https://groups.io/g/taigtools

Starting out I looked closely at Taig and Sherline and decided they were too small for what I wanted, and biased to small precision work rather than the clunkier general-purpose turning I do. I bought a mini-lathe instead, learned a lot from it, and decided it was too small as well!

Small precision work like clock making and OO gauge railway modelling is well served by high minimum RPM, table-top machines fitted with collets, but general-purpose machining is easier with larger machines with a low minimum RPM and a chuck.

Looking at the PM #3 on their website for difficulties, I see a few:

1. The kit is castings based, and they have to be held firmly on the lathe.
2. The diameter of the flywheel is 2¼" . I'd hold that in a chuck or faceplate: 5C collets are unsuitable, though it might be done with a stub mandrel. The Taig appears to have enough 'swing' to make the flywheel.
3. The piston cylinder needs to have the ends skimmed square and the interior bored to size and well-finished. I'd hold the casting in a chuck. Taig should be big enough to hold the job.
4. The valve is drilled, so a tailstock and drill-chuck are needed (both extras). Looks as if the valve cylinder is part of the piston casting, so some way of holding the casting off-set to centre the valve cylinder is needed. A 4-jaw chuck would do it, but needs to have enough jaw movement: I don't know if the Taig 4-jaw has enough capacity. Otherwise mount on a faceplate, or clamp to the saddle and drill with the spindle.
5. Not shown in PMs photo are the eccentric and other valve gear details hidden behind the flywheel. Should be OK, I doubt any of them are beyond the Taig's capabilities.
6. My biggest concern is machining the main casting. It's 6" long and might be too big or awkward to hold on a small lathe. But it might be possible to do most of the work by hand – skimming the base flat could be done with a file. Even big lathes aren't ideal for odd shapes like the base, which is why we all buy milling machines if we can.

Mostly guesswork on my part: I've never built a PM#3 or used a Taig in anger. The best answer will come from a Taig owner who builds engines!

As an aside, don't get hung up on precision unless it's specifically needed. Most Model Engineering is done ±0.02mm ( ±0.001" ) and any lathe in reasonable condition will do that. Engines like the PM#3 actually work better when built a bit loose – they jamb when made to close tolerances! High precision and accuracy seem highly desirable, but in practice they're rarely needed in a home workshop where parts are tweaked to fit together rather than guaranteed interchangeable straight off the machine. We don't need jigs, fixtures, gauges or anything else made to tool-room standards unless something special is afoot.

Dave

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I have a Taig lathe, but don't build engines so I can't help with the detail of the build. In my view Taigs are very capable and very reasonably priced, but they are the basis for creating what you want rather than ready to run out of the box. A Sherline or a Chinese mini lathe would be better out of the box.

Look at John Bentley's  modelengines.info  website to see what can be done on a Taig

The Taig Lathe and Milling Machine (cartertools.com) has lots of information on how people use and modify the Taig.

I opted for the ER16 collet spindle and am very glad I did. As John says 5C has the disadvantage that the collets are expensive and only hold one size while ER collets hold a 1mm range of sizes. (You can actually get 11 and 12mm ER16 collets from Gloster Tooling). I have a 12mm one and it works well.

Taig supply 3 & 4 jaw chucks which screw directly onto the M22 x 1.5 ER spindle nose so no need for a backplate. The sherline 3 jaw M22 x 1.5 threaded chuck also fits ( but is considerably more expensive than the Taig soft jaw version). I have swung 4" diameter on the lathe (nominally it will turn 4.5", and they also do a riser block that adds another 1" of clearance to the bed (albeit with some loss of rigidity) so up to 6.5" is possible.

As Francis says the recommended induction motor is very heavy, bulky and in my view very limited as the minimum spindle speed is about 450rpm which is a bit fast for turning cast iron. A variable speed DC motor is a much better choice. Mine is currently fitted with a BLDC 220W DC motor on a home made mount. which gives me 75-10,000 rpm at the spindle.

I bought the vertical slide and milling vice with the Taig. I have successfully used it to do small scale milling, but the setup is such a faff that I eventually bought a Sieg SX1LP mill.

