Using a tapping guide with taps not designed for one

[Bill PhinnParticipant @billphinn90025]

I’ve noticed that an increasing number of newly made taps out there have a square end like the one in the picture, i.e. with no hole or point to accept the male or female end of a typical spring-loaded tapping guide.

When tapping by hand with one of these taps held in the spindle of a milling machine, what type of tapping guide is it feasible to make to guide the tap?

I’ve made some tapping guide ends with 90 degree recesses courtesy of spotting drills, but because of the fairly extensive width of the round tables on the ends of these sorts of taps the tapping guide ends inevitably end up being a little too wide to fit within the jaws of a standard 90-degree-jawed tap wrench.

As an alternative solution, I’ve drilled small recesses in the ends of some of these taps with carbide drills, but I’d prefer not to have to do this. I’d also prefer the 90 degree jaws of my tap wrenches not to grip on the round shanks of the taps but on the corners of their square ends.

Obviously a chuck-type tap wrench would get round the problem, assuming the wrench itself had a recess in the top of it, but you can’t apply very much torque with chuck-type tap wrenches because, being designed for taps at the smaller end of the size range, they have relatively short handles.

While we’re at it, does anyone know why taps increasingly have these sorts of ends on them? The answer that they’re primarily designed for tapping under power doesn’t seem to be the explanation.

[Anonymous]

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

[JasonBModerator @jasonb]

I have a piece of 6mm silver steel drilled one end with a ctr drill and a 60deg point turned on the other. That goes into the collet or drill chuck after drilling the tapping size hole and I bring the quill down so it engages with the tap and apply light pressure while turning the tap wrench. Small taps may need the wrench positioned to grip on the round shank not the square but that is no problem.

If you are using a commercial sprung guide then rather than a point on the opposite end just drill a hole so it slips over the end of your guide’s point.

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

[noel shelleyParticipant @noelshelley55608]

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.

[JasonBModerator @jasonb]

Might just be easier to get a tapping guide that can do both, this one has a reversable male/female end

[Martin ConnellyParticipant @martinconnelly55370]

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

[noel shelleyParticipant @noelshelley55608]

bedroom – workshop.com has the dimensions to make a tapping guide ! Noel.

[Howard LewisParticipant @howardlewis46836]

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

[Bill PhinnParticipant @billphinn90025]

Thanks for everyone’s replies.

I used to use Andrew’s method when tapping, i.e. holding the tap directly in a drill chuck to start the tap and then mounting a tap wrench on to the now partially inserted tap to finish, but I didn’t really like the two-step process of having to get a tap wrench on to and off the end of a tap every time I tapped a new hole. Also, with small taps particularly, it’s a somewhat delicate process mounting a tap wrench on to a tap in this way since any sudden hand movement might break the partially inserted tap. Avoiding this isn’t always easy when it comes to applying torque to tighten the jaws on to the tap. I should perhaps add that I don’t have two normally functioning arms to work with; only one.

I don’t really want to free-hand a tap into a hole unless I have to, and a hole just drilled on a milling machine is one situation where I don’t have to. Of course, if I’m re-tapping with a plug tap after first using a taper or second tap, I tap freehand then, but then all the orientation work has already been done and you’re just following the track of an existing thread.

I’m not sure, from some of the other replies I’ve received, that I’ve described the problem explicitly enough. To re-state things more clearly, the problem is that none of the commercially available tapping guides I’ve seen, including the Arc ones Jason links to, (or the one from Noel at “bedroom-workshop”) will work with the kind of tap shown in my original photo.

You need to be aware that the flat round table at the blunt end of that M10 tap is 1/4″ in diameter. I have made two tapping guide ends that work with these sorts of taps, but the problem with them, as explained in my opening post, is that the free space on the tap end’s 90 degree chamfer that the edges of the tapping guide need to sit in is very narrow and very close to the tap wrench jaws, which means the tapping guide doesn’t always have enough space to get down between the jaws and contact the tap. I realize I could have made my tapping guide ends straight sided rather than tapered, but this would reduce the strength of the tips considerably. It’s a bit tedious that you have to make a different sized opening for practically every different size of tap. I have only made two so far. I need to make another four, I think. Yes, I could tighten the wrench jaws on to the round portion of their shanks instead, but I don’t really want to do this with anything bigger than about 6mm because of the higher torques involved.

To reiterate a related point I made in my opening post, the higher torque needed on the bigger taps is also the reason why I don’t always want to be restricted to using a low torque, chuck-type wrench with these sorts of taps, and I have about a dozen chuck-type wrenches, from the smallest to the largest available.

Howard, I’ve not met Tap Tru tap guides. What do they look like?

[MacolmParticipant @macolm]

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.

