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iOptron SmartEQ Mods and Partial Disassembly

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#1 russdirks

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Posted 24 October 2012 - 11:44 PM

Hello all,

Just got the SmartEQ mount from iOptron, upon which I mounted a used NexStar 4GT that I got for cheap. It's my first telescope after being out of the hobby for about 20 years.

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#2 russdirks

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Posted 24 October 2012 - 11:47 PM

The main points of my post are:
  • How I improved the rigidity of the tripod
  • How I addressed the problem of the tripod extensions slipping under weight
  • How I got rid of some slop/play in the RA axis
  • What those 4 nuts/set screws are for on the outside of the drive case


#3 russdirks

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Posted 24 October 2012 - 11:49 PM

Wobbly Tripod

After reading of others who had done the same, I decided to epoxy the plastic couplings that are at either end of the top tube, to the tube itself. The single screw that is present just doesn't provide enough rigidity. The epoxy made a very significant difference. Before the epoxy, I would have given the tripod a 2 out of 10 for rigidity and strength, considering the kinds of loads it is claiming to be able to handle. After the epoxy, I would give it an 8 out of 10.

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#4 russdirks

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Posted 24 October 2012 - 11:49 PM

...

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#5 russdirks

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Posted 24 October 2012 - 11:51 PM

Just a couple of things I found helpful.
  • I glued the bottom coupler on first, after completely removing the bottom sliding tube. This allowed me to clean excess glue that oozed out into the inside of the coupler. A paper towel soaked in alcohol worked great for that. (Alcohol dissolves epoxy when it is still wet.
  • I applied the epoxy to the inside of the coupler, and then inserted the tube. This would push some of the glue further into the coupler, with little left at the end of the coupler, where you want it the most to really lock the coupler onto the tube. So after inserting the tube, I put a glob of epoxy onto the ledge of the coupler and then used a heat gun to warm it (which makes it runny) so it would seep down into the coupler and run nicely around the edge.


#6 russdirks

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Posted 24 October 2012 - 11:55 PM

Tripod Extensions Slipping

Others have reported that the tripod extensions collapse/slip under very little weight. One forum member used a clamp, which I'm sure works great. After looking closely at the tripod, though, I determined that the problem with my tripod is that the thumb screws don't have enough thread on them. The shoulder of the thumb screw contacts the lug on the coupler before you can get any decent pressure on the leg extension. The simple solution was to use a sharp knife to remove a couple of millimeters of plastic off the shoulder of the thumb screw. Now I can put much more pressure on the leg, and it doesn't slip near as much. Ie. it's much better, but still not perfect. Good enough for the kind of weight I will be putting on a tripod like this.

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#7 russdirks

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Posted 24 October 2012 - 11:57 PM

Too much play in RA axis

I hadn't noticed it before, with the tripod being so wobbly, but once I got that fixed up, I noticed that there was a fair bit of play in the RA axis, even with the friction lock on as tight as I could get it. I wasn't sure if it was a natural consequence of nylon gears, or whether some of the gears were a bit loose or out of adjustment. Since I had to partially disassemble the mount to deal with some electronic problems I was (and still am) working through with iOptron customer support (who have been great so far), I thought I would dig a little deeper to see where the sloppiness was coming from. First some disassembly pictures for those that might be interested:

The top cover comes off with 4 screws:

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#8 russdirks

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Posted 24 October 2012 - 11:58 PM

There are 4 connectors you have to disconnect, then you can set the cover aside:

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#9 russdirks

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Posted 24 October 2012 - 11:59 PM

The DEC shaft:

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#10 russdirks

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Posted 24 October 2012 - 11:59 PM

Next remove the 4 screws from the bottom. This allows you to remove the entire DEC head, housing and shaft. Be careful … there are thin washers in between the two parts of the housing. They easy to miss and lose.

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#11 russdirks

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Posted 25 October 2012 - 12:00 AM

Pictures with the DEC assembly removed:

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#12 russdirks

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Posted 25 October 2012 - 12:01 AM

another:

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#13 russdirks

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Posted 25 October 2012 - 12:01 AM

I started looking closely at the shaft with the RA worm gear on it. At first I thought it was one complete shaft all the way from one side of the case to the other, but then I realized there are 3 pieces: the shaft in the middle with the worm gear, and two short pieces that but against the middle piece from either end.

