screwcutting

You need to set the knurdle pinion to line up with the rimshaft.

Failing that go back and re-read your post and see if you could answer it given the complete lack of information like model and some details.

You need to list the pitch or TPI of your leadscrew, all the changewheels you have, the number of teeth on the spindle gear and the ratios if there is a gearbox between the last changewheel and the leadscrew. Without this information it is not possible to do any calculations.

Les

To actually answer your question a bit more informatively the A and B probably refer to diagrams which you might not have noticed that show some additional gears.

for example this screwcuttign chart is for a Boxford and shows several diagrams to show the different set-ups.

Found this bit of the ARC site with diagrams but no reference to which is A & B. Nice idea Ketan but can you do some for other lathes please.

Here we are at last an article which I don't have time to read at the moment but don't see the diagrams - guess who wrote the article    

Edited By Bazyle on 27/08/2016 15:07:56

O K, you have all poked a bit of fun at 'Here again' but to help him, Bazyle turned up Neil Wyatt's article in his third reference.

​The wheels are identified as Mandrel A, meshed with the intermediate gear B; that is in turn coupled to wheel C which then drives wheel D on the lead screw.

Look at the photo in the article which shows the set up for a 1 mm pitch thread on a 16 tpi lead screw mini lathe, and how they are arranged to do that. Read the article too, it will tell you much

Brian

And when you've set the gears up, engage the carriage/ leadscrew drive, turn the chuck round by hand say 10 times ( more for a fine thread ) and measure how far the carriage has travelled and you'll be able to check it will cut the right pitch thread.

John

Don't be surprised at the op's reaction. I would have been inclined to react the same way. Ok. he never provided the vital info, but certain folk could simply said "give us more info " no need for sarcasm. Its little wonder why a lot of good posters have left this site.

The charts (which are stuck on the gearbox of new lathes) include diagrams clearly showing how the gears should be fitted to the banjo. The clue is that the diagram showing three gears applies to setups with three gears and the diagram with four gears appllies to setups using four gears.

I suspect Ketan only supplies the data for lathes he sells! - and that article looks very familiar

Neil

No true he never provided enough or even any usable information.

Now I'll help anyone out but why should I or anyone else bother to help anyone who's just too plain idle to even ask for help correctly. and as regards reaction the deleted post said it all.

It wasn't sarcasm but humour, OK perhaps not your type but coming back, saying sorry yes what I meant to say was etc would have got him far more results.

Hi John, It wasn't your post that I was referring to it was one of the others that was nothing more than impudence. And other than the impudent reply from another poster I dare say the OP would probably have come back with more info. Being a bricklayer i'm certainly thick skinned , but even I would have taken one of the posts as cheek, nothing less.

Cheers.

OK Raymond and to try to keep this post on track I'll send you a PM.

http://www.woodworkforums.com/f65/lathe-thread-cutting-change-gear-calculator-118398

This is a terrific little program for change gears.

Suggest you read any introductory text or website to grasp the basic concepts (ie Sparey) , do some of your own calcs to test your understanding then use the above program.

It will calculate all possible combinations within a user specified error band.

It will accept imperial or metric leads crew and calculate closest threads in either system.

You key in your leadscrew specs and list of changears.

Bill

It also allows key in of your gearbox ratios if you have one.

Hi Bill,
That sounds like a useful program but I could not get to the program via your link. I use a similar program called nthreadp.exe which is available hear. It does not have the take into account a gerbox so I have just made a a list of the effective pitches available. (Actual leadscrew pitch multiplied by the gearbox ratios.) I Have bought a selection of gears at various ME exhibitions (And bushed them or bored them to fit.) to supplement those supplied with my lathe. With these I can get very close to any thread I want to cut. These programs save a lot of time when the ratios required are not simple obvious ones. But as none of us have a crystal ball we cannot answer the OP's question with no information.

Les.

Looks like the chap who wrote it has killed his old website and is now distributing it as an app rather than a PC program.

Try here for the app download https://apkpure.com/pocket-lathe-gears/com.embarcadero.PocketLatheGears

I can vouch for the PC program but have never tried the app. Will have a play with google and see if I can find a PC download site

Bill

Cannot find a PC version - all sites I find refer back to a website that no longer exists

Edited By Bill Wood 2 on 29/08/2016 12:54:28

My favorite online change gear calculator is this one here

**LINK**

.

I have just put the App on my phone, but I don't hold-out too much hope

100 downloads, 7 reviews, average rating 2.3

... Will have a play tonight.

MichaelG.

OK,

I contacted the Lathegears author.

Download for PC available here

9dt553xj8vnwzyf/LGV1.2.exe?dl=0 >**LINK**

Why I think its so good ............

You can set a maximum error ie 0.3% and it will only calculate combinations inside that tolerance

You can include all gearbox ratios as well as all change gears

You can specify certain gears must stay in certain positions.

If no combination exists it will calculate the number of teeth required on the missing gear

Will calculate both metric and imperial threads for both metric and imperial lathes

Will output all results to a file on PC and you can then copy and paste or print or do further calcs in excel.

Bill