AVX - tapered roller bearing for RA axis

[Alexp]

Hi all,

I have tried to find and read as much as I could find on disassembling the AVX, adjusting the gears and cleaning and regreasing everything. In general, my AVX works fine - it used to work quite fine before opening it up, but it does work better now. Except for taking apart the worm and ring gears in the RA and DEC axis, I cleaned the gears, relubed them, and adjusted them as best I could to remove backlash. 

Best I could get by now is .61" total RMS error in PHD2. On average I am seeing about .85" total RMS error, which should be fine considering my imaging scale (SW150/750pds and Canon eos650d - 1.19arcsec/pixel) and as long as there aren't too many outliers in guiding corrections. From the experiences of others that I have read about I believe these numbers aren't too bad for an AVX mount.

Nonetheless, bad weather doesn't currently allow for imaging and I wanted to continue working on the mount in the meantime. Besides, tinkering with the mount and getting to know it better can't hurt anyway and is actually quite "fun". I ordered a tapered roller bearing to exchange the old ball bearing in the RA axis (Timken 32007X).

I disassembled the mount and took the RA axis out of its housing but I unfortunately found out that for some to me unkown reason I cannot remove the old bearing and the ring gear from the RA axis, no matter what I tried. In all the forum posts and pictures and in all the videos it was never really shown how these two parts were taken off and I assumed they could just be slipped off the RA axis, yet it wasn't possible in my case.

Since these parts seem to really be stuck in their place I wouldn't think that the grease inbetween has become so sticky that I cannot remove them. Is there anyone here that has experienced something similar and how did they solve the problem? Or am I missing something or have I forgot something when trying to remove the old bearing and the ring gear from the RA axis? Any help would be greatly appreciated!

Cheers and clear skies

 

[doublevodka]

I suspect you are right with the grease, having a quick look round haven't seen any mentions of difficulty with the bearing

Assuming you are going to degrease and regrease anyway, liberal application of wd40, let it soak in and pry it off with something plastic as to not cause damage - like these - https://www.ebay.co.uk/itm/261308052856 ?

[newbie alert]

Don't force it off, gravity is your friend here spin it 180 degrees and a gentle tap of the spindle  on something hard like wood should shift it.. it needs to be pulled of square or it will lock up on the spindle... unless you've forced it slightly and twisted it, locking it up.. if you can see where it's slightly higher and a gentle tap should sit it back down square... 

[Alexp]

Thanks you two for the input and the effort! Reading both your comments I just tried a little bit of both. First I degreased the small seam between the ball bearing and the spindle. Then I tried to carefully lift it with a plastic tool that is similar to what you suggested. That didn't work so I started looking if the ball bearing might have shifted a little bit. It didn't look that way so I carefully used a rubber hammer on the ball bearing to see if it may have been shifted. What ultimately helped was turning the spindle 180 degrees upside down and - I was not a huge fan of that - using force and knocking it on a piece of wood finally made the ball bearing come off. Now I will be curious to see how the nea tapered ball bearing will fit. 

Btw, I attached a picture after I have opened up the RA axis the first time. I do not know which grease they used but the amount of grease used was rather... generous 🙈.

Guys, I thank both of you for taking the time and helping me remove the ball bearing from the RA axis! 

Cheers to you and clear skies

[doublevodka]

No problem at all 👍

Calling it grease is somewhat generous tbh, more like glue and unfortunately it seems the same across the board, why use it sparingly when you can use half a tub.... 🤣

Glad to hear it's finally come apart 👍

[Alexp]

Hahaha, I agree. It looks and feels more like glue 😅. 

I've already reassembled the RA axis and readjusted the worm gear to fit the ring gear. I left the nylon washers out between the ring gear and the tapered ball bearing, but I greased everything without using the entire tub.. I'll see how it goes and if this'll help balancing and/or if there is a negative or positive impact on the backlash of the RA axis because of the readjustment. Now only to wait for clear skies... 

Thanks again and cheers