Lathe alignment

[NJHParticipant @njh]

Hi Michael

Not offended but a bit mystified!

I followed your link and must say that I thought that the video left much to be desired – iffy capture, awful musak and no explanation of the function of the device or what was being done. However a little further investigation led to THIS link which then made things a bit clearer!

Regards

Norman

 

 

Edited By NJH on 31/03/2013 16:16:11

[Michael GilliganParticipant @michaelgilligan61133]

Posted by NJH on 31/03/2013 16:12:15:

However a little further investigation led to THIS link which then made things a bit clearer!

Regards

Norman

.

Quite so, Norman

Unless something went wrong with my YouTube linking; there should be a clickable hyperlink under the video. … That's what I really wanted people to see.

MichaelG.

Posted by Michael Gilligan on 31/03/2013 11:34:50:

Most important; he gives a link to Mr. King's patent.

MichaelG.

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Graham Meek on 31/03/2013 14:00:22:

As you say as long as the level is reading the same at both ends of the bedways then all will be fine ,BUT even then it is the trurning test that proves the Alignment, and in my experience the bed will still need tweaking.

I agree with you completely, it was the gist of my comments in the other thread – the true test is: will the lathe turn a parallel bar? A level may help one get to that situation more quickly but the turning test still has to be done.

Much of the advice given on the forum seems to be to buy another piece of kit. Poor old Kane is desperately trying to learn how to use his new lathe to turn a rectangular prism and the advice is to buy a shaper – really!

grumpy old Rod (is it ever going to get warm?)

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hello again ,

(1) All bed alignment methods explained by the experts are a waste of time if spindle axis is not in primary alignment with bed axis . With old lathes this is where a lot of the general alignment error starts and no amount of fiddling with levels and packing will put this problem right .

(2) Similar for a bed with variable wear along its length .

(3) Any local packing of bed mountings intended to twist bed to improve alignment should be minute – couple of thou max – and what anyone is really doing is untwisting the bed back to being true and in minimal stress condition – if bed needs actual bending to sort it out then its scrap

(4) Machine beds don't just have simple twists in them – they are just as likely to be hogging or sagging and this needs a different set of procedures to sort out .

(5) Lathes – and in general all machine tools – are flexible . The amount of flexibility depends on the detail design of machine and on its installation .

With Myford 7 series lathes installed in the usual simple manner it is sometimes possible to twist tailstock end relative to headstock end by by a couple of thou (measured front to back on bed ) just by pushing and pulling by hand . To consistently do any better needs a proper sub bed – like channel discussed in earlier thread .

True alignment under load is not nescessarily the same as alignment under no load .

Main point though is that flexibility of lathe bed and further flexibilities in bearings etc. set a fundamental limit to how accurate a lathe can be set up and how accurate the work produced can be .

Regards ,

Michael Williams

[David LittlewoodParticipant @davidlittlewood51847]

Posted by Graham Meek on 31/03/2013 13:11:22:

One would never think we went through all this less than a month ago with the Sabel lathe, and still people are so died in the wool that they will not take on board that when Engineers talk about a machine being Level they are really talking about Alignment, as Martin says.

Well, if one uses a word in a way totally contrary to the way the other 99+% of the English-speaking world understand it, confusion is inevitable. There is a certain Teedledum/Tweedledee approach here.

David

[Anonymous]

I'm with Humpty Dumpty regarding my use of words :

'When I use a word,' Humpty Dumpty said in a rather scornful tone, 'it means just what I chose it to mean – neither more nor less'.

