10-02-2023, 05:56 PM
(This post was last modified: 10-02-2023, 06:05 PM by Pete O.
Edit Reason: extra info
)
Here's a gear pitch calculator that will help you determine what DP your gears are https://evolventdesign.com/pages/blank-calc you'll need to work backwards with that one i.e. guess what your DP probably is (I'd start with 12 just from the photo) and see if the resulting diameter matches the diameter of your gear. Then you can search for a suitable gear or someone to make one (or make them yourself, after all that's one of the 'F' bits in MWFF).
If I may be so brave as to disagree with Willie, on a simple gear train it doesn't matter how many idlers there are- one tooth moves one tooth all the way through the gear train so a 10-tooth drive gear will drive a 100-tooth driven gear at a 1:10 ratio no matter how many idlers are used to take up the distance between them, odd numbers of idlers reverse the rotation and even numbers correct it. (When I was 15 I had an exam question that showed a gear train with about 5 idlers, gave the input RPM and asked the final RPM, I spent ages figuring out every ratio across the train to come up with the final RPM- which was the same as the input RPM with the same gear size! Live and learn.) Different with compound gears like the drive gear at the top of your photo, two gears of different sizes on the same spindle alters the RPM.
Edit: re-read your post and saw the dimensions; your gears are indeed 12DP. Pressure angle is the other parameter but I've been informed (rightly or wrongly?) it is not critical to match it in something as simple as a manual lathe change gear train. To reduce your driven speed, you need a larger driven gear by a factor of whatever speed reduction you want, and an idler of suitable diameter to take up the space between driver and driven.
If I may be so brave as to disagree with Willie, on a simple gear train it doesn't matter how many idlers there are- one tooth moves one tooth all the way through the gear train so a 10-tooth drive gear will drive a 100-tooth driven gear at a 1:10 ratio no matter how many idlers are used to take up the distance between them, odd numbers of idlers reverse the rotation and even numbers correct it. (When I was 15 I had an exam question that showed a gear train with about 5 idlers, gave the input RPM and asked the final RPM, I spent ages figuring out every ratio across the train to come up with the final RPM- which was the same as the input RPM with the same gear size! Live and learn.) Different with compound gears like the drive gear at the top of your photo, two gears of different sizes on the same spindle alters the RPM.
Edit: re-read your post and saw the dimensions; your gears are indeed 12DP. Pressure angle is the other parameter but I've been informed (rightly or wrongly?) it is not critical to match it in something as simple as a manual lathe change gear train. To reduce your driven speed, you need a larger driven gear by a factor of whatever speed reduction you want, and an idler of suitable diameter to take up the space between driver and driven.
Lathe (n); a machine tool used in the production of milling machine components.
Milling Machine (n); a machine tool used in the production of lathe components.
Milling Machine (n); a machine tool used in the production of lathe components.