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Metric Threading on 918

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agfrvf

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#1
Trying to thread Metric 1.25 thread. Since i cant find a threading suplement for the 918 i am using the 10F as a refference. To the best i can figure
A(sB 64F)
B(24B 52F)
Screw 44B

Can anyone confirm
 
Last edited:

wa5cab

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#2
Although I haven't run the numbers and can't say for certain what pitch that would produce, it isn't what is shown on the threading table of metric threads for the 9" and 10" up through 10D. For the table (and other information), go to DOWNLOADS and download Part 7 of the original version of the MOLO.

Atlas MOLO 1937-V1 Part 7.pdf 2016-01-15

http://www.hobby-machinist.com/resources/atlas-molo-1937-v1-part-7-pdf.2812/


On PDF fIle page 42 of 64 (printed page # 134) you will find Table IV -- GEAR SETUPS FOR METRIC THREADS.
 

agfrvf

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#3
Yea, calculations were backwards should have multiplyed the 48t by 2 instead of dividing to compensate for 16/32 tumbler.
Thank you.

Just need to make a spacer bushing, I dont want to turn down my 20t.
 

wa5cab

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#4
Well, not really. You shouldn't have either multiplied or divided by 2 as the 9" and early 10" don't have a Tumbler and the Tumbler gear on the early 12" is a simple 32T, not a compound gear.

Also, you do not need to machine the teeth off of the 20T gear. Any place where one of the charts shows "20S" you just use a 20T gear as a spacer. It's teeth do not engage anything. If you happen to have an extra spacer, you can use it if you wish.
 
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