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Skipper Billy

Sizes of bearings for HEQ5/Orion Sirius ???

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I would like to replace all the bearings in my HEQ5/Orion Sirius with really high quality ones.

Anyone know of anywhere I can find the sizes of whats required ???? 

I really don't want to strip it to measure them then order them as that would guarantee a succession of clear nights whilst its out of action !!!!!!

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It will always be clear while you strip the mount - thats a given :)  Bear in mind that although strip down can be done in a day, getting the mount tuned can be hard work - the first time I did it it took about three days of messing about to get it tuned really well.  The RA is really tough to get right on the HEQ5 - on the EQ6 its usually the DEC which is the tougher of the two to get tuned perfect.

The HEQ5 Pro uses 6006Z bearings - the taper bearing is weird and I have never found a replacement for that but I also haven't looked very hard either :) To be honest the standard bearings were ok in mine and the few EQ6s I have built have had good bearings as well apart from a very old one I did for someone whose bearings were very badly mashed up thanks to misuse.

I have reservations over super high quality bearings and heres why.......

A lot of stuff is talked about replacing with super high spec ceramic bearings but ceramic does not work optimally in cold conditions - most telescope mounts will be cold unless you plan on rotating them at 10,000rpm :) 

If you have a look at an EQ6 build I did called 'The Demon Mount' you can see that almost every aspect of the mount was bad, mased up washers, busted bearings, scored up shafts and filled with something that resembled caulking...despite all this the mount ran within the tolerances that most would consider acceptable.  Any piece of engineering that can run like this is clearly not super precision and therefore any extra precision in the bearings is unlikely to make a huge difference.  In short of something is engineered to 1/100th putting in stuff thats engineered to 1/1000 probably wont make much difference.

I much wary of claims of hypertuning because no solid evidence is ever offered that would show a quantifiable improvement.  Adding some ceramic bearings wont turn an HEQ5 into a Losmandy.

Now none of thats a counsel of despair.  the average HEQ5/EQ6 is built to a budget at the factory and the factory isn't in the business of turning out super tuned mounts so they run on averages - from the factory they will be neither terribly bad or amazingly good - though you may get the one in a thousand thats absolutely perfect of course.  Lets face it most of these mounts will be bought by people who never use them so it makes no sense of SKywatcher (or anyone else) to super tune stuff for mass market consumption.

Most of the strip down guides (mine included) came from a period when the QC on the mounts was potentially suspect (mine for instance had swarf and stray rubbish inside and the grease was hideous).  The grease by the way makes perfect sense from the factories point of view - thick heavy grease with glue like consistency makes for a quiet mount that pleases the customer in a shop rather like  a second hand car dealer filling the engine with STP or babananas it quietens down a rattly engine.

A rebuild can improve the operating characteristics of these mounts and careful worm turning will provide a quieter and smoother mount, mine is exceptionally quiet after two rebuilds (or is it three) with the grease replaced by a high quality synthetic lithium so it is worth doing (especially if its an older mount) but a new mount I have messed with ran damn near perfect out the box so QC at the factory is undoubtedly improved and for that mount my advice to its owner was leave well alone - we did just tweak its DEC worm tuning to get it a bit slicker but thats it.

By all accounts new mounts have better grease from the factory and I suspect better bearings too - my own HEQ5 had identical SKC bearings to the spares I bought for someone else.

So I guess what I am saying is don't do it unless you need to and be wary of bearing replacements as you may see no real advantage.

Edited by Astro_Baby
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I replaced all the bearings in my HEQ5.

Two of the original 6006 were very rough.

The taper rollers were ok but did replace them and the tiny worm bearings as well.

As above it took me a few goes to tweak the mount to get the best out of it.

Don't over tighten the tapered ones, it's easy to do.

I deal with bearing replacement on a daily basis at work so it was'nt to hard for me.

Don't buy C3 get just normal clearance bearings.

Massed produced bearings vary quite a bit in quality and tolerance so go for a known make

like FAG or SKF......Timken for the taper ones.

There are super precision bearings out there but they cost an arm and a leg and won't really help

in this case.

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Many thanks for the comprehensive and informative replies.

I have seen some SKF bearings that are designed for high load, low rotational speeds which sounds ideal for a mount - they aren't super precision but having experienced SKF bearings they will no doubt be pretty good.

I think I will leave it until the summer when we have 5 months of no imaging opportunities and strip it and clean it in slow time rather than rush it. At the moment I have a smooth guiding graph and round stars so perhaps best left alone although I am a compulsive tinkerer !!!

I know that changing the bearings wont turn it into a Losmandy but whilst its in bits it seems sensible to replace the bearings rather than put the old ones back in given that they are so cheap.

AstroBaby - I have downloaded your excellent guide and used it to hugely improve my tracking graphs - excellent piece of work - thank you!!

