Startrite Mercury drill

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Clive Brown 1 on 21/04/2020 15:11:20:

Well, he says that the minor diameter of the nuts he was sent is 15.5mm. That isn't 5/8" BSF which he ordered, it's larger.

That though doesn't really tally with them not even starting on the male thread on the drill.

.

So my question is still open

One parameter has been checked, and is GO

… but the tpi and thread-form of the nuts remains a mystery.

MichaelG.

[not done it yetParticipant @notdoneityet]

Posted by Keith Long on 21/04/2020 13:39:53:

Posted by not done it yet on 21/04/2020 12:52:43:

The standard pitch for 16mm is 1.5mm and 16mm coarse is 2mm. I doubt if 16mm x 1.75mm pitch anything is available – unless to special order. Fingers crossed that the new nuts supplied were metric instead of imperial!

Actually "standard" metric pitch ie metric coarse and what you'd get over the counter if you just asked for an M16 nut or bolt is 2mm, the 1.5mm pitch is the usual metric FINE value.

16mm x 1.75mm pitch certainly would be an odd ball, even Tracy tools don't do one that matches that, although they do list taps and dies for 16mm dia. in 0.75, 1, 1.25, 1.5 and 2mm pitches.

NOT according to the chart posted by Gary on the first page🙂. And a lot of the other charts on the web. As I noted earlier it would be unusual, but not unknown, for a company to make ‘specials’ so spares supplies are limited mostly to themselves (usually at a much-inflated cost). I’m now thinking it is more likely some n———-l has supplied metric instead of imperial.

[Fowlers FuryParticipant @fowlersfury]

This has provided a not-so-welcome break from the trials & tribulations of Walschaerts valve timing.!
I thought it'd be easy to help the OP as I have a Startrite, as well as an e-copy of their brochure with specs.(PM me if you want a copy). Nothing on the brochure about the depth gauge though.
However, I removed the threaded depth stop bar and went through an extensive collection of old nuts from BSC to metric with a view to finding a couple to send on to the OP. No such luck, nothing fitted BSF, BSW, UNC etc.
My thread pitch gauges didn't help with identification either. It looked metric but if it is, it must be between whole numbers. So herewith an attempt to lure the thread experts into an answer:-

 

Edited By Fowlers Fury on 21/04/2020 16:45:32

[Michael GilliganParticipant @michaelgilligan61133]

Thanks, FF

… That doesn’t look like 14 tpi to me

.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

I hardly dare mention this, but …

According to RotaGrip, 13.5 tpi is German Conduit Thread

**LINK**

http://www.rotagriponline.com/datasheets/Wiseman/tap%20and%20die%20price%20list.pdf

MichaelG.

.

Edit: But, if true, then this Wikipedia page must be wrong

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

… The plot thickens !!

Edited By Michael Gilligan on 21/04/2020 17:27:45

[not done it yetParticipant @notdoneityet]

That first list includes a 16 x 1.75mm pitch. Wonder whether we call that nearly standard or nearly coarse?🙂

[Michael GilliganParticipant @michaelgilligan61133]

Posted by not done it yet on 21/04/2020 18:13:43:

That first list includes a 16 x 1.75mm pitch.

.

Where ?

[DC31kParticipant @dc31k]

Posted by Michael Gilligan on 21/04/2020 17:22:37:

According to RotaGrip, 13.5 tpi is German Conduit Thread

Rotagrip are incorrect. They conflate the PG number with the thread pitch.

This site is very good in case you have not seen it before:

https://www.gewinde-normen.de/en/pg-thread.html

There is an M16 x 1.75 tap listed on page 2 of the Rotagrip catalogue though.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by DC31k on 21/04/2020 21:48:21:

Posted by Michael Gilligan on 21/04/2020 17:22:37:

According to RotaGrip, 13.5 tpi is German Conduit Thread

Rotagrip are incorrect. They conflate the PG number with the thread pitch.

This site is very good in case you have not seen it before:

https://www.gewinde-normen.de/en/pg-thread.html

There is an M16 x 1.75 tap listed on page 2 of the Rotagrip catalogue though.

.

