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Member postings for david bennett 8

Here is a list of all the postings david bennett 8 has made in our forums. Click on a thread name to jump to the thread.

Thread: Chuck backplate error
26/01/2021 16:12:01

Ah, thanks for clarifying - I couldn't read that before . I was maybe hoping it was the elusive clearance!

Dave.

26/01/2021 15:57:02

Hmm, what do you read the 38.453mm dimension as (on the w20 nose) ?

Dave.

26/01/2021 04:19:43

Michael G, sorry to be so long responding. Those Schaublin nose specifications look interesting. Since the thread diameters are about 0.5mm larger than the register size, it looks like Schaublin doesn't belleve in close fitting backplate registers either.

Dave.

Thread: Another watchmakers lathe
14/01/2021 18:26:11

Hi Dells, have just seen better pics on NAWCC site. I still think its a flipover toolholder, but it sits on a WW lathe bed .I doubt it would fit an IME without some alterations.

Dave.

14/01/2021 16:06:33

The slide thingy might be a flipover toolholder for either/both boring or threading. Very useful for taking measurements without disturbing the settings. It sits  on top of the compound slide.

Dave.

Edited By david bennett 8 on 14/01/2021 16:08:36

Thread: Chuck backplate error
12/01/2021 22:32:47

Anders Be, is that the tolerance on the diameter? what is the tolerance on run-out? what is the tolerance on thread/register runout? was the thread and register machined at the same setting in the machines own bearings? On a Schaublin it may well be so, but not on all hobby lathes. On myfords for example the register may well not be concentric to the thread. All the tolerances can combine to conspire against the user. If you have a recommended diameter to cut, how will you measure it? or will you cut-it and-try-it? If you are successful please carefully measure it and educate us all.

 

Dave.

Edited By david bennett 8 on 12/01/2021 22:34:14

Edited By david bennett 8 on 12/01/2021 22:42:03

11/01/2021 16:13:26

Back to the topic, I wonder how many people actually measure the bore of a backplate after making it a close fit to the radial register? I would not be surprised if it is considerably greater than those last few tenths achieved by cut-and-fit due to tolerances in manufacturing the spindle. Could some people actually measure bore/register figures from well fitting chucks and let us know?

Dave.

11/01/2021 00:31:20
Posted by old mart on 10/01/2021 21:25:05:
Posted by Lathejack on 10/01/2021 01:13:44:
Posted by old mart on 09/01/2021 17:34:47:

Lathejack, you have had good results with close fitting radial registers, but you do not mention any experiance of using loose radial registers. So you are an expert on the subject?

Unfortunately there are times when I feel that you are coming across as rather unpleasant. Surely the rest of us should be able to comment on our experiences and opinions, just as you do, without receiving remarks such as in your last sentence?

Edited By Lathejack on 10/01/2021 01:16:50

Edited By Lathejack on 10/01/2021 01:33:52

Perhaps you could make a comment on the recent post by David Bennet 8.

Since I seem to have been dragged into this chat about good manners, I do not regard myself as an expert, just experienced. I hope I would never throw an insult at someone who may have less (or more - how would I know?) experience. This is, after all, for beginners questions. All my answers are for anyone to ignore or not.

Dave

09/01/2021 20:00:34

This argument reminds me of arguments on religion - no-one will be convinced until they try it. For what its worth I intuitively believed that the radial (horizontal) register was important. What made me rethink this was not so was when I realised I was using an ML7 chuck on an ML4 with no collar. It repeated perfectly. Since then I have made many backplates for different lathes, so I could experiment. Experience has shown me that the close fitting spindle (horizontal )

register does nothing to aid repeatability, but can in fact interfere with a free running thread cut into a backplate with the shoulder (vertical register) cut at the same setting. I have made backplates for many Myford sized lathes (Wolf Jahn, Cataract, etc) but my interest is in smaller precision lathes such as Pultras, Unimat 3 and SL's and watchmakers lathes..On none of them do I bother to closely size thespindle (horizontal ) register. I will take expermental resuls over intuition ever time.

Dave

06/01/2021 20:42:04

A loose fit is unlikely to produce a wobble. Dave.

06/01/2021 20:11:59

The point re. a drunken thread is that is not possible to turn the vertical register true to the thread at the same setting. This is essential. The horizontal register is not important.

Dave.

06/01/2021 18:38:58

Chris, if your backplate goes on with a wobble it suggests your backplate thread is "drunken" This is very bad for repeatability.

Dave.

Edited By david bennett 8 on 06/01/2021 18:39:50

Thread: Meteror II Screw cutting lathe
03/12/2020 21:46:33

I understood from Tony's website only the Flexispeed Major had the hand finishing to the bed etc. I too would be astonished if it applied to the Meteor11

Dave.

Thread: Myford ML4 Restoration: Headstock bearings and spindle removal
19/05/2020 12:56:30

Luke, something you said there made me think the term "repeatable" may be being misunderstood. Do not expect that you can remove a piece of work from the chuck and then replace it and have it run true. Turn a piece of work true. Do not remove it from the chuck. Remove/refit the chuck with the work still clamped in the jaws, if it then runs true it is repeatable (apologies if you knew that)

Dave.

18/05/2020 12:53:02

Luke, thanks for clarifying that. All lathe noses have different errors. The whole purpose of the chuck backplate is to allow you to eliminate them . (Except the axial play - that is adjusted by the threaded collar at the rear end of the headstock ) For a full description of truing the backplate, see Tony's famous website "lathes.co.uk" the article "fit a new chuck"

Regards, Dave.

16/05/2020 14:28:26

Luke sorry, I put my edit (or within spec) in the wrong place Any slight error in the spindle vertical register will be eliminated when the backplate is trued on the lathe. The backplate should be absolutely true and repeatable,if nothing interferes with the fitting.

Dave.

Edited By david bennett 8 on 16/05/2020 14:29:48

16/05/2020 13:18:22

Luke, I am getting cofused here. I was under the impression that you had added a collar to your spindle to fit a new chuck. Do not cut anything from your original spindle. The horizontal register should be absolutely true. If it is indeed a collar that you have added, that too should be absolutely true (or within spec.) The chuck backplate is the loose plate that screws to the lathe nose, which should be trued before the chuck is bolted on. The register is simply the plain bore of the backplate. Can you measure the old chuck backplate bore that fitted to the original 1.125" horizontal spindle register.

Dave.

Edited By david bennett 8 on 16/05/2020 13:18:54

16/05/2020 03:22:25

Luke, as a matter of interest, would you measure the register clearance on your old ml4 backplate? ( mine has a 20 thou' clearance.)

Dave.

'

16/05/2020 00:43:17

Luke, I agree with Brian Wood's comments about where to measure the run-out . If the vertical register is true, then too snug a fit on the horizontal register can interfere with the self-centering action of the spindle threads. ( if carefully done, you might be able to see this with the aid of a little marking blue on the register)

Dave.

04/05/2020 22:33:54

Luke thanks in advance for your future efforts for science!.The ideal time to try this is when you

are trueing your new backplate to your lathe. When it is true,de-mount the backplate, then try to re-mount it off centre.Let us know if you can.

Dave.

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