Backgear

Technical Technical Discussion
1

I’ve recently been studying the lovely little Atlas model 618 lathe and discovered a quite clever device it has called a backgear. Does anyone else know what a backgear does? It is pretty neat. It allows for more reduction in a smaller amount of space. Take a look at this link http://www.lathes.co.uk/latheparts/page4.html

The 4 step pulley and small gear SG are permanently connected and ride freely on their shaft. All the other gears are affixed to their shaft.

I wouldn’t use engage and disengae this setup for shifting, but it (engaged) seems like a good idea for a high reduction yet space saving gearbox for FRC applications.

In case it isn’t clear, the 4 step pulley is the input and the threaded shaft is the output in this particular picture.

2

yeah its your best friend if your trying to properly knurl anything. i spent a whole night in my teams shop this season trying to get ours to work properly, and i couldn’t be more glad that i did (for those of you with 50some odd year old south bend lathes like my team has, you need to pull out the bull pin under the little guard thing on the headstock right behind the chuck for it to work).

if you want to learn more cool tricks with old lathes my team’s head faculty adviser gave me his machine and metalworking text book from 1961 which he stole from the last school he worked at. its got all the old school techniques and has taught me almost all i know on the lathe, just pm me if you want me to get you a copy of the lathe section of it.