Re: Oops, I broke my sprocket
Richard:
I have sent you an email off-list.
Bill Conrad
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Richard, ? Sorry to hear of your issues with the tracking system on your UC.? Hope you can get it fixed fairly quickly. ? Jack ? Jack Huerkamp Jack's Astro Accessories, LLC 38388 Pine Street Pearl River, LA 70452-5192 985-445-5063 mallincamusa@...
30.37N? 89.76W ? All of us get lost in the darkness.
Dreamers learn to steer by the stars. ………………………………….Neil Peart ? ? ?
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From: [email protected] < [email protected]> On Behalf Of Richard Sent: Monday, November 6, 2023 9:27 PM To: [email protected]Subject: [ServoCAT] Backlash ? I think I know what may have happened.
I have too much stuff now in my rocker and while moving the Alt I think my mirror impacted something and halted the scope.
After this is when I noticed the backlash.? I am now guessing that is when I damaged this sprocket.
You can watch the set screw locations on the brass part and the sprocket part move out of sync with each other (large backlash).
I will rearrange all my stuff in the rocker of the UC or move it to outside the scope so there is no danger of any impact.
Hopefully I can get a replacement part to restore my scope's operation.? I am really liking my new camera.
Here is my last photo before I broke the sprocket.?
Richard
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I think I know what may have happened. I have too much stuff now in my rocker and while moving the Alt I think my mirror impacted something and halted the scope. After this is when I noticed the backlash.? I am now guessing