Regards,

Andrew

[Rufus RoughcutParticipant @rufusroughcut]

Hi Gents

I'm a bit confused now!!!!!

are we aligning or levelling and is this in the horizontal? >>>>>><<<<<<<<or the vertical? vvvvvvvv

^^^^^^^^

At present my workshop in which my lathe and milling machine stand is neither level nor aligned yet they appear to machine absolutely fine is there some critical issue I'm missing,

Is the idea that fixing a rotating machine to a ground that is rotating at a significantly faster speed made of ever moving plates which heave, twist and sag at leisure, then completely ignore angular momentum and gravity, with the expectation that a bubble of trapped gas in a liquid where its meniscus curve is governed by applied and ambient pressure, temperature and every other physical effect in the universe will produce a perfectly level, flat and parallel work piece when looked at, measured and inspected by our ageing eyes assisted by warp inducing bifocals which were never really prescribed for us but where purchased cheap at a car boot sale because of their intended use which was to help us see finite detailed changes and inaccuracies in our equipment including the levelling and aligning gadgets we use. then to top it all when we are happy that all the universe revolves round our lathe spindle we decide to machine cock eyed and make a taper or crank, engineering is insane! !!!!!! Me too

Barry

[Mark CParticipant @markc]

I thought my lathe was perfectly set true and level (coplanar with perpendicular planes parallel with the prevailing gravitational conditions). I then noticed a hazel twig on the floor and picked it up, only to find that it indicates a leyline running at an angle across the ways – this must be the reason why I sometimes get parts that are not to size/specification?

Mark

[blowlampParticipant @blowlamp]

Anyone familiar with working wood to achieve a flat surface will have heard of Winding Sticks and these are used to help level the wood when it is 'wound' (warped or twisted) like you would with a machine level, i.e. they are used in comparison against one another and this is how a Machine Level is used – check the level at one end of the bed and compare with the reading at the other end until there is close to zero difference. The point is that you don't have to have the wood level with the face of the earth in order to use the sticks to get a level surface.

Martin.

**LINK**

[Will RobertsonParticipant @willrobertson16447]

Hi Jan,

I've got much less experience than most folk on here so please treat my two contributions with a pinch of salt:

From the 0.3mm test piece taper you mentioned I'd guess that this is due to tailstock misalignment. It would be best to clean the ways, clean the tailstock taper, ensure the taper of the centre is free of any bumps and then adjust and perfect the tailstock alignment before starting any adjustment of the lathe bed.

A piece of swarf caught between the tailstock and the ways might throw the tailstock significantly out of alignment but I don't know your lathe in detail so I'm not sure.

You mentioned 'mild steel' – steel sold as 'mild steel' can vary a fair bit – some of it is easy to machine to high precision and good surface finish and some of it is impossible to machine to precision and good surface finish – this can cause problems when making precision measurements like this. A specific grade of free cutting steel (or something cheaper – e.g. aluminium) designed for good machining properties may help.

Will

 

Edited By Will Robertson on 31/03/2013 22:32:37

[David LittlewoodParticipant @davidlittlewood51847]

Posted by Andrew Johnston on 31/03/2013 19:04:41:

I'm with Humpty Dumpty regarding my use of words :

'When I use a word,' Humpty Dumpty said in a rather scornful tone, 'it means just what I chose it to mean – neither more nor less'.

Andrew,

Apologies, I obviously misremembered the source of the quote; I couldn't find it in my dictionary of quotations.

David

[Anonymous]

David: No need to apologise. I checked the quote in my Oxford Dictionary of Quotations. One would certainly hope that, in this case especially, the OUP would get it right.

Regards,

Andrew

[blowlampParticipant @blowlamp]

I don't know much about Humpty Dumpty and Tweedledum and Tweedledee, other than to say it sounds like they work in the legal system.

Plenty of words can have subtleties to their meaning, so I can't see the problem with the word 'level' when used in this context.

Martin.

[Sub MandrelParticipant @submandrel]

Perhaps we should be talking about the difference between horizontal and straight…

Neil

[NJHParticipant @njh]

Well said Gray

As far as the "Model Engineer" term goes though I guess it could be taken Three ways – the two that you cite and then the perfectly crafted and formed replica of an engineer!

OK I'll go out to my workshop now!

