Originally Posted by
ozzie34231
Hi Ian,
The construction of your unit sounds much different from mine.
In my unit there is a single bushing, the length of the housing, hard steel. In the bore of this bushing there is a centered undercut about an inch wide, maybe 0.100" deep. So, in mine a single bushing does the job of the two on yours. The top outside of the bushing has two short V-shaped grooves, offset from each other by about 22 degrees, one running length-wise, the other radially. on the top of the housing, in places that match the bushing, there are set screws, one directly on top, the other toward the rear. The combination of the screws and grooves are surely to lock the bushing in a very specific position, and I assume to press it against the air inlet hole, so that a hole in the bushing is aligned with the one in the housing.
The manual, (bought separately), goes to great lengths about how to clean the unit without clogging the air inlet, even suggesting leaving the air supply on while cleaning so as not to block the passage. It says that once blocked the passage may be nearly impossible to unblock! So it is small. It is so small that I cannot see it. Like yours there is an air inlet pipe thread and presumably a concentric hole going through the housing, but no light passes through it, and inside the bore I cannot see any hole where it should be, or anywhere. There should be a matching hole in the bushing and I know the approximate location because of the locating screws. However I can not see or detect any hole inside or outside the bushing.
There is some minor corrosion pitting on the outside of the bushing which might be camouflaging a hole, but even under 10X magnification I cannot see a hole. I cannot see a hole inside the bushing.
I agree with you that the air escaping around the shaft should control the air flow, so why the tiny hole. What can its purpose be?
Air going through a small hole would increase in velocity while in the hole. It would cool as it expands. So what? Maybe it was a temperature control scheme?
Anyway, I think that the tiny hole is not needed to make the spindle float. I just need to get air through the housing and then through the bushing, and of course get bushing and spindle clean and parallel. If I can't drill the bushing I'll just make a new one.
I'll take some pictures to make my posts clearer.
Ozzie