4 replies to this topic

[Ar3s701]

I have an EQ6R that I bought second hand from the CN Classified and in 2023 I did a "hyper tune" myself. Well, really all I did was replace every bearing in the mount and cleaned it up. Pretty good results, but the only bearings that showed any signs of wear were the ones for the worm gears. So maybe I didn't really need to replace every single bearing.

 

Anyway, I followed several guides and videos on the process and the mount has been working slightly better than it had been. The only thing that was not covered anywhere has to do with the tension on the tapered roller bearings for both the DEC and RA axis. Nothing tells me how tight to make those and how tight is too tight. You can find a little bit on info on the DEC side with videos covering backlash tuning, but again nothing on RA.

 

So, does anyone know exactly what how tight or loose they should be? Any idea on how to determine too tight vs too loose? Its been bugging me for a long time and I think it is an area that needs improving on the mount.

[bignerdguy]

As far as how tight, that's going to be subjective to your mount.  You want it tight enough to prevent backlash but loose enough that the motors can move the mount without binding and without excessive strain which would excessively wear the motors or worm gear.  Really you're going to have to adjust them until the backlash has *Just* been removed but the mount can move freely and not too stiffly.  There is really no one right answer to your question.

[Yomamma]

I loosened both of mine until they turned freely with no up/down play. I keep the motor drive belts tight(3-4 mm down when pressed with small screwdriver head) when the seeing is good I can do .5-.6 with 23 pound refractor

[kgb]

I have always tightened to the point where it is about to bind then work backward before I see any measurable backlash.

[Applal]

After 11 years of tuning and retuning my EQ-G (similar physical properties) I found no benefit from trying to get them too tight, or trying to reduce any end play. Do this all with the ota off the mount.

These bearings are massive for the job they do, and most of the work is side deflection not end play. I have to admit also that I just tightened till I felt the bearing begin to snug up, and back it off a 1/4 turn, and then spin the head all the way around to ensure there were no high spots. IF I sensed a high spot I would back it off 1/8  turn more. 

The real guiding issues are going to be found in the end play and gear mesh areas/adjustments. I did use a similar method there though too. Feel the snug, back off a bit, though then I would drive the head all the way around listening very carefully for any load or strain on the motors. I would usually do this twice to make certain of any "settling in" that might occur on the first go. After I was certain of the no tightness in the lash, I would tighten up the bolts and test it one more time. 

There is a lot of metal mass in these heads, and the actual temperatures can change clearances. Slightly loose will be better than slightly tight. 

Then mount up the scope and carefully balance it. 

Clear skies to you!