HEQ5Pro Bearing replacement

[TerryMcK]

My SW HEQ5Pro is a bit sticky in RA but not affecting the guiding too much - I can get around 0.7RMS minimum but hoping for a little better.

 

However I watched a YouTube video produced by astrobloke earlier on and is has spurred me on to do a bearing replace in the mount. It is about 2.5 to 3 years old and also occasionally develops "the knock" which I have tuned out from time to time. This is just the backlash in the worm drive and is easy to adjust. However I have wanted to replace the factory grease with some low temperature stuff so may as well overhaul the bearings at the same time.

 

So I have ordered:

• 4 x 689 2RS - the 2RS means 2 rubber seals
• 6 x SKF 6006 2RSR deep groove sealed bearings
• 2 x 30205 SKF roller bearings

 

My mount already has the Rowan belt mod kit installed.

[AstronomyUkraine]

25 minutes ago, TerryMcK said:

My SW HEQ5Pro is a bit sticky in RA but not affecting the guiding too much - I can get around 0.7RMS minimum but hoping for a little better.

 

However I watched a YouTube video produced by astrobloke earlier on and is has spurred me on to do a bearing replace in the mount. It is about 2.5 to 3 years old and also occasionally develops "the knock" which I have tuned out from time to time. This is just the backlash in the worm drive and is easy to adjust. However I have wanted to replace the factory grease with some low temperature stuff so may as well overhaul the bearings at the same time.

 

So I have ordered:

• 4 x 689 2RS - the 2RS means 2 rubber seals
• 6 x SKF 6006 2RSR deep groove sealed bearings
• 2 x 30205 SKF roller bearings

 

My mount already has the Rowan belt mod kit installed.

I should think it's relatively straightforward to replace the bearings in the HEQ5 compared to the EQ6. Access is way better for the HEQ5 than my EQ6, especially trying to feed the belts through the mount to connect to the motors. That's the fiddliest part of the job. I never replced the tapered roller bearings on my mount, they seemed to be in good shape, but I changed all the others.

 

I used this grease for my mount, it comes in two flavours, one for the worm gears etc, and one for the shafts. I found the mount gets stiff at -20° with this grease. I don't know the rating for it, but I suspect you won't be out in -20° too often in the UK. 😊

 

https://www.astroshop.eu/miscellaneous/geoptik-grease-for-equatorial-mount/p,48895#tab_bar_0_select

[paul]

I follow these HEQ5 threads with interest.

 

I must have struck lucky. I stripped down, cleaned and re-greased my HEQ5 using the Astro-baby guide probably 7+ years ago but otherwise kept it stock. It did remove some swarf and I got to replace some production damaged grub screws.  

 

With a light load (under 10kg) it guides better than the resolving power of scope+camera and its very rare I reject a frame due to guiding issues.  When I balanced my OO250mm on it that was a different story😀 (that combo was one of the reasons I lost interest for a few years).

 

[Padraic M]

@TerryMcK will be interested to hear how you get on. I bought a full set of SKFs. Replaced all bearings and re-greased the RA axis, but really didn't notice much difference. It took me so long to get the backlash and tuning corrected and back to where I was before I started, I didn't have the heart to tackle Dec. It's currently guiding around 0.5"-0.8" evenly in both Dec and RA so I don't particularly see the point. In fact if it did make a difference in Dec I would then have eggy stars!

 

You've got more experience tuning than me so hopefully you'll have a better result.

[TerryMcK]

I’ll keep you all informed as to how I get on Padraic

[TerryMcK]

So I started stripping down my HEQ5 Pro. One of the original  DEC bearings has issues. I noticed that the outer race moved quite independently of the inner race. Not talking about rotation which it is designed for but rocking in latitude.

I took it off the shaft and it didn’t have any manufacturers markings but did have the model type. Certainly not SKF or FAG quality.

 

Also there was a lot of grease inside the DEC housing, too much in my opinion. There was also some paint residue inside that hadn’t been removed at the factory.

It looks like Skywatcher quality control is a bit lax. Even though the design and manufacture of the parts is really good it is attention to detail they are not doing. Anyway when I have finished with it then it will be as it should have been when it left the factory.

