"Hypertuning" my HEQ5 Pro mount

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
Post Reply
thesmiths
Im an EXPERT!
Im an EXPERT!
Posts: 356
Joined: Mon Jun 04, 2012 8:13 pm
Has thanked: 7 times
Been thanked: 223 times

"Hypertuning" my HEQ5 Pro mount

Post by thesmiths »

I spent a full day recently doing a "hypertuning" of my SkyWatcher HEQ5 Pro mount. The HEQ5 Pro mount is widely sold (sometimes under a different name in some countries) and is a very capable mid-level mount. It is a very adequate mount for telescopes up to about a 4 inch refractor and I have even put a Celestron 9.25 on it for planetary imaging.

The version I have was bought new in April 2010 and is the all white version that is still sold today. Over time, the fast slewing became louder and both the RA and DEC axes became a bit "wobbly". At this point, I would like to make a distinction between what I call "tuning" and "hypertuning".

It is possible to make some fairly simple adjustments to readjust the motor gears to quiet the loud noises while fast slewing; tighten up the worm carriers to eliminate wobble; and to adjust the position of the worm carriers with respect to main drive gears to reduce backlash -- these improvements I will refer to as "tuning".

What I call "hypertuning" involves additional steps that are more involved and challenging but will give a better final result. However, I would not recommend doing "hypertuning" yourself unless you are very capable with mechanical things, have a fair amount of physical strength, a lot of patience and attention to detail, and sufficient room to disassemble a fairly complex and greasy machine (which may potentially end up being in a state of disassembly for a few days). "Hypertuning" involves doing a Rowan belt upgrade (some mounts may have this already), disassembling the mount, replacing the bearings of the worm carrier, removing old grease and putting in new grease, repositioning the worm carrier, and reassembling the mount. Replacement of other bearings may also be necessary if some are found to be defective.

A very plausible course of action is to first do a "tuning" and then later do a "hypertuning" if necessary or desired. This is actually what I did. By doing a "tuning" first, it will give you familiarity with how the mount works and you will have more confidence undertaking a full "hypertuning". Next, you can do the Rowan belt upgrade, which will give you more confidence and will improve the performance some more. Finally, if you are very adventurous and are searching for perfection, you can attempt the "hypertune".

My key recommendations before embarking on either "tuning" or "hypertuning" is study what needs to be done beforehand (references provided below); order the necessary parts, materials and tools; make some free time for yourself, and of course plan downtime for your mount. One key tool that you should acquire is what's called a "lens spanner". These are readily available from Amazon or eBay and will be very helpful to disassemble and reassemble certain parts. A lens spanner is very useful for many telescope and optical projects so is a worthwhile investment.

A lens spanner from the company Neewer. Very useful for disassembly and retightening of the worm carrier, in particular.
A lens spanner from the company Neewer. Very useful for disassembly and retightening of the worm carrier, in particular.
lens-spanner.jpg (23.96 KiB) Viewed 89 times

Video references: for projects like this, watching YouTube videos is a lot more instructive than reading an article. So I highly recommend watching the following three videos (there are actually not many more videos on this subject). Each one takes a slightly different approach and I have some disagreements with each of them. But by watching all of them you will end up having a good familiarity with the internal construction of the mount and the steps for disassembly and reassembly.


Video 1: Astrobloke


Video 2: Martin's Astrophotography


Video 3: Ivan Ionov

The videos are listed in the order I would recommend watching. I suggest viewing at 1.5x speed and for the third one, which is in Russian, turning on the auto-translate subtitles.

The best (and the original) write up for this process is by Mel (Astrobaby): https://www.astro-baby.com/astrobaby/he ... ius-mount/. However, I found the videos to be a lot easier to follow and each of the YouTubers have added some interesting hints and instructions on how to solve particular problems they found along the way. Another useful reference is by David at Dark Frame Optics: https://www.darkframeoptics.com/product ... mount-tune. His business does mount repair and upgrades and his website has a lot of interesting information on why you would want to do a "hypertune".

One thing I discovered while taking apart the HEQ5 Pro is how good the components are and how generally well put together it is. The main axial (RA and DEC) shafts each have 3 very large deep groove ball bearings (30mm ID, 55mm OD, 13mm wide) along their length and a large tapered roller bearing at the end (25mm ID, 52mm OD, 16.25mm wide). The main gears are made from massive pieces of brass and the worm gears are made from stainless steel (in cheaper mounts, the worm gear is brass and the main gear is aluminium). The large ball bearings in my mount looked to be of good quality and in good condition and did not need to be replaced. [These large ball bearings are designed to operate at hundreds of RPM, with hundreds of pounds of load. In a mount, they might do a few hundred rotations per year under a load of tens of pounds.]

