Colchester Bantam crosslide gib strip adjustment

[Ianb]

I need to adjust the crosslide gib strips, but have been unable to find anything in the manual or online, as can be seen in the photos there are the Allen bolts along the side, but there also appear to be some on the top face of the slide. Are both adjusted or do the top ones do something else, if both do you adjust the top or side first?

Many thanks

 

[Pete.]

The top ones are clamp screws, they hold the gib pieces tight up under the cross slide. The side ones are jack screws, used to adjust the gib. You can't adjust the gib with the top ones done up tight but you need the gib to be a snug fit before adjusting.

There are two gibs and you have to take the compound swivel off to adjust them both because it covers one of the clamp screws. Loosen each top screw in turn and nip them up so that you can just about push the gib with the jack screws. Once you're happy that you have the gibs set how you like them do the top ones up tight. If this causes the drag to increase, go back and do it again.

 

[Ianb]

Thanks, I will give it ago.

Looking as you have photos of lathe parts, is there any adjustment for the cross slide backlash? From what I have read there isn't unless the crossslide had hole/bolt/something in front or behind the central hole shown (that has the hex head/oiler) in your photo?

Some Bantams have a 3rd shaft along the front of the bed, I only have 2, is that todo with screw cutting?

 

[Pete.]

Backlash in the cross slide screw is normal. Every lathe has it, the amount is an indication of how worn the screw and/or nut is.

The top shaft you have in the pic is the screwcutting lead screw. The lower one is the power feed shaft - used to drive the surfacing and sliding feeds. The missing one is the motor power control shaft it would have a lever bottom right on the apron that controls the motor fwd/reverse. My guess is that your machine has a single phase motor fitted. Normally they remove that control shaft when doing a single phase conversion.

 

[Ianb]

Thanks, I am not sure what the machine was originally, it now has a 3 phase motor with a VFD, thanks for the info about the missing lower shaft.

 

[Ianb]

Just been looking at the pictures, I now see the gib adjustment screws on the top seem to be the second row in of screws, what are the rfirst row of screws close to the edge, there are 3 obvious ones in the middlle front to back (Pete.'s photo has another hole right on the centre one)? Thanks