ballen
Diamond
- Joined
- Sep 25, 2011
- Location
- Garbsen, Germany
Hi Richard,
I decided to "prove" my findings by adding shims to compensate for the missing material under the swivel table. Here are the three shims, thickness 130 microns = 0.005", 75 microns = 0.003" and 25 microns = 0.001". None of these needed to be "forced" into place. This did improve the geometry, but not quite in the way that I had expected, so it was worthwhile.
Here are the shims:
This fixed the problem with the table drooping by 30-70 microns on the left. Here's a video showing that with these shims in place the swivel table is level. Indicator is 2 microns = 0.00008" per division (a bit less than a tenth).
Next I aligned the swivel table parallel to the travel (you have to click on the link since PM only allows one embedded video per post!)
Testing swivel table for parallel to travel
Then I aligned the workhead so that the spindle axes was parallel to the travel. This is WITHOUT the tailstock (you have to click on the link since PM only allows one embedded video per post!)
Testing workhead spindle for parallel to travel
Finally in the next clip I engage and disengage the tailstock. The tailstock is off in horizontal position by about 7 microns = 0.0003" (you have to click on the link since PM only allows one embedded video per post!)
Checking tailstock alignment front-to-back
BUT the tailstock is still too high, by about 70 microns = 0.003" (not shown).
Summary of the effect of shimming the swivel table to compensate for the missing material and make it flat:
(1) The workstock spindle now droops down rather than pointing up. This is completely consistent with what I see on the surface plate. Before shimming the swivel table, the tilting of the swivel table top was making the workstock spindle point up!
(2) The tailstock is now almost in the correct front-to-back alignment. Apparently the swivel table was twisting the workhead spindle axis when the table was clamped down.
So it looks like the right order to fix things is:
(a) Get swivel table ground flat and parallel
(b) Scrape the bottom of workhead to get the spindle axis tilting slightly up
(c) Scrape bottom of tailstock to lower it to the same height as the workhead spindle axis.
I need to do step b before step c. Step a can happen anytime.
I decided to "prove" my findings by adding shims to compensate for the missing material under the swivel table. Here are the three shims, thickness 130 microns = 0.005", 75 microns = 0.003" and 25 microns = 0.001". None of these needed to be "forced" into place. This did improve the geometry, but not quite in the way that I had expected, so it was worthwhile.
Here are the shims:
This fixed the problem with the table drooping by 30-70 microns on the left. Here's a video showing that with these shims in place the swivel table is level. Indicator is 2 microns = 0.00008" per division (a bit less than a tenth).
Next I aligned the swivel table parallel to the travel (you have to click on the link since PM only allows one embedded video per post!)
Testing swivel table for parallel to travel
Then I aligned the workhead so that the spindle axes was parallel to the travel. This is WITHOUT the tailstock (you have to click on the link since PM only allows one embedded video per post!)
Testing workhead spindle for parallel to travel
Finally in the next clip I engage and disengage the tailstock. The tailstock is off in horizontal position by about 7 microns = 0.0003" (you have to click on the link since PM only allows one embedded video per post!)
Checking tailstock alignment front-to-back
BUT the tailstock is still too high, by about 70 microns = 0.003" (not shown).
Summary of the effect of shimming the swivel table to compensate for the missing material and make it flat:
(1) The workstock spindle now droops down rather than pointing up. This is completely consistent with what I see on the surface plate. Before shimming the swivel table, the tilting of the swivel table top was making the workstock spindle point up!
(2) The tailstock is now almost in the correct front-to-back alignment. Apparently the swivel table was twisting the workhead spindle axis when the table was clamped down.
So it looks like the right order to fix things is:
(a) Get swivel table ground flat and parallel
(b) Scrape the bottom of workhead to get the spindle axis tilting slightly up
(c) Scrape bottom of tailstock to lower it to the same height as the workhead spindle axis.
I need to do step b before step c. Step a can happen anytime.
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