Yet another EQ3 tune-up thread, my variation on the needle bearings and thrust washers etc..

[Kilohertz]

I've had my new to me NEQ3-Pro mount for over 2 months and have yet to use it. Between just learning all this astrophotography stuff, software, new scopes etc. and of course a month of complete cloud cover, there just hasn't been any opportunity to capture astro images, so......I decided to pull apart my mount to install the needle thrust bearings as described in several locations on the web. I ordered all the bearings and teflon grease and completely dismantled my mount and started reassembling it, immediately found it impossible to get the worm drive gear aligned properly as the mounting screw slots weren't long enough to place the 2mm washers under the worm drive mount, plus I had to drill a little hole in the side of the RA housing to get at the 3 little grub screws holding the aluminum plate on the 1" shaft as the original hole was too far below the plate to get into the holes of the allen screws. All this got me frustrated and I pulled everything out and am now ready to return all the bearings, but not before I try something else. 

One thing I noticed in the video by Petter is that he placed thrust bearings where they are not needed as the clutches in both axis are normally locked and the surfaces are just fine with just the red fiber washer, we really only need bearings on the outside ends of the DEC and RA shafts, and thru some extensive research I found a bearing to replace the AKX2542 (which needs some grinding to clear the 1" shaft) and the new part is a TC1625, dirt cheap on Amazon and elsewhere and has a 1" bore and 1 9/16" outside which fits under the RA worm gear perfectly, you only need one. I also found on Aliexpress very thin stainless shims, again just the right size and only .1mm thick as apposed to the .75-1mm thick plates which come with the bearings. They will be here in a few weeks. This will bring the worm gear closer to its original position and should make alignment possible again. I was a little uneasy about his running the bearings without the steel shims in place, running hardened steel rollers on soft aluminum may cause some indentations or galling if you crank down the end nuts too much. 

Now, as I am also into a lot of other hobbies, auto restoration, metal fab, stereo building and modding etc. I have a fair bit of experience in slipitivity, my own word for the lack of friction between 2 surfaces, the opposite of course being gription. I know PTFE (Teflon) has very low coefficient of friction so I have ordered a sheet of .1mm thick pure PTFE to cut out and replace the existing red fiber washers currently in place. I spent a day trying to find precut PTFE shims with no luck, the sheet was cheap $15 for 300mmx1M, it should be here tomorrow from Amazon. I am going to try replacing just the red fiber washers with PTFE and leave out the thrust bearings altogether, for now.

As there is no end in site for cloudy nights, and I have some time off work, I thought I would try it as another experiment that I thought might be a great solution.

I will update as I make progress, and of course welcome all comments and corrections if I have made any incorrect assumptions.

Cheers

Paul

Edited December 29, 2023 by Kilohertz

[wimvb]

Interesting. The thickness of the bearings and shims as suggested in the original video was a problem. Post any updates here please, I would like to see this mod work. Atm I'm also thinking about replacing the gears with a belt drive. Only thinking, mind you, not doing any actual replacements yet.

[Kilohertz]

7 hours ago, wimvb said:

 I'm also thinking about replacing the gears with a belt drive. 

I might also, I wanted to play with ONSTEP for possible upgrades on my Meade 853 so I ordered the Terrans EQ3 kit with motors and pulleys etc.  Since all of the kits would require mods to work on the Meade, I thought I might as well order the one for the EQ3 so I have options.

I'll keep this thread updated once the PTFE arrives.

cheers

[Kilohertz]

Well I just realized that I haven't updated this thread in a while and I have made some more mods to my NEQ-3PRO mount. The PTFE arrived and I cut out washers to replace the red fiber washers. I used synthetic 10W oil instead of grease on them as my mechanic friend said it would work better in the cold. The thin .1mm stainless shims arrived from China so I can use the thrust bearings without too much mis-alignment of the worm but I haven't replaced the teflon as I want to make some tests first, and as I am STILL mucking about learning polar aligning and plate solving and the weather is STILL crap, I won't be going back to the thrust bearings for a while. The PTFE seems to work very well, the mount axis are very smooth and no discernable stiction. 

