Is it possible to machine a lathe more accurate than the one you machine it on? If so, how?

[Michael GilliganParticipant @michaelgilligan61133]

Whilst you were posting that, Henry … I was digging through some old posts of mine, and unearthed this from 2012:

__________

The full text of Jesse Ramsden's paper is available here: **LINK**

and an excellent commentary, here: **LINK**

Both thanks to the expert Mr Morris

**LINK**

___________

These may or may not be the same links that you found yourself, but I’m mentioning them anyway in case anyone else is interested. You will discover that various aspects of ‘Dividing’ feature quite frequently on this forum.

MichaelG.

[Roger BParticipant @rogerb61624]

I think, and this is seriously stretching my memory that L T C Rolt produced a book on the development of machine tools and especially averaging devices to improve lead screws (I am prepared to be completely wrong on this ;-( )

[Mike PooleParticipant @mikepoole82104]

LTC Rolt wrote Tools for the Job which I found an interesting read. It has had some criticism but overall I enjoyed it.

Mike

Edited By Mike Poole on 29/10/2021 20:27:24

[John PParticipant @johnp77052]

Posted by Henry Bainbridge 29/10/2021 17:47:16

I am not sure what you mean by incorrect. I posed a recursive question
deliberately because AFAIK there are some parts of a lathe
that can only be made by a lathe and I wondered how that can be.
I take your point though, so for the sake of argument let's say the
thought experiment is about how some tools are recursive in nature, and
that being so, how accuracy comes about.

————————————————————-

Perhaps a poor choice of words on my part ,but if if you take the
opening statement of:-

Is it possible to machine a lathe more accurate than the one you
machine it on? If so, how?

If you mean "make" as in machine then the answer would be no.
It may well be that some parts of a lathe can be made on a lathe
but i doubt if many of the the parts would finished on one , you only have to
look any lathe on sale just about every surface is finish ground and
with that comes the accuracy of the machine.

As far as being able to make another lathe there is simply not enough machining
capacity with a lathe to be able to make another one, but you can use a lathe
to make other machine tools to assist in making the lathe.

There is no doubt if the ingenuity of some of these early pioneers of the
industrial age were up against it . I just wonder how many others who perhaps
were attempting much the same but just simply fell by the wayside and those
who succeeded just were in the right place at the right time and had the
good luck to see it through.

Perhaps an example of this can be seen in this interview,
Sir Tom Sopwith interview with Raymond Baxter.
https://www.youtube.com/watch?v=4y0rBfJ8VGw

In the closing question Sir Tom was asked

At 96 a lifetime of amazing achievements behind you What do you attribute
your success?

He responded with "Pure luck"

Perhaps getting back to the thread in general if you look at some of the answers
they are all on the theoretical mostly what has been read in books, the
complete lack of documented and practical examples by respondents on
here can lead you to only one conclusion .

John

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John P on 29/10/2021 20:31:12:

[…]

the complete lack of documented and practical examples by respondents on
here can lead you to only one conclusion .

John

.

Perhaps not only one conclusion, John

The other legitimate conclusion is that the chosen examples demonstrated by others are intellectually obviously correct, and therefore do not need repeating by every student.

Joseph Whitworth described the three plate method of making flat surfaces in sufficient detail for me to know that it works.

Jesse Ramsden described how to make a screw thread and use it as a hob to make a large wormwheel … in sufficient detail for me to know that concept works.

Two roughly made ‘centres’ in a bodger’s lathe can obviously be used to turn a better point than either of them … because the inherent rotational symmetry works in our favour.

So the alternative conclusion is that the expert demonstrator relieves the intelligent observer from the need to re-invent the wheel.

MichaelG.

 

Edited By Michael Gilligan on 29/10/2021 21:38:31

[Chuck TaperParticipant @chucktaper]

The following, perhaps not directly relevant to OP, but……etc.

The machine that made everything.

FC

[John PParticipant @johnp77052]

Posted by Michael Gilligan 29/10/2021 21:37:33

Jesse Ramsden described how to make a screw thread and use it as a
hob to make a large wormwheel … in sufficient detail for me to know
that concept works.

Hi Michael,

Whilst the OP was just getting enough postings just to look at the classifieds
and has yet to get a lathe and asked the opening question.

Various respondents have pointed to the early names of pioneers
of the industrial revolution.
If you look at this video

was Jesse Ramsden inventing anything or just
re-inventing the wheel and much the same could be said for the others
since many the skills and techniques had been invented thousands
of years ago and i guess nobody really knows by who.

I suppose the only thing the early pioneers did was to get out of their
armchairs and actually get on with something, some on this forum
could learn a few things by doing the same.

I suppose i would say to the OP when you get your lathe and have used it
for a while you will have the opportunity to find out some of these things
yourself instead of popular pastime of just reading it out of a book.

John

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John P on 30/10/2021 11:50:29:

[…]

was Jesse Ramsden inventing anything …

.

