Collet Chucks

[Tony ThomasonParticipant @tonythomason]

Has anyone purchased a Boxford ER32 collet chuck???

I have purchased one from Chronos and checked the TIR at about 2 thou which is consistent along the taper and over the external surface which indicates they where all machined at one setting so why the error. Further checks found that the 1.5000 bore was actually 1.5005 meaning that the bore for the register was 5 thou oversize hence the error.

Is this normal????

[Tony ThomasonParticipant @tonythomason]

ER32 by Soba

[JasonBModerator @jasonb]

Do you mean 5 thou or 5tenths?

[Tony ThomasonParticipant @tonythomason]

11/2" and 5thou

[Tony ThomasonParticipant @tonythomason]

1.505 and should have been 1.500 a bit of finger trouble on the 0 button. must be my age.

[SillyOldDufferModerator @sillyoldduffer]

Sounds suspicious, but what did you measure – the chuck alone, or a test rod held by a collet properly fitted inside the chuck?

You might have a dud but it's not unknown for chaps to get in a stew by measuring the wrong thing. (Don't ask how I know!!!) If the runout is poor when measured against a test rod in a collet, speak to Chronos.

If you're new to ER collets, check fitting as per this advice on the ArcEuro website. That catches people out sometimes.

Dave

[Clive Brown 1Participant @clivebrown1]

If the chuck register is 1.505", then I think that you've got a Friday afternoon job.

I've just measured a Boxford o/e backplate for my lathe. The register is, as close as I can measure, 1.501" at the most.

[not done it yetParticipant @notdoneityet]

0.005” oversize on a registration surface is not acceptable. 0.0005” would likely be required to ensure a sliding fit as the item is screwed on.

I just checked my machine’s tolerances for this fit. Not a Boxford. Surprisingly, the earlier model showed no tolerances and both nose and part to be fitted as exactly the same. But the manual for the later model, while supplying tolerance of +0.000”, -0.001” for both, shows the nose as 0.0005” larger than the part screwed on! I think they got the manual wrong!

[Tony ThomasonParticipant @tonythomason]

Thanks chaps you've born out my suspicions I just thought it was a bit outside limits that's all.

I measured the bare chuck at 3 points along the taper and the body outside all readings similar. You can't expect the collet to run true if the chucks out to begin with.

Any collet run out is an entirely different story, I felt that the run out should be under a thou my 3 jaws within 3 thou .

[not done it yetParticipant @notdoneityet]

Noo! The same issue. It is the register that determines how the holder fits to the spindle nose. It is possible that there are more problems, but if the register is nowhere near a good fit you have no chance of consistent seating of the tool on the spindle.

[Tony ThomasonParticipant @tonythomason]

I have just check it again and get a consistent 0.08mm all up the taper it's seems the register is the problem. I'm not going to get any repeatability which was my intention.

[Russell EberhardtParticipant @russelleberhardt48058]

Personally I would send it back as not fit for purpose and make one myself. It's dead easy, I made one about 15 years ago for my Atlas which has the same spindle nose as a Boxford. You make a plug gauge to the dimensions of the spindle nose and then turn the spindle end of the adaptor to fit the plug gauge. Then screw it onto the spindle to bore the taper and cut the thread for the closing nut. That ensures the accuracy. Just buy the nut.

I have the ER chuck on the lathe at present so I just went into the workshop, put a bit of silver steel in it and checked the run out. It's still well under half a thou.

Russell

[Tony ThomasonParticipant @tonythomason]

That's what I expected to get with this chuck. It wasn't a fortune so some abnormalities are expected. I think your right it needs to go back.

[Tony ThomasonParticipant @tonythomason]

Just an update I have returned it to Chronos, they checked all their stock and told me they are all the same.

[BazyleParticipant @bazyle]

As with a chuck backplate they should be supplied half a thou undersize so they can be lapped to a good fit, or fit well on a worn lathe nose. Have Chronos advised they will send you a replacement when they get the replacement stock in or just a refund perhaps indicating they won't be sending the old ones back.

If I were a trader I'd make sure to mark the failures so they can't be passed off on someone else. Chances are there are hundreds of these made wrong in shops round the world.

[Tony ThomasonParticipant @tonythomason]

No they have agreed to a refund on receipt of my returned chuck. I asked them to check their stock and they said they where all about the same, the item is still on eBay so I assume they will continue to sell them as is.

I only checked mine by chance as Chronos said they hadn't any TIR figures for the chuck but said they had not had any problems. I checked it just to give them the figures in case anybody else asked for some.

They have sold 6 so far so obviously someone is happy or blissfully unaware. My concern wasn't run out it was repeatability.

I assume these are purchased in quantity with no chance of return so I have some sympathy with their predicament. They may have a channel for feedback to Soba but a replacement wasn't offered.

They are cheap so some shortcomings are to be expected, I'm not sure where Soba manufacture but it wont be in the midlands that's for sure.

I have put the cost of return postage down to experience.

