Double Tilt Way Tubes.
Posted: Thu Jul 25, 2024 1:45 pm
In another thread, the subject of Double Tilt (DT) way tubes came up. If you use the DT Upgrade Kit on a Mark5/V, the way tubes are too short to seat in the Base Arms and the instructions call for centering the tubes, leaving a gap at each end inside the Base Arms. I've always had reservations about this, when the machine is tilted to either vertical position there is a lot of weight on the way tubes and only the small setscrew to keep them from seating, closing that gap, or migrating under the weight and vibration of normal operations, gradually closing the gap.
On a conventional Mark 5/V, the difference between bench and way tubes is 3/4", the way tubes being the smaller of the two. On a DT machine, the nominal difference between bench and way tubes is ~1/8", the way tubes again being shorter. (Nominal meaning it allows the way tubes to fully seat in the Base Arms.)
There are several options to eliminate the gaps. Filler plugs have been suggested for the inside of the Base Arms. Trimming the bench tubes was also suggested. I also considered trimming 1/8" off of a set of good bench tubes and using them as way tubes. In the other thread, jpg mentioned using PVC plugs with a piece cut out to allow them to fit. This sounds like a great solution to me, I had previously considered cutting filler plugs from bench or way tube scraps but was concerned that these might be noisy due to normal machine vibration. But 1-1/2" (ID) Schedule 40 is a bit oversized, so cutting about 1/2" out of a plug allows you to compress it to install and results in a tight fit against the Base Arm walls.
I made four 5/16" PVC plugs and the fit was perfect. No more gaps, and the Base Arm comes down on the hinge pin right where you expect it to be. PVC is very easy to work, I used the bandsaw and keep a blade that I use primarily for PVC and other plastics because I'm unsure about wear.
- David
On a conventional Mark 5/V, the difference between bench and way tubes is 3/4", the way tubes being the smaller of the two. On a DT machine, the nominal difference between bench and way tubes is ~1/8", the way tubes again being shorter. (Nominal meaning it allows the way tubes to fully seat in the Base Arms.)
There are several options to eliminate the gaps. Filler plugs have been suggested for the inside of the Base Arms. Trimming the bench tubes was also suggested. I also considered trimming 1/8" off of a set of good bench tubes and using them as way tubes. In the other thread, jpg mentioned using PVC plugs with a piece cut out to allow them to fit. This sounds like a great solution to me, I had previously considered cutting filler plugs from bench or way tube scraps but was concerned that these might be noisy due to normal machine vibration. But 1-1/2" (ID) Schedule 40 is a bit oversized, so cutting about 1/2" out of a plug allows you to compress it to install and results in a tight fit against the Base Arm walls.
I made four 5/16" PVC plugs and the fit was perfect. No more gaps, and the Base Arm comes down on the hinge pin right where you expect it to be. PVC is very easy to work, I used the bandsaw and keep a blade that I use primarily for PVC and other plastics because I'm unsure about wear.
- David