EQ5 RA dissassembly : ring nut pin tool or how to get it off otherwise ?

[powerlord]

Hi chaps, so this old EQ5 I got - after a bit of a  clean and adjust of the worm to DEC axis is fine, but the RA is very stiff. and worryingly stiffer in some bits than others.

If I'm lucky I'm thinking hardened grease to clean out and replace. If Im unlucky - knackered bearings ?

But, its locked in with a round ring nut with two small 1.5 mm or so holes in it (42mm or so apart). And it's locked tight. I've tried a pair of needle nose pliers, and I've tried 2 small allen keys put together, but it's not for shifting.

Is there a specialist tool for this ? If not, what do you reckon is best way ? Is it worth heating it with a hot air gun ?

pic attached.

[michael8554]

Get a long length of wood about 60mm wide.

Drill two correct size holes 42mm apart close to one end

Put two of the correct size drill bits in the holes with the plain ends protruding just enough to bottom out in the ring nut.

Apply anticlockwise torque.

Michael

 

[Dr_Ju_ju]

A variation on the above, especially if you have\access to a 3D printer, its relatively easy to knock up something that can hold a pair of M4 bolts (I think that's the size, but may be M3) to do the job...

[Budgie1]

First off, have you undone the 2mm grub screws around the outside of the alloy ring? If not then you'll never get it undone and may wreck the screw thread on the shaft by trying.

If you rotate the shaft and look down the hole for the setting circle locking thumbscrew then you'll see the grub screws. 

Once these are undone, done take them all the way out, you can try the pliers again or get one of THESE, which is what I used for mine. They are also handy for changing the bearings on the worm gears.

If you're needing bearings then I got them from Simply Bearings.

This is the main RA axis bearing: SKF 60072RS1

The closest to the thrust bearing on the RA is the SKF 51107 but this is thicker than the SW bearing and you need to take some metal off the setting ring, so I didn't bother changing this one, I just cleaned it up and regreased it.

Worm Gear Bearings: 6862RS

I stripped, cleaned, changed the bearings and rebuilt the mount yesterday and it took 3-4 hours to do.

Edited February 28, 2021 by Budgie1
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[powerlord]

aha! I read a dissassebly guide for a similar mount, and it said there were grub screws and to look through the hole - but there were no holes around outside... except the one circle locking one which I completely didn't register as a hole. duh.🤪

so they are out. pliers still don't shift it, so as @Dr_Ju_ju above suggests, I'm CADing up a tool on the printer. It's M2 bolts btw

 

@Budgie1 thanks for the links - just what i need (probably). oh - btw I'm a regular to Fort William area for one of my other hobbies - paramotoring - flew over Ben Nevis 4 times so far... here's a video from a few years ago:

It was missing fine adjustment knobs too, so CADed up some replacements for those.

And as I had to replace the alt/asc bolts (one bent, the other naff) - I used stainless hexagon bolts. The rear one through the grinder to give a smooth ball. And I've CADed caps for those to make them easy to adjust too.

And I've CADed up an LED polarscope illuminator as well, since theres nothing to them, and I ain't paying 30 quid for that..

So - getting there. It's projects like this that the 3d printers really come into their own. 😃

stu

Edited February 28, 2021 by powerlord

[Budgie1]

Lovely bit of footage there Stu. The best I can do for views like that of this area is footage from my drone, but that hasn't been to the Ben yet because I only got it late 2019 and we couldn't go anywhere last year.

Glad you found the grub screw, once released it is a bit tight and may benefit from a drop of oil on the shaft thread as you remove it but you should be fine.

I found with mine that the worm gear bearings were notchy when they were taken off the mount but are nice and smooth with the new bearings in them. There's some really sticky grease in there so it should work a lot better with that replaced,  

Have fun with the rebuild.