Spiral Flute Tap?

These are normally described as “machine” taps but I’ve just seen a supplier say they can be used by hand.

**LINK**

Anyone know why they aren’t just called spiral taps? Where does the machine part come from and why aren’t all taps like this? Just being nosey LOL.

I think some of my taps are getting a bit worn so need to get some new ones.

Spiral point taps push the swarf ahead to drive it out the other end of through holes, whilst spiral flute taps pull it out of blind holes.

Some one has not been reading the last two issues of MEW, I have also written on here about using them

The machine part comes from the fact you don't have to back them off to break the swarf so they can be driven in under power

The shorter lead taper on the spiral flute and spiral poimnt taps can make it a little hardet to start freehand so they are best guided either by the machine that just drilled the hole or a tapping guide/tool.

I've not tried the Axminster ones and unlikely to at that price, ARC ones seem to work quite well and easier on the wallet. Got some brand name ones too that fall between the two price ranges.

Edited By JasonB on 13/09/2019 16:06:08

All my tapping is done in the lathe or on the mill so I’ll try a couple and see how I get on. Thanks.

Spiral flute and spiral point taps are intended for machine use, and the important feature is that the swarf is controlled. A spiral point tap has straight, angled, cutting edges that push the swarf ahead of the tap, ideal for through holes. A spiral flute tap actually has spiral flutes, which push the swarf back and out of the hole. In a ductile material the swarf tails can be inches long.

To re-iterate both types can easily be used for hand tapping. I find it ok starting spiral flute taps by hand up to about M6. Above that it gets more difficult. A spiral flute tap only cuts on the first thread or two, so is as good, or better, than a bottoming tap for threading depth in a blind hole.

While I often use spiral flute taps by hand they really come into their own under power. With the right tapping heads they can be run fast. I run from 500rpm to over a 1000rpm on my manual machines. It's way quicker tapping the hole than drilling it in the first place.

Andrew

Edited By Andrew Johnston on 14/09/2019 00:01:38

I saw a YouTube video a couple of years back showing the difference between spiral flute and spiral point taps and how they work.

The question was why there were described as machine taps but are now described by some as suitable for hand use.

They're described as machine taps as that is how industry uses them. The hobbyist market for them is insignificant. Of course that doesn't preclude their use as hand taps in the hobbyist community, but it's not how the main market uses them. In the same way you can use ordinary hand taps under power in a machine, but it's not how they're generally used.

Andrew

As you do not need to back them off to break the swarf you do not have the problem of swarf jamming the flutes and helping to break you normal hand taps, particularly taper taps! I rarely use hand taps now.

I thought I coverd that

"The shorter lead taper on the spiral flute and spiral point taps can make it a little harder to start freehand so they are best guided either by the machine that just drilled the hole or a tapping guide/tool."

They are not easy to start just by hand you need a cachine or guide to start them and to get the best performance drive them under power, Andrew tends to use a slightly larger tapping drill size than me so that may be why he finds it easier. Hobbiyists don't need the performance so they can be turned with a tap wrench with the top of the tap guided.

Not sure why they say “1 tap needed”. I guess that’s true for tapping any hole, but I have spiral taps in starter & bottoming. If I’m tapping a through hole I only use the starter, but if hole is blind I’ll use both.

would be harder to start with the Axminster one.

That's interesting; I've never seen spiral flute taps described as anything other than spiral flute. Definitely no options have been listed. I've always tapped both through and blind holes with one tap only. Where are the different types of spiral flute tap advertised?

Andrew

Struggling to follow this discussion, and the terminology

I found Axminster's illustration unconvincing as a 'universal' tap: **LINK**

https://www.axminster.co.uk/axminster-hsse-universal-spiral-flute-taps-ax938282

[ is that really suitable for 'bottoming' or 'plug' use ? ]

.

Then I discovered this document: **LINK**

http://www.ymwtapsusa.com/download/newsletters/Understanding-the-basics-of-spiral-fluted-taps.pdf

... which is very informative, but lists many variations on the theme

I guess the expedient solution must lie somewhere betwixt these extremes !!

MichaelG.

