Awful motor noise on EQ3 Pro motors...help / advice needed please

[dazzystar]

Hi All,

I picked up my EQ3 Pro and ST102 yesterday and have only just put the mount together. Is it normal for both motors to make an awful noise when initially moving (in either direction). I tried reducing the rate from max (9) to 7 and that doesn't help. The RA motor noise is even worse at this speed. Here's a small video (turn up the volume as I recorded it quite low). 

 

Cheers

Daz

[ONIKKINEN]

That sounds like backlash noises, quite similar in my EQM35 (very similar mount). The sound is from the gears in the transmission being slightly loose and racketing between themselves, ideally there would be no such sound but i cant completely get rid of mine without binding, although this sounds unnecessarily loud.

You can adjust this and its not that difficult. Pop out the motor covers with a philipshead screw driver and watch out for the tiny concrete soluble screw when pulling it out, if you drop it you'll never see it again. Loosen some of the allen head screws and try to bring the gears tighter together and then retighten the allen screws. Maybe not the best explanation but youll understand once you pop out the covers and see for yourself. You can put the hand controller to a low speed like 3 which makes it very easy to see the backlash, adjust it so that there is a minimum amount of it left. If you overtighten things you can get binding, which makes a horrible grinding noise and the motors stall. Dont sweat it though, stepper motors are not damaged from stalling and it only sounds bad.

You should probably adjust this even if the noise is not an issue since you will have inaccurate Go-tos with backlash that is so noticeable.

[Pete Presland]

It is louder than my EQ3-2, but you are running different motors to me. I also think it sounds like backlash maybe, when you change direction or initially start the motor. I don't think the sound when you slewing is much louder than my Atlas EQ6, but as @ONIKKINEN  has said worth looking at the backlash.

[dazzystar]

Thanks guys. I'll have a play tomorrow with it. Every single video I've watched their motors sound lovely!

[dazzystar]

Here's a pic of one of the motors and gears. I'm no engineer but it doesn't look right to me. Any advice appreciated!

[ONIKKINEN]

15 minutes ago, dazzystar said:

Here's a pic of one of the motors and gears. I'm no engineer but it doesn't look right to me. Any advice appreciated!

Its clearly not set properly. Loosen the screws holding the motor to the mount body, set it properly and retighten. Since this is the DEC axis motor, there is only 1 screw holding it to the mount body which is the allen screw visible in your first video.

[dazzystar]

Thanks for the reply. If only I could find a manual / video on how they should be set. I assume everything should be level at the very least?

[ONIKKINEN]

1 minute ago, dazzystar said:

Thanks for the reply. If only I could find a manual / video on how they should be set. I assume everything should be level at the very least?

Just loosen the screw a bit and wiggle the motor around, you'll see how it moves then. Press the motor assembly tightly against the other gear so that they are both leveled and do not have any extra play between them. As it is now they are clearly at an angle, which makes the gears bite improperly and have play between them. Then just tighten the screw again once good.

[dazzystar]

I tried that on the DEC motor quickly (I'm tired so didn't spend too long) and it made a very slight improvement but still produced this noise when starting off and coming to a stop. 

[malc-c]

12 hours ago, dazzystar said:

Thanks for the reply. If only I could find a manual / video on how they should be set. I assume everything should be level at the very least?

It would seem the motor has been pulled to tight to the mount, causing the gears to mis-align. They should all be in the same plane - The two lines in the image below need to be parallel.  Assuming the motor kit was for this mount then there should be no reason for them to get so misaligned, but inserting a couple of spacers / washers between the mount and the motor to permit the gears to be squared up may be needed

 

 

[dazzystar]

I'm going to align each motor as best I can and take a video of it in operation again. Thanks very much for the replies.

[dazzystar]

I've just taken the cover off the RA motor and this is what the gears look like:

 

 

[malc-c]

I don't have one of these mounts but that's clearly not right - they should mesh better than that !!

[dazzystar]

Here's a link to a video I just shot. I tried adjusting the position of the motor a little but there's not much wiggle room. 

I have noticed there's some small grub screws on the motor but no idea what they do and won't fiddle with them unless I'm told to. Also, the two grub screws on the small gear attached to the worm screw shaft were quite loose but I've since tightened them.

 

[dazzystar]

So. I allowed the motor to move without it contacting the gears and it would appear that it's making the noise. Here's another short video.

 

 

[dazzystar]

Here's yet another video showing the main gear attaching to the stepper motor gear. Is this wobble 'normal'?

 

[malc-c]

You'll get some noise when a stepper spools up, but it shouldn't sound like that.  Was the mount purchased new or second hand ?