[MarkAR]

Chinese manufacturing can be really hit and miss. One guy will wipe off a little dirt, another will leave his lunch in the mechanism.

[AstronomyUkraine]

18 hours ago, TerryMcK said:

It looks like Skywatcher quality control is a bit lax. Even though the design and manufacture of the parts is really good it is attention to detail they are not doing.

Are they still using that horrible black stuff they call grease in their mounts? I remember stripping my EQ6 down originally, it took 2 can of brake cleaner to remove all the grease from the mount.

[TerryMcK]

No it was just ordinary amber coloured grease. Just too much of it.

[AstronomyUkraine]

On 11/26/2021 at 9:50 PM, TerryMcK said:

No it was just ordinary amber coloured grease. Just too much of it.

I changed all my bearings around 18 months ago. I had one fail the other week, and I had another fail this week. They were both SKF bearings, but whether they were the Swedish version or the Chinese version, I don't know. Strangely enough, the failed bearings were in different axis, but both on the side of the worm shaft that holds the belt. The one I changed today, hadn't just failed, it was seized solid.

Edited November 28, 2021 by AstronomyUkraine

[TerryMcK]

Interesting.

I completed the whole bearing upgrade yesterday, also setting the worm drive backlash in both RA and DEC and it is now really smooth in both axis with no stiction.

The bearings are all Swedish SKF if the packets can be believed, the tapered roller bearings are made by Timken which I believe are USA made.

 

I’ve also taken the opportunity to reconfigure/simplify the cable management to ensure the head does not carry any devices/peripherals at all. The only extra thing that is on the moving part of the mount, on the RA part, is the voltage stabiliser. The mount will now carry just the scope in use at the time. I think I had previously added so much extraneous weight to the moving parts of the head it upset the balance and guiding.

Now the scopes balance really well in both axis and the cables no longer add to the resistance of movement. I have simply made larger loops. I have some open mesh split sleeving on order to encapsulate the cables.

[AstronomyUkraine]

11 hours ago, TerryMcK said:

he bearings are all Swedish SKF if the packets can be believed, the tapered roller bearings are made by Timken which I believe are USA made.

The bearings I purchased, have made in Italy on the packet, and SKF do have a factory in Italy. I find it strange that SKF bearings fail after 18 months. It's not as though there is a massive load on them, or they are overused. I was trying to read the writing stamped on the bearings, but it's that small I would need a microscope to read the print.

Edited November 29, 2021 by AstronomyUkraine

[TerryMcK]

Bearings do fail but as you say failure after 18 months of low speed loading is unusual.

The unknown manufacturer factory fitted bearings that I removed from my mount have play between the inner race and outer race on a couple of them. Again low speed, relatively low loading but moderate wear after about 2 1/2 years of intermittent usage. I didn't see any black particles in the grease so probably not worn so much that metal wear was leaching out.

One of the small bearings that holds the worm drive shaft had a bit of a click at one point in its revolution so replacement was probably a good idea at this stage. I used some Loctite Super Lube PTFE based grease which is supposed to work over a wide temperature range -23°C to 176°C  not that it ever gets remotely as low as that in the UK. Of course the higher temperatures are when the bearings are in something like a motor that run at hot temperatures.

[AstronomyUkraine]

27 minutes ago, TerryMcK said:

One of the small bearings that holds the worm drive shaft had a bit of a click at one point in its revolution so replacement was probably a good idea at this stage.

That was the exact problem I had in one of the bearings in my ra axis, I changed both while I already had it stripped down. The bearing I changed in the Dec axis had just seized solid. The scope was actually vibrating as I slewed the Dec axis, it was that bad. I opened the bearing up, but couldn't see what the problem was.

[TerryMcK]

Guiding has improved immensely since changing the bearings, cleaning out excess grease, replacing it with PTFE based grease and also removing excess mass from the moving bits.

The balance is so much easier to achieve in all axis and I seem to have average guiding at about 0.6" RMS total - occasionally dropping well below that. It was previously just over 1" and only ever dropped below that when the seeing was very good.

 

 

[TerryMcK]

If anybody is interested I followed AstroBlokes excellent video on the subject of Hypertuning the HEQ5Pro