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Watchmakers lathe collets

maclerche

By maclerche
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maclerche WRT Addict

maclerche

Posted
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Then I finally bought a watchmaker lathe that is on the way with the mail. Now I have to buy some collets for the machine!

If money was not a problem, I would ...

Buy schaublin B8 71-137 from 0.3 to 8.0 mm or Bergeon 03 to 8.0 mm.
Unfortunately, the money is not that easy so look for alternatives ..
There are some Chinese sets of all sizes, approx. 77 pieces for approx. 500 pounds. Are they worth throwing money after?
Next option is Vector, which is negotiated by bla. Boley they can be acquired for approx. 38 pounds each.

What do you use and what would you advise ... The machine can take 8mm. B8 or WW collets!

salespic1.jpg

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oldhippy Distinguished Member

oldhippy

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I quite often see second-hand 8mm collets on ebay. Look out for strained collets, these are ones that have been forced to take a larger size then they should, they will be out of shape. Others I have seen that do not close evenly and have a raised edge around the centre. Rusted ones I would leave them.

I had a watchmakers Boley lathe with a full set of collets, so I never needed to buy.

Thats a nice looking lathe you have.

 

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rodabod Distinguished Member

rodabod

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10 hours ago, maclerche said:

No, it takes "normal" 8mm. watchmakers collets B8 and WW types! 

You can read a'lot more about this machine here https://watchmaking.weebly.com/cowells-90cw.html and here http://www.cowells.com/90cw.htm 

Ok, well I strongly recommend getting an ER collet set if the collets match the standard “Boley” profile.

https://www.ebay.co.uk/itm/282388953876 

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maclerche WRT Addict

maclerche

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Regarding to ER collets!

The Cowells 90CW (newer ones after 2005) Has a spindle nose with 3 M4 holes. In these holes it is possible to mount an adapter so that the nose gets a thread M14 x1 That way it is possible to mount a chuck. This adapter can be ordered at special dimensions, such as fits a Sherline chuck too and you can get it with center in MT0 And I'd actually thought to get it done so it's a holder for ER8 or ER11 which also features super præsice. The disadvantage of ER collets is that they are designed to hold tools and preferably have material throughout their length or min. 3/4 of the length! A watchmaker collet can hold quite small pieces! But ER is definitely a good option to have too!

http://www.cowells.com/Gallery/CW-headstock.jpg

http://www.cowells.com/Gallery/G13.jpg

https://www.shop-apt.co.uk/er-collets-super-precision-0005mm-runout.html

Edited by maclerche
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rodabod Distinguished Member

rodabod

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ER collets: well, they are very nice to use, and make the choice of collet for the work simpler as they tend to work over a wide range (often 0.5 or 1mm for the smaller types). 

So, I can survive with just 9 collets to cover 0.5 - 5.0mm range. 

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measuretwice WRT Addict

measuretwice

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4 hours ago, rodabod said:

I should add that I also own a full set of split collets too. 

ER's can work and might be a solution; many use them on lathe's.  But to compare between them, ER's are for tool holding and split collets are preferred for work holding.   A general view is that split collets hold with better alignment and concentricity than ER's; as ER's were meant for tool holding (TIR matters slightly less)  I won't argue too strongly on that one, a lot probably comes down to the quality of manufacture vs form factor, but I would expect a quality split collet to have the least run out.

The main reason though, is holding shorter pieces.  A split collet will hold work properly with only a short length to grip, whereas ER collets are suppose to be able to grip essentially along their length; they don't maintain alignment or concentricity nearly as well as a split collet with short work pieces....which I would think would often happen.  Again, part of the design legacy as a tool holding collet.

imo its really important to have minimal run out, especially with this small work.  1/2 a thou TIR might be ok on a 2" dia piece, but if you're making a balance staff with a 3 thou pivot, its not.  Precision is expensive, I believe its solidly in the get what you pay for category.  Not wanting to or able to spend $38 per collet, I've always chosen to used ones in good shape made in the developed world: Swiss, German, British, American.  Well truth be told, I've only bought lathes that come with good sets, but these collets are a pleasure to use and not too expensive.  Ebay can be a good source, although I prefer to buy in person so I can see them.  Ebay does have the advantage of the return policy if an unscrupulous vendors ships a set of beaters. 

 

Edited by measuretwice
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  • 2 weeks later...
mbhorology Member

mbhorology

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Interesting and good info.  Do you happen to know if they were referring to the collets which come with their lathe package https://www.ebay.com/itm/New-Unused-Mini-Precision-Watchmaker-Lathe/282991424601?hash=item41e39a7459:g:9WAAAOSwM0FXIAbV

 

or did they refer to these which are available separately https://www.ebay.com/itm/77-Pieces-Collets-for-8MM-for-Watchmakers-Lathe/401089759992?hash=item5d62d00af8:g:-ggAAOSwZ8ZW6fio

 

Thanks

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jdm Distinguished Member

jdm

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Posted
5 hours ago, mbhorology said:

Interesting and good info.  Do you happen to know if they were referring to the collets which come with their lathe package https://www.ebay.com/itm/New-Unused-Mini-Precision-Watchmaker-Lathe/282991424601?hash=item41e39a7459:g:9WAAAOSwM0FXIAbV

or did they refer to these which are available separately https://www.ebay.com/itm/77-Pieces-Collets-for-8MM-for-Watchmakers-Lathe/401089759992?hash=item5d62d00af8:g:-ggAAOSwZ8ZW6fio

These identical. No different manufacturing for a same product.

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