Can plug tap sometimes mean second and sometimes bottoming?
Here is RS's plug taps selection, some of them look like they get close to the bottom, others less so.
Is there a definitive answer?
ta
when I was serving my engineering apprentceship many moons ago, I was told that taps are named as First, Second, and Plug taps
A plug tap does not have any tapering of the threads, while the first tap has quite a bit, and the 2nd tap has about half as much.
I hope that helps
+1
You live and learn. I never knew that. I recently bought one of those combined drill bit and taps and was surprised it worked quite well in 6mm aluminium amd some softwood.
In message snipped-for-privacy@googlegroups.com, misterroy snipped-for-privacy@gmail.com writes
I rather think things have moved on since my 6 weeks in the apprentice school 1960 or so.
We were shown how to drill holes and tap threads. Electrical component manufacturer so we learned a lot about BA threads:-)
Hand taps came in packs of 3 (first, second and plug). Looking back, they were made of carbon steel and rather brittle. Half turn forward and quarter back to break the swarf.
I think the idea of the taper was that the tap would follow the hole rather than cut the thread at an angle. The second tap followed the threads formed by the first cut. The plug tap was only used if the hole had a bottom.
Modern stuff is much stronger with better control of hardness. I suppose RS assume their market is manufacturing where machine tools will ensure threads are cut parallel.
Yup... a plug tap is the same as bottoming one - no taper at the end, so needs a mostly already threaded hole to be able to carry on and do the last bit in a blind hole.
Not sure those pictures actually match the descriptions in many cases.
Yes use Tracy Tools who specialise in taps.
Sadly, you still need to keep it square to achieve this.
A tip that might help some. Put the tap in your pillar drill. Work square in its vice. Turn the chuck by hand while applying downwards pressure via the handle.
This is a proper plug tap:
Cutting compound is always helpful, too. At a previous place of work it was Trefolex (green snot).
In message snipped-for-privacy@davenoise.co.uk>, "Dave Plowman (News)" snipped-for-privacy@davenoise.co.uk> writes
Yes. I also use the lathe for anything that can be clamped in the chuck. Gripping HSS in the tailstock takes some doing.
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