Lathe for non-metals

andrewnummelin
Posts: 184
Joined: Mon Jul 21, 2008 9:43 am

Lathe for non-metals

Postby andrewnummelin » Sun Nov 22, 2015 5:01 pm

My daughter's fiance has asked for advice on getting a lathe for work with various plastics, resins or hard woods - he's a model maker but not (yet) a railway modeller so is not after something for metal turning or working to high precision.
I've only ever looked at small metal working machines (Unimat, Sherline, ...) and had never really considered working with non-metals but on consideration I think there may well be some things normally turned from metal that could just as well be made from other materials.
Do any of you have experience of turning non-metals?
Do any of you have suggestions where to obtain good advice on the subject?
Regards,

Andrew Nummelin

Winander
Posts: 113
Joined: Thu Mar 20, 2014 12:19 pm

Re: Lathe for non-metals

Postby Winander » Sun Nov 22, 2015 5:52 pm

Wood turners usually work freehand with specialist long handled chisels (that's probably an over-simplification, but a reasonable description) placed on a steady-rest. This arrangement replaces the function of a tool post used when turning metals. A steady rest is no more than a T-bar arrangement parallel to the rotational axis of the lathe that enables the turner to slide the tool along the work piece. I think Terry Bendall in his series on machine tools in the Snooze covered the topic as there is nothing to prevent metal workers using them, in fact jewellers often do.

Depending on scale, I imagine any lathe used by us would be suitable provided you can provision a steady rest and place the work piece between two centres. I'm no expert on using lathes, however, and cannot advise on the relative power the motor would need to turn wood, plastic etc. but I think you are right.

If he's in the market, there's a woodturning lathe languishing in my father's garage - by all accounts it weighs 1.5T :)

Hope I'm not preaching to the wise and it helps.
Richard

Alan Turner
Posts: 535
Joined: Sun Jul 20, 2008 4:24 pm

Re: Lathe for non-metals

Postby Alan Turner » Sun Nov 22, 2015 6:01 pm

The turning of non-metals is no different to turning metals. So the same lathe can be used.

The speed differs from metals, with wood probably requiring the fastest speed (you would need to check that the lathe was capable of wood turning speeds). Traditionally wood was turned free hand but so were some metal watch parts as well.

Some plastics require care as if they are turned at too high a speed they can get hot and give off poisonous vapours - which can kill! PTFE being a case in point.

Others such as Perspex (Acrylic) can just melt.

regards

Alan

David Knight
Posts: 620
Joined: Sun Jul 20, 2008 6:02 pm

Re: Lathe for non-metals

Postby David Knight » Sun Nov 22, 2015 6:13 pm

It all depends on how big he wants to work. Small lathes such as Sherline, Unimat et al can be used for wood, metal and plastics interchangeably. I have a Taig http://www.taigtools.com/ which has the virtue of being very basic and can be set up for wood or metal with as much or as little sophistication as you are prepared to pay for. It is quite small though, so there are limits to what it can handle. I'm not sure if Taig is available in the UK.

HTH

David

nigelcliffe
Posts: 488
Joined: Mon Jul 21, 2008 8:31 am

Re: Lathe for non-metals

Postby nigelcliffe » Mon Nov 23, 2015 8:33 am

The Taig is known as Peatol in the UK, and available.

Another approach, depending on size wanted, might be watchmaker's lathes. The "real thing Swiss" examples are silly expensive, but there are Chinese copies around, some of which are excellent.

Or, one-step up in size from the small machines (Sherline/Unimat/Taig) might be the small Chinese machines from SAIC and the like. See suppliers such as Axminster Tools, Arc-Eurotrade, and others. Or, similar size but a higher budget, the machines from Proxxon.


I use a Cowell, an excellent machine which can be picked up and put in a cupboard. But, Ebay prices are in the "slightly scarey" levels, and new is now very expensive.


- Nigel

Terry Bendall
Posts: 1597
Joined: Sun Jul 27, 2008 7:46 am

Re: Lathe for non-metals

Postby Terry Bendall » Wed Nov 25, 2015 9:27 am

andrewnummelin wrote:My daughter's fiance has asked for advice on getting a lathe for work with various plastics, resins or hard woods


A very simple question, but the answer could take a long time :) The problem is that we are talking about a vast range of materials, all with very varying properties. A close grain hardwood timber such as beech will have very different properties from an open grain timber such as chestnut, and the wide range of plastics materials available will all have different properties again.

Winander wrote: I think Terry Bendall in his series on machine tools in the Snooze covered the topic as there is nothing to prevent metal workers using them, in fact jewellers often do.
.

Yes I did and it works well for things such as chimneys and domes.

Winander wrote: Wood turners usually work freehand with specialist long handled chisels (that's probably an over-simplification, but a reasonable description) placed on a steady-rest


Yes that is correct but it is possible to buy small wood turning lathes, just as we can buy small metal turning lathes and the tools will be correspondingly smaller. Wood turning is a popular hobby and there are a number of magazines devoted to it and courses that can be attended to learn the basics. One of the best books on woodturning that I have come across is "The Practical Wood Turner" by Frank Pain. This was first published in 1957and I bought my copy in 1965 and it is still available. It is obviously a bit dated in style but still offers very sound advice.

The purist would shudder at the thought of turning wood on a metal turning lathe since the shavings and dust will clog things up and absorb the oil but if you can live with that it can be done. Just provide a tool rest and invest in a set of suitable turning tools. Close grain hardwood timbers can be turned with cutting tools used for metal and a round ended tool will give a fairly good finish. Use glass paper if you must but take the tool right out of the machine and wear a proper dust mask. A proper craftsman (or woman) will keep their tools sharp and finish things from the tool and not use glass paper at all. :)

Alan Turner wrote:Some plastics require care as if they are turned at too high a speed they can get hot and give off poisonous vapours - which can kill! PTFE being a case in point.


Possibly but unlikely with care.

My advice would be to buy a metal turning lathe and then buy (or make) a suitable rest for the wood turning tools. Most plastics that model makers are likely to use can be treated as metals and turned using the same sort of cutting tools. The best book I have forum on metal turning is The Amateur's Lathe by L H. Sparey, again very old but still available and a very sound source of advice.

And a bit of advanced publicity.... my offer to provide a demonstration at Scalefour North next year on using machines tools in railway modelling has been accepted so come along and ask your questions then. :) Perhaps I had better bring my wood turning lathe as well. :D

Terry Bendall

Philip Hall
Posts: 1244
Joined: Mon Aug 10, 2009 7:49 pm

Re: Lathe for non-metals

Postby Philip Hall » Wed Nov 25, 2015 10:37 am

I agree with Terry about buying a metal turning lathe. My very old Unimat SL gets used for plastic as well as metal. As an example I use it to skim the centres of plastic centred wheels when I get an eccentric one. I would say that in this case I always take the driving belts off the lathe and spin it by hand, because I need to take so little off the plastic usually and this enables me to get right in close safely. But with a sharp tool it works just fine. I have used it with wood on occasion, too, but always vacuum the machine afterwards to get rid of the dust.

Philip


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