HEQ5 worm bearings

[dph1nm]

A question for those who have stripped down their HEQ5 mounts:

Is the RA worm supposed to rotate ultra-smoothly in the worm housing? Because mine doesn't, and I suspect one or both bearings have gone. With the worm housing off the scope, if you rotate the end of the worm with your fingers then it 'sticks' at various points and feels very rough. There is no obviously play though.

I was hoping to get away without removing the worm bearings but ...

NigelM

[Astro_Baby]

The worm beariings, this is the worm roller end bearings. They are the worst part of the mount. The main bearings are usually of good quality but the end bearings for the worm rollers are usually the worst of the lot. They should just tap out quite easy though.

The wrom roller shoukd be smooth but it wont free wheel usually. The sticky points suggest either the end of the worm roller is a bit rough or the end bearings are shot or badly lubricated.

[dph1nm]

Better take them out then I guess. Any ideas on how to remove the end float locking ring? Mine seem far too tight for the two screwdriver trick.

NIgelM

[Astro_Baby]

Try the tw screwdriver trick. It will most likely work, it may be these retainers are too tight and that may be the source of your stickyness.

[dph1nm]

Finally managed to slacken the locking nut off with a pair of long-nosed pliers, and the worm rotates completely freely! So it looks like they were too tight.

NigelM

[dph1nm]

Just one further update. On my HEQ5 it is simply not possible to safely remove/refit the worm carrier with the worm in place. The clearance between the edge of the worm and the opposite side of the carrier is very slightly smaller than the diameter of the main brass gear. You have to release the worm, take out one of the bearings, then move the carrier. It might also be possible to remove the brass gear with the worm carrier in place, but I can't move the brass gear at all on mine, so I can't test that theory.

NigelM

[Astro_Baby]

Not sure I understand that, can ypu post a pic ?

[dph1nm]

Ah, unfortunately I have just reassembled it all. I had no trouble with the dec worm carrier, which could be lifted over the brass dec gear without any issue. However, the clearance of the ra worm carrier was about 0.25mm too small to pass over the ra brass gear ring. This was very apparent when adjusting the worm carrier set screws. The ra worm was pretty well engaged without the set screws in place (!) - the dec was very loose and took a lot of adjustment to get it to engage. I guess there is a certain tolerance in the production methods and mine was right on the limit.

Are the dec and ra worms identical by the way - I was wondering about swapping them round to see if the PE improved?

NigelM

[Tommohawk]

Are the dec and ra worms identical by the way - I was wondering about swapping them round to see if the PE improved?

NigelM

Hi All. I realise this is a bit of a dead thread, but the OPs final question was unanswered and I have the same question. Does anyone know if the RA and Dec worms are interchangeable?

[dph1nm]

Well I can tell you I never found out (and didn't swap them)!

NigelM

[Tommohawk]

Well after nearly 2 years of waiting I think you deserve an answer!

I've had the RA in bits a couple of times, but not the Dec. The width of the the dec assembly is the same, so I'm guessing the worm must be the same. Reason I'm interested is that depite re-adjusting and cleaning /lubing the tracking is still a bit patchy. This may be inevitable periodic error, and could maybe be improved with PE training, but I want to get the mechanics as good as possible before trying to apply fixes.

So when I have a moment - maybe one cloudy night (plenty to choose from) - I'll pull th dec to bits and try swapping. Course, it might be worse!

Cheers

Tom

[Tommohawk]

Quick follow on. Was looking for something unrelated and found this thread: http://www.iceinspace.com.au/forum/archive/index.php/t-89035.html

from which:

05-04-2012, 05:30 PM

Thanks Barry, I sort of did that but discovered the RA motor was buzzing, quite a bit. local (brisbane) service place is shut, all I could find on the web were motors in the UK for 80 quid, thats got to be $150 here, add labor and gas and its over a quarter of the price of the mount. You don't look through it while using the dec motor, so I pulled it to bits and swapped them around. It works in the kitchen, fingers crossed for tonight. My only concern is not having a clue how tight the gears are supposed to mesh, and since I did all of them it should be obvious early on if it was correct.
Thanks everyone for the assistance and will advise tomorrow morning if it worked.
Peter

So looks like the answer is yes, you can swap.

[Brian Nordstrom]

Better take them out then I guess. Any ideas on how to remove the end float locking ring? Mine seem far too tight for the two screwdriver trick.

NIgelM

Get a mate to help , 2 people make this job much easier , not to mention safer as you can stab your hand with a screw driver if you slip ,, I have the scar to prove it .

Brian .

[Tommohawk]

OK well I now have the answer to the question regarding RA and Dec assembly part swaps

It definitely is possible to swap RA and Dec worms, and the brass gear barrels upon which they bear, or indeed the entire worm housing.  Unfortunately its been cloudy ever since I did this last weekend, so no chance to check if its actually going to make any difference in my case. 

Hope that may help somebody out there!