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iOptron SmartEQ Mods and Partial Disassembly

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#26 *skyguy*

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Posted 31 October 2012 - 09:51 AM

I'm thinking a bad servo motor or 'stiction' in the gear train. Hopefully, iOptron will sort it out.


I own a good number of motorized equatorial mounts and the iOptron Smarteq has ... by far ... the strangest sounding drive of them all ... and loud! I find it very disconcerning to hear a loud "groan" then a soft "groan" then another loud "groan" then a soft "groan" .....! The mount certainly tracks well ... even at high powers ... with no discernible problems, at least for visual use. However, I do find the drive noise very strange ... or should I be kind and say "very unique?"

#27 russdirks

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Posted 31 October 2012 - 03:30 PM

skyguy, I noticed the same thing. After taking the above pictures, I disassembled a bit more to where I could see the stepper motor and attached gears. The motor has a shaft coming out both ends. On one end is the usual drive train, and on the other end was a type of sprocket with about 15 square'ish looking teeth, which I'm guessing is some kind of optical encoder. I powered up the mount and watched it operate. I had a good view of the encoder sprocket. During the relatively silent periods inbetween the "groans", as you put it, the sprocket was rotating in a nice uniform way. But during the "groans", the sprocket vibrated back and forth very rapidly, by about 10 - 30 degrees of rotation, all the while maintaining a somewhat regular rotation rate. So, in other words, it would advance one way a certain amount, then back-up the opposite direction, and so on, but always advancing more than it backed up. Mind you, the vibrations were faster than what the human eye can resolve, so I'm guessing slightly as to what was happening. I would assume it is a solid shaft going through the motor, which means the gear sets on the other side are being exposed to the same intense vibration. Over time I would think that could lead to some early failures of the gear sets, not to mention the motor itself. My guess is there is somekind of software/firmware bug in the driving algorithms. Hopefully iOptron is aware of this and can provide a fix eventually.

#28 Astronewb

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Posted 01 November 2012 - 08:51 AM

But during the "groans", the sprocket vibrated back and forth very rapidly, by about 10 - 30 degrees of rotation, all the while maintaining a somewhat regular rotation rate. So, in other words, it would advance one way a certain amount, then back-up the opposite direction, and so on, but always advancing more than it backed up.


Wow, nice diagnosis Russ, what you observed seems to perfectly match up with what I see when imaging. Putting 40 images into a video at 1 sec each shows the star field moving up and down (with corresponding star trails) just as you described the gear doing.

If the 'groaning' occurs at 1 1/2 to 4 minute random cycles, then my issue seems to be explained. First chance I get I'm going to duplicate what you did to see it first hand and time it.

Thanks..........!

Paul

#29 orlyandico

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Posted 01 November 2012 - 09:27 AM

it's not a stepper motor, it's a servo. and if the optical encoder on the other end has only 15 slots.. that's one low-resolution encoder (even worse than the old Meade DS).

if it has a tendency to stall / go forward/backward sometimes which causes trailing, that sounds like a problem in the servo control loop. Hopefully something that can be fixed in software....


by the way, Paul, your M31 is really darn impressive coming from an achromat, this mount, and 30-second exposures. You must have really dark skies, i'm envious :o

#30 Astronewb

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Posted 01 November 2012 - 10:00 AM

by the way, Paul, your M31 is really darn impressive coming from an achromat, this mount, and 30-second exposures. You must have really dark skies, i'm envious



Thanks, I live in a Bortle Orange zone. The skies are pretty good, but I have several street lights in the East which makes imaging in that sector a challenge. Long dew shields and a Baader ND filter helps a bit in that respect.

Best,

Paul

#31 EFT

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Posted 01 November 2012 - 10:30 AM

The problem could also be mechanical. The metal shafts stuck onto the end of a plastic worm assembly are very unlikely to be straight and could easily cause the worm to be binding during part of its rotation at which point the motor starts to strain which may in turn be triggering an electronics issue in regard to the power being supplied to the motor. I honestly can't believe that metal and plastic worm assembly. A cheap brass worm would have been far better, even with the plastic worm wheel.

#32 russdirks

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Posted 01 November 2012 - 11:33 AM

Paul,

Skyguy didn't specify for his mount, but on my mount, each 'groan' only lasts about 1 second, with about a 0.5 second of quiet inbetween. It's very regular ... sounds like someone snoring. So I don't know if that explains your tracking problem. Does your mount make any such noise, or does it run quietly?

orlyandico : You're right. Servo, not stepper motor. Should have caught that from the previous posts.

#33 *skyguy*

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Posted 01 November 2012 - 01:41 PM

My mount also "groans" at approximately 1 second intervals. As you slew the mount at progressively greater rates, the "groans" get faster until they blend together at the highest slew rate.

#34 EFT

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Posted 01 November 2012 - 01:46 PM

My mount also "groans" at approximately 1 second intervals. As you slew the mount at progressively greater rates, the "groans" get faster until they blend together at the highest slew rate.


If you can run it with the cover off so that you can watch the gears turning, you will likely see a wobble in the worm or spur/transfer gears that corresponds to this groaning.

#35 russdirks

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Posted 01 November 2012 - 01:53 PM

I can't do any further testing with my mount for a couple of weeks, as I had to send it back to iOptron to fix an unrelated problem. It should be in their hands next week, and I am definitely going to press them to examine this tracking issue in addition to fixing the original issue.