In my opinion, John … Emphatically YES

But , I will 'admit' that I have just as much interest in the history of technology as I do in getting my hands dirty.

… I am not really interested in arguing with you though.

MichaelG.

.

P.S. __ I was delighted to see that Henry actually contributed something to the forum, and I think that deserves our encouragement.

[Howard LewisParticipant @howardlewis46836]

Sorry to appear to pour cold water on our transatlantic cousin with his first French made lathe, but it seems to contain an awful lot of screw threads, and those Vee beds must have involved an unbelievable amount of hand fitting and offering up!

And if it was preceded by watchmaling lathes, it could not have been the first.

This implies that Maudslay and Whitworth were there first, and presumably with lathes to make the parts that they were standardising.and measuring.

The Levant engine Cornwall (1824? ) contains only four nuts ) Probably made by hand by a local blacksmith ) everything else is staked together with cotters or keys.

Hence my scepticism

Howard

[Oily RagParticipant @oilyrag]

Now if you want to see a truly amazing machine there is / or was a 'Trip Hammer' displayed at the Birmingham Science Museum (now relocated to the 'Think Tank', Millenium Point, Curzon Street – not as I erroneously stated 'Centre Point' in my earlier post)

The trip hammer was a water wheel driven tree trunk with protrusions which hit another tree trunk at right angle to it, this caused the long slender trunk to rise sharply and contact a tree trunk set at the rear where upon it 'bounced' back and a cast hammer head then struck an anvil. The tool was made in 1756 and worked in Wednesbury in the Black Country until 1974. It was used to forge shovels and was so fast (250 beats a minute) that no machine bettered it until the 1970's! Not a nut or bolt was used in its construction – all was held together by wedges and keys.

Martin

[SillyOldDufferModerator @sillyoldduffer]

Posted by Howard Lewis on 30/10/2021 13:53:29:

Sorry to appear to pour cold water on our transatlantic cousin with his first French made lathe, but it seems to contain an awful lot of screw threads, and those Vee beds must have involved an unbelievable amount of hand fitting and offering up!

And if it was preceded by watchmaling lathes, it could not have been the first.

This implies that Maudslay and Whitworth were there first, and presumably with lathes to make the parts that they were standardising.and measuring.

The Levant engine Cornwall (1824? ) contains only four nuts ) Probably made by hand by a local blacksmith ) everything else is staked together with cotters or keys.

Hence my scepticism

Howard

I don't see that at all. The machine being made circa 1760 checks out. Vaucanson's lathe was described at the time in the Encyclopédie, which was published between 1751 and 1772. Though it must have cost a fortune to make a metal lathe that big, the technology to make it existed then. The screws were probably handmade.

Fairly advanced big lathes existed earlier, but were made of wood and metal. From Grace's Guide: 'Smeaton's description establishes that, as early as 1741, Hindley's workshop contained not only the wheel-cutting and dividing engine but a great lathe capable of turning pieces over 2½ feet in diameter and a chock (chuck) lathe with a lead-screw and change-wheels.'

I suppose Vaucanson's lathe didn't catch on because it specialised in making rollers for the patterned Silk industry. And demand for patterned silk may have sagged due to customers being guillotined during the French Revolution.

Henry Maudslay was 9 years old when Vaucanson died in 1782 and Whitworth wasn't born until 1803, 21 years later. (Whitworth worked for Maudslay when he grew up). Their contributions to precision engineering were enormous, but although they invented the screw-cutting lathe as we know it, they stood on the shoulders of giants just like the rest of us!

The Old Guard were dead against Maudslay's innovations. They disparagingly called his saddle sliding on a precision bed-way 'Maudslay's Go-cart'. Anything that requires less skill and improves productivity must be fatal to 'quality'…

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 29/10/2021 19:41:23:

[…]

The full text of Jesse Ramsden's paper is available here: **LINK**

 

Not that anyone appears to have noticed … There is an error in that link ^^^

It should be : **LINK**

http://www.fer3.com/arc/imgx/Text.pdf

NOT http:// http://www.fer3.com/arc/imgx/Text.pdf

MichaelG.

Edited By Michael Gilligan on 30/10/2021 15:23:50

[Mike PooleParticipant @mikepoole82104]

Hand in hand with the improvements to machinery went the improvements to metrology. If you can’t measure what you are doing then how do you know what improvement has been achieved? Machining for internal combustion engines certainly improved to the point that running in is now barely necessary, of course lubrication also improved. It is not necessarily that surface finish and dimensional accuracy could not be achieved but the cost of obtaining it has made it economical for mass production.

Mike

[Henry BainbridgeParticipant @henrybainbridge40560]

Posted by Michael Gilligan on 29/10/2021 19:41:23:

Whilst you were posting that, Henry … I was digging through some old posts of mine, and unearthed this from 2012:

__________

The full text of Jesse Ramsden's paper is available here: **LINK**

and an excellent commentary, here: **LINK**

Both thanks to the expert Mr Morris

**LINK**

___________

These may or may not be the same links that you found yourself, but I’m mentioning them anyway in case anyone else is interested. You will discover that various aspects of ‘Dividing’ feature quite frequently on this forum.

