11-23-2017, 06:46 PM
Thanks Greg.
I sat down with a strong coffee and a calculator last night as I knew the 6/4 ratio would be the key to changing to 6mm pitch, but I couldn't mentally get my head around how to apply that practically.
In the end I worked out that if I either reduce the input change gear tooth count by 1/3, or increase the output gear teeth by 1/2 then all is good.
For example if the input gear on my current 4mm chart is 90, then it becomes 60.
Or if the output gear is 80 it becomes 120.
The good thing is I've only got the change gears that were fitted to the lathe, so am making the missing ones anyway. Blanks are roughed out to thickness and bored but only 2 are at finished diameter ready for cutting the teeth. If I make the decision to change to 6mm then I'll just cut the gears to suit that instead. I'd definitely be less inclined if I'd just finished cutting a full set to suit 4mm..
I can get 2m of quality 30x6mm for just over AUD$300 delivered (local stock). Not exactly cheap, but not outrageous.
A fair bit of image googling also turned up a image of the gear chart for a 6TPI leadscrew. If I could just find an image of the 6mm chart I'd be set :)
Steve
I sat down with a strong coffee and a calculator last night as I knew the 6/4 ratio would be the key to changing to 6mm pitch, but I couldn't mentally get my head around how to apply that practically.
In the end I worked out that if I either reduce the input change gear tooth count by 1/3, or increase the output gear teeth by 1/2 then all is good.
For example if the input gear on my current 4mm chart is 90, then it becomes 60.
Or if the output gear is 80 it becomes 120.
The good thing is I've only got the change gears that were fitted to the lathe, so am making the missing ones anyway. Blanks are roughed out to thickness and bored but only 2 are at finished diameter ready for cutting the teeth. If I make the decision to change to 6mm then I'll just cut the gears to suit that instead. I'd definitely be less inclined if I'd just finished cutting a full set to suit 4mm..
I can get 2m of quality 30x6mm for just over AUD$300 delivered (local stock). Not exactly cheap, but not outrageous.
A fair bit of image googling also turned up a image of the gear chart for a 6TPI leadscrew. If I could just find an image of the 6mm chart I'd be set :)
Steve