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EQ3-2 Strip Down


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[Posting this in a new thread as its too large for the current EQ3-2 guided imaging thread]

Thank's to Stans description and links in the EQ 3-2 guided imaging thread, I've made my recently purchased EQ3-2 silky smooth now.

One axis was badly suffering from backlash, the other axis was too tight and suffering from stiction, it was even squeaking.

As promised, I'm posting the full Dec and RA axis strip-down images for the skywatcher EQ 3-2 mount to complement Stan's description.

Hopefully, these images and Stan's write-up in the other thread will let anyone willing to put in 2 hours work, improve their EQ3-2s performance.

Tools:

  • 3 in 1 - White lithium grease spray
  • 3 in 1 - Degreaseer
  • Allen keys, various
  • Pliers
  • 15mm and 16mm socket wrench.
  • Patience

Dec Axis

Step 1

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The mount head removed from tripod and ready to go.

Step 2

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This is the nut inside the polar scope aperture we want to loosen to separate the Dec axis. But we need to move to step 3 before we come back and loosen this nut.

Step 3

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To access the previous nut, we first loosen the 15mm nut at the top of the saddle.

Step 4

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The nut inside the polar scope aperture should be loose now. I needed to use a pair of pliers to hold the nut and turn the head slightly to get it loose.

It comes loose with a black washer and a metal washer.

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Step 5

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Carefully slide off the Dec head now from the rest of the mount, be careful not to lose the red washer.

Step 6

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Remove the 4 bolts holding the worm gear using an allen key. Then separate the worm gear assembly.

Step 7

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Separate the elements of the worm assembly. First, remove the retaining nut with a wrench, then use a screwdriver to remove the threaded bolt. The brass worm gear should come out now, with two little metal rings and two brass washers.

Also now you can remove the Dec gear and its two red washers.

At this point I discovered another washer (white) and the plastic cover for the RA locking mechanism that were covered in gunk and stuck to the main mount where the Dec shaft had been removed. I also put these aside for cleaning, just remember to put them back correctly.

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Step 8

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Everything that was covered in the skywatcher gunk was degreased with 3 in 1 degreaser and cleaned with a cloth. Everything looks shiny and nice now!

Step 9

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I regressed all of the moving parts and especially the gears, then reassembled the Dec gear, worm gear assembly and loosely reattached it.

When reassembling the worm gear, Make sure that you don't over tighten the threaded nut. You want it just tight enough not to allow lateral movement of the brass spindle, before you secure it with the bolt. It should move freely without any noticeable friction or sticking.

At this point I made all four bolts finger tight and used an allen key to do the same to the Dec adjustment (between the two long allen bolts).

I spent a good 20 minutes gradually loosening the adjustment bolt and slightly tightening the two short allen bolts until I had no backlash detectable and it was smooth to turn but not too loose. I put back on the manual adjustment knobs to test this. You can tweak this further when its all back together and the scope is mounted.

I made sure all the bolts were tight then reassembled everything carefully, making sure to regrease all the moving parts with the white lithium grease.

RA Axis

Step 1

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Remove the polar scope (if you have one) from its holder by gently unscrewing it.

Step 2

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Now fully loosen and then remove the RA circle thumbscrew and carefully remove the RA setting circle.

Step 3

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There are three hidden retaining bolts in the RA ring nut. Using a small allen key, you can carefully unscrew them by popping the allen key through the hole where the RA setting screw used to be. Be careful as these may fall out and down inside the assembly. I just let them drop out to the table by holding the mount at an angle.

Step 4

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Now we need to unscrew the RA ring nut. You use the two holes to do this. Some people use two nails hammered into a piece of wood to loosen this. I used two small allen keys (one for each hand) to get traction and get it loose to unscrew it.

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It will come loose with a white plastic washer allowing you to separate the two parts.

Step 5

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Now you can access and remove the RA worm gears, just like earlier using an allen key on its 4 retaining bolts.

Again, separate it into its component parts just like we did for the Dec axis.

Then remove the RA gear and its red washer for cleaning.

Step 6

Again, clean and degrease all the moving parts that were covered in skywatcher gunk.

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mmmm. shiny!

Step 7

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Grease up and rebuild the worm gear assembly. Again, make sure not to over tighten the threaded bolt before you secure it with the nut, it should run smoothly and freely.

Step 8

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Reattach the gears and washers (all nicely greased up with lithium grease) then reattach the worm gear assembly on top. Loosely tightening the nuts so that we can adjust it as we did with the Dec axis. Again, I adjusted mine so that there was no backlash that I could feel and it wasn't too tight causing stiction. Fine adjustments can be made later.

Step 9

Reassembly follows the reverse of disassembly, being careful to put washers in the right places and make sure everything under friction is regreased.

Once everything is all back together, make sure it all moves as it should and then you can tweak the gear adjustments with a scope mounted to get it perfect.

Thanks again Stan for making me brave enough to try this.