Norman

[Sub MandrelParticipant @submandrel]

Hi Gray,

I was not seriously suggesting changing the words, it was my pop at those who put semantics above pragmatics

That said, I have a current project, which if it comes to fruition, will make me the target of this sort of criticism for year to come!

Neil

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

I've never had any difficulty in understanding what ' levelling a lathe ' means since I was about ten years old .

Conceptually ' levelling a lathe ' has the same meaning as ' tramming a milling machine ' ie setting the alignments of all the axes which define the accuracy of a particular machine to as near as practical their true design values .

Most commonly axes exactly parallel or exactly at right angles to each other and each axis true within itself .

Regards ,

Michael Williams .

Edited By MICHAEL WILLIAMS on 01/04/2013 11:45:15

[Rufus RoughcutParticipant @rufusroughcut]

Hi Gents

touche' Micheal and Norman

I think the engineer refered to is a prototype seeking to become one of the engineering in miniture Illuminati, I nearly forgot what the thread was about oh and hears a Cake Decorating picture for Gray to work on

With number plate obsured for tax purposes

Regards

Bazza

[David LittlewoodParticipant @davidlittlewood51847]

Posted by Graham Meek on 01/04/2013 10:08:42:

It is obvious to me that some people will never accept this term, they jump straight in with their ten penneth, stating it's an old wives tale that a lathe has to be level(led), (that's the bit they miss off), which only adds more confusion and purely because they do do understand what is being said.

Rather than coming to these pages either to give information or tap into a lifetimes experience in various forms of engineering they are more content with scoring points.

Graham,

If the above was aimed at me, then I must strongly deprecate your comment, and its personal nature. In my opinion, clarity and certainty of expression is fundamental to any discussion which has any claim to be scientific and rational. If participants have different views as to what words mean, communication is hampered. Then unless the meaning of a word can be agreed, it is best avoided, and a non-contentious alternative should be used. I hate to think how many beginners have been confused by this particular example in the past.

David

[Tony Pratt 1Participant @tonypratt1]

Rufus, where is the promised picture, my wife might be interested? I guess we are all cold and bored judging by how this thread has deteriorated into petty squabbling.

Tony

[Rufus RoughcutParticipant @rufusroughcut]

Hi Tony

I see the picture on this end however these are prescrition lenses I'm looking through have now put it in album

Rufus

[Rufus RoughcutParticipant @rufusroughcut]

Hi Gents

As a novice I was asked what this is?????

With all guarded response and discriptions clear for a novice to understand what would you say ???

Rufus

[Sub MandrelParticipant @submandrel]

A lump of metal.

Neil

[MichaelRParticipant @michaelr]

It could be owt

[Harold Hall 1Participant @haroldhall1]

Personally Graham I do not disagree with the terms level or levelling being used providing that they are explained to the novice when used in the context being discussed here. Also, when used in articles in a magazine, in books or on other threads on the subject. This I think is vital as the vast majority will not be aware of its meaning in this situation.

Unfortunately, this very often is not done and the novice is faced with suggestions that in some cases give the impression that the bed must be set up level ( as most understand the word, me included) at both ends using an engineers level, whilst other will say this is not necessary providing the bed is not twisted. Then some saying that using an engineers level is a good way of testing this if one is available.

Regarding the comment about lathes on board ship, I probably was responsible for starting this. Consider the novice confused by the lack of precise detail as mentioned above, he, or she, may go away and say that Harold Hall says that the lathe need not be level whilst man B gives the impression that it should be.

Having given the two approaches consideration it would be understandable if the decision was taken to go with man B as Harold himself owns up to being just an electrical engineer. As a novice is involved, one needs at this stage to avoiding getting too deep into the detail and referring to a lathe on board ship seemed to me to be one that the novice could understand.

I would also say to Michael W. If you have understood the term levelling from an early age you are in a fortunate position regarding the term used in this context. Where you acquired the knowledge from would be interesting but in my estimation a very large proportion of those owning a lathe will not have that knowledge and need it explaining in detail.

Harold

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