Sieg C6 Lathe new threading possibilities

Thanks John - anything for a simpler life. Please give details of the 4mm combo.

I did some new threads today. Figured why the hell not if I'm going to all the trouble. They are 0.25mm, 0.3mm, 0.45mm and 0.75mm. This now completes all standard metric threads in common use today. In addition, the C6 will cut two miniature threads - the 40UNM and 80UNM if interested. That's 254 and 127 tpi. Incredible.

John I have completed my C6 gear charts, added new threads and found one transcription error.

May I have your email address to send it to you? Thanks. Ian

Ian, you mentioned earlier that you had identified some additional gears that would be useful - do you have the 'tooth counts' (I don't know the technical expression!) for these wheels?

Steve

Steve,

Tooth count is very technical - go for it.

Ian,

Email addy is john [at] stevenson-engineers.co.uk

Not much point in doing a PM to keep it secret, it's all over the web anyway.

Hi Steve/John,

supplementary gears for C6 (not available yet) are 28, 32, 36, 48, 54, 56, 58, 64, 68, 72, 96.

Those 11 gears combined with the 16 supplied with the machine (in Australia) give a total of 47 threads. This includes 5 UNM miniatures, which are 0.4, 0.8, 1.0, 1.2 and 1.4mm. I have also spread the extent of the threads from 0.1mm to 5.0mm, and from 257 tpi up to 8 tpi, but the new gears above will allow 7 and I think 6 tpi as well.

Because I have not received supplementary gears yet the 6 and 7 tpi are theoretical, but note that the 5mm thread which I have used is 5tpi. So they turn the Sieg C6 into a very useful machine. I remind users that some of my calculations using the existing gear set are very close to desirable specifications, but with the supplementary set will all be "perfect".

John with your email address, I get the latter part from @ but not the part before.

I will email final gear cards to you asap when I comprehend how to write "addy is john". Sorry to be so dumb.

By using the word addy, John means address.

so his address is john [at] stevenson-engineers.co.uk

Ketan at ARC

Hi Ketan, thank you for showing me.

You must be the Ketan at Arc Euro?

John will have the new, revised chart in 3 minutes.

Yes, that's me - Ketan at Arc Euro.

Are they going to send the gears to you directly or are they coming in Stevens' next consignment?

Ketan at ARC

Hi Guys,

have held off adding anything to the forum until now. Sieg has informed me they are proceeding to have component suppliers make the accessory gear set. C6 owners should have access through their preferred supplier, but I can't yet say when. I do not yet know if a metallic thread chart will be available.

Re. the gear charts. With my own calculations using the existing gear set, my machine can cut about 47 threads in common use today. But with the additional gears, and Sieg's engineer's spreadsheet, I will be able to cut no less than 51, all quite accurately.

As soon as I can I will post a new chart with the FINAL thread cutting set ups. No doubt the engineer will revise some of my calculations. Not many I hope.

Guys,

you're not going to believe this but - after all the calculating I've done - on the Sieg C6 gearing, I found a person on the web yesterday who had already programmed a computer to do the same thing! His combos are a mix of compound and double reduction, with 2 simple combos. I have checked all the math, and they are all very accurate (like 0.001 mm to 0.006mm). Now I am going to make sure they all physically fit on the machine. You would be aware that computer generated combinations do not take into account physical limitations of the banjo.

Hope to provide you with a FINAL chart soon. By the way, these calculations are for the existing gear set. No additional gears needed!!

Ian

Ian,

Worth noting that some manufacturers ship different sets of change gears

e.g my Axminster C6B didnt come with a 55 tooth gear.

The standard set in mine was

25,30,33,40,42,50,52,60,66,70,75,80,80,90,90

Ontop of that I made the following

25,63,81,84,100,100

This allows me to cut a bewildering array of threads, right down to 0.05mm pitch for fine feed work (although you do have to have the door open as the 100 tooth gear fouls the door when in 0.05mm pitch.

