BUILDING THE WORDEN GRINDER

Part 12+1 by Vince Cutajar

Finally, the traverse kit. Not many bits and pieces. There was also a plastic pipe/tube. This will be the guide tube for the threaded rod. The OD of the plastic pipe is about 20mm and has a wall thickness of about 2mm.  According to the instructions I needed to machine both ends of the pipe to 3/4" and then thread 3/4" X 26TPI. Now, 26 TPI is very close to 1mm pitch and trying to cut a 1mm pitch thread on a tube with just 1mm wall thickness is just asking for trouble. So I used a 0.5mm pitch thread instead.

I tapped the tube clamp nuts 19 X 0.5mm. 
I made a test male thread to see if the nuts I made can be screwed on easily.  It worked.

That gave me the confidence I needed to make the threads on the plastic tube. To reduce the plastic tube diameter from 20mm to 19mm I used a parting blade. That was the only cutting tool I could get in there as I was supporting the tube with a live centre.

With the end turned down to 19mm, it left a wall thickness of less than 1mm. I used this contraption to help me in threading.
The small cylinder will go in the tube to support it and the large disk will keep the die holder square to the tube. Threading with the die was easier than I anticipated.
Both sides threaded with the clamp nuts screwed in.
I cut the slot in the plastic tube.  I made it 6mm instead of 1/4".
Finally, I completed to traverse kit. What did I do different? For starters I used a stainless steel leadscrew instead of that one that came with the kit. I seems to work better and the travel is smoother most probably because the threads on the stainless steel version are better. I changed the handle. Instead of a solid handle, I made one which rotates freely as you are turning the handle.
Here is the completed unit.
The leadscrew is in the black plastic tube.
The traverse kit in the disengaged mode.
And in the engaged mode.