My Pulrta 10 Lathe

[Titanium]

I got a Pultra lathe and I'm very happy to finally have a watch makers lathe so I though I'd share some photos. Now I need to find collects that I can us to clamp drill bits into the tail stock and I'm happy. Any advice would be appreciated.

 

 

 

 

. 

[oldhippy]

They take 10mm chucks. Google pulrta and you will find a few places that sell accessories.

[measuretwice]

Very nice, Pultra's are high quality machines, they were a brand of Smart Brown who rank among the finest lathe makers, ever.

I'm pretty sure that lathe is 8mm, despite the name.  Tony's lathe site explains it all - the 8 and 10 geneva lathes were both 8mm.  Can you measure the body dia of a collet and let us know?

http://www.lathes.co.uk/pultra-8-and-10/

As for drilling, I don't think its going to happen readily with that tailstock.  Few 8mm lathes seem to have that function - tailstock collet mounting.  The reason is (afaik) that its not really needed, holes are made by make a making a small centre mark with a graver then drilling with the drill held in a pin vise.  The hardest part is make the centre without a pip in the centre of it, but ounce that is figured out its quite easy and  being handheld, is very sensitive which is needed for small drills.

Pultra definitely made a 10mm lathe -  a shot of mine is below.  its a treat to use, its a bit bigger than the 8mm collet lathes

https://imgur.com/EVGFDOG

 

Edited June 15, 2018 by measuretwice

[Pip]

Fascinating stuff, and coincidentally I’ve got a pultra on the way too. I’ll have a good measure up when I get my hands on it.

 

 

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[Titanium]

Thanks for the reply's. I was thinking I might not find a drilling tail stock. I have plans in my head to make one so I'll post it here if it works.

The collets are definitely 8mm (apart from one 6mm which I didn't even know existed).

Also it came with documents so I think I'll PDF them and send a copy to Lathes.co.uk as they were asking for some.

[Usluyan]

excellent. I am trying to find a nice lathe as soon as possible.


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[Pip]

Thanks for the reply's. I was thinking I might not find a drilling tail stock. I have plans in my head to make one so I'll post it here if it works.
The collets are definitely 8mm (apart from one 6mm which I didn't even know existed).
Also it came with documents so I think I'll PDF them and send a copy to Lathes.co.uk as they were asking for some.

Could you make the odd available here too? ;0)


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[Titanium]

16 hours ago, Pip said:

Could you make the odd available here too? ;0)


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This is the paperwork that came with it. Turns out it cost £21 in 1952 which is a bit more that the £300 I paid. I hope these are of some interest.

Pultra Information.pdf

Pultra Price List.pdf

Pultra Receipt.pdf

[Pip]

Thanks, will have a read after all the footy later. [emoji3]


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[Sid]

On 6/13/2018 at 3:24 AM, Titanium said:

I got a Pultra lathe and I'm very happy to finally have a watch makers lathe so I though I'd share some photos. Now I need to find collects that I can us to clamp drill bits into the tail stock and I'm happy. Any advice would be appreciated.

 

 

 

 

. 

@Titanium What size collets does this lathe take? Also what other manufacturer collects can this one take?

[oldhippy]

It takes 10mm size collets with a 20 mm shank. Try ebay. 

[rodabod]

No, it uses 8mm collets. I own this exact lathe. Most 8mm collet brands will fit, but Conflex were the originals supplied with the Pultra 10.

[oldhippy]

The info I got was from the net from various people asking the same question.  

[Sid]

12 hours ago, rodabod said:

No, it uses 8mm collets. I own this exact lathe. Most 8mm collet brands will fit, but Conflex were the originals supplied with the Pultra 10.

So here starts my confusion when you say most 8 mm collet brands will fit.

In the attached image, Pultra 10 collect dimensions are mentioned. These dimensions exactly match with Boley 8mm, B.T.M and Webster-Whitcomb. All other brand collets vary in dimensions.

I think collets that do not fit precisely in the lathe will affect its work holding capability hence, quality of the end product.

Also it will affect health of lathe adversely.

I may be wrong here but my assumptions are based on attached pic and reading on various internet fora.

It would really help us if you could shed some light on following questions.

=>>Are you using different manufacturer collets on your Pultra 10 ?

=>>Exactly which brand collects are you using? (So that I can also buy same collets to avoid potential wastage of money)

=>>How they affect work holding in the lathe?

=>>How much accuracy you are able to achieve with this setup.

=>>Other tips you may have on this topic are earnestly welcome.

 

Thanks in advance.

[nickelsilver]

The original standard was developed by Webster Whitcomb. If you look at many of the above sizes they are either the same or very very close. The thread pitch of 40tpi comes out to 0.635mm, and in the real world that's close enough to interchange almost all the time. What gets sticky is the thread diameter; if you look at Lorch they have a 0.625mm pitch but the thread diameter is 0.275", which is big enough to bind in many drawbars intended for the 0.268 WW thread. You can see there are several including Bergeon and Wolf Jahn with a 0.270" thread diameter, and from experience these work well across many makes.

 

Differences in length B of a couple of millimeters doesn't generally pose a problem, it's sort of a silly dimension callout there, as there are varying head total diameters (Bergeon, Wolf Jahn, Schaublin and others are a full millimeter larger than WW) which will throw off that length without changing the function. The keyway may vary a bit over different makes, and some lathes may have a slightly larger key which interferes. It is OK to very carefully reduce the key size with a sharp file. If the lathe spindle is well made the file won't touch it anyway, but the key is soft enough to cut.

