Thread gears for Warco GH-1322 lathe.

[Tristan LuscombeParticipant @tristanluscombe46103]

Hello everyone,

 

I had such fantastic responses to my thread on the Senior Milling Machine that naturally my first thought was to ask here again with my next quandry.

Our DT department has had a Warco GH-1322 lathe (affectionately known as 'Big Green' ) in the department for as long as anyone can remember. Legend has it that it came from another school, but it has never been hooked up to the power let alone used.

Anyway, being a good 50 years newer than the next youngest lathe I decided it would be an idea to get our service partner to wire it to the three phase when they were doing their annual check last week and so I've spent the last couple of days playing with it. My assumption (I know, I know) was that as a 'new' lathe in the UK it would naturally come with Metric threading gears, but my attempt to follow the chart on the gearbox to produce threads of a given pitch failed. I took the gear cover off and checked and instead of the 42-127-120-42 gear series that I believe it ought to have for Metric threads it has 32-85-100. According to the chart this appears to be for mm/r instead. This is a notation I haven't encountered before. Does anyone know what this is for, if there is a way to get this to cut 'usual' threads like M10x1.5 or if there is a way to still get alternative change gears for this lathe?

I'm very aware that this is stuff I 'should' know, but my experience with lathes was from a long long time ago and it was using them, not setting them up, so I apologise for any exasperated eye-rolling my cluelessness may be causing.

 

Thanks folks!

Edited By Tristan Luscombe on 04/05/2022 09:41:59

[Tristan LuscombeParticipant @tristanluscombe46103]

[Thor 🇳🇴Participant @thor]

Hi Tristan,

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

Thor

[JasonBModerator @jasonb]

That chart is for carriage and cross slide feed rates not gear cutting. There should be another chart for screw cutting

You want to be looking at the top third of the chart shown on page 13 (12 actual) of the manual for metric and imperial threads, Module and DP in the middle are seldom used and the feeds you show are at the bottom.

Edited By JasonB on 04/05/2022 10:09:56

[John PParticipant @johnp77052]

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

[Tristan LuscombeParticipant @tristanluscombe46103]

Hi Thor,

It's entirely possible. The only reason I was looking at that chart was that it's the only one that has the same three gears that I found within the gearbox. The other charts (Pitch, TPI, Module and DP) all have four gears of varying sizes. For reference, I was looking at the gears at the far left of the headstock, the only ones readily accessible without dismantling the whole thing as far as I can see.
(yes, I know it needs cleaning, I haven't got that far yet! 😀 )

[Thor 🇳🇴Participant @thor]

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

[Tristan LuscombeParticipant @tristanluscombe46103]

Hello everyone,

I see quite a few people responded while I was replying to Thor, thank you everyone!

Sadly it doesn't look as though we got any more gears with this lathe, only a couple of faceplates so I'll have to see if I can find a Metric set online and hope the school will splash out on them as I really wanted to show the students screwcutting on the lathe as an alternative to the tap and die sets they usually use.

Thanks again to everyone for your help, at least I wasn't missing something obvious.

Cheers!

Tristan.

[Martin ConnellyParticipant @martinconnelly55370]

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 LuscombeParticipant @tristanluscombe46103]

Thanks Martin, that manual is orders of magnitude better than the manual from Warco! Brilliant!

[peak4Participant @peak4]

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

[Tristan LuscombeParticipant @tristanluscombe46103]

Thanks Bill, I'll be sure to keep my eyes peeled for any anomalies between the two.

For some reason I vaguely had the notion that Warco were no longer trading in the UK, but I did a search and found them and I've sent them a query about accessories and spares. No-one on the staff was here at the time this lathe arrived, so no-one knows if it came with anything else. I suspect I would have clocked a spare set of gears laying around in the time I've been here. Still, never say never, I do occasionally unearth treasurein the depths of the stock room!

[JasonBModerator @jasonb]

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.

