Is this a plug tap

Hi,

I need to tap an M3 thread for 4.5mm in a 5.5mm deep hole. For this I thought I would need a plug tap, So I bought one, and I was surprised that it has a point at the end.

I was expecting a plug tap to have a square end. When buying it I had a choice of taper, second and plug, to me this looks like second. Am I wrong in expecting a square end?

Thanks

Adrian

Lots of plug taps around now in that style. I just grind the point off.

plus one grind it flat

Looks almost like a 2nd tap to me. You'd be better off using a spiral flute tap.

Andrew

Even then you may still want to grind the point off depending one what make the Spiral Flute taps is.

Taps can have external or internal centres. The plug, second and taper taps each have a different number of threads in the taper. Even a plug tap has a lead but may be only a couple of thread pitches. Machine taps are different to hand taps. For full description have a look at someone like Emuge, they make taps including specials. The variation in lead from one manufacturer to another can be quite a lot as some ere on the short side others on the long. As has been said modify what you have to suit to get maximum depth, but use the taper and second first otherwise you may break the tap.

Well, just to add to the confusion, our transatlantic cousins apparently call second taps plug and plug taps bottoming. I wonder how many plug taps we buy are really second taps.

Of to the grinder I go.

Adrian

Recently, needing a thread in a very short, blind hole, I ground the end of a 5 x 0.5 mm plug tap back until it was flat.

The ends will be pointed for the purpose of making the Tap, and the leading end will have little purpose for most of our uses.. Pointed ends tend be on the smaller Taps, with centres on the larger, where there is metal to accommodate a centre drilling.

If the other end is pointed, rather than centre drilled, it can be used with a female centre to hold the Tap vertical to the job.

Howard

Many moons ago I was demonstrating how to tap a hole. 1/4” BSF, no 4 drill with the ” half a turn forward. Half a turn back. Hal’s turn forward etc. The class started giggling quick check of zip the tap was twisting!!! It had not been hardened. Manufactured in north London they sent me a dozen in recommence.

they don’t make em like that any more!!!

.

I have set of Sutton Tools (Australian) B.A. taps. Each size came in taper, intermediate and plug sizes. The plug (2 black stripes) have a square cut end with a minute tapered section.

What I did find interesting is that the diameter of the threaded sections gradually increases from the tapered to the plug version so that when changing from taper to intermediate the tap will cut the previous thread a bit deeper.

Quite useful if one is tapping a 'tight' thread such as for a model diesl engine compression screw.

For tapping a blind bottomed hole the pointy ones look a bit useless.

* Danny M *

Danny, you have what are known as "sequential taps" hence the diameter difference and the marking rings.