Michael, I have several of these YG-1 general purpose* taps and they show the lead taper, in this cast 2 -3 threads which is not a lot more than may bottom/plug taps particularly if they have a pointed female ctr on the business end so they will thread almost as close to the bottom. Add the fact that no swarf will have dropped down the hole to get compacted in the bottom and they may even go deeper.

The term General purpose here refers to the fact they will work over a range of materials rather than being material specific which as hobby users we don't really need to go into as most people can't afford one tap of each threda for each material.

This video from Hass explains things quite well.

I’m not surprised. No one seems to have read or perhaps understood my OP. I didn’t ask how they worked as I already knew. Your linked document though is very interesting and proves it’s not as simple as I or many others on here thought given the large range of spiral taps available. I don’t think anyone knows the answer to the original question but that’s ok the thread has turned out to be quite informative not least due to your post.

I will buy a number of spiral flute taps and see how I get on with them as I often tap blind holes.

.

Thanks for trying, Jason ... but (a) the Axminster one has a male centre, and (b) 2-3 threads is about double what 'bottoming' taps normally had.

MichaelG.

Vic, I took it that you asked "why are they called machine taps" I thought I answered that they really need a machine to guide them be that directly under power or using the machine to guide them. They are not easy to start by hand.

Michael many of the saller size "machine" taps come with a pointed end as do hand taps so really you need to compare like with like, unfortunately I tend to grind these pointed ends of my taps so that I can get further into the bottom so don't have any photos to show.

However this red box contains a set of three Dormer E500 seriesM6 x 1 hand taps in the usual 3 tapers together with a YG-1 spiral flute tap at the top. All four have had the pointed end ground off and as you can see there is very little difference in how far a full thread could be cut to within the bottom of a hole, probably less than one turn.

And the two together

If you also take into account the swarf at the bottom of the hole as illustrated on the thumbnail of the video there really is not a lot in it.

Edited By JasonB on 15/09/2019 12:33:20

Vic, you may also have been asking this question "Anyone know why they aren’t just called spiral taps?"

That is simple, as there are two distinct styles in common use they need to be called spiral point or spiral flute. I also have some spiral point hand taps so that is another reason to give separate names separate them.

I think we should all get used to using them, at least those of us with a few years to go as hand taps are going to become harder to find, just looking a one doorstop size catalogue I have here there is about 6 pages of hand taps and over 30 of "machine taps" and even more pages given over to thread milling. Industry is what all the main makers produce for so the home machinist will find it harder and harder to get what their grandads used.

Also from the same catalogue, half a turn in it.

Edited By JasonB on 15/09/2019 13:18:36

Jason,

I regret to say that your catalogue clipping further confuses the issue

It illustrates the Modified Bottoming Chamfer, not the Bottoming Chamfer

The 'Chamfer Styles' tab on this page **LINK** does rather better

https://www.mscdirect.com/basicsof/taps

... interestingly; it also distinguishes between 'bottoming' and 'plug' in a way that makes sense, but is, perhaps, uncommon.

[some other sources use those words as US/UK variants]

https://en.wikipedia.org/wiki/Tap_and_die

MichaelG.

Edited By Michael Gilligan on 15/09/2019 14:04:26

Not sure what your first link really shows, it says that a bottoming tap can have upto 2 turns of chamfer, The link to the YG one I posted has from 2 turns so depending on what is actually being used you could get to two turns of the bottom with either. It is also interesting to note that The Dormer ones that I bought from MSC state that one in my photos is sold as a bottoming tap and that has more than two turns so it does vary from make to make. 

Agree you won't get as deep as a bottoming tap with one turn of taper but you could get as deep as one with two turns. 

So that would seem to cover your question "are they suitable for bottoming" , the small pointed end on the AXI one would fall within the cone of the drilled hole unless you are drilling flat bottomed holes Though Axi don't state what tapers theirs have.

That link I posted was for one of about 30 spiral flute taps that YG-1 do, and the tapers do vary on then so you may even be able to find one with less than 2 turns if needed in just the same way shopping around for a different bottoming tap may get you closer to the bottom with one make than another, eg 1 turn as per your link. Or just grind the end of an old or broken one down to zero taper as those that get out to the workshop do when a thread is needed as deep as possible.

Edited By JasonB on 15/09/2019 14:43:39