Pm1236 Change Gear Dimensions Question

[ih8beingold]

My lathe appears to use the same gears as the PM1236. I am missing the 22 and 26 tooth threading gears for imperial threading. I need to know the dimensions (blank diameter, pitch etc) so I can attempt to make replacements. If somebody has those dimensions for the 22 and 26 tooth gears I would REALLY REALLY appreciate it if you could help me out. Thanks in advance.

 

[T Bredehoft]

You can figure the diameter, measure an existing gear, for instance, 18 pitch. Measure the diameter exactly, multiply by 3.1416, divide by 18. Multiply that by 22 and 26, divide each of them by 3.1416 to get their diameters.

If you don't have the equipment to make gears, then yes, you need gears.

 

[ih8beingold]

Thanks for the formula. I have a 24 and a 48. I measured both and and found a difference between the two. i then divided that number by 24 to find how much the gear grew for each additional tooth count from 24. Then I added that number x2 to 24 to find the diameter of a 26 and for the 22 i subtracted from 24. Clear? lol
My 24 tooth measured 32.15 mm
My 48 measured 62.34 mm
The difference between the two is 30.19 mm
30.19 divided by 24 is 1.25792
So every increase or decrease by one tooth would change the outer dimension by 1.25792 mm by my math. Probably wrong.
I'll try your formula T Bredehoft when my brain cools down . Thankyou
I'm going to take a try at fly cutting them on the mill.