8666 forum posts
Thanks again one and all. That's most informative.
It hadn't occurred to me that it would be easier to thread a spindle than to flange it, but that must have been the case for many years before welding was perfected. And of course the quick-change aspect is very handy in it's own right.
All my lathes have had flanges. I get on fine with them except bolting up is admittedly rather time consuming. Dropping the nuts and washers is the most obvious disadvantage though it helps to have smallish fingers. Being a trainee, I appreciate the solid simplicity of bolting and being able to run the lathe in reverse at full-power if need be. One thing I'm not sure about is the extra overhang; I'd guess that does increase run-out a tad.
I had no intention of bashing Mycroft; many good lathes of that period have threaded spindles. Digging around the web this evening I found many references to damage caused by unsticking chucks. A range of faults worth looking out for if you're thinking of buying a used lathe of that type methinks.
|Roger Williams 2||18/04/2017 22:19:32|
|346 forum posts|
Hello all, in my opinion, the Hardinge taper lock is the best, so quick to change a chuck. But I wouldnt like to run in reverse though with the chuck fastened clockwisei. Quite frightening probably !. In fact, its always confused me as to why the KL1 (HLVH) needs to be run in reverse anyway.
|161 forum posts|
Like John Rudd, I have lathes using all three methods of attachment:
In the smaller size lathes, with chucks up to 125 mm, I find the screw-on chucks much easier to fit and have had no problems with chucks becoming "locked-on".
I have no experience with small Camlock chucks but on the big lathe I don't think I would be able to change chucks using anything other than the Camlock system.
With all systems the key to fitting (and accuracy) is meticulous attention to cleanliness of the mating surfaces, screw threads etc. It is generally possible to fit a screw thread chuck with less attention to cleanliness of surfaces but resulting accuracy will be affected and threads and mating surfaces damaged, something I have to remind myself of when doing quick chuck swaps on the smaller lathes.
|Neil Wyatt||19/04/2017 07:16:44|
19032 forum posts
I can only imagine it was a prescient attempt to differentiate you from the other Johnston...
|2538 forum posts|
Yes, I see they gave you an E for effort! I think it was right in the contents section so two out of three...
|Martin Kyte||19/04/2017 09:43:58|
2751 forum posts
I think most of the postings have covered the question.
I do have one thought to add regarding the Myford and similar lathes. Primarily the Super 7 and it's ilk are centre lathes where work is either turned between centres in the spindle and tailstock tapers or in collets, again using the headstock taper as a reference surface. Chucks being a secondary option. The threaded nose allows the use of a closing nut for collets and is available, with the register to attach scroll chucks. I know things have moved on and as turning between centres and faceplate work are less heavily relied on the use of scroll chucks has perhaps dominated perhaps masking their less important historical role in lathes of this type.
|2538 forum posts|
There is a useful discussion of this topic in Cliff Bower's Book of the Lathe and his conclusion is worth quoting:
"The possibility of making special attachments for the spindle nose should be borne in mind by the lathe purchaser. If it is expected that many of these will be required, the screwed or flanged types are preferable. If standard work-holders are to be used, which is highly probable, and it is expected that these will have to be changed frequently, the tapered type of spindle nose offers advantages because of speed with which attachments can be mounted and removed."
This is an old book from 1955 and I understand the Camlock came into use after this date.
|Mike Bondarczuk||19/04/2017 10:49:50|
|91 forum posts|
The Hardinge taper has two positions, and turning the chuck clockwise sets it up for normal forward rotation work and turning the chuck anticlockwise sets it up on the other side of the taper keyway for anti-clockwise rotation.
Would not recommend allowing the chuck to reset itself and always stop the motor and then turn the chuck, but do agree that I cannot think of any reason why the chuck should turn backwards, so to speak, as patron g off is very easy and safe and threading is straightforward with the proprietary Hardinge system.
8666 forum posts
Mike's comment left me wondering "why is reverse needed at all" so I did a search. Practical Machinist has a surprisingly long list, including:
Quicker not to disengage half-nuts when cutting short threads; parting-off; grooving; boring in difficult materials such as bronze; cutting some metric threads; many internal operations; tool-post grinding; chamfering; winding springs; making matched inside and outside tapers; right-hand internal threading; tapping (or rather removing the tap under power); quick stop (not all lathes); and my favourite "unwinding a trapped shirt-sleeve".
One good point made about internal turning is that it's easier to see what you're doing with the lathe in reverse and an upside down tool . Also, running in reverse, it's possible to work out from an internal shoulder.
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