Thread: Sieg C6 lathe new threading capabilities

Ian,

The accuracy that can be obtained with the supplied gear set on the C6 when cutting imperial threads is within 0.006mm over a thread length of 1", and sometimes much better.
I doubt that I would ever need to be more accurate than that with the type of work I do on the lathe.

Change gear chart for these threads can be found here https://www.woodworkforums.com/f65/si...ml#post1715312

Andrew.

Hi Andrew,
thanx for your prompt reply. Wish I had known of your work BEFORE I spent so much time on the C6 gearing. Have you actually tried them all for fit on the lathe? With some of my unsatisfactory combinations they would not physically fit.
Talk about rediscovering the wheel!
Ian

Hi Ian,

I can't say that I have tried them all for fit (and some of the large pitch threads may strain the leadscrew).
However, I was mindful that many variations of each gear combination would not work due to cluster interference and I took some time to select each combination that was likely to work.

I will leave it to others to final check each combination(as they need them. I generated the chart more for my practical use as I was unhappy with the inaccuracies and missing TPIs on the standard Sieg chart, and I needed to cut several imperial threads of different TPIs.

Andrew

Hi Andrew,

my title says it all. You must have engineering or math qualifications to work out all those double reduction, compound and a couple of simple gearing combos?? I have checked the math of every combo in your chart. They are all very accurate.

How can we meet? Maybe business to discuss.

Ian

Originally Posted by Ian J. Hansen

...which produce a total of 51 threads on Sieg's C6 lathe.
The Sieg factory General Manager doubts whether anyone would purchase an accessory set of between 7 and 11 new gears, to add to the 16 supplied with the lathe in Oz.

He's probably right. Here we are more likely to make the gears ourselves.

Michael

Hi Michael,

are you able to cut gears here in Oz? Do you know anybody who does?

Ian

A number of us cut gears.
If you are wanting commercial quantities then that is not on but for one off's it's not terribly difficult

Michael

Hi Michael,
thanx for that. I am presently trying out all the combos of C6 gears that Andrew has generated. Hopefully I won't need extra gears cut.

Andrew generated a lot of double reduction combos, and it will take me a while to go through them all.

Ian

Guys,

have begun testing Andrew's gear combinations. The first three tried (0.25mm, 0.45mm and 0.75mm) do NOT fit the banjo of the C6.

Andrew, could you give me alternatives for those?

Also, for some reason, 0.3mm is missing from your chart. Could you also generate combos for 5.5mm, and 11.5 tpi and 60 tpi??

Thank you so much. The computer gives a good place to start. Ian.

Ian,

For 0.3mm pitch, try gears 66, 52, 70, 30 and 90 in that order from spindle to leadscrew (pattern Y)
For 60TPI, try gears 42, 33, 90, 40 and 66 in that order from spindle to leadscrew (pattern Y)

11.5TPI has no very close combinations, but I will look for the closest I can find.
5.5mm pitch has several exact combinations, but none appear to be usable due to cluster interference, and also the leadscrew and gears will be heavily loaded as the leadscrew will be turning nearly 3 times the speed of the spindle. Probably not a wise setup.

I will look into the combinations that will not fit the banjo.

Andrew

Ian,

For 11.5TPI, try gears 80, 70, 66, 52 and 25 in that order from spindle to leadscrew (pattern Y). This will have an error of about 0.03mm over a 1" length, which is just over 1 thousandth of an inch. This should not be a problem for most purposes.

Andrew.

Ian,

Finally, try these combinations:

For 0.25mm pitch, try gears 60, 33, 66, 30 and 80 in that order from spindle to leadscrew (pattern Y)
For 0.45mm pitch, try gears 40, 30, 70, 42 and 80 in that order from spindle to leadscrew (pattern Y)
For 0.75mm pitch, try gears 40, 30 and 80 in that order from spindle to leadscrew (pattern X) (simple gearing)

These combinations should shorten the required length on the banjo.

Good Luck...

Andrew

Hi Andrew,
thank you for all your trouble. I will try those combos.

This morning - these don't fit - 3.5mm, 4.0mm, 5.0mm. But 4.4 was okay.

TPI - these don't fit - 6, 7, 8, 9, 10, 11, 12, 13. But 14, 16 are okay.

Our Englander cousins tell me there is a rule for fit on the C6 - I'll send it in my next message after I look it up again.

Thanx again. Ian

Ian,

Just as a note that may be helpful, the first, third and fifth gears can be placed in any order, and the second and forth gears can be placed in either order, and this will not change the final gearing of the leadscrew.

Therefore, for example, 66, 52, 70, 30 and 90 can be changed to 90, 30, 66, 52 and 70 to see if the fit is better etc.

This may help in finding workable combinations.

Andrew