Thanks for confirming my suspicion

MichaelG.

[not done it yetParticipant @notdoneityet]

Posted by Michael Gilligan on 21/04/2020 18:20:55:

Posted by not done it yet on 21/04/2020 18:13:43:

That first list includes a 16 x 1.75mm pitch.

.

Where ?

In the list🙂 page 2?

Tap M16 x 1.75 £11.38 T1405

[Dennis RParticipant @dennisr]

My old Startrite floor standing machine, serial number 73698 has a 5/8" x 14 BSF thread, confirmed with thread gauge.

Dennis

[Fowlers FuryParticipant @fowlersfury]

My apologies for creating any additional confusion. Dennis R is correct, the thread is 5/8 BSF. I had no BSF taps & dies >1/2″ & obviously no nuts of that thread. I had to place the rule on top of the threaded rod on the scanner and thought there’d be no parallax yet the set up “lost” half a tooth.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by not done it yet on 21/04/2020 22:54:33:

Posted by Michael Gilligan on 21/04/2020 18:20:55:

Posted by not done it yet on 21/04/2020 18:13:43:

That first list includes a 16 x 1.75mm pitch.

.

Where ?

In the list🙂 page 2?

Tap M16 x 1.75 £11.38 T1405

.

Sorry … I obviously misinterpreted your reference

Thought you meant the chart posted by Gary Wooding

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Fowlers Fury on 22/04/2020 00:45:33:
My apologies for creating any additional confusion. Dennis R is correct, the thread is 5/8 BSF. I had no BSF taps & dies >1/2" & obviously no nuts of that thread. I had to place the rule on top of the threaded rod on the scanner and thought there'd be no parallax yet the set up "lost" half a tooth.

.

… and they used to think that the camera couldn’t lie

Many thanks for clarifying that.

MichaelG

[Brian GParticipant @briang]

Posted by David Galt on 21/04/2020 12:31:10:

…

next question is if it is M16x1.75, then where would I buy a couple of half nuts? Or even better, knurled thumb nuts?…

If you can wait for delivery perhaps the easiest thing to do is get them from eBay. The third listing I looked at offers M16 x 1.75 RH thin nuts in 304, but if want to make your own, a tap is cheaper than two nuts.

Brian G

[FarmboyParticipant @farmboy]

Since the consensus among those who actually own the machine corresponds with the measurements in the original posting my money would be on 5/8 BSF. The supplied nuts would appear to be wrong, as MichaelG and others suggest.

I never take anything for granted, but I can't think of any reason the makers would have chosen an obscure thread for such a simple device. A call to Machine Spares might clarify the matter as they do list most of the spares. ( I have no connection with the firm, not even as a customer )

Mike.

[Brian GParticipant @briang]

Posted by Farmboy on 22/04/2020 10:34:08:

…The supplied nuts would appear to be wrong, as MichaelG and others suggest…

A pencil or coffee stirrer pressed against the thread of the nut may take enough of an impression of the thread to measure, or at least to compare to the thread on the machine.

Brian G

[not done it yetParticipant @notdoneityet]

With reference to an earlier post…

Clearly, as ‘electromechaniical-sam’ has these in stock, he is likely a better supplier than Tracy Tools (for some things)🙂.

Perhaps that is where they get their less-common taps and dies from?

Now, I wonder which pitches are really the coarse and fine…. with seven different options and the most coarse is 2mm pitch?

As I recall, the last time (a long time ago) I needed a 16mm x 2mm bolt, one of my local agricultural machinery suppliers had options of both 2mm and 1.5mm pitch… I wasn't aware, at the time what was ‘standard’ but the first offering from his stock was a 1.5mm pitch (which clearly did not match the thread I wanted) so he went and picked a coarser thread from his stock – 16 x 2mm pitch..

[David GaltParticipant @davidgalt22481]

Ok, I think I can finally put this one to bed. I have taken one of the supplied 5/8” -14tpi nuts, and put a large counter sink either side of it to clean up the entry and exit. This nut now goes on the feed thread and runs freely. So I can confirm it is a 5/8 BSF with 14tpi.

thanks for all your help and sorry for any confusion.

[Author]

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