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Re: Relationship between needle bearing wobble and variable worm mesh and backlash

 

Hi gang,

I want to correct something.
That is, whether the ring gear has its own cylindrical needle bearing or not.

It turns out that the G11 has one and the GM8 does not.??

The removal of the cylindrical needle bearing from the design is how the GM8 got "shrunk" from the G11 design.??

Here is what I find in my GM8 and G11 versions.??

(Yours may be different: a new G11 I looked at has a ring gear that was black, and likely anodized black aluminum.? My G11 has a ring gear that looks like steel, and is nonmagnetic. The upper thrust bearing and it's races are placed under the ring gear is loosely centered around an aluminum boss.? )?

? Element? ? ? ? ? ? ? ?GM8.? ? ? ? ? ? G11
Composition? ? ?Aluminum.? ? ? ?Steel appearance
?Magnetic?? ? ? ? ? ? ?No.? ? ? ? ? ? ? ?No
? Has a cyl?
needle bearing?? ? No.? ? ? ? ? ? ? Yes
Teeth.? ? ? ? ? ? ? ? ? ? 180.? ? ? ? ? ? ?360
?Worm period.? ? ? ?480 sec.? ? ? 240 sec
Clutch disk OD.? ? ?3.0 in.? ? ? ? ?4.25 in.

When the RA is driven at high speed slew, the GM8 sounds louder than the RA axis.? If the maximum speed of rotation (degrees per second) are identical in a GM811, the GM8 axis should be driven by the gearbox? half as fast on the GM8 axis as for the G11 axis.??

The Gemini-2 handset shows one digital speed setting, so that seems to be used for both axes.? It really should have the digital speed for each axis set separately.? The software could easily be coded to split these out.??

If you have a GM8 mount, the RA will not only have the coarser 180 tooth ring gear, that ring gear will be rotating around a metal cylinder, not a rolling bearing.??

The G11 ring gear has 360 teeth, is (nonmagnetic stainless) steel, with a cylindrical needle bearing inside, rolling on the metal cylinder.??




?


On Tue, Aug 3, 2021, 12:00 AM <sandro.barbanera@...> wrote:
Michael,
the shaft and the round plate on its end are definitely aluminum. Its weight is inconsistent with
a different material i.e. stainless steel. The areas with wearing signs (discolored) are fairly smooth
under finger touch, no scoring anywhere, but nevertheless, following your suggestion, I checked the
thrust bearing and the two washers just before the clutch knob, and they are fine and smooth, BUT, the spring washers
of both axes have serious burrs internally and are potentially dangerous to touch, so that might
explain the markings in that area of the shaft, although this doesn't cause problems on the DEC axis.
Anyway I removed the two spring washers and was more generous with grease on the thrust bearings
and the result of this is that the grip now is better than before and the overall stiffness is higher.
Thank yo so much for your precious hints.
Sandro.

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