There are a pair of small ball bearings on each worm gear that I would recommend replacing. They of course rotate much more often than the large bearings and also are under a lot of radial force in order to keep the worm gear engaged. They seemed to feel a bit rough while the large ones felt very smooth. The part number to replace the small ones is "689 2RS ceramic hybrid ball bearing". I bought them from https://www.bearings-online.co.uk/ and the cost was quite modest (a total of 4 are required).

Replacement ball bearings (from video 1). Only the small ones typically need replacing, in my opinion.
Replacement ball bearings (from video 1). Only the small ones typically need replacing, in my opinion.
ball bearings.JPG (55.48 KiB) Viewed 89 times

The part numbers for the large bearings are 6006 2RS1 (total of 6 required) and 30205M (2 required). I would actually recommend not even removing the 3 large deep groove ball bearings from their housings as they are tricky to remove and reinsert. If any of them are damaged (for example, if they are leaking), they should of course be replaced. But I would not bother to repack them with grease (as shown in video 2 above).

The large tapered roller bearing at the bottom of each axis will typically fall out when the axis is removed. These are the Timken ones in the photo above. There is an outside sleeve that does not need to be removed (unless the whole roller bearing needs to be replaced, which I think will be very rare). The inside roller bearing can be cleaned with a degreaser and new grease can be reapplied.

Speaking of grease, there is some debate about which kind of grease to use. For a long time, standard lithium grease was typically recommended. More recently, it seems synthetic grease is preferred. I chose to use "Loctite Synthetic Superlube Grease". The advantage seems to be that it behaves better at low temperatures (which of course is quite a common condition in astronomy), while many other greases are optimised to work at higher temperatures and therefore become too thick at cold temperatures. The Superlube grease that I used was also quite clean and transparent and did not make as much of a mess as normal grease. It was, however, quite a bit more expensive than a typical lithium grease.

Stiffness in the main axes seems to usually be caused by old grease that has hardened with time. When you remove the main axes, it's easy to wipe off the old grease with paper towels. I thoroughly degreased and cleaned the stainless steel worm gear and replaced the small 689 ball bearings. I didn't think the main brass gear needed extensive degreasing. When reapplying grease, I turned the worm gear such that the main gear rotated through 360 degrees, then wiped off any excessive grease (too much grease is also not a good idea).

It is recommended to start with the DEC axis since this is easier to disassemble and reassemble. Once you have done DEC, you can proceed to the RA axis; this can be done on a different day, if desired. There are some rotational locking screws on the RA axis that can be hard to difficult to remove. The videos above show a few tricks on how to remove certain parts so if you get stuck, go to the parts of the videos for some suggestions. Be very careful not to damage anything though and I would be very wary of using a hammer for anything at all. By the way, I would suggest trying to do as much as possible with the mount attached to the tripod.

Another important thing to keep track of are the thin plastic washers that go around the main axels. These are actually spacers that provide for the proper height of the worm gear with respect to the main brass gear. They therefore need to be put back in the right location (there may be more than one of them, by the way, and they might be transparent, which then makes them easy to misplace).

Thin plastic washers that are important not to misplace or forget where they go during reassembly (from video 1).
Thin plastic washers that are important not to misplace or forget where they go during reassembly (from video 1).
plastic washers.JPG (28.29 KiB) Viewed 89 times

One of the important points that is not emphasised enough in the videos is the proper tightening of the end screw that holds the worm gear in its carrier. This should be tight enough to prevent "wobble" but not too tight such that the worm gear does not rotate freely.

Work carrier end screw adjustment (from video 1). Here a flathead screw driver is used -- I would recommend using a lens spanner.
Work carrier end screw adjustment (from video 1). Here a flathead screw driver is used -- I would recommend using a lens spanner.
worm carrier.JPG (37.16 KiB) Viewed 89 times

A critical step is repositioning the worm gear to minimise backlash. My trick is to push the stainless steel worm gear firmly with your fingers against the main brass gear and tighten the 3 bolts which lock the worm carrier in place. Then turn the gear that connects to the motors with your fingers. You should be able to turn this fairly easily and thereby rotate the axis. You can then make some very minor adjustments with the two adjustment screws on each side (you need to loosen the position bolts slightly in order to allow the worm carrier to slide). The idea of the two adjustment screws is you screw in one and screw out the opposite one, thereby displacing the worm carrier. This has the effect of changing the pressure of the worm gear against the main gear. By turning the "motor gear" with your fingers, you can quite accurately feel if there is any backlash and, on the other extreme, if the pressure is too high and the rotation is excessively stiff. Make sure to remember to retighten the three position bolts (it should not be the case that the two small adjustment screws are holding the worm carrier in place -- they are just for positioning). Note that retightening the three large bolts can shift the position slightly so you need to check if the worm gear still moves nicely -- with no noticeable backlash but also not too tight. You may have to repeat this a few times because of the shift in the final retightening.