#36 Astronewb

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Posted 01 November 2012 - 02:16 PM

Paul,

Skyguy didn't specify for his mount, but on my mount, each 'groan' only lasts about 1 second, with about a 0.5 second of quiet inbetween. It's very regular ... sounds like someone snoring. So I don't know if that explains your tracking problem. Does your mount make any such noise, or does it run quietly?

orlyandico : You're right. Servo, not stepper motor. Should have caught that from the previous posts.


To be honest, in slewing, it sounds like a Swiss watch, very pleasant. I never really paid attention to the noises it makes when tracking..?

I posted the video of the tracking issue on Flickr, it's only 40 seconds long, but if you put your cursor on the larger star in the starfield it's obvious there is a problem. Full screen the video for the best effect.

Not a problem for visual observers granted, but even wide field AP'ers are going to have some issues with this going on...:)

http://www.flickr.co...011/8145500655/


Oh, just a note, I posted a comment in the iEQ45 mod thread about the polar scope. To remove all the funky play in the polar scope focuser, just wrap the threads with Teflon Pipe tape...it takes all the play out of it and makes it enjoyable to use.

Best,

Paul

#37 orlyandico

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Posted 01 November 2012 - 10:26 PM

Ed, I was going to comment on that plastic worm gear but you beat me to it.

Maybe it is one of these new structural plastics... could be better than the horrific worms and wheels put on EQ-1's and EQ-2's.

#38 EFT

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Posted 01 November 2012 - 11:36 PM

Ed, I was going to comment on that plastic worm gear but you beat me to it.

Maybe it is one of these new structural plastics... could be better than the horrific worms and wheels put on EQ-1's and EQ-2's.


There are some great plastics out there and some are very slick requiring very little lubrication. But fast wear and poor accuracy can be immediate issues if not done right and done with the best materials. It is good that the metal shaft goes all the way through the worm apparently. It is not good that the worm appears to be slid onto the worm and then jammed onto some grooves to lock it in place. It would be much better to form the plastic worm over the metal shaft and then hobb the worm right on the shaft. In addition, I would image that it is very likely that the worm wheel is simply molded platic where you would really want machined plastic, just like metal.

It's possible to do a lot of things with plastic now, but many things are simply made like the cheap plastic toys that have been made for years rather than manufactured with high-tech machinable plastics. Just wait until they start using 3D printers to make telescope mounts.

#39 *skyguy*

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Posted 02 November 2012 - 08:45 AM

Just wait until they start using 3D printers to make telescope mounts.


Is that like "wait good" or "wait bad"? ;)

#40 tango13

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Posted 27 January 2013 - 07:06 AM

[/quote]Yes George...Ive done some short exposure stuff with it, but my particular mount has some periodic error issues. Basically, 30-40% of my images over 30 seconds exhibit star trailing, like the drive motor is slowing or speeding up at random intervals. I took 40 images and put them in a video for iOptron to see the stars bouncing up and down, they have forwarded it to the engineers...no answer yet.
[/quote]
Hi Paul, nice to see you here too :)

After so many days of bad weather I finally managed to test my new SmartEQ Pro mount under the stars (well let's say under my almost fully illuminated urban sky... ;) )

Unfortunately, it hasn't been a very pleasant first test because I had quite a few problems, the worst of them being an awful tracking.

Has there been any answer from iOptron that solved your problem with your mount?
I'm asking because my mount seems to show exactly the same problem as yours, I've assembled a short video with a string of 40-second shots and I can see that the stars bounce back and forth forcing me to discard a whole lot of frames before stacking :confused:

I hope I can fix all the issues with my mount and enjoy using it in the future because it is hardly usable in this state... :(

Thank you.
Piero

#41 hectar

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Posted 27 January 2013 - 12:25 PM

The problem could also be mechanical. The metal shafts stuck onto the end of a plastic worm assembly are very unlikely to be straight and could easily cause the worm to be binding during part of its rotation at which point the motor starts to strain which may in turn be triggering an electronics issue in regard to the power being supplied to the motor. I honestly can't believe that metal and plastic worm assembly. A cheap brass worm would have been far better, even with the plastic worm wheel.

I would agree to that it could be mechanical problem. Either worm/spur shafts are not straight (bent) or gears are machined poorly. (noise is cyclic).
In the real world, if gears/shafts are large enough and you can access them easily, I would shut down the power, set a dial indicator on the shaft and check TIR's (Run out). It must not be more than 0.001"-0.002". You must take account of bearing play as well.
I would also check the back lash of each gear at 4 spots (set the dial on the teeth of one gear's teeh perpendicularly, jam/hold the other/opposite gear, then move/wiggle the first gear(with dial on it) back and forth, tiny bit, till you feel the stop. and read the dial). Repeat/rotate 90 degrees, do the same process again, and every reading must be consistant. say if you are getting 0.004", it should be same at every 90 degrees of rotation. If not, your gears are eccentric or teeth are worn out (or machined poorly if new).
ps: you can buy cheap dial indicators with magnetic base at local tool shops @30-40 bucks. They are good for larger gears, smaller ones like used in here will require additional extensions/setup.

#42 Jeff2011

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Posted 28 January 2013 - 11:12 PM

I was interested in this mount for a light weight portable mount for a DSLR and light refractor. I am not encouraged by the feedback y'all are providing. However, I noticed that the pro version comes with metal gears. Does anyone have the pro version and are you having the same tracking issue?

Jeff

#43 sgtcombs

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Posted 19 February 2014 - 11:53 AM

This just shows the locknut and short segment of screw that is used to sandwich the worm gear shaft.


I recently up graded my sEQ to the pro spec and the one issue I had was that there are little bearings on the end of the worm shafts, it took a spot o grease and a mr quickster to get it put together correctly. Did you have any issues?






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