While I'm waiting for clear skies I decided to bring the mount inside and add some knobs to make polar alignment easier. I just bought a 3D printer last month and am having a blast learning to use it as well. I made the knobs and new threaded shafts and it works AWESOME! So much easier than the steel slippy rod things. 

I'll update again once I have tested my PTFE washer mod and then again with the bearings.

Cheers

 

Here is the way I installed the PTFE washer with the polished stainless thrust washer from the bearing set. If you want the correct size bearing that doesn't need grinding it's TC1625 and is used on both ends of the RA shaft. Try to locate .1mm or .2mm thick stainless shims so you don't have to work too hard to get the worm gears re-aligned. The ones that come with the bearings are .75mm.

 

I found this bearing which Petter couldn't locate in the hyper-tune video, but as it turns out, it's not needed, only the very ends of the shaft need bearings so I removed it.

 

The bearing AXK1024 is needed for the very top of this shaft, circled in RED but not the one below it. The bearing at the bottom of the DEC shaft is AXK2035.

I also changed the worm drive bearings. 686-2RS 

[JeromeW]

Paul,

I found these PTFE washers on eBay.

Jerome

 

https://www.ebay.com/itm/404688923477?itmmeta=01HQGSCBW62EXYVHQB2ER46C92&hash=item5e3956eb55%3Ag%3AFYoAAOSwtfJlf6ON&itmprp=enc%3AAQAIAAAAwFNHxkuKA%2FwsA0yGZ9U8A7ArJRJO16ydOtF4ySmWwbYJe1U%2FqjR1XfXgR85mEtceZ1vvlV7HB2f4ZxU5nOz5ptY9YS7air67o9WgIz2UgA8cTPyw9foy9WBa7FUomTGxYtGOvXYD%2Bf9L%2BQGnTRSVlzlA368F31ZgpYt4MGN4jD8d7tmdFNVPmwfeSwlbboBQGStF4rkJt5Lq8Z0DUND1ajWTR7X%2Fn6jd52pqC4eGVRH%2FJJyDRxspjNxzbXEe7PLY%2Bw%3D%3D|tkp%3ABk9SR5i-sZm8Yw&LH_BIN=1

 

https://www.ebay.com/itm/404688923477?var=674687056860

 

[JeromeW]

Paul,

Wow!! Your teflon washers was a great idea!!

The friction in my DEC axis is now less than half!!

I'll let you know how it turns out tonight if we have clear skies.

My teflon washers were 2mm thick, but I was able to make them work by creating a shim.

In the first picture my wife took the measurement about 1 year ago, it didn't take me long to notice something was wrong.

Jerome

[Kilohertz]

Nice work Jerome, looking forward to hearing how it tracks, good luck.

Cheers

PS I haven't pulled mine apart to replace the .75mm shims with the .1mm shims yet, I've been working on building an automatic focuser and getting my new Canon T3i connected and working in NINA.

[JeromeW]

Previously, with my EQM-35 mount in stock configuration I was never able to get it to guide in DEC with Askar V telescope. The DEC axis was too stiff for the stepper motor to overcome the friction. The belt conversion did help.

I tested my mount outside tonight. The sky's were about 70% overcast.

Tonight I was able to reliably guide. However, my results were not as good as yours. I was able to maintain a total RMS between .95 and 1.4. But it was able to guide, the teflon washers make a diffinate difference.

Last night with my 3D Printed DEC axis I was able to maintain .34 to about .7.

Thank you very much for sharing your teflon upgrade.

[JeromeW]

Thank you very much for sharing your teflon upgrade. It has turned my EQM-35 mount from a piece of junk, to a well functioning precision piece of equipment. Last night I was able to maintain an RMS between .68 and .98

I believe one thing that also has helped with this upgrade was the use of the HELIMAX-XP Optical & Instr Helicold Grease.

https://www.ebay.com/itm/123651606955