I have a computer program that you provide with the list of changegears, some dimensional information on diameter of spacers, size of banjo and it will basically give you the gear combo with the minimum error for every metric pitch from 0.05 to 3.0mm in 0.05mm increments and every imperial pitch from 8 to 80 TPI (although actually these can be expanded if need be). This program helped me alot when defining my new threading charts once I had made my extra gears, unfortunately to adjust the values requires a certain knowledge of C++ programming and the ability to recompile programs. However if you give me your list of change gears I dont mind sending you the output for you to verify your combinations.

John,

I think you have a couple of the columns the wrong way round.

Graham

Ian,

Heres some proposed mods. Not guaranteeing they will fit on the banjo, but worth checking. The software that I used to generate them does take into account geospacial limitations, but may not get it right in every case. Ive just used your standard set of gears taken from your tables.

Note in the gear listing below a : means on the same shaft. a - means teeth are meshing. The first 40 is the spindle shaft gear and the last gear is the leadscrew gear.

Heres some more metric threads and some corrections

0.2mm - 40-70:30-90:42-80 - 0% error
0.25mm - 40-75:50-80:30-80 - 0% error
0.3mm - 40-70:40-80:42-80 - 0% error
0.35mm - 40-80:70-75:30-80 - 0% error
0.45mm - 40-70:60-80:42-80 - 0% error
0.55mm - 40-80:66-60:40-80 - 0% error
0.65mm - 40-80:52-66-80 - 0% error
0.75mm - 40-80:75-60:42-70 - 0% error
0.9mm - 40-70:75-50:42-80 - 0% error
1.1mm - 40-80:66-80-60 - 0% error
1.2mm - 40-80:60-66-50 - 0% error
1.3mm - 40-50:52-80:75-60 - 0% error
1.4mm - 40-80:70-66-50 - 0% error
1.6mm - 40-66-80-50 - 0% error
1.8mm - 40-66-80:90-50 - 0% error
2.2mm - 40-80:66-80-30 - 0% error
2.25mm - 40-66-80:90-40 - 0% error
2.4mm - 40-80:60-80-25 - 0% error
2.8mm - 40-80:70-80-25 - 0% error
3.2mm - 40-66-80-25 - 0% error
3.5mm - 40-80-52:75-33 - 0.099% error. Yours has 2% error
3.6mm - 40-66-80:90-25 - 0% error
4.0mm - 40-80-50:75-30 - 0% error. I Think there is an error in your table for this one.
4.4mm - 40-90-40:66-30 - 0% error
4.5mm - 40-90-50:70-25 - 0.44% error. Best I can do. I Think there is an error in your table for this one.
4.8mm - 40-80-60:90-25 - 0% error

Imperial threads

8TPI - 40-70-80-25 - 0.78% error. Yours had -1.7% error
10TPI - 40-66-60:80-42 - 0.0125% error. Yours had 0.06%
11TPI - 40-75-42:80-66 - 0.0125% error. Yours had 0.06%

12TPI - 40-66:70-80-40 - 0.2147% error. I would check yours. I think the gears train may be too short to mesh with the spindle.
13TPI - 40-80-30:66-90 - 0.0875% error. Yours had 1.7% error
15TPI - 40-50-90:80-42 - 0.0125% error
16TPI - 40-66-42:75-90 - 0.0125% error. Yours had -0.78%
18TPI - 40-80-60:70-66 - 0.2147% error. Yours had 0.79% error
20TPI - 40-75:50-80-42 - 0.0125% error. Yours had 0.06% error
22TPI - 40-66:40-80-42 - 0.0125% error. Yours had 0.06% error
24TPI - 40-66-42:50-90 - 0.0125% error. Yours had -1.22% error
26TPI - 40-52:50-90:80-70 - 0.0125% error. Yours had -0.08% error
28TPI - 40-70:75-42:40-90 - 0.0125% error. Yours had -9.2% error
30TPI - 40-90:80-70:50-60 - 0.0125% error. Yours had 0.74% error
32TPI - 40-70:75-60:50-90 - 0.0125% error. Yours had 0.17% error
36TPI - 40-52:50-90:66-80 - 0.0606% error. Yours had 0.22% error
40TPI - 40-52-70:50-90 - 0.0125% error. Yours had 0.06% error
44TPI - 40-90:75-70:40-66 - 0.0125% error. Yours had 0.06% error
48TPI - 40-90:80-42:25-80 - 0.0125% error. I think there is an error in yours
56TPI - 40-60:66-80:33-80 - 0.0394% error
60TPI - 40-90:80-60:25-70 - 0.0125% error
64TPI - 40-90:75-60:25-70 - 0.0125% error
72TPI - 40-80:66-52:25-90 - 0.0606% error
80TPI - 40-90:80-70:25-80 - 0.0125% error

Hope this is of some use, maybe get some of your errors down on the imperial threads and fill in some unusual blanks.

