40t Change Gear Rare?

[Uglydog]

Send me a PM if/when you decide you are ready.

Daryl
MN

 

[cdhknives]

The 101.28900 12" lathe(with QCG) uses a 40T that drives a twin set of 48T gears. If you remove the spacer and add a 20T on to the 40T hub and then drive the 48T gear with the 20T the speed in cut in half ( Note that one of the double 48T gears must be removed for clearance). Only one 20T gear is needed for the modification, everything else is already there. The half speed messes with the threading settings but in most cases all you have to do is set the threading levers at half of the threads you want so its not really a big problem. I just thought it would be handy to have everything put together on separate mounting bolts so I wouldn't have to be swapping out each individual gear. Just loosen two nuts, remove the gear sets, replace with the different gear sets and tighten their two nuts. I have everything I need but another 40T . I dont have to get one now so I will just wait and see what comes up. I thought it was odd that the two I found were as expensive as they were.

Ok, after some study on my machine I see it now. On my QC54 that is the 'sliding gear' allowing extra coarse (up to 4 TPI) threads and you are converting that spindle to a fixed 2:1 reduction gear. After the conversion the actual TPI would be double the nameplate TPI, i.e. an 8 TPI setting actually cuts slower, to a 16 TPI. I do see where that conversion would be nice if it were easily reversible as you are suggesting. 16 TPI is a pretty high minimum. Adding another spindle sure looks nicer...let us know if you buy the Boston gear. I'm curious how it turns out.

 

[VSAncona]

I just sold one last month on ebay for $18 with free shipping. They come up for sale pretty frequently. If you're patient, you should be able to snag one in the $15-$20 range easily enough.