Hercus spindle thread form?

[neksmerj]

Dear members,

I recently purchased a face plate advertised as suitable for a 9" Hercus lathe, however, it will not screw on. In fact, it won't even start to screw on.

According to my records, the Hercus spindle thread is 1.5" x 8 TPI

My thread gauge confirms the face plate thread is 8 TPI, which can only leave two other problems. A. the thread is undersize, or B. the thread form is incorrect.

Q1. What thread form is correct, 55 degrees or 60 degrees?
Q2. What should the inside thread diameter be?
Q3. Would a suitable tap be available?
Q4. If yes, where can I borrow one for a day?

In a bit of strife, so any suggestions are welcome.

Ken

[etd]

Hi Ken
Thread ID is 1.369", the unthreaded bore (about 10mm deep) is 1.510" inside diameter.
Definitely 8 TPI, but difficult to pick the difference between 55 and 60 degree form, anyway that should not stop the thread from starting if the diameters are right.
Can't help with a tap, 1.5" BSF is the nearest 8TPI.
Good luck!!
Evan

[pipeclay]

Ken are you able to chase the thread on your lathe,can you grab the face plate on the rear spigot.
Other choice if your not sure make up 2 dummy spindle shafts one 55 & 60.

[bollie7]

8 tpi on that dia is a pretty course thread. with a set of decent screw pitch gauges you should be able to tell if its 55 or 60 deg. I reckon it would be 55 deg, but thats just an educated guess.

regards
bollie7

[Quasimodo]

These lathes are clones of the US made Southbends so the threads are more likely to be 60 degree - the Hercus manual actually lists 1-1/2" x 8 USS thread (ie., the obsolete United States Standard).

There are reports of some early Southbends having a 1-1/4" x 8 thread - maybe you have a faceplate for one of these see:

http://www.lathes.co.uk/southbend9-inch/page3.html

Grind a 60 degree point on a small strip of metal to test the thread if you haven't got the thread guages.

[neksmerj]

Dear members,

Thanks for all your advice. Think I might be out of trouble, the chap I purchased the faceplate off is more than happy to take it back, and re-tap the thread.

Will keep you posted if all works out, and will request from seller what thread form it actually is.

Ken

[bollie7]

The reason I thought it might be 55 deg is that a lot of old stuff in Oz followed the Whitworth std, probably because we are part of the old empire.
I could be wrong about the thread, I'm usually wrong more times than I'm right. In fact if you listen to my teenage sons, I'm always wrong LOL.

regards
bollie7

[wannabe]

Ken,
I was just looking at the attached PDF file and it states the spindle thread is 1 1/2" x 8 U.S.S. That's the old US standard 60 degree thread form.
I'm not sure where I downloaded this document from originally. Possibly from one of the Yahoo Southbend groups.
Have a look at page 5 of the PDF document (page three of actual document) for the specs.

Edit:
Just tried attaching the document but it's 15MB and the limit for PDF's is 393KB.

[.RC.]

I would have thought with it being a South Bend clone it would be a 60 degree thread, but then Hercus might have Australianised it by using a whitworth thread form.....I would imagine the bolts used in it would be whitworth ones...

[wannabe]

I too have been wondering what thread form the spindle form was as I'm looking at making an ER32 collet chuck for mine so I can use the ER32 mill collets on the lathe. Dreading the thought of doing an internal thread though as I haven't tried that one yet. I know I can do the external thread but the internal one could be a totally different story.

From what I've played with on my lathe all the thread forms appear to be UNC/UNF 60 degree form.

Try this attachment. It's not pretty but you may be able to see it.

[neksmerj]

Wannabe,

Many thanks for the info, without realising, I too already had this info, it's in the Hercus Owner's Manual.

What a dummy am I!

Ken

[jmk89]

Ken

Did this guy make the faceplate himself? If so, could you put me in touch with him, as I may talk to him about makinga faceplate for my Zyto (and a backplate that could take a 3 or 4" 4 jaw independent chuck).

[neksmerj]

jmk89,

Have sent off an email to my man and will let you know as soon as I find out.

Ken

[bitza500]

Having purchased a lot of South Bend 9" lathe Parts every part including main shaft, carraige, cross slides Tailstock, every gear imaganable all are a perfect fit as I have it all installed on my Hercus 9" and all the threads were the same, While buying there was quite a few SouthBend 1 1/38" headstock mainshaft and chucks so maybe it was a very early South Bend Faceplate but let us know Ken as is this guy local or not ???
all the best Derek

[neksmerj]

The face plate I purchased, supposedly to suit a 9" Hercus, turned out to be for some other lathe, thread unknown, and was returned to the seller in NSW.

He does not make them, and offered a refund.

Ken