Morris Minor Owners Club

hi all
does anyone have a axle drain plug tap i can borrow to clean out the threads on an axle I'm building up?
i believe its a 1/2" BSPT ?
i would of course pay for the postage if not local (N-East Scotland)
cheers
Stu

Hi Stu
I have a spare 1/2"x14p BSP tap, I will post if it helps.

Regards Win

hi mate
that would be great let me know how to pay for the postage
is it a BSPT? as that's what i have been told is the correct thread
unless you know different?
many thanks
Stu

Hi

These are only £8 new....

https://www.tracytools.com/taps-and-die ... 4-tpi-bspt

Note this states 14TPI...

Taupe

Are you sure it is BSPT on the axle? I would have thought that the plug is tapered and the axle a parallel BSPP thread.
Regards
Declan

I vote for tapered thread.

I am not 100% sure what the thread is, my tap is 1/2" BSPP 14 TPI 1st taper tap.

Stu
If you want this tap to try and clean up the thread very carefully, please PM me your address, i will be happy to post.

Kind regards Win

Hello all,

I think Declan is spot on. It's usually a parallel hole and a tapered plug.

BSP = British Standard Pipe. The extra "T" on the end would mean a taper whilst a "P" would be parallel.

That way, the hole tap is parallel and easily and cheaply made whilst the die machines that cut the plug thread are set at the taper angle with the die teeth retractable for a quick machine cycle.

There's also then no need for a seal and shoulder to screw the plug against if you had both threads parallel. The parallel hole/tapered plug seals when one thread graunches tight against the other usually with the help of some PTFE tape etc.

Sorry to ramble on. Cheers, Colin.

When win states “ 1st taper tap.” I think you might understand that as the ‘first tap of a set of three’.

Threading taps are supplied in several forms. His will be the first of a set where the taper on the tap facilitates starting a thread, continuing to the full diameter muchn further down the tap (good for starting a thread but limited to through-holes of limited depth and only appropriate for starting the threading process for blind holes); the second ‘intermediate’ tap is less tapered at the end of the tap and the third is also called a ‘plug tap’ which would be third tap used to achieve a good thread close right to the end of a blind hole.

The other three-set type are called ‘serial taps’; each one is of a slightly larger diameter, but with little taper at the start. This allows less metal to be removed for each pass, starting with the smallest diameter, thus allowing easier hand tapping without risking breakage. By removing metal from the ‘hole tapping size’ in stages (which takes into account the thread depth).

There are other tap types, usually for machine thread cutting. Generally two types - spiral point and spiral flute , the difference being which way the metal removed is ejected. Spiral flutes push the swarf ahead and spiral flute type ejects the swarf behind the thread (so the ‘flute’ type are far better suited for machine tapping of blind holes).

Hope the above helps those who know little about tapping.