Thread cutting on a Stanko 1A616

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ksor:

--- Quote from: RussellT on November 22, 2013, 03:22:08 AM ---Well you could save stock and make it easier to test a lot by putting a fine marker pen or a pencil in the tool post and cleaning off between trials, or if you stuck a piece of paper on a piece of stock you would have a record for each setting you tried.

Yes, please try and post a picture of the table.

Russell

--- End quote ---

Thx, what a bright idea :thumbup: :thumbup: :thumbup: for documenting !

I'll go over to the shop right away to do some test threadings ! :med: :smart:

ksor:
Now I did some test cutting, but I have some problems in finding out how much Deep to cut !

I found a formula saying:

Pitch * 0,8660

But it's way too Little, so I proceeded to the threads "look nice" - :doh: :doh: :doh:

You can see some details down on this site - Google translation to the right just under the menu line:

http://kelds.weebly.com/gevindskaeligring.html

RussellT:
Hi Ksor

I’ve had a look at the thread cutting chart on your website.

When you change from normal to coarse thread the thread pitch is 8 times as big.

As you go from I to IV the thread pitch doubles for each step.

Settings 1 to 6 provide pitch increases by factors of 1, 1.4, 1.6, 1.8, 1.9 and 2.4 in metric mode and pitch decreases by those factors in imperial mode. (The drive through this part of the gearbox must reverse in imperial mode.)

When you change from metric to imperial it applies a correction factor of 4.064.

All the other corrections are taken care of by change wheels and you appear to have the complete set.

So to take a metric thread as an example:

Let’s say metric,coarse, III, 4, changewheels 30:36

0.375 *8 *2*2*1.8*30/36

gives you a pitch of 18mm, which is what the chart says. 0.375 is a constant related to the pitch of the leadscrew and the basic gearing in the gearbox.

Let’s try another

Imperial, fine, II, 6 changewheels 30:36

0.375*4.064*2/1.8*30/36

gives you a pitch of 1.4111. Divide that into 25.4 and you get 18 threads per inch.

For module and diametral pitch the sums are exactly the same, but the numbers on the chart are different because of the need to bring in PI. For example to cut a worm to mate with a module 2 gear the settings are

metric,coarse, II, 3, changewheels 36:55

0.375 *8 *2*1.6*36/55

gives you a pitch of 6.28364

For module gears module = circular pitch /Pi

6.28364/PI = 2

You can do a similar calculation for diametral pitch but you need to bring in 25.4 as well as PI because you need to convert from inches to millimetres.

Russell

ksor:
>> Russell

:thumbup: :thumbup: :thumbup:

Thx for your time - I will study your post together with the tables and levers on the Stanko .. to see if I can get some knowledge out of it :loco: :loco:

But I thank you for your time involved ! :beer:

As you can see on my website I have managed to do some threading ... but I made BOTH the inside and the outside and THAT isn't so hard to do !

I think it's worse to make some threads witch shall fit with some factory made ones ... inside or outside ... so I think I'll challenge myself by making some of these types next.

:D

I'll give it a try one of the first days.

Ned Ludd:
Hi Ksor,
If the formula does not produce a deep enough thread,could it be that you need to go twice the dial reading. The reason is that the convention on a metric lathe is that the cross slide dial reads in diameter reduction not actual movement, so to get a specific depth you have to double the dial figure.
Ned

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