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#14 russdirks

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Posted 25 October 2012 - 12:02 AM

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

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#15 russdirks

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Posted 25 October 2012 - 12:03 AM

By loosening the locknut, you can either increase or decrease pressure on the worm gear shaft. In my case, a slight increase in pressure removed the excess play I was experiencing. I would caution against tightening too much. I found that only a light pressure is needed to remove excess play.

I found a problem though. I was experimenting with different amounts of pressure on the right hand set screw, and found that after a certain point, increasing pressure began to introduce excess play in the gears. At first I couldn't figure out why, but then I saw it. There is a small triangular brace that is too close to the set screw. (See below). As you tighten the set screw, the threads and outer portion of the set screw comes into contact with that brace, driving the whole assembly away from the main gear, creating excess play. I thought about carving a bit of that brace away, or grinding the tip of the set screw a bit, but in the end found that by putting minimal pressure on the right-hand set screw, and using the left-hand set screw to add a bit more pressure, I could get a setup where there was no discernible play in the gears, so I just left it that way. Not feeling too adventurous I guess. ;)

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#16 russdirks

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Posted 25 October 2012 - 12:03 AM

You can see below that the DEC worm gear shaft assembly has the same triangular brace, except it is on the left hand side. I didn't experiment at all with the tension on the DEC set screws, so I don't know if the same kind of interference exists.

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#17 russdirks

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Posted 25 October 2012 - 12:04 AM

So, if you notice any excess play in either axis that you think is coming from the gear assembly, you might want to try loosening the locknuts and checking to see if a little extra pressure cures the problem. The nice thing is you don't have to take anything apart. The adjustments are totally external.

That's all for now.

#18 *skyguy*

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Posted 25 October 2012 - 09:17 AM

Great job with the disassembly instructions and images on your Smarteq mount. I just bought one several weeks ago and it's nice to see how easy it is to adjust the drivetrain. After using small GOTO mounts from Meade and Celestron that had excessive amounts of backlash, I was surprised to see how well the drivetrain "slop" was controlled in my Smarteq. Maybe I "lucked out" with a well adjusted mount! :)

Thanks for the post ....

#19 Astronewb

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Posted 25 October 2012 - 10:56 PM

Very nice thread, thanks for all the images and explanations, it's very useful. Oh, dont forget to get a 5mm/25mm cap screw or knob for your top mounting plate..I see you have a hole, mine didn't have a set screw in it, had to install a cap screw to remove all the vertical play it caused with an OTA in place.

Clear skies,

Paul

#20 russdirks

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Posted 25 October 2012 - 11:51 PM

Just picked up one today, actually! I saw your thread over on the other astronomy site.

#21 ghataa

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Posted 26 October 2012 - 05:52 AM

Has anyone tried AP with his mount yet?

George

#22 *skyguy*

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Posted 26 October 2012 - 06:54 AM

Oh, dont forget to get a 5mm/25mm cap screw or knob for your top mounting plate..I see you have a hole, mine didn't have a set screw in it, had to install a cap screw to remove all the vertical play it caused with an OTA in place.

Clear skies,

Paul


The new Smarteg Pro shows a knob installed in the top mounting plate:

http://www.ioptron.c...e6-9e82c223c1a6

I wonder if iOptron will supply them to customers who purchased the standard Smarteq that didn't have a knob installed?

#23 Astronewb

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Posted 30 October 2012 - 10:41 PM

Has anyone tried AP with his mount yet?

George


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.

But here's an image off the mount that only needed short exposures:

[img]http://farm9.staticflickr.com/8052/8117928050_5ceb8e...
M31 Borg 50mm achromat. by Astronewb2011, on Flickr

Hope the info helps,

Paul

#24 rmollise

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Posted 31 October 2012 - 02:36 AM

I would not be at all surprised to hear that a little mount in this class was limited to about 30 seconds. If the motor is speeding up and slowing down randomly, that is NOT periodic error, and you have some kind of problem with the electronics, likely.

#25 Astronewb

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Posted 31 October 2012 - 06:40 AM

I would not be at all surprised to hear that a little mount in this class was limited to about 30 seconds. If the motor is speeding up and slowing down randomly, that is NOT periodic error, and you have some kind of problem with the electronics, likely.


Very true, not periodic error, my bad. Basically, in a string of 40, forty five second exposures, it will have 3 or 4 perfect images with round stars. The next 2 to 3 will all have severe trailing, then perfect stars again for 1 or 2 images. The pattern is random but basically cyclical. I'm thinking a bad servo motor or 'stiction' in the gear train. Hopefully, iOptron will sort it out.

Thanks for the input,

Paul






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