Sieg SC4 change gears

I need to cut a 20TPI left hand thread with my Sieg SC4 lathe.

I have the appropriate gears in place and moved "A" to the left so that the lead screw goes in reverse.

However I am unable to get the AB gears to mesh as the gear to the right of the picture is in the way.

**LINK**

Can this be removed, if so how please, or am I missing something!

This is my first attempt at changing gears and cutting a thread. Maybe not ideal to have to be a left hand one but it has to be.

Help much appreciated

Richard

There should be (at least there is on mine) two flats on the stud so you can unscrew the whole thing. From memory you need a 13mm spanner.

Edited By AndrewD on 30/10/2021 15:06:27

As well as being able to loosen the studs so they can be slid along the banjo you can also loosen the banjo where it clamps around the lead screw boss which will help with getting the gears to mesh you can see the cap head screw for this far right of picture

Andrew, that picture is very helpful and almost answers the question. There are 2 small allen screws top and bottom on mine, which I assume lock it in place, presumably these have to come out 1st ?

thanks for your advise

Richard

You don't need to touch those. I think all they do is hold in the threaded block that the above shaft screws into. You can see the back of it if you take the top cover off. Anyway, it's a bit fiddly depending on how long your spanner is because the lead screw can get in the way but the whole assembly simply unscrews.

The Operator's manual should show you how to set the mesh of the gears.

You have to be able to move the studs along the banjo, and swing the banjo around t's mounting.

This will allow you to set the mesh of the gears. Too little will cause wear and noise, too much will be noisy and may reduce accuracy and quality of finish (due to gears rattling )

To set the backlash, run a sheet of paper about 0.003 (0.075 mm) thick into the mesh and then clamp up.

Probably easier to swing the banjo first to set the backlash on the first mesh, and then to move the studs to set the backlash on the other gears.

Howard

Well, I think the gear change is all OK.

Many thanks

Richard

Ricardo,

You have PMs in your In Box

Howard

Interesting that Sieg have apparently formed the flat in the first photo in a lathe.

I imagine it is a cnc lathe with powered tooling coming in at the side.