Graham

Edited By Graham Wharton on 29/01/2014 22:43:37

Forgot to say,

I was assuming that the limitations on my C6B are the same as yours, i.e the banjo is the same size etc.

The limitations/assumptions i have in place for the software to give me those recommendations are

• Leadscrew pitch is 2mm
• Fixed gear on spindle is 40 teeth
• Mod 1 gears
• Distance from spindle axis to leadscrew axis is 174mm
• The distance from the leadscrew axis to the axis of the bottom gear shaft on the banjo cannot be less than 80mm
• The distance from the leadscrew axis to the axis of the top gear shaft on the banjo must be less than 150mm
• The clearance between two gears positioned on adjacent shafts, but not meshing should be at least 6mm. (when measured using pitch diameter.... The actual gap between teeth will be smaller than 6)
• The diameter of a spacer is 22mm
• The first gear (the one that meshes with the spindle gear) must have more than 50 teeth or the banjo will foul on the spindle.
• When there are two gears on the 1st shaft (top of the banjo) the gear meshing with the spindle must have a diameter 6mm larger than the gear next to it on the shaft, otherwise the gear will foul with the spindle.
• There are no checks made that the gears do not foul on the door.

If anyone wants the software, and can handle the code hacking, please let me know and I will provide a copy.

Graham

Edited By Graham Wharton on 29/01/2014 22:38:09

Edited By Graham Wharton on 29/01/2014 22:39:21

Sorry to nit pick but 19 and 27 are a must for pipe threads

they often list 11 1/2 as well but to be honest in all my time I have never come across it.

The threads I posted above were just additions where Ian was missing a thread, or where I could improve on his accuracy.

I can improve on the accuracy of the 27TPI thread after relooking

27TPI - 40-52:50-90:66-60- - 0.06% error

And while were at it, Ive just modded my software to include half TPI threads

11-1/2TPI - 40-66:60-80-33 = 11.525TPI = 0.2191% error (although this configuration is close on the "When there are two gears on the 1st shaft (top of the banjo) the gear meshing with the spindle must have a diameter 6mm larger than the gear next to it on the shaft, otherwise the gear will foul with the spindle." rule.)

Graham

Edited By Graham Wharton on 29/01/2014 23:08:19

Wow Graham, you've given me a lot to work on. I'll be seeing star ...er gears, in front of my eyes!

The computer program I told you about yesterday - well, of the first 15 combos I checked for fit and useability on the C6, 13 did not fit. The danger with computer generated stuff is that people don't check the fits before publishing.

Graham, my C6 does not have a 55 toothed gear either - they are the same as yours. I've written out so many charts little boo boos creep in and sit, waiting to be discovered!

Sieg has decided NOT to go ahead with manufacturing supplementary gears because of commercial reasons- like, not enough people will purchase them.

Thanx everyone for your input. Very much appreciated. Ian

Guys, the "rule" for the C6 -

Where there are 2 gears at the top of the banjo, the gear meshing with the spindle must have a diameter at least 6mm larger than the gear next to it otherwise the gear will foul the spindle.

Hope this helps in determining fit without messy hands!!!!!

Chaps

I've already done a program for a basic threading scenario

**LINK**

It's in TPI, think TPI, not mm

25 change wheels allowed

You can even state your max allowable error

Edited By Ady1 on 30/01/2014 02:16:51

Actually, I went back and looked at that rule, and looking at my machine, that makes no sense to me now as there is plenty of room as the banjo gear set does not mesh directly with the spindle, but with the intermediate gear that sits permanently engaged just below it.