[DC31kParticipant @dc31k]

Posted by Thor 🇳🇴 on 04/05/2022 10:33:23:

The 42-127-120-42 combination of gears you give in your first post is for metric threading…

If the standard chart on the machine gives the feeds in mm per revolution, that suggests to me that it a native metric machine.

Why would you need a 127 gear to do metric threads on a metric machine?

Looking in the manual that Jason linked to, the 127 gear is shown behind the 120 gear when metric threading, so is not in mesh with anything. In addition, the 120 gear is only an idler between the two 42t gears, so the ratio is 1:1.

So, if the OP only wants to cut metric threads, he absolutely will not need the four gears above. Depending on the physical layout of the lathe and adjustment possible on the banjo, it may be possible to buy just a single 32t gear and use the 100t as an idler. If not, a pair of gears of identical but larger tooth count would do.

Edit: look for a piece of software called GearDXF if you want to go the 3DP route.

Edited By DC31k on 04/05/2022 13:15:59

[CalumParticipant @calumgalleitch87969]

Posted by DC31k on 04/05/2022 13:14:55:

Why would you need a 127 gear to do metric threads on a metric machine?

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.

[Tristan LuscombeParticipant @tristanluscombe46103]

What an interesting thought, we do have a couple of 3d printers, I never imagined you could print a gear that would be robust enough to function in a lathe! Ooooh… I will have to look in to that!

Thank you DC31K, it hadn't occurred to me that not all those gears would be engaged, you make an excellent point!

[Tristan LuscombeParticipant @tristanluscombe46103]

Another thought occurs to me, does anyone have any recommendations for a quick change toolpost that might be suitable for this lathe? I intend to upgrade all the department lathes to them eventually but this would be a good place to start.

Thanks again for everyone's input, by the way

[peak4Participant @peak4]

Posted by Tristan Luscombe on 04/05/2022 14:00:07:

Another thought occurs to me, does anyone have any recommendations for a quick change toolpost that might be suitable for this lathe? I intend to upgrade all the department lathes to them eventually but this would be a good place to start.

Thanks again for everyone's input, by the way

Mine has the Warco version of the 250-200, which is the piston locking style of dovetail toolpost. (top right on the link. https://www.warco.co.uk/2926-quick-change-tool-posts
It works well enough and has the advantage, over the Dickson type, that extra tool holders are easy enough to make.

There is a similar one available now which uses a wedge lock on the dovetail, rather than a piston. I'm guessing it's a copy of the Aloris one.

p.s. you may find that Toolco's closing down sale will include the gears you need.
http://www.toolco.co.uk/

Bill

Edited By peak4 on 04/05/2022 14:47:00

[Tristan LuscombeParticipant @tristanluscombe46103]

Fantastic, thanks Bill!

[DC31kParticipant @dc31k]

The spirit of John Stevenson came upon me and reminded me what he did with his Bantam: he removed the change gears altogether and replaced with a toothed belt and pulleys.

On the machine in this thread, you would just have to measure the pulley centres and choose a combination of belt size and tooth count to suit that distance.

[not done it yetParticipant @notdoneityet]

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.

[Tony Pratt 1Participant @tonypratt1]

3 holders are nowhere near enough.

Tony

[not done it yetParticipant @notdoneityet]

Posted by Tony Pratt 1 on 04/05/2022 21:13:17:

3 holders are nowhere near enough.

Tony

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.

[Tristan LuscombeParticipant @tristanluscombe46103]

Good morning folks,

 

More fabulous advice on here, thank you all! I will check out Toolco and ArcEuro today. The idea of a toothed belt instead of gears is fascinating, I will definitely read up on that.

We do indeed have a Senior M1 mill and since its service last week where it had some links removed from the drive belt it now cuts metal!

I can't begin to say how much I appreciate the help and knowledge you're all sharing with me, your input will be instrumental in getting this department back up to where it should be.

 

ETA: Incidentally, I'm in Ickenham, Middlesex.

Edited By Tristan Luscombe on 05/05/2022 08:44:46

[Howard LewisParticipant @howardlewis46836]

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

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