Hi Tristan,

Are you sure you are looking at threading? To me, mm/revolution sounds like you are looking at the feed chart.

Thor

Hi the plate you have shown is the lathe feed chart.

In this video there should be above this at 1.03 minutes

shows the listings for pitch. TPI ,module and DP.

https://www.youtube.com/watch?v=d3km1zmAasY
John

Hi Tristan,

The Warco 1322 with 32-85-100 gears are the setup used for metric feeds. It should be possible to remove those gears and replace them with others. The 42-127-120-42 combination of gears you give in your first post is for metric threading, other gears are needed for imperial threading as given in the manual Jason linked to. You should have a collection of change-gears for the lathe.

Thor

I suggest looking at this Grizzly manual for their G9036 lathe which I think is the same as yours but as usual Grizzly have far better manuals than seem to be supplied in the UK.

Martin C

Tristan, just a quick warning that there might be slight differences between the Grizzly and Warco manuals, though the lathe is essentially the same.
I think that the Grizzly, being for the American market, has an 8tpi leadscrew, and your Warco might well have a 2mm one; it may, or may not, affect the use of the thread cutting indicator.

I'd have a word with Warco and see what spares they can supply in the way of change gears.
If it's of any help in your search, my own Warco GH1330 came with a all the eatra gears etc packed in a red metal toolbox.

Bill

Does the school have any 3D printers? You could print some of the missing gears and provided you don't get too greedy with depth of cut they will do to cut some threads for yourself as well as showing the students.

Most CAD packages have a gear drawing function so should be easy enough to produce a file to print, thickness and bore can be measured from the other gears as well as using them to calculate the MOD size of the teeth.

I'd guess it was listed as such to act as a spacer.

Tristan, it's worth looking at your chart and thinking carefully about what's physically going on, because there's often different ways of doing something when it comes to the change gears. My lathe for example lists a specific setup for most metric pitches, one of the gears for which I don't have (my lathe also came from a school and arrived without the other changewheels…some kind of vortex, perhaps). However, close inspection reveals the "missing" gear is just an idler, so can be replaced with any gear that can be made to fit.

It's also worth figuring out what the calculation is to derive the thread pitch, as once you have that you can then work backwards and invent your own change wheel combinations.

I would not (but a school might) buy a set such as shown. I would buy only the tool post and, say, three tool holders, initially. I bought a full set when I bought mine and have regretted it🙂 .

You give no indication of your locality/area. Arceurotrade, near Leicester, are a very much favoured (by the forum) supplier for all sorts of machinery and accessories. Ian is a very helpful and knowledgeable person to speak to. Likely better prices than some other suppliers for the same or similar items, as well.

You,ve (clearly?) not looked at the Arceuro offerings? Tool post separate, or with 3 tool holders.🙂🙂

The school has a mill. Both gears, and extra tool holders, should not be difficult to make? It’s what I did.

Reverting to the original query.

Since the lathe appears to have a gearbox in the drive between thye spindle and the Leadscrew, fewer changewheels will be required to cover a range of threads, or feed rates.

Is the 127 – 120 gear a compound one?

If so it is intended as an Idler to provide an easy means of changing to screwcutting an Imperal thread on a lathe with a Metric Leadscrew, or vice versa.

Assuming that your machine has a Leadscrew with a Mteric pitch, using the gear as a simple Idler will allow you to produce a thread with a Metric pitch.

If the drive is taken to the 127 T side of the gear and onwards via the 120T section, that should allow an Imperial thread to be cut.

The pitch of the thread can be arranged by the settings of the 2 knobs and 2 levers on the lower part of the control panel, (As by now you have learned from the Warco and Grizzly manuals. )My own lathe, not a Warco GH1322, has a 3 mm pitch Leadscrew, and uses this method, between the spindle and the gearbox.

Because it has a gearbox giving a large number of ratios, only two change gears are required to cut most of the standard Metric thread pitches, (0.25 to 7.5 mm pitch ) and the 127 / 120 Idler allows an even greater variety of Imperial threads to be cut. (From 4 tpi to 112 tpi with just one change wheel )

By suitable arrangement of the knobs and levers the GH1322 will provide an even wider range of threads, and feed rates to be produced.

What you are doing is setting up a suitable ratio between the Spindle and the Leadscrew to move the Saddle a given distance for each revolution of the spindle.

So, IF the lathe had a 3 mm pitch Leadscrew, and you wish to cut a 1.5 mm pitch thread, you would set a ratio of 1:2 between the spindle and the Leadscrew. In this way the Saddle would rotate more slowly than the spindle., and move 1.5 mm for each revolution of the spindle .

You would do well to buy and read Martin Cleeve's booik, No 3 in the Workshop Practice Series, "Screwcutting in the :Lathe". Another good book, on the subject is Brian Wood's "Gearing of Lathes for Scxrewcutting"

If you are new to using a lathe, it would be worth buying some of the books available on using a lath, to learn the basics..

Suitable authors would include, Former editors and the current editor of Model Engineers Workshop, such as Stan Bray, Harold Hall and Neil Wyatt. L H Sparey "The Amateurs Lathe" and Ian Bradley "The Amateurs Workshop" although older, will provide some enlightenment.

When you are setting up a feed rate for turning, you are effectively setting up the lathe to cut a thread with a fine pitch, but using a cutting tool which should provide a smoother finish. The object is still for the Saddle to advance at a rate related to the rotation of the spindle. So a feed rate of 0.05 mm per rev would requires a reduction ratio of 60:1 between the spindle and the 3 mm pitch Leadscrew..

One of the best ways to learn, is to get some mild steel, grind suitable tools, set them to centre height, and start cutting metal. You will make mistakes, but you will learn from them. (We have all trodden that path! )

Howard