I think my dividing head makers needs….

[Sub MandrelParticipant @submandrel]

In his first post Duncan says he's already emailed the supplier. I await their comments with interest.

Neil

[Gone AwayParticipant @goneaway]

Posted by Joseph Ramon on 13/05/2013 11:01:47:

There uis a very good reason why the holes may not be evenly spaced – so you can swap plates and put them back on in the same orientation without needing a key.

Why do you need to?

[Donhe7Participant @donhe7]

Posted by Dusty on 13/05/2013 14:50:53:

I don't think it matters if it is a rotary table or an all singing all dancing dividing head. If it was sold as a unit with all parts compatable. It must fall into being 'not fit for purpose' if part of the set up is defective.The plates must fit and be usable on the dividing head/rotary table without modification.

The suggestion was made, that "maybe the plates and the table were supplied as separate articles", seems to have been missed by most of the respondents to this post.

What I believe was meant, was that the plates were made to suit a differernt table, and so when supplied with the table for which they were intended, (and made), they were correct. As they were supplied with the wrong table, (which they were never intended to fit), of course they were drilled wrongly, (Try fitting your aforementioned Fiat wheel on your Ford, bet you it doesn't fit)

donhe7

[Gone AwayParticipant @goneaway]

What I believe was meant, was that the plates were made to suit a differernt table, and so when supplied with the table for which they were intended, (and made), they were correct. As they were supplied with the wrong table, (which they were never intended to fit), of course they were drilled wrongly,

From the pictures, the holes appear to be on the correct PCD. The only question for me is whether the unequal spacing of the holes is a manufacturing error or if it is done deliberately – presumably so that the plate will only fit in one orientation. I still don't see what that would achieve on any device.

I have both a Myford dividing head and a rotary table with division plates. As far as I recall the mounting holes are equi-spaced and the plates fit in any orientation on each device but I'll check tomorrow.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Sid Herbage on 14/05/2013 04:13:18:

What I believe was meant, was that the plates were made to suit a differernt table, and so when supplied with the table for which they were intended, (and made), they were correct. As they were supplied with the wrong table, (which they were never intended to fit), of course they were drilled wrongly,

From the pictures, the holes appear to be on the correct PCD. The only question for me is whether the unequal spacing of the holes is a manufacturing error or if it is done deliberately – presumably so that the plate will only fit in one orientation. I still don't see what that would achieve on any device.

.

If you are seeking that last "Gnat's Whisker" of certainty, then it's always a good idea to mount a dividing plate in the same orientation on the spindle. It can reduce eccentricity of the circles of holes.

It is worth doing the Math, to understand how much angular error can be introduced by a few thou' of eccentricity. Probably not significant to the average Model Engineer but, the best plates are made that way.

MichaelG.

[LambtonParticipant @lambton]

Some confusion has crept into this thread.

Dismaldunc clearly stated his opening post:

Just got my nice new rotary table with dividing plates from one of the big suppliers (who shall remain anonymous until they reply to my e-mail ) attempted to fit the dividing plates and found the holes out of line see the piccy below.

Les Jones offered the following possible explanation:

Is it possible that the holes are not spaced at exactly 120 Deg. on purpose so that it only fits in one position ?

To which Dismaldunc replied:

I thought that might be the case so gave it a twiddle but tis the same in all three positions ( i also tried the other 2 disks) Dunc

To me this is very clear that the items purchased were not fit for purpose yet some contributors persist in trying to find what amounts to excuses for the supplier.

As suggested let’s see what the supplier has to say in response the Dunc’s email but don’t hold your breath expecting a detailed answer just an apology and an offer to replace or refund the purchase price.

This will seem reasonable to some contributors but it is the minimum the law requires and does not address their obligation to supply good quality items first time.

I formally invite the owners of these companies to explain to us all exactly what their quality control policy and procedures are.

[DismalduncParticipant @dismaldunc]

I got an email today from the supplier, they are sending out a new boss for me, which I am quite happy with as it would be a right faff to package up the thing and send it back . I have had quite a few other strange tools from various sources, an eccentric slitting saw arbour and oval shaped knurls all promptly replaced. But this is what you get when buying on the cheap.

i would love to buy "quality" but don't have the dosh, however these cheap tools let me make things and bring me a lot of enjoyment .

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Dismaldunc on 14/05/2013 08:41:55:

I got an email today from the supplier, they are sending out a new boss for me, which I am quite happy with as it would be a right faff to package up the thing and send it back .

.

Sounds like a good result.

MichaelG.

[BazyleParticipant @bazyle]

All my division plates from various sources have equally spaced holes and are unkeyed so can be fitted in any orientation. Even photos of a Hardinge dividing head show no key or equivalent. This allows the plates to be rotated effectively trippling the number of holes which in extremis might allow you to get an index otherwise outside your range.

BTW repeatability of mounting orientation is probably assured by the natural instinct to mount the plate with the list of numbers upright.

[Michael GilliganParticipant @michaelgilligan61133]

Although Renishaw's metrology kit is several orders of magnitude more accurate than anything we are ever likely to use … this is worth reading.

MichaelG

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Lambton on 14/05/2013 08:32:14:

I formally invite the owners of these companies to explain to us all exactly what their quality control policy and procedures are.

.

I doubt that would qualify as formal

MichaelG.

[Sub MandrelParticipant @submandrel]

I can see that if you are in production and fitting a jig to a dividing head for a part, you might want to cut teeth or splines or drill holes in the same angular relation to the jig each time you set it up. For numbers not divisible by 3, this would require the dividing plate to be fixed in a unique orientation.

One point, Dunc is being sent a replacement part and NOT been asked to send back the defective one. So the retialer is not planning to palm the defective part off on the next punter.

Neil

Edited By Stub Mandrel on 14/05/2013 20:06:10

[Author]

Posts