New Chuck won’t screw on

[Michael GilliganParticipant @michaelgilligan61133]

Returning all the way back to the original ‘Myford Series 7’ …

KWIL posted a dimensioned and toleranced drawing of of the mandrel [spindle] nose, here: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=122670

Unfortunately it is not directly credited to Beeston, and some of the tolerances look ill-stated, but it may be the best available to us.
​​​​

MichaelG.

Edited By Michael Gilligan on 01/08/2021 07:26:21

[JasonBModerator @jasonb]

So with the thread allowed to be up to 0.002" undersize it is quite possible RDG are testing their goods on Myford spindles and it just so happens theirs are towards the bottom of that tolerance and those who have a job getting them to fit have spindles that are on size or only just below.

[Michael GilliganParticipant @michaelgilligan61133]

Yes, that looks likely, Jason

Which is why, on p1, I wrote: That’s the disappointing bit ^^^

Supplier needs to understand GO/NOGO gauging

MichaelG.

[Richard JarvisParticipant @richardjarvis95040]

The disappointing bit for me is that they were adamant no problem existed and it was ok, even though someone else had exactly the same problem that week. It has been mentioned faulty goods should be sent back, but delivery to me can take over a week and if I have to stand return cost you are soon out of pocket.

Thanks Richard

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Richard Jarvis on 01/08/2021 08:46:38:

The disappointing bit for me is that they were adamant no problem existed and it was ok, even though someone else had exactly the same problem that week.

.

Yes, that’s what I meant by :

“Supplier needs to understand GO/NOGO gauging”

[emphasis added]

MichaelG.

[EmgeeParticipant @emgee]

Posted by Richard Jarvis on 01/08/2021 08:46:38:

The disappointing bit for me is that they were adamant no problem existed and it was ok, even though someone else had exactly the same problem that week. It has been mentioned faulty goods should be sent back, but delivery to me can take over a week and if I have to stand return cost you are soon out of pocket.

Thanks Richard

You shouldn't have to pay return postage for faulty goods, that should be paid by the seller.

Emgee

[Graham MeekParticipant @grahammeek88282]

I did point out back on page 2 of this post. That checking a part, using another machined part was "asking for trouble".

There are clearly Spindles in use that are larger than the "Inspection Part". It certainly does not take much to work that out. If a part is going to be checked this way then the Inspection Part needs to have the largest permissible sizes, or MMC, otherwise this check is useless.

As a small Spindle will pass all the parts.

Regards

Gray,

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Graham Meek on 01/08/2021 11:56:11:

I did point out back on page 2 of this post. That checking a part, using another machined part was "asking for trouble".

There are clearly Spindles in use that are larger than the "Inspection Part". […]

.

Quite so, Gray … and it was good to have your endorsement of my point

MichaelG.

[Howard LewisParticipant @howardlewis46836]

If the spindle being used as a gauge is not hardened, it will not be much use as a gauge for long, if at all.

Every chuck or backplate that is screwed on and off will cause wear, even if only a minute amount, but the later backolates will be checked against a worn thread and so pass although actually under the drawing minimum size.

A proper GO / NO GO screw thread gauge will be hardened, to avoid this, AND should be checked periodically to ensure that it is in calibration, for high volume manufacture.

In this case, that appears not to be the situation!

RDG are the vendor, but the manufacturer appears not be ISO 9000 certified, judged by these complaints..

"You write down what the procedures are, and then you demonstrate to the ISO inspector that you are working to them".

Howard

[JasonBModerator @jasonb]

But if they wrote down that they would test with an old Myford spindle and did that then they would still be OK under ISO 9001. It does not say what method to use just that you follow what you say you will use.

[Michael GilliganParticipant @michaelgilligan61133]

Spot on, Jason

Been there, done that, got the certification.

[ including, for a Marketing Operations department, where the written ‘Procedure’ was to go out and negotiate with the potential customer ]

MichaelG.

[Tony Pratt 1Participant @tonypratt1]

Any competent manufacturer of say 'Myford backplates' would require a properly toleranced drawing to quote against because as we know nothing can be made to an exact size, I have a feeling the retailer is most probably using nominal sizes & letting the end user do the quality check??

Tony

[roy entwistleParticipant @royentwistle24699]

Surely it's better for a backplate to be too tight, at least it can be made to fit. If it was sloppy to start with it's worse than useless.

Roy

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Richard Jarvis on 28/07/2021 13:04:13:

Posted by JA on 28/07/2021 12:56:21:

Do RDG/Myford read these postings? Perhaps they should.

JA

Well they did not answer my last correspondence seven days ago so I decided to have a go myself with help from the group.

.

Just picking-up this point :

As stated many times before … RDG and Myford are two separate Limited Companies.

MichaelG.

[Graham MeekParticipant @grahammeek88282]

I think an assumption has been made about ISO 9001, as I do not see any ISO 9001 accreditation on the vendors website, unless I have missed something.

The certification process allows for the withdraw of the accreditation if it can be proven the laid out procedures have not been followed. It costs money to acquire this standard, and there is an ongoing cost for checks by a Quality auditor. Those companies who get the standard, make sure they do not loose it.

