Hi, I was after some help with calculating change gears as I have just bought as secondhand lathe that didn’t come with all the change gears. The change gears that are missing are less common sizes like 42, 52, etc. Most of the change gears for sale on eBay and Aliexpress are dividable by 5, like 40, 45, 50 etc so I wanted some help to do the calculations to substitute the specified gears with close enough base 5 gears.
In terms of background, the lathe is a TopTech Turner 210 with speed change via belts, searching via google only shows the 210V model which is largely the same but has the additional feature of electronic variable speed. The gear change set specified for it is:
25, 30, 33, 40, 42, 52, 60, 70, 75, 80, 90, 90
I currently have the following gears that came with the lathe:
25, 33, 80, 90, 90
which leaves me missing:
30, 40, 42, 52, 60, 75
The metric thread pitch for the lead screw is 2mm, it has a 40 tooth drive and the gear change table for cutting metric threads looks like:
My question is that given that I can’t easily find replacement 42 or 52 tooth gears, what gears should I buy (that are divisible by 5) and what would an alternate combination be to cut the metric threads that have a 42 or 52 specified. Thanks in advance for your replies.
In terms of background, the lathe is a TopTech Turner 210 with speed change via belts, searching via google only shows the 210V model which is largely the same but has the additional feature of electronic variable speed. The gear change set specified for it is:
25, 30, 33, 40, 42, 52, 60, 70, 75, 80, 90, 90
I currently have the following gears that came with the lathe:
25, 33, 80, 90, 90
which leaves me missing:
30, 40, 42, 52, 60, 75
The metric thread pitch for the lead screw is 2mm, it has a 40 tooth drive and the gear change table for cutting metric threads looks like:

My question is that given that I can’t easily find replacement 42 or 52 tooth gears, what gears should I buy (that are divisible by 5) and what would an alternate combination be to cut the metric threads that have a 42 or 52 specified. Thanks in advance for your replies.
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