[DiogenesParticipant @diogenes]

I don’t leave the partially-started tap in the work between machine and bench – even with just a turn-and-a-half to start with, I usually find the tap can be safely removed and will pick up again where it left off.

Edit – Jason, didn’t you post a slim tap wrench at some point on the old forum?

 

[JasonBModerator @jasonb]

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.

[Howard LewisParticipant @howardlewis46836]

Tap Tru tap guides came as a set of three with spring loaded coned ends, three with spring loaded concave ends.

Each one is held in a drill chuck and the chuck is lowered onto the tap (with tap Wrench in place).

This compresses a spring, moving a small pin down a short slot in the body , so that as the tap “bites” and begins to move into the work, the tap is still guided/supported by the end piece,

When the travel of the pin is exhausted, the chuck is merely moved down to maintain the support.

Howard

[JasonB]

On 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.

[JasonBModerator @jasonb]

One that is not such a cheap set and two it was taken to illustrate the use of a tap guide in my series in MEW and my book so needs to be taken in context with the text. Taps were also supplied by ARC Euro Trade who sponsored the articles in the mag that formed the basis of my book so they got used for the photos.

Machine taps be they spiral flute or spiral point can still be used by hand not only for their swarf clearing capacity but also to save time backing off and/or following up with a 2nd or plug.

You do also have to be careful when using the spiral flute taps in blind holes that you don’t hit the bottom when power tapping, so doing it by hand can be safer. Unless of course you have rigid tapping on your CNC which will stop at the required depth.

60rpm is a bit tame, the SX2.7 is limited to 500rpm in tapping mode but I find 200-250rpm OK for steel and you get time to react and reverse the tap before it gets drawn in too far. This is M6 into a 5mm hole in steel

[Nicholas FarrParticipant @nicholasfarr14254]

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.

[JasonB]

On JasonB Said:

One that is not such a cheap set Forgive me ‘as Jasons photo’ was intended to imply ‘looks like’ but obviously failed and two it was taken to illustrate the use of a tap guide in my series in MEW and my book so needs to be taken in context with the text. Taps were also supplied by ARC Euro Trade who sponsored the articles in the mag that formed the basis of my book so they got used for the photos. Thankyou, so now I know why the tap wrench is there. I only posted to let Bill know that there may be another way round his issue if only for metric

Machine taps be they spiral flute or spiral point can still be used by hand not only for their swarf clearing capacity but also to save time backing off and/or following up with a 2nd or plug.

You do also have to be careful when using the spiral flute taps in blind holes that you don’t hit the bottom when power tapping, so doing it by hand can be safer. Unless of course you have rigid tapping on your CNC which will stop at the required depth.

60rpm is a bit tame, the SX2.7 is limited to 500rpm in tapping mode but I find 200-250rpm OK for steel and you get time to react and reverse the tap before it gets drawn in too far.

Btw the bold is not meant to be shouting and only to pick out my reply.

[Dave Halford]

On Dave Halford Said:

On 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

[HOWARDTParticipant @howardt]

I think the method of manufacture defines the design shed at the drive end of the tap and on the other end unless the design requires shorter length beyond the thread.  If you look at a tap manufacturers catalogue such as Emuge there are a lot of different tap designs to suit material and matching processes.  In production machining taps are held in tap holders which only hold the tap in a way to allow it to square itself to the hole, it is only hand tappers like ourselves who tend to rely on a guide to square up the tap.  When I first started in engineering we had to rely on our eyes to square up the tap, all holes were tapped by hand no machine tapping.

[Nigel Graham 2Participant @nigelgraham2]

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.

[Bill PhinnParticipant @billphinn90025]

Thanks a lot for the further contributions.

The only tapping under power I’ve done has been with spiral point taps (in through holes, obviously). This has worked well on materials up to and including the toughness of mild steel. I’ve not tried it on more difficult materials.

Following Jason’s lead, I suppose I could have a go at power tapping with spiral flute taps as well.

I notice Jason’s SX2.7 has a dedicated tapping mode. I’m not quite sure what this involves. I see from his video of four years ago “SX2.7 tapping mode” that you press the tapping mode button before tapping, and I’m guessing the second beep I’m hearing means a second press of the button stops and reverses the direction of the spindle in one go. My Warco mill doesn’t have a specific tapping mode button. I just use the lower of the two gear ratios and tap at around 100-200 rpm. It’s then a three step process of killing the power, selecting reverse, then starting up again.

On the topic of tap types, you can see that the tap in my first image is a red ring tap. This is aimed at alloyed steels. I’ve also got some bright finish black ring taps, but I’ve forgotten what the target materials are for these. I’m not sure that there is unanimity among different manufacturers on how the colour schemes work, i.e. what each colour means as far as the tap’s suitability for different materials.

[JasonBModerator @jasonb]

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

[Author]

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