Regards

Gray,

[Richard JarvisParticipant @richardjarvis95040]

When I first started thinking about replacing my original Chuck about two months ago, I recall the RDG advert stating that the backplate was machined by one of there engineers. I might be wrong but I am not convinced that RDG machine the backplate themselves, but they come with the Chuck from the manufacturer. I might be totally wrong of course.

Thanks Richard

[JohnFParticipant @johnf59703]

Something similar came up on another post relating to ER chucks, accuracy TIR and fit. I had a problem with an ER chuck purchased from and made in Europe — I eventually found out they were using UNF form threads instead of Whitworth form so I do wonder if some of the Far East product has the same problem ?

During my conversations with the producers of the ER chuck I acquired the correct thread tolerance dimensions for Go / No Go gauges for the "Myford" thread and made a GO gauge as close to these dimensions as possible with the equipment I have — I am confident its close enough to the limits specified for practical purposes. I used a full form tip to make the gauge measuring over wires with an indicator micrometer.

The sizes were calculated as a favour to me by a UK gauge maker so I don't feel it would be right to publicise them, however if any forum members want them please PM me with an email address and I will pass them on.

Why any commercial company manufacturing a precision product would operate without the proper gauges is beyond belief !!

Another problem I have found with much of the imported Myford spindle tooling offered by suppliers is the register diameter on both male and female units is woefully outside the tolerance it needs to be to ensure TIR accuracy

Regards John

Photo of my gauge

[speelwerkParticipant @speelwerk]

It is not only imported spindle tooling or RDG/new Myford giving problems. Very long time ago bought a new Burnerd chuck with fitted back plate direct from old Myford. Cannot remember the error the chuck had on the back plate but had to redo it to get what I wanted. Niko,

Edited By speelwerk on 02/08/2021 13:22:21

[brian jones 11Participant @brianjones11]

Well long suffering Myfordians, I can report 100% success with getting my new chuck to fit onto my spindle. I ran the new 1 1/8 tap i ordered through the adapter plate and 10 mins later my chuck fitted back on with the precision of a swiss sewing machine

So guys thats what worked for me , hope it helps, i also eased up 2 faceplates i had which were stiff

So the moral here, if you buy a new adapter plate dont expect it to fit properly without some work.

[old martParticipant @oldmart]

Good result, and lucky to be able to get hold of a tap.

[brian jones 11Participant @brianjones11]

I plan to sell it on after a breather at cost less 10%, as new only used to skim three threads 1 careful owner. Will advise here when ready. I doubt I shall need it again only to leave it idle on a shelf

I propose to invite pms and give an Ebay site to contact for easy payment and guarantee

Hope it may get some else out of trouble and then they can pass it on like this to other members.

[JasonBModerator @jasonb]

We have a "For Sale" classifieds section which will save the hassle of PMs

[brian jones 11Participant @brianjones11]

So while I am resting on Myford's bed, I mused – where did JW get his thread from?

Here's my take

BTW a lot more info is available on the Whitworth society pages

https://www.whitworthsociety.org/history.php?page=2

JW grew up through the early 1800s through the shop floors of Machinery Makers of the time and noted how there was no standard way of making nuts and bolts etc. So he set about amassing a collection from many of the factors around the Midlands area. He then deduced an average for Pitch (tpi) preferences and settled on an average angle of 55deg without further thought. He arrived at the form recognising that sharp points were impractical and made bolts weak

So armed with a compass and a set square here is what occurred

I hope the simple arc and set square construction is obvious and results in the well known radius crest/root

What looked simple on paper was difficult for production work and crests were flattened and tolerances loosened and so victorian engineers staggered on and this thread was eventually recognised by the Board of Trade as a de facto standard in the absence of anything better

Notice the red areas where there would be conflict with tightness when crests were not sufficiently rounded. A devil for internal point cut threads, requiring chasers to be made increasing production time and cost. The truncated form was established roughly for production.

This form was challenged in the States by the Sellars Corp who pushed through the UTS form 60deg with flat crests greatly simplifying manufacture but the standard retained most of the original Whitworth pitches

Notice that when specifying the Pitch, all other dimensions are dependent on this number – the OD of the shaft has no influence.

BSW and UNC in the field are often interchangeable (bad practice but inevitable but makes for a weaker fastening)

One notable exception to the above is 1/2BSW vs UNC (12 vs13 tpi). It was thought that this size was so important in construction that you didnt want bolts getting mixed

BSF and UNF are no where near compatible with UNF offering much finer pitches favoured in the emergent motor industry and great improvements in the quality of HT steel

The ISO metric followed the UTS form with rounding roots but used metric pitches

So now we know why Myford has such a quirky nose job

I wont drone on showing UTS and ISO thread forms

BTW JW went on to perfection in gunnery, made a hexagonal rifle improvement on the Lee Enfield that became the Whitworth sharpshooter but the smaller calibre was rejected by the Royal artillery but was taken up enthusiastically by the French who went on to show its superiority. Further info from the Whitworth Society on the stupidity of armchair generals

Edited By brian jones 11 on 04/08/2021 08:48:06

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