Pratt Burnerd 100mm Chuck

I wonder how bad this particular one might be : **LINK**

https://www.ebay.co.uk/itm/373455423925

... and how mediocre the ‘acceptable’ ones are : **LINK**

https://www.mscdirect.co.uk/PRA-00206D/SEARCH:CATEGORY/product.html

How the mighty are fallen

MichaelG.

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Apologies for the typo in the thread title ... it should read Pratt Burnerd

Could a moderator please correct it, as I cannot 

Edited By Michael Gilligan on 11/02/2021 17:31:32

I saw that ad from RDG on ebay, I wonder if the original buyer knew how to measure runout. P B chucks are not likely to suffer from bad quality control. It is still a lot to pay for a 100mm chuck.

I feel very lucky to have picked a NOS one with both sets of jaws for £25 + £15.50 postage back in 2019 on ebay. It runs as true as expected, 0.002" tir at any size. Ifound a pic of it.

Edited By old mart on 11/02/2021 17:55:19

Edited By old mart on 11/02/2021 17:59:02

I have a PB 80mm version of the 3 jaw SC front mounting chuck bought from a long established company up north, the 1st chuck I received was returned to the firm because of over spec run-out, the replacement was just within the stated specification which from memory was 0.003", you have to buy the Super Precision to get any guaranteed better run-out.
All I can add is the chuck has maintained the same inaccuracy after about 10 years use.

Emgee

Does anyone have a link to a copy of the relevant standards for scroll chucks, both standard and high accuracy? Not found much so far.

I am trying to understand what are the allowable limits for runout at various distances from the chuck jaws;

My 'new old stock' Griptru chuck can be set to virtually zero runout close to the chuck jaws but measured using my 5/8" dia Arrand Test Bar. is showing a couple of thou runout 5 3/8" away.

Good question, Peter

PB seems rather coy about such useful details ... but Bison is more forthcoming:

**LINK**

https://www.interempresas.net/FeriaVirtual/Catalogos_y_documentos/239013/BISON-MANUAL-LATHE-CHUCKS.pdf

MichaelG.

My PB didn't meet this TIR

For what it’s worth:

The current edition is BS ISO 3089:2005

from which we learn that

• This British Standard reproduces verbatim ISO 3089:2005 and implements it as the UK national standard. It supersedes BS 1983-2:1994 which is withdrawn.
• This third edition cancels and replaces the second edition (ISO 3089:1991), which has been technically revised. In particular, the tables and figures have been modified.
• Unlike the previous edition, this International Standard specifies only one accuracy class.

MichaelG.

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Hopefully, the BSI will not object to my quoting those three brief statements by way of reference.

If you do a search, on youtube. P.B show there range of chucks. From the standard through to the griptru & better ones. Do not have a link as it was some time ago i watched it. Found it. Pratt burnerd chuck ranges.  

Steve.

Edited By Steviegtr on 12/02/2021 15:20:36

States from 170mm diameter upwards, so not sure where smaller chucks are made, I thought all were UK made but perhaps not.

Emgee

I found a 160mm 3 jaw self centering Rohm type ZA chuck on sale at MSC, Wednesbury in the 'sad section' (clearout specials) no box but external jaws and chuck key bagged and taped to the chuck body. Looked like it had been dropped as there was a small 'ding' on the body. Think I paid £80 + Vat for it. One of the best chucks I have ever had, so good in fact that I then recommended a similar chuck to a good friend for his rather worn out original on his Triumph 2500. He finished up with a detachable jaw Dura T type 200mm Rohm which he is over the moon with, again bought from MSC 'clearout' section for a fraction of the list price. A new chuck is the best single item which can transform a lathe.

Its about five years ago, so things might have changed, but I bought a P-B chuck from a well known chuck specialist, integral thread for Myford, had to be returned, as did it's replacement. Ended up paying difference for a Bison which is excellent and has retained it's accuracy. From our conversation at the time normal accuracy P-B chucks are made by the same maker as TOS, Griptrue chucks were made in the UK. I've got a NOS Griptrue Myford chuck that I found unopened in a cupboard at work and was given, dates from 1973, which can be adjusted to repeat very accurately at a set size, but if used as a normal chuck runout varies at different jaw openings up to .004".

Dave

PS It may sound lucky to have been given a griptrue, but we were all losing our jobs as the works closed down, everything comes at a price!

Edited By Dave Wootton on 13/02/2021 12:50:44

That 100mm Burnerd which I bought cheaply is made in England, (see picture), so predates the 600 Group offerings. The current ones don't seem to have a country of manufacture on them, which I find somewhat suspicious.

Full list of Pratt Burnerd chucks. Its a long list but shows all the present models.

Steve.

Pratt Burnerd chucks pdf file

Last page says Michigan USA.

Edited By Steviegtr on 13/02/2021 17:22:43

I can't believe Pratt Burnerd chucks are made in the UK, & the Colchester lathes from 600 group I'm sure are made in Taiwan? Glad to be proved wrong.

Tony

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Dated 2015, and [so far as I can see] identifies Michigan as the company address.

Edit: ... and their home-page states : Pratt Burnerd America (PBA) supplies high quality Workholding Solutions to Automotive and Machine Tool shops throughout North America. We offer both Pratt Burnerd and Atlas Workholding products that provide you with high-value, low-cost solutions.

MichaelG.

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Eureka! : See the opening paragraph here : https://prattburnerd.com/about.php

Edited By Michael Gilligan on 13/02/2021 17:44:41

Edited By Michael Gilligan on 13/02/2021 17:49:08

Maybe so. It would not surprise me if they are made in the east. As most top manufacturer's have to show big profits to there shareholders.

Steve.

Edited By Steviegtr on 13/02/2021 17:41:23

If a company is unwilling to put the country of origin of their products, I wonder why.

My old firm in the UK, made pneumatic mining drills for a well known firm from the USA by the name of Numa. These drills were for use in Italian marble quarries and drilled the multiple holes for explosives. The drills carried stickers with the name on them, but we were forbidden to include any evidence of the country of origin, even in the wrappings.