If new then contact the seller and point them to these videos as clearly that motor sounds poorly (well compared to my HEQ5 it sounds more like a coffee grinder !).  I would be inclined to ask the retailer to issue an RMA and have them collect the mount with a view of replacing the drive kit.  If they collect the mount complete then they can make sure the new one is working before sending it back to you

[dazzystar]

I bought it used from a guy who says it was purchased last June. I'm still awaiting the receipt.

[malc-c]

20 minutes ago, dazzystar said:

I bought it used from a guy who says it was purchased last June. I'm still awaiting the receipt.

It doubt it will  be much use to you as I believe that under UK consumer law the contract is between the retailer and original purchaser, and warranties are not transferrable.

[ONIKKINEN]

I wouldn't worry about it. All of this happens on a brand new model. Either the previous owner didn't properly attach the motor assembly or this model won (lost?) the Skywatcher quality assurance lottery and was assembled by a monkey. Note that a lot of these mounts are assembled by monkeys.

This is also the DEC axis, which is not under constant motion and stress when in use so even less to worry about. When you do end up guiding this mount you may find that there is no way to guide DEC normally and you have to use one directional guide impulses or no guiding in DEC at all, so the DEC backlash issues are either fixed or mitigated. Note that this is not the main source of backlash with the model, the main source is the meshing between the worm gear and the worm drive itself and this you cannot completely adjust to perfection anyway. The weak DEC axis is why the EQ3 class of mounts is usually not recommended for astrophotography, and these issues would be part of the why.

But everything in the videos so far has been "normal" for the model, if a bit louder than mine though.

[malc-c]

1 minute ago, ONIKKINEN said:

I wouldn't worry about it. All of this happens on a brand new model. Either the previous owner didn't properly attach the motor assembly or this model won (lost?) the Skywatcher quality assurance lottery and was assembled by a monkey. Note that a lot of these mounts are assembled by monkeys.

But everything in the videos so far has been "normal" for the model, if a bit louder than mine though.

Really?? - Before I purchased my HEQ5 (second hand) I had a new EQ5 which uses a similar arrangement as the EQ3 motors and the meshing and clearances were a lot better.  The motors also didn't grate in the same way. - Maybe I was lucky and circa 10 years ago Skywatcher QC was better back then.

[ONIKKINEN]

Just now, malc-c said:

Really?? - Before I purchased my HEQ5 (second hand) I had a new EQ5 which uses a similar arrangement as the EQ3 motors and the meshing and clearances were a lot better.  The motors also didn't grate in the same way. - Maybe I was lucky and circa 10 years ago Skywatcher QC was better back then.

The EQ3 and 5 models of mount differ in design quite a bit, including motors. The EQM35 is basically an EQ3 with a slightly different RA axis and a removable DEC head, but the motors and transmission are the same. Rickety rackety gear sounds since day 1 👍.

[dazzystar]

7 minutes ago, malc-c said:

It doubt it will  be much use to you as I believe that under UK consumer law the contract is between the retailer and original purchaser, and warranties are not transferrable.

I hope that you're wrong as if that is the case that is completely and utterly unfair and I'm sure Skywatcher or the retailer (who I won't mention at the moment) would offer some form of assistance and help.

[dazzystar]

8 minutes ago, ONIKKINEN said:

I wouldn't worry about it. All of this happens on a brand new model. Either the previous owner didn't properly attach the motor assembly or this model won (lost?) the Skywatcher quality assurance lottery and was assembled by a monkey. Note that a lot of these mounts are assembled by monkeys.

This is also the DEC axis, which is not under constant motion and stress when in use so even less to worry about. When you do end up guiding this mount you may find that there is no way to guide DEC normally and you have to use one directional guide impulses or no guiding in DEC at all, so the DEC backlash issues are either fixed or mitigated. Note that this is not the main source of backlash with the model, the main source is the meshing between the worm gear and the worm drive itself and this you cannot completely adjust to perfection anyway. The weak DEC axis is why the EQ3 class of mounts is usually not recommended for astrophotography, and these issues would be part of the why.

But everything in the videos so far has been "normal" for the model, if a bit louder than mine though.

The motor noise is from both motors. Worst at slew rate of 7, and gets better the slower I adjust the rate.

[dazzystar]

Below is a reply from the UK distributor of Skywatcher regarding my issue with the motor noise. They reviewed all 4 videos I sent them of the issue.

'I have watched all the videos and I can really say these are within normal parameters as I have seen a great deal of these mounts working.
 
You get a start-up noise with this mount and other similar ones which is quite normal.
 
Sometimes when there is a fault with the PCB you get a really loud buzzing/vibrating sound – Before I saw the videos I thought that is what the customer was referring to but it is not the case here
 
Kind regards,
Robert'

The way I read the above is, 'our build quality isn't really that great and some mounts leave the factory with issues which we deem are within our quality parameters which are pretty much average for the cost of the product'...not great but nothing I can do except look for better products next time.