 

What's really important in buying collets is that they are truly 8mm, or more specifically 7.99mm plus a few microns. The original WW spec is 0.3147" which comes to 7.993mm. This is because the bore in the lathe is very precisely 8mm in diameter, and they wouldn't fit in if they were also 8mm. The bore is where 90% of the accuracy comes from, the angled face of the spindle and corresponding angle on the collet are to close it- they must also be extremely accurately made of course, but the bore and collet fit are where the real business takes place.

 

From experience older American made collets from Derbyshire, Levin, Hardinge (often marked Dale), are all good. European makes of Wolf Jahn, Bergeon, Schaublin, G.Boley, Boley Leinen, and certainly some others are all good. I have used all of the above in several makes of lathe including Webster Whitcomb, Levin, Leinen, Boley. Likewise from experience Starrett (nothing to do with the measuring tool manufacturer) and Peerless are some of the worst. They are soft, and undersized. You can see above Marshall/Peerless, the body size is 0.312" or 7.93mm. That's enough undersize to seriously affect accuracy and repeatability.

 

Any collet however good it may look may be useless due to abuse in the past. Some ugly collets run perfectly. When buying used you just have to accumulate and sort through, make a set of really good ones, keep another set for rough work.

Edited October 29, 2019 by nickelsilver

[Sid]

16 minutes ago, nickelsilver said:

The original standard was developed by Webster Whitcomb. If you look at many of the above sizes they are either the same or very very close. The thread pitch of 40tpi comes out to 0.635mm, and in the real world that's close enough to interchange almost all the time. What gets sticky is the thread diameter; if you look at Lorch they have a 0.625mm pitch but the thread diameter is 0.275", which is big enough to bind in many drawbars intended for the 0.268 WW thread. You can see there are several including Bergeon and Wolf Jahn with a 0.270" thread diameter, and from experience these work well across many makes.

 

Differences in length B of a couple of millimeters doesn't generally pose a problem, it's sort of a silly dimension callout there, as there are varying head total diameters (Bergeon, Wolf Jahn, Schaublin and others are a full millimeter larger than WW) which will throw off that length without changing the function. The keyway may vary a bit over different makes, and some lathes may have a slightly larger key which interferes. It is OK to very carefully reduce the key size with a sharp file. If the lathe spindle is well made the file won't touch it anyway, but the key is soft enough to cut.

 

What's really important in buying collets is that they are truly 8mm, or more specifically 7.99mm plus a few microns. The original WW spec is 0.3147" which comes to 7.993mm. This is because the bore in the lathe is very precisely 8mm in diameter, and they wouldn't fit in if they were also 8mm. The bore is where 90% of the accuracy comes from, the angled face of the spindle and corresponding angle on the collet are to close it- they must also be extremely accurately made of course, but the bore and collet fit are where the real business takes place.

 

From experience older American made collets from Derbyshire, Levin, Hardinge (often marked Dale), are all good. European makes of Wolf Jahn, Bergeon, Schaublin, G.Boley, Boley Leinen, and certainly some others are all good. I have used all of the above in several makes of lathe including Webster Whitcomb, Levin, Leinen, Boley. Likewise from experience Starrett (nothing to do with the measuring tool manufacturer) and Peerless are some of the worst. They are soft, and undersized. You can see above Marshall/Peerless, the body size is 0.312" or 7.93mm. That's enough undersize to seriously affect accuracy and repeatability.

 

Any collet however good it may look may be useless due to abuse in the past. Some ugly collets run perfectly. When buying used you just have to accumulate and sort through, make a set of really good ones, keep another set for rough work.

Wow this is some intense knowledge. Big thanks for elaborate description. 

[vinn3]

On ‎10‎/‎27‎/‎2019 at 6:09 AM, Sid said:

@Titanium What size collets does this lathe take? Also what other manufacturer collects can this one take?

    Beware;    their are mm threads ( UK )   AND  S.A.E.   ( US ) thread forms. AND " nare the twain will meet"   vin

[Sid]

12 minutes ago, vinn3 said:

    Beware;    their are mm threads ( UK )   AND  S.A.E.   ( US ) thread forms. AND " nare the twain will meet"   vin

Thoroughly noted. Thank you.  

Is there any means by which we can make a distinction between the threads?

Thanks, Sid.

[nickelsilver]

29 minutes ago, Sid said:

Thoroughly noted. Thank you.  

Is there any means by which we can make a distinction between the threads?

Thanks, Sid.

You can use a thread gage. If you have inch (tpi, threads per inch, for 8mm collets generally 40tpi) and metric (distance from one thread to the next, as above for standard 8mm collets 0.625mm) gages, you will see that they are for all intents and purposes the same. You might not be able to differentiate, and almost all drawbars will be happy with either.

Edited October 29, 2019 by nickelsilver

[Sid]

2 hours ago, nickelsilver said:

You can use a thread gage. If you have inch (tpi, threads per inch, for 8mm collets generally 40tpi) and metric (distance from one thread to the next, as above for standard 8mm collets 0.625mm) gages, you will see that they are for all intents and purposes the same. You might not be able to differentiate, and almost all drawbars will be happy with either.

@nickelsilver Thank you very much

[vinn3]

5 hours ago, Sid said:

Thoroughly noted. Thank you.  

Is there any means by which we can make a distinction between the threads?

Thanks, Sid.

   measure the thread diameter,  count the threads per inch and look it up in the machinery handbook.  cheers  vin

[rodabod]

I sound that some drawbars I have which are quite worn-in are not fussy at all about slight differences in 8mm threads.

The biggest variability you will likely find among 8mm collets is the condition. Idiots use an incorrect size and either crush them or over-expand them, leaving them wrecked.