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| Metric threds |
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| chipenter:
I have a 9" South Bend the with a modified Clausing gear box fitted , I would like to cut metric theads the fly in the ointment it the banjo has a fixed spindle for the idler gear , 24 teeth on the tumbler 96 teeth on the idler and 24 teeth on the 8 tpi lead screw , the banjo pivots to the tumbler I can change the idler gear but nothing works , I can cut new gears but they have to add up to 120 at 18 DP , help please . |
| chipenter:
took the gears off to mesure properly its 16dp not 18 as I first said , if I use 20dp gears I can fit a 127/100 with a 40 tooth gear on the lead screw , just have to make a spindle and buy a 127 gear , still don't know what gear on the tumbler gears to fit or the formular to work it out . |
| chipenter:
Cracked it the internet provided the answer , 32 gear on tumbler 127/100 and 40 on the lead screw gives 12.7 tpi , that gives me 2 mm pitch lead screw , from the set of Myford gears I am missing 32 and 127 so this mod will cost less that 50 quid . |
| chipenter:
Just orded 127 and 32 change gears from RDG special offer both gears came to a total of £20 :jaw:. |
| AdeV:
TBH, this is exactly why I bought lathe with a gearbox.... the thought of having to deal with change wheels put me right off, maths having never been my strongest subject. When I discovered that my 'box would do metric AND imperial, well, I was a very happy bunny indeed... I've never really got to grips with how changewheels work exactly. OK, I understand the basic principle, but how do you get the different sized gears to mesh properly, and why is a "tumble reverse" so called? Is that the same as the "tumbler" you mention in one of your posts above? |
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