Badgers

Edited by badgers
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[Posting this in a new thread as its too large for the current EQ3-2 guided imaging thread] Thank's to Stans description and links in the EQ 3-2 guided imaging thread, I've made my recently purchased

Great write up Badgers! This is a much needed addition to the net in general let alone SGL. I bet theres loads of EQ3 owners that will benefit from this write up. Thanks for taking the time... Stan

Hi My eq3-2 has a broken dec gearing any one know where I can get spares thanks   

Great write up Badgers!

This is a much needed addition to the net in general let alone SGL. I bet theres loads of EQ3 owners that will benefit from this write up.

Thanks for taking the time...

Stan :)

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Thanks Stan,

Given that there wasn't a full walkthrough of the RA disassembly online it seemed silly not to take some snaps during the process, and I thought I might aswell document the Dec axis too as I was doing the whole thing in one session.

Badgers

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I only spotted some minor differences from the old black EQ3-2.

Some slightly different washers, including on the worm gear spindle, but everything else seemed exactly the same.

I'm glad I was taking photos as I disassembled, as I lost track of where a few things had come from and had to refer to my own guide to put it back together.

So just make sure to document where things came from, which order and the orientation and you'll be fine.

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I think that's very good advice when stripping anything down :p It's often confusing when putting things back together - some things can go back in more than one way round as well as in a different order, as you say. I've had that problem before with other things. Screws of different lengths can be a particular headache.

Edited by Gina
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  • 4 months later...
  • 6 months later...

Many thanks for this strip-down photo sequence. I used it to help with stripping down the DEC axis of my CG-4 mount (identical except for TWO red washers - step 5) which I found had very little grease at all and what was there was white, rather than black. I didn't have time to strip the RA axis, but intend to do so this weekend. The DEC axis is super smooth and no backlash, having tweaked the tension on the brass worm screw engagement with the worm gear.

Question, though, regarding the use of grease on the outside of the bushing containing the worm gear (see photos step 9 DEC axis and step 8 RA axis). The worm gear and inside the bushing where it rotates on the shaft need greasing, but I think that the outside of the bushing should not be greased where the little plastic clutch grips it, otherwise the axis might slip when it's at extreme angles. I know that what I did before re-assembly was to clean off any grease in that area and my declination clutch locks solidly, but I wasn't sure if it would make any difference. Did you find that there was any slippage? Am I over-thinking it! :confused:

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Hi

Had a "slack" dec worm gear so decided to give it a clean.

Thanks for the info and photos.

Did the RA as well, took a while to get the adjustment just right as you mention.

I think it's fair to say the components are of the mass produced variety.

So it takes a while to get everything just right

My main dec gear would bind a bit on the motor drive.

I ended up rotating the motor ninety degrees in its casing.

It then ran smoothly.

Patience and conservative application of lithium grease was the order of the day.

Working really smoothly now.

Thanks

Neil

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[Posting this in a new thread as its too large for the current EQ3-2 guided imaging thread]

Step 3

6905597661_20950b6609.jpg

There are three hidden retaining bolts in the RA ring nut. Using a small allen key, you can carefully unscrew them by popping the allen key through the hole where the RA setting screw used to be. Be careful as these may fall out and down inside the assembly. I just let them drop out to the table by holding the mount at an angle.

Thank you for this!!! I was dismantling my EQ5 yesterday and got stucked on the part.. couldn't remove the axis from the actual mount... those 3 hidden screws played me well!!!

Didn't have lithium grease but the previous owner had put in SO MUCH yellow thick grease that the axis had a hard revolving withouth anyweights on it!

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  • 1 year later...

I've just followed this for my RA gears, couldn't do the Dec because of lack of tools but after taking the RA apart I found they had put the grease on the shaft and none on the gears!! No wonder my clutch wasn't working properly... Thanks for this!

I know its an old post but its still providing useful information!!!

Just need to get the scope on and make fine adjustments and it should be all ready to go and hopefully the crazy amount of backlash has gone down a bit.

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  • 8 months later...

Just plucked up the courage to slacken off the Dec axis off on my EQ3-2 thanks for this, my scope is a lot easier to balance now! Thanks for posting this Badgers.

Edited by chaotician
Forgot to say thankyou
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  • 3 years later...

Thank you very very much, Badger. I have just finished re-greasing my EQ3-2 and CG-4, which I couldn't have done without these instructions. I feel much more confident now that I know my gear inside and out. 

Forgive me for posting in an old thread, but I'd like to make a small supplemental point that might be helpful to others:

In Step 4 of the RA Axis instructions, I find it much easier to unscrew the RA ring nut by inserting a thicker allen key (or any metal rod that will fit) into one of the three setting screw holes, use it to hold the nut in place, and do the unscrewing by turning the head (instead of using two allen keys because the holes are rather shallow). 

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I'm finding this old thead just now. I had only one problem with my EQ-3 that required opening it, stiction in DEC; the red disks were rough. Pulled them out, smoothed them, I don't remember if I did it with fine sandpaper or a rough kitchen sponge, lubed them, don't remember with what. Stiction is gone. The other axis had the same issue when the mount was new but trying different settings with the adjustment bolts made it better.

Still not good enough so for two or three weeks I turned the RA axis maybe 40 or 50 times every day, in both directions. That alone solved the RA problem without dismantling anything.

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