Mine like Francis' and all standard Taigs doesn't have a leadscrew. I don't find the rack feed much of an issue. It is quick to move, but does provide accurate positioning. I plan to add a motor driven leadscrew and power feed when I get round to it.

Typos!

Edited By Peter Cook 6 on 07/03/2022 17:48:46

Jan-Willem;

I was amazed by following the build of a 3-1/2" (1:16) Shay geared locomotive. On Sherline equipment.

Have a look at:

Chris Rueby's Shay Build

(https://www.modelenginemaker.com/index.php/topic,3778.0.html)

He's a prolific builder, so look at any of Chris Rueby's photos on his more recent builds to see what he does with this limited (hah!) sized equipment.

I've now got some Sherline equipment. The metric version has a 6.3mm x 1 pitch feed screws (6.3 is 1/4 inch). My only complaint was the UNC (UNF??) screws, but a metric thread is almost equivalent; seemingly some metric screws will fit, and if too tight, a simple "run the metric tap through" will help. That was from Sherline's web page. (I purchased a bunch of cap screws that I keep separate from my metric standard – wish I had figured this out earlier) I won't put the equivalent metric thread here in case I get it wrong. (not near my workshop at the moment)

The lathe can have a vertical mill column attached in which case (like the Unimat) the headstock mounts vertically. Years ago I had a Unimat SL, and liked it, but the Sherline is 100 times the machine than my little SL was.

I'm impressed, and I put my money where my mouth is, so to speak, and have purchased a lathe and mill from them.

Edited By John Alexander Stewart on 07/03/2022 21:12:30

Another thing to consider is time. Although you may be able to physically fit the item onto a small lathe it will take a lot longer to machine as they will only be able to take shallow cuts. For example on the smaller machine you may only be able to take a 0.1mm depth of cut but on something larger a DOC of 1mm would not be a problem. So that means it will take you 10 times longer to machine a part on the small machine that a larger one.

I made my first steam engine casting kit, a Stuart 10V on a Unimat3 but it is slow going both in machining as well as setup time.

At the risk of causing confusion, here are my comments.

You will find that your horizons expand, and need a larger machine.

A Leadscrew allows you not only to screwcut, but to set up a power feed, which can improve the turned finish.

Although a mini lathe is liable to be Metric, a 63T gear will allow Imperial threads to be cut, should you need anything larger than those that can be produced using Taps and Dies..

The suggestion of having a mini lathe on a roller cabinet is a good one. The cabinet results in additional bench space, which can be moved around yo suit your requirements at the time.

My mini is on one and the drawers provide lots of storage for tools, a spare chuck. (3 or 4 jaw jaw, depending on which is in use ), ER collet chuck, faceplate, change wheels, etc.

You can get a Vertical Slide for the mini lathe which will allow a limited amount of milling.

if you require, a radius turning attachment, they are available.

By all means gain experience with a micro lathe, but a mini is likely to more useful as time goes on.

Howard

The Taig lathes do offer a power feed,and some people have come up with ways to cut short threads etc.

A guy who sells Cue making lathes in the USA Chris Hightower, is worth making contact with as well. He has a wealth of knowledge with Taig Lathes, and was the first to make a cue making lathe with the Taig lathe system. He has Riser blocks that allow for larger centre heights etc, as well as bearing steady rests, and support for things that hang out the back of the lathe. He also has an indexing plate that fits the spindle etc.

My cue lathe, I don't have the power feed or screw cutting options on it yet, but that maybe changing. I have done several model engineering things on the big bore Taig type lathe that I was not able to make in the Myford S7. Having the ability to hold Ø26mm bar has been the biggest asset, as most mini lathes are only able to hold 14mm or so bar to make bar stock parts from, unless cut into very short lengths.

Taig also make a little compound slide that has been most useful as well.

I would not get too hung up about thread cutting as most sizes used can be done with taps and dies these days. Sets even in HSS are not the commanding price that they used to be. Then there are die holders that you could make for the Taig tailstock arrangement. A friend has owned a lathe for about 28 years and only this year I showed him how to screw cut a thread that he could not get a die for off the shelf. There is the electronic leadscrew project, and oneday, it may well be available for the Taig or Sherline type lathes.

No matter what size lathe you get, one day you may need to make something bigger than it's capability.

Neil