I think what you are proposing is very much in line with the spirit of things here so good luck with it. There are some threads on here that amount to such major re-engineering of a mini lathe that they are not far short of starting from scratch,

Lathes come in many shapes and sizes and each major component tends to be in proportion to the others so it would probably be a good idea to define the sort of shape and size that you are intending – comparable with the Taig/Sherline perhaps? Or bigger? Or smaller?

Another fertile ground would be providing components as the basis for upgrading other lathes – for example I've seen several examples of Taig/Sherline spindles being used as a vertical milling add-on to an existing lathe… or using components to make other things altogether… like a gear hobbing machine perhaps.

I allready have four lathes though so am not really in the market for another one

If you think tweaking a Chinese lathe for better accuracy etc is a lotof work then surely starting from scratch is even more work. Seems a little illogical. You can also consider if you actually need such accuracy. Mostly you don't in model engineering and home shop work.

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… and the rest of us don’t get to watch any of it

”https://www.youtube.com/ Link removed see Code of Conduct”

MichaelG.

Lee,…Interesting post and subject but I feel that I must take you to task a little!….hope you don't mind!

In your third para. you make some statements and assumptions about lathes and mini-lathes which are, for me anyway, not properly analysed….. I used a Chinese mini-lathe for 10 years and eventually did some good work on it and without any changes apart from removing the rubber feet and dumping the dangerous chuck guard. I made my first clock largely on that lathe and I'm still waiting for someone to look critically at it and mention how they can see which bits were made on the Schaublin lathe.

Lathes are just tool for crafts and they are best chosen for the particular craft just as ancient man cast around for a better boulder or a sharper twig etc., but you have not addressed this essential matter. For every 20 or 30 or however many lathes in well loved pristine condition there is a bloke in a shed with a clapped out Myford making fantastic little gem-like items. Both 'camps' have a viable and honest hobby which keeps them happy, but NOT the SAME hobby!

In the end I changed my Chinese mini-lathe for a slightly better lathe not because I saw it as a " substantial project to turn into a reasonably accurate machine" but because I realised that it was of fatally flawed design…..you can't make a silk purse out of a pigs ear!

Is there any reason why the OP should not give sufficient clues/tags to allow the video to be found?

By "accurate", how many decimal places are we talking, be they of inches or mm?

And to what end use?

Many people buy the "Chinese" (or Taiwanese…) made hobby-grade machine-tools from our reputable suppliers, and most seem to manage a decent standard of workmanship and accuracy. I would not dismiss "most" owners of the smallest "mini lathes" as "very inexperienced", as their choice may reflect what they actually make.

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What is the lathe for? Many unique or very low-batch items, or many of a small range of identical items? Hence….

Are we simply re-working what is still a lathe, irrespective of how it is operated; or an exercise in building a numerically-controlled lathe?

That distinction is important. We could design a conventional lathe with future NC drives in mind, a lathe built from the outset with both manual and computer options, or a fully-NC lathe inoperable manually.

A lot of model-engineers now are using NC-machines, some converting manually-controlled machines to NC; and learning the programming adds a stimulating extra challenge to the hobby. So, pros and cons?

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Fully-CNC lathes include turrets, milling/drilling spindles, auto bar-feed, through-tool coolant etc. They cannot be used manually, but are enormously valuable in industry for churning out very accurate, very precise items at prodigious rates.

How far can we design a practical all-CNC lathe for a hobby workshop? We would still need a conventional lathe for most projects, to avoid spending more time programming and machine-setting for just a few parts, than machining them manually. For best CNC advantage you are also confined to insert-tooling, economical in the trade (the customers pay!), and possibly industry-standard tool-mountings too. Getting expensive…..

The trade-off: the NC lathe happily sits making the two or three dozen union nuts you can probably buy for less than the cost of the electricity and brass you would use; but what of the two or three larger parts for the same project?

SO I would suggest if you want CNC, either make the thing useable in both modes, or make sure you keep the conventional lathe too.

If we design and build any machine-tool for our own workshops I suggest first thinking deeply why. Is it an exercise in its own right? What is to be used for? How frequently?

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What of the lathe itself?

Many manufacturers have used different forms, but it must be more than mere conservatism that modern lathes are still basically what a Victorian engineer would recognise.

Drummond Bros. produced both round-bed (ground-steel tube) and conventional box-bed lathes, and typically fitted the leadscrew along the bed axis. That gives more balanced forces on the saddle. On the round-beds, this also shields the screw and nut from the swarf. Many refurbished specimens of both are still returning good work, used with sufficient skill and care.

Many CNC lathes place the saddle above and behind the bed. This lets the swarf fall clear of it, but I think also allow space for active tailstock tooling.

Those are some basic ideas. Can we develop them?

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Thoughts I have had for some years – but I own enough machine-tools and unfinished projects already! These are for fully-manual or optional manual / NC; not full NC.

– Bed: three cylindrical members, full machine length, the top two far enough apart for full use of the faceplate above the central, lower, third rail. Also gives greater support for the cross-slide. The parts mounted on it are based on plates with identically-patterned borings for rigid or bearing mountings.

– Spindle bore: as large as possible for machine size; cam or similar nose-fitting.

– Lead-screw and feed-shaft placed axially (re Drummond).

– Tailstock set-over has definite centre-location – or use an easily-fitted taper attachment plus cross-slide half-nut.

– Boring-table saddle. (Myford, Drummond, Ehrlich…)

– Top-slide on worm-wheel: simple taper-setting even for facing shallow cones; also for forming partial spheres.

– Self-acting cross and long; optionally inter-geared for generating tapers including tapered threads. That idea is not original either!

– Feed / lead clutches: repeated travel limiting, including for fast screw-cutting. Think Ainjest.

– Gearbox: Imperial and Metric threads, fine feeds.

– All gears, bearings etc, stock commercial items.

– Drive. Optional 1ph or 3ph+ with VFD. Still needs countershaft / reduction gearing in primary drive.

While not open hardware, what about looking at the Gingery designs for workshop equipment?

I think the video may be of interest to me. Can anyone suggest a search term I might use to find it or is that against the rules as well? TIA.

But the guy has a load of links to a particular supplier/market place.

Well I watched it all and it actually cut metal quite well, as to weather the cylinders are parallel I have my doubts as I'm sure many here would not consider an old rusty roofers square the ideal look to set the head true to the bed horizontally and I saw nothing to check it was lined up vertically

Edited By JasonB on 15/05/2021 16:18:15

Coincidentally… an interesting 'shop made' lathe with bed bars on eBay just now…

https://www.ebay.co.uk/itm/184830364809?hash=item2b08bf8c89:g:FjcAAOSwnZ5gmrUJ

I've come across some daft stuff on the Internet but a thread discussing a video we aren't allowed to watch is right up there with the best!

There are several possible candidates on YouTube, can anyone tell me the colour of the final machine to narrow it down please.