.

On 8 December 2023 at 16:26 Dave Halford Said:

On 8 December 2023 at 12:30 JasonB Said:

 I only posted to let Bill know that there may be another way round his issue if only for metric

 

You can get machine taps in most thread forms so driving under power can be used for all types, can even be done with traditional taps if not too thick a material. Shopping around will find them in all price brackets

I’ve sometimes used the bench drill itself as “tap wrench”. Unplugged at the mains, belt slipped off the pulley, tap held in the chuck itself and the work allowed to “float” radially at first (unless I’ve drilled the hole there with a bolted-down vice.)

Using the chuck as a handle is hard on the hand, but this approach has been useful sometimes for short tasks.

I do though have and use sprung guides, especially if the work is on the milling-machine whose quill is far too stiff for any sensitive handling.

That’s right Bill you can hear me pressing the green button that quickly stops and reverses the spindle all with one click. It can be done with the on/off switch but as the pitch of the thread goes up you need to react quicker as the tap gets drawn in quite quickly. I also think that when it is in tapping mode the torque/overload settings of the control board change, this is best done with brushless motors as they have sensors in them that feed back the motors speed to the board.

Of the spiral flute and point taps that I have which are colour coded mine are black which is “general purpose” as far as the maker YG-1 goes. You can see the colours of the taps shown for each material group here