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It may be worth noting that ball and taper bearings are designed for high speed and continuous use - around 500rpm and upwards for at least an hour at a time.  They are not designed for telescopes!  We are likely to require 500 complete revolutions in a lifetime and at a rate of 1 rev per day!

The only reason they are used is for cheapness - its far cheaper than making a bronze/hardened steel bearing and hand scraping the surfaces to  a perfect fit.  The rest is just sales pitch from the manufacturers.

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Actually - I am going to backtrack a bit - the bearings thats are worth changing are the worm roller bearings - the teeny ones at the end of each worm - on my HEQ5 these were dreadful and nasty - changed for SKF ones (typo in my first post had them as SKC). Roger is right on this - bearings in a scope are hardly likley to ever even get close to their limits - 1 rev per day is hardly taxing :)

Interestingly my eldest asked me on the last rebuild why I am bothering to put any grease in at all given the very low speed and the fact the bearings run freer with none and it got me thinking that perhaps very light grease might work best of all - I aim to try that at some point - a very low viscosity grease and veey little of it on the next rebuild.

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Actually - I am going to backtrack a bit - the bearings thats are worth changing are the worm roller bearings - the teeny ones at the end of each worm - on my HEQ5 these were dreadful and nasty - changed for SKF ones (typo in my first post had them as SKC). Roger is right on this - bearings in a scope are hardly likley to ever even get close to their limits - 1 rev per day is hardly taxing :)

Interestingly my eldest asked me on the last rebuild why I am bothering to put any grease in at all given the very low speed and the fact the bearings run freer with none and it got me thinking that perhaps very light grease might work best of all - I aim to try that at some point - a very low viscosity grease and veey little of it on the next rebuild.

  

Many thanks for the comprehensive and informative replies.

I have seen some SKF bearings that are designed for high load, low rotational speeds which sounds ideal for a mount - they aren't super precision but having experienced SKF bearings they will no doubt be pretty good.

I think I will leave it until the summer when we have 5 months of no imaging opportunities and strip it and clean it in slow time rather than rush it. At the moment I have a smooth guiding graph and round stars so perhaps best left alone although I am a compulsive tinkerer !!!

I know that changing the bearings wont turn it into a Losmandy but whilst its in bits it seems sensible to replace the bearings rather than put the old ones back in given that they are so cheap.

AstroBaby - I have downloaded your excellent guide and used it to hugely improve my tracking graphs - excellent piece of work - thank you!!

Hi Skipper Billy, just to add to Astrobaby's comprehensive answer, if you search my threads I did one on the replacements for the worm drive bearings. I found the originals to be causing spikes in the guiding trace. There are photos of the required bearings in the thread.

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I replaced all the bearings in my HEQ5.

Two of the original 6006 were very rough.

The taper rollers were ok but did replace them and the tiny worm bearings as well.

Actually - I am going to backtrack a bit - the bearings thats are worth changing are the worm roller bearings - the teeny ones at the end of each worm - on my HEQ5 these were dreadful and nasty - changed for SKF ones (typo in my first post had them as SKC). Roger is right on this - bearings in a scope are hardly likley to ever even get close to their limits - 1 rev per day is hardly taxing :)

   Hi Skipper Billy, just to add to Astrobaby's comprehensive answer, if you search my threads I did one on the replacements for the worm drive bearings. I found the originals to be causing spikes in the guiding trace. There are photos of the required bearings in the thread.

Hi all! Considering Skipper Billy's original question: would it be possible for you to list the replacement bearings types? I've been searching for such a list for some hours now, so I think it would be a very useful resource in general and hopefully not very much work to list them.

Edited by Apharov

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Just to add some things I found.

Based on Astro_Baby's rebuild guide it seems the bearings are as follows:

RA - 3 x roller bearing, 1 x tapered bearing

RA worm - 2 x small bearing

DEC - 2 x roller bearing, 1 x tapered bearing

DEC worm - 2 x small bearing

Adding the information from StarMich's old post at http://stargazerslounge.com/topic/103685-hypertuning-the-heq5-pro/, suitable bearings would be as follows:

roller bearing = SKF 60062Z Metal Shielded Deep Groove Ball Bearing 30x55x13mm

tapered bearing = SKF 30205J2Q Metric Single Row Taper Roller Bearing 25x52x16.25mm

small worm bearing = 6892Z Metal Shielded Deep Groove Ball Bearing 9x17x5mm (?)

Does this part list seem accurate to you?

Edited by Apharov

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The small worm bearing required is a 689-ZZ type.  They are less than £5 a pair including postage from Simply Bearings in the UK.

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The small worm bearing required is a 689-ZZ type.  They are less than £5 a pair including postage from Simply Bearings in the UK.

Thanks, I've now ordered the bearings I listed in the previous post. I'll get back once I see if they're the correct fit.

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