Stainless steel worm gear, brass main gear and (red) plastic spacer washer (from video 1). Turn the motor gear with fingers to ensure everything is turning smoothly. The two small adjustment grub screws are visible at the top and bottom of the worm carrier. The three large holes at the perimeter are for the bolts that lock the worm carrier in place. Make sure there's no excess paint on the sliding surfaces or it will make adjust more difficult.
Stainless steel worm gear, brass main gear and (red) plastic spacer washer (from video 1). Turn the motor gear with fingers to ensure everything is turning smoothly. The two small adjustment grub screws are visible at the top and bottom of the worm carrier. The three large holes at the perimeter are for the bolts that lock the worm carrier in place. Make sure there's no excess paint on the sliding surfaces or it will make adjust more difficult.
worm carrier reassembled.JPG (25.15 KiB) Viewed 89 times

When everything feels right when turning the motor gear by hand, you can reconnect the motors and see how the mount moves under high speed slewing. My experience is if it feels good under "finger slewing", the mount will work fine with the motors attached. With the clutches locked, check if there is any "wobble" by trying to shake the axes in RA and DEC. I find this is the final adjustment and you can only sense wobble when everything is reassembled and you can get a good grip on the mount. If there is wobble, the worm carrier retaining screws can be tightened very slightly using a lens spanner even when the whole mount has been reassembled (they are under the little round black rubber covers). But, again, be very careful not to overtighten. Best to check with a finger turning test (remove the belt to the motors to do this).

After the tuning and hypertuning my mount, the axes now move much more freely and with no wobble or noticeable backlash. The mount is also now significantly quieter. If you have any questions or need some clarifications, please enter them as comments below and I will attempt to answer them.
Last edited by thesmiths on Tue Nov 30, 2021 1:58 pm, edited 1 time in total.


User avatar
marktownley
Librarian
Librarian
Posts: 32610
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 6263 times
Been thanked: 2955 times
Contact:

Re: "Hypertuning" my HEQ5 Pro mount

Post by marktownley »

Doug, this is an excellent write up, thank you very much!

I did a 'tune' of my EQ6 in february earlier this year and is very much worth doing, for me the important bit was having a long enough block of free time to do it in. I'm very much considering the Rowan mod on it this coming february (february is just a good time for me doing jobs like this - I have a week off work and the weather is normally awful so no chance of any astro).

I'm also glad to hear you're pleased with your EQ5. I'm very much considering one for a larger travel mount. I have the AZ GTI and also the solar quest, which is good up to about 80mm with my fracs, but that is pushing it, but are looking for something portable (to take away on the boat) to mount my new 100/800 apo and also potentially the 8" HaT, where I can seek out better skies than my urban home... I suspect a tune and a hypertune with the EQ5 would give it that bit extra that might be needed for using the larger scopes above.

I don't have questions now, but you may fine me asking early next year ;)

Mark


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
thesmiths
Im an EXPERT!
Im an EXPERT!
Posts: 356
Joined: Mon Jun 04, 2012 8:13 pm
Has thanked: 7 times
Been thanked: 223 times

Re: "Hypertuning" my HEQ5 Pro mount

Post by thesmiths »

Hi Mark, the newer EQ6-R PRO now comes with belts but older ones likely would benefit from a Rowan belt mod.

I think the HEQ5 and EQ5 are built rather differently inside, from what I can see from the tear downs on YouTube. The HEQ5 has a brass main gear and stainless steel worm gear, along with 4 ball bearings on each axel. The EQ5 seems to have an aluminium main gear, a brass worm gear and 2 ball bearings on each axel. The HEQ5 is essentially a smaller version of the EQ6. The EQ5 is basically a copy of the Vixen GP2. For a 100mm APO and a 8inch SCT, I would go with the HEQ5.

By the way, maybe this writeup can be put in the Solar Reference Library at some point?


User avatar
marktownley
Librarian
Librarian
Posts: 32610
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 6263 times
Been thanked: 2955 times
Contact:

Re: "Hypertuning" my HEQ5 Pro mount

Post by marktownley »

Thanks Douglas, yes, we'll definitely get a copy in the library.


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
Post Reply