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[4]

[Wanted] Pt32k54nk1 54 Tooth Gear For Sb 9a

January Project of the Month [3]
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PaPa_Jack

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#1
Looking for a 54 tooth gear for my 9A. Need to cut some metric threads.

Thanks,

Jack
 

wa5cab

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#2
I don't have any of them in any case but are you sure that you need a 54T gear? The common conversion that yields "close enough" results is usually the 44T to 52T compound pair.
 

PaPa_Jack

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#3
I don't have any of them in any case but are you sure that you need a 54T gear? The common conversion that yields "close enough" results is usually the 44T to 52T compound pair.
I have an 80T and in conjunction with a 54, I can get the 1.5mm I need. I haven't figured out the combo you mention.
 

wa5cab

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#4
OK. If it will work for you, one gear is most likely cheaper than two.

44/52 is close enough to being a factor of 25.4 (the inch to mm conversion figure) to allow the cutting of some of the finer metric threads on some QCGB equipped lathes with the GB set to specific inch thread pitches. For example, if you replace the two 48T gears driving the GB on an Atlas 10" or 12" with a 52T and 44T compound gear, with the sliding gear OUT the machine still works for threads from 8 tpi to 120 tpi. Move the sliding gear IN so that it now meshes with the 42T gear and you can cut several metric threads using the gearbox settings. 60 tpi yields 1.0 mm, 48 yields 1.5 and 30 yields 2.0, and etc. The error is small enough to work for typical thread lengths. You couldn't use it to make a metric lead screw, though. You have to give up 4 tpi through 7.5 tpi (or undo the conversion). Whether that would work with a 9A or not I can't say. A lot of gearboxes apparently don't do 30 tpi.
 

4gsr

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#5
I was able to do it on my 9" SBL. Yeah, it does require a 54 tooth gear. My lathe was a 9"C before it was converted to a "A" lathe. Still have the loose change gears. And no, I will not part any of them. They come up often on eBay with all kinds of pricing. Another option is changing the stud gear by two teeth. Should yield the same results. Ken.
 
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