MichaelG.

Yes, that's the one, I was going to point out the broken link, but see you already did that.

I found a really nice high-res copy of the illustration in a Sotheby's auction (now printed on A3 for the wall).

https://www.sothebys.com/en/auctions/ecatalogue/2018/the-library-of-erwin-tomash-l18409/lot.539.html

[Henry BainbridgeParticipant @henrybainbridge40560]

Posted by John P on 30/10/2021 11:50:29:

Whilst the OP was just getting enough postings just to look at the classifieds
and has yet to get a lathe and asked the opening question.

Hey! How did you know I don't have a lathe? The pedant in my says actually I have owned and operated a lathe every day of my working life for the last 18 years, albeit a disc mastering lathe, so not quite the same thing I grant you, but still.

You are right though, I don't have a lathe yet, hence my visit to the classifieds, but I am not a total novice when it comes to metalwork lathes either, I learnt on a Colchester Student (I think) at school back in the 1980s as well as a woodworking lathe I don't recall. Incidentally I came across this photo of the wood workshop at my school (in the 1940s I am guessing?), it had the same benches I used! https://images.app.goo.gl/DHLLz81mUnf7K8ht5

Anyway, back to the matter. I spend several hours a day using a lathe that can turn at precisely 33.33rpm across the entire face of a disc for 20+ minutes, while varying the pitch to keep the grooves as close together as possible, without so much as kissing each other (let alone twining). Bearing in mind the grooves are rarely wider than 100 microns (50 deep), the amplitude of the signal is constantly varying with >60dB of range and comprises two orthogonal forces being exerted on the disc at the same time. Added to that, if you speak too loudly next to the lathe when its running, your voice will be transferred onto the disc, so the lathe must operate as close to silent as possible. And you only have one pass per side. A mistake on either side means you have to bin the whole disc.

I wonder if that qualifies as not sitting in an armchair?

How that machinery is made is an exquisite problem I can't help wondering about, and I often come across this forum when looking for answers, so I can assure my interest in accuracy is not just a vehicle to seeing the classifieds.

[Ian ParkinParticipant @ianparkin39383]

I don’t know whether this has been posted before but there’s this video on you tube where a guy makes a Colchester student sized lathe with a minimum of a few hand tools cordless drills and angle grinders and a mig welder and it looks good

innovative use of wood and a workmate grinding the ways..

search for “making big lathe from scratch with basic tools”

my hat is doffed to him

Edited By Ian Parkin on 31/10/2021 14:41:58

[Howard LewisParticipant @howardlewis46836]

In answer to the original question, the answer has to be YES

Otherwise how have we arrived at the high precision machines mused in industry, and the less sophisticated ones that we hobbyists use.

Hopefully Henry will now have enough posts to allow him to participate in the Sales and Wants sections.

Not to mention an award for lighting a blue touch papet!

Howard

[Henry BainbridgeParticipant @henrybainbridge40560]

Posted by Chuck Taper on 30/10/2021 10:40:07:

The following, perhaps not directly relevant to OP, but……etc.

The machine that made everything.

FC

It's a piece of the puzzle, and it led me to this one: https://www.youtube.com/watch?v=gNRnrn5DE58 another good video from Machine Thinking to go with the one John P referenced, all about the origins of precision

[John PParticipant @johnp77052]

Posted by Henry Bainbridge 31/10/2021 14:21:36

Hey! How did you know I don't have a lathe? The pedant in my
says actually I have owned and operated a lathe every day
of my working life for the last 18 years, albeit a disc mastering
lathe, so not quite the same thing I grant you, but still.
You are right though, I don't have a lathe yet.

————————————————————-

Before answering most posts on here i generally look back through
the posters history as this can sometimes help with giving a reasonable
answer ,most half decent engineer's will do their homework,
of course there are exceptions one of the posters who replied to you in
this thread was giving someone some chapter and verse advice
on how the set the dovetail gibs on his milling machine on a machine
that had square slide ways ,clearly would you take advice from
someone with such a sloppy approach.

Getting back "How did you know"

Your posting here 28/10/2021 19:33:03

The relevant bit i have put in brackets.

Hi there, just posting so I can see classifieds.
I will stop by again (if I get a lathe), and I have
some genuine queries

John

[Henry BainbridgeParticipant @henrybainbridge40560]

Posted by John P on 31/10/2021 16:50:21:

Getting back "How did you know"

Your posting here 28/10/2021 19:33:03

The relevant bit i have put in brackets.

Hi there, just posting so I can see classifieds.
I will stop by again (if I get a lathe), and I have
some genuine queries

John

D'0h! You got me!

[Author]

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