Bernd,
We use the same taps, but name them slightly different, taper, second cut, plug.
Now on with my post.
I was hoping this would be the last one, but I could only manage about an hour today, so I will show you the results.
This part of the job is a 'wing it' exercise, in other words, make to fit.
Because the new blocks are a lot thicker than the original crappy gib strips, a problem occurs where the gear that runs on the rack for moving the saddle, actually fouls the newly made blocks.
This is from the side.

Front shot.

By taking the gear off it's spindle, I managed to get the apron bolts in and the spindle almost resting flat on the top of the block.

This will do for me to mark out where the cuts need to be.
I run a pencil down the outside of each side of the spindle. I then found the rough middle between the pencil marks, measured the diameter of the small gear, halved it, added 1/16" and marked out from the centre line on both sides.
I thought I had taken pics, but couldn't find them, so the above description will have to do.
Senility is definitely setting in.

I checked that the gear clearance was ok either side.

Stuck my scriber through the middle of the gear, and held the scriber on the top of the block, and pushed the gear down as far as it would go, and marked it up plus a little bit. It measured up at 0.200" down.

I am showing off here, because I had a bull nosed cutter of the right size, but I could just as easily cut out the square recess.

Block mounted back onto the saddle.

Apron fitted into correct location.
If I must say so myself, it worked out a lot better than I thought it would.
It is about time I had a bit of luck.

So the rack was mounted onto the lathe, followed by the above assembly. I put the gibs in position and tried it out.
Looks like we are onto a winning streak.
Bogs