I bought a small 9 X 20 lathe from a friend of mine. After getting it home and set up I discovered that there was no provision to reverse the feed. This is not a problem for most applicatoins, however if one wants to cut left hand threads being able to reverse the feed is a must. One of the things I wanted to do with this lathe was make drag links for my VW steering kits that are used on the MGTC. This requires the cutting of left hand threads. I found a couple of websites  (www.gunsmith.fuselier.com/tumbler.htm) and (http://bedair.org/9x20camlock/9x20project.htm)  where others had installed a reverse idler gear into a lathe like mine. It looked like something that I could do, so I decided to give it a try.

This first picture is of the lathe as it came from the factory. Note the plastic gear in the top right of the picture. This gear was fixed in position using a stud/post screwed into the housing. It was not adjustable nor movable:

I removed that gear and made a plate with a reverse idler gear similar to that which is used in an automotive transmission. The large gear replaces the plastic gear and the smaller gear is used to reverse the direction of the larger gear when the smaller one is engaged. When the large gear is engaged in its original position the lathe feed rotates in the same direction as the chuck and the material being turned:

The following pictures show the plate mounted on the lathe in forward position. The larger gear is engaged in its original location and the lathe feed screw moves in the same direction that it originally did:

In these pictures neither the large gear nor the smaller one is engaged. This is a neutral position used when you do not need the feed at all.

In the following pictures the smaller gear is engaged which reverses the direction of the larger gear and all the gears that it drives. This reverses the feed direction:

The final picture shows the lathe reassembled and working again, now with the ability to reverse the feed direction.