Re: Metric Transposing [1 Attachment]


john kling
 


Do the newer lathes that offer both metrics and american standards threads have essentially a 100/127  gear as part of the QC box or do they do it with step motors and electronics?


From: Davis Johnson
To: SOUTHBENDLATHE@...
Sent: Tuesday, December 10, 2013 5:47 PM
Subject: Re: [SOUTHBENDLATHE] RE: Metric Transposing [1 Attachment]

 
STUD LEFT
HAND
TUMBLER
THREAD PITCH IN MM
FEEDS IN MM
20 A 2.5
0.8532
2.2222
0.7584
2
0.6826
1.8182
0.6205
1.7391
0.5936
1.6667
0.5688
1.5385
0.5251
1.4286
0.4876
20 B 1.25
0.4266
1.1111
0.3792
1
0.3413
0.9091
0.3103
0.8696
0.2968
0.8333
0.2844
0.7692
0.2625
0.7143
0.2438
20 C 0.625
0.2133
0.5556
0.1896
0.5
0.1706
0.4545
0.1551
0.4348
0.1484
0.4167
0.1422
0.3846
0.1313
0.3571
0.1219
20 D 0.3125
0.1067
0.2778
0.0948
0.25
0.0853
0.2273
0.0776
0.2174
0.0742
0.2083
0.0711
0.1923
0.0656
0.1786
0.0609
20 E 0.1563
0.0533
0.1389
0.0474
0.125
0.0427
0.1136
0.0388
0.1087
0.0371
0.1042
0.0356
0.0962
0.0328
0.0893

Output from my gearbox chart calculator (attached). Note the 1st and 3rd pitch columns. 5mm and 4mm pitch require the 40 tooth stud gear. 1MM pitch takes care of probably 90% of my metric needs. That won't be true for everybody.

I've attached my gearbox chart calculator. It is in an HTML file. You will probably be asked if you want to enable javascript or active content or some such (exact wording depends on browser and/or mail client). You will need to say yes if you want to use it. To get the above chart: change box type to "singe tumbler", "compound in" to 127, "compound out" to 100, uncheck "threads per inch" and "feeds in thousandths", check "MM pitch" and "feeds in MM".

You can change the stud gear to any of the stud gears listed on the metric transposing chart to see what it looks like.

On 12/10/2013 5:03 PM, Jim B. wrote:
 
I just looked at a chart I have for the Workshop 9/10K with a 127/100 transposing gear.
With a 40T gear on the stud, and not changing that gear, and using the gearbox, with a 56 T gear, you can cut EXACTALY the following metric pitches
5, 4, 2.5,2, 1.25, 1, 0.625, 0.5 mm
So the only one metric pitch statement is not correct.
I use a change gear lathe for metric work so I do not know all the stud gears.
 
Attached is an Excel work sheet, put together by Guy Caldron (I may have misspelled his name) some years for the purpose of sorting out these issues.
 
Jim B.



Join SouthBendLathe@groups.io to automatically receive all group messages.