[Martin 100Participant @martin100]

Maybe eight or ten years ago not long after Chronos first brought onto the UK market the Soba ER32 chucks for the Boxford lathe they wouldn't even thread on the spindle nose more than a turn or two because although they were bang on 8tpi they were supplied with a 60 degree unified thread form rather than a 55 degree whitworth thread form

Phoned up, same story, about them 'all being the same' and 'no one else had a problem' exchanged for another one, exactly the same issue.

Was it my spindle. No. I tried it on my other Boxford (1950's rather than 1960's) then on a spare 'used' spindle I picked up long ago and finally on a brand new 350 quid 1980's produced spindle still in the wrapping from Boxford.

Total waste of my time, their time, the CNC time and 40 quid or whatever. (The only thing even remotely acceptable quality was the collet nut but I've since replaced all mine with the ball bearing type)

So I bought a backplate and ER32 chuck from Arc Euro and although it's slightly more bulky it fits both lathes perfectly and runs true although to be honest that is with a 10ths indicator – I haven't measured it with my 0.5 um Mahr comparator.

[Tony ThomasonParticipant @tonythomason]

I perhaps should have left it alone when they said no TIR figure was available, I didn't expect something akin to a Swiss jig borer accessory but would have been happy with a usable tool.

I just saw it on eBay and thought "now there's the answer" how wrong could I be now £4.60 lighter and back to square one.

I've always avoided this stuff and shall certainly avoid it like the plague it the future.

I'm sure lots of customers are happy with their purchase but just like some of the cheap new lathes you get what you pay for.

[JezParticipant @jez]

Posted by Martin 100 on 02/07/2018 17:04:07:

Maybe eight or ten years ago not long after Chronos first brought onto the UK market the Soba ER32 chucks for the Boxford lathe they wouldn't even thread on the spindle nose more than a turn or two because although they were bang on 8tpi they were supplied with a 60 degree unified thread form rather than a 55 degree whitworth thread form

Phoned up, same story, about them 'all being the same' and 'no one else had a problem' exchanged for another one, exactly the same issue.

Was it my spindle. No. I tried it on my other Boxford (1950's rather than 1960's) then on a spare 'used' spindle I picked up long ago and finally on a brand new 350 quid 1980's produced spindle still in the wrapping from Boxford.

Total waste of my time, their time, the CNC time and 40 quid or whatever. (The only thing even remotely acceptable quality was the collet nut but I've since replaced all mine with the ball bearing type)

So I bought a backplate and ER32 chuck from Arc Euro and although it's slightly more bulky it fits both lathes perfectly and runs true although to be honest that is with a 10ths indicator – I haven't measured it with my 0.5 um Mahr comparator.

Yes, I bought one of those. Returned it for a replacement which turned out to be, as you say, exactly the same. I ended up turning a bit of bar in the 3 jaw, mounting the collet chuck "backwards" on it and screwcutting a whisker off the thread.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Jez on 02/07/2018 20:07:36:

Posted by Martin 100 on 02/07/2018 17:04:07:Yes, I bought one of those. Returned it for a replacement which turned out to be, as you say, exactly the same. I ended up turning a bit of bar in the 3 jaw, mounting the collet chuck "backwards" on it and screwcutting a whisker off the thread.

Yes, it's important that the register locates the backplate and not the thread so the thread should be on the loose side. I had the same problem with a backplate for a 3 jaw chuck a while ago. I eased off the thread and it locates fine now.

Russell

[Ketan SwaliParticipant @ketanswali79440]

Hi Tony,

I would like to pick-up on a few points you made.

I understand that the product was faulty and you got a refund from Chronos.

There are some presumptions which are made which I would like to address:

• You state: "I assume these are purchased in quantity with no chance of return so I have some sympathy with their predicament. They may have a channel for feedback to Soba but a replacement wasn't offered.
• They are cheap so some shortcomings are to be expected, I'm not sure where Soba manufacture but it wont be in the midlands that's for sure.
• I have put the cost of return postage down to experience."

My response: If the product was faultly, Chronos could get compensation from their supplier. They are not that cheap. They are made in India by Soba or one of its sub-contractors. About 12 years ago, two U.K. suppliers (not ARC), had exactly the same problem with the same product, 'Made in the U.K.' which were made and sold for use on Myford and Boxford direct nose mount.

If the testing was done correctly by you, which from what you suggest was conducted correctly – inside the female ER32 taper (rather than any outside reference), and if Chronos said to you that it is faulty, then you have grounds for asking for refund of the return postage. However, this is a matter between you and Chronos.

Around 12 to 13 years ago, we were considering the direct nose mount, but were directly against the idea by our adviser, the late John Stevenson. His reasoning was that if the lathe spindle register and thread were damaged or worn, this could effect the accuracy of a directly mounted ER system. At the same time, we were coming across some direct mount ER chucks, 'Made in England', which were faulty, as reported to us by certain customers who had perfectly good lathe spindles. I do not know who was making them.

As a result, ARC decided to consider and develop the backplate with separate ER lathe collect chuck arrangement. If there were any inaccuracies with the spindle, these would be 'taken out' for want of word, when the backplate was turned to the correct register to accomodate the ER lathe collet chuck. Turning of the register has to be done on the lathe to which the lathe collet chuck is to be fitted.

ARC logs faulty goods returned. If we find three faulty products returned to us in a short period of time from three different customers, we pull the products from sale, check the batch, and decide how we wish to proceed. i.e. – scrap the product, or depending on the accuracy/fault – sell it in clearance specifying the fault/accuracy eg. uncoated/coated drill bits, and claim the compensation directly or in kind from our supplier. This process can take long but it is a matter to resolve between us and our suppliers.

• You state: "I perhaps should have left it alone when they said no TIR figure was available…
• I've always avoided this stuff and shall certainly avoid it like the plague it the future….
• I'm sure lots of customers are happy with their purchase but just like some of the cheap new lathes you get what you pay for….

My response: The fact that no TIR figures were available, does not mean that ALL cheap products should be avoided. ARC does not quote TIR figures, for various reasons, to include how a product is checked for TIR, and under what conditions. Similar statement applies to lathes/mills. ARC considers certificates supplied with machines by some suppliers to be of very little relevance. We simply don't want to get into a discussion/argument with a customer over it. We deal with each product fault/customer on a specific case by case. It is not a cop out.

Although it does depend on where you buy your product from, and not all cheaper Indian or Chinese product are crap. It is sad you had poor experience with your purchase from Chronos. Equally, Chronos does sell good products, to include some Soba branded products – eg. SOBA parallel test bars which are (currently) better then other U.K. suppliers, with which many have had satisfactory experience.

I guess the idea needs to be product related/product specific, followed by who the supplier experience is, and finally the country of origin. So I would request you to re-consider your blanket presumptions. Just as not everything cheap is crap, not everything expensive is good value for money. This statement applies to us, Chronos as well as some of the well known U.K. suppliers to the hobby. At the same time, I do understand and respect your views, keeping in mind the fact that the issue of quality and accuracy will be variable and product specific.

Enjoy the hobby and good luck with which ever direction you choose to follow.

Ketan at ARC.

[Tony ThomasonParticipant @tonythomason]

Thanks Ketan for your very detailed assessment of my comments regarding the ER32 collet chuck.

I accept that all expensive is not good quality and all cheap is not rubbish, I never used the word "crap" and my posting was not done to demonise Chronos who readily volunteered to refund me less return postage of course.

I was quite surprised that they had sold "lots without any problem" and posted to see if this was a common complaint or had I just been unlucky. I would have been very happy to get an accurate replacement from them but this wasn't offered.

Actually I'm an ex professional not just a hobby engineer ( I worked as Technical Manager for a very large Japanese manufacturer world famous for their quality control for 27yrs) I posted my question to satisfy my personal interest and any comment's I made where my personal opinion and no offence was intended.

I purchased this item as a quick answer to a current problem(I still work a bit) and was quite surprised that it nowhere near fulfilled what is to be expected of it. I always assumed collet chucks to be accurate and precise with better than general repeatability(it was repeatability I needed) I was able to tolerate some inaccuracy but needed to be able remove and replace whilst still work holding.

I cannot see from what little experience I have that given the register had been the correct size this type of fitting couldn't work successfully with the added benefit of much smaller size this was important for my operation.

Chronos where courteous and reacted quickly, I have no complaints about their service, my problem was with the product and feel rather sorry for them as I feel they are the "piggy in the middle" with a difficult task of satisfying some very demanding customers.

I still find that having sold many and I was told they are all the same that mine is an isolated case. If anything remotely like this had happened in my professional career something akin to word war thee would have broken out.

Kind Regards

Tont

[Tony ThomasonParticipant @tonythomason]

Just a PS Ketan

The register bore has machined oversize it's as simple as that, and a back plate bored oversize would have just the same problems.

In the world of manufacturing as a general rule "Quality comes at a price" that's why a Lexus cost's more than a Yaris even taking into account the size difference.

[SillyOldDufferModerator @sillyoldduffer]

Just a thought, I'm not familiar with the Chronos product.

Some collet chucks come with adjusting screws to match the machine accurately. Cheaper versions are trued by tapping them into position – the register is a deliberately loose fit. It wasn't one of those was it?

Dave

[HOWARDTParticipant @howardt]

Found this while researching er spindle bore accuracies.

l**LINK**

As a machine tool designer in my working life we were allways looking a spindle/tool holder/ tool accuracies to achieve a sigma capability for the life of the machine. Life of a special purpose machine was the production life of the part it produced. Production life could be as much as five years producing thousands of parts a week all of which had to be writhin a percentage of drawing tolerance. Other than for standard tools, drills reamers and taps, tools were held directly on the spindle nose. Even then the tools would be tuned to give as close to zero runout.

Both my mill and lathe are small Sieg machines I accept the inaccuracies of the cheap tools and holders and work to achieve the tolerances I require by matching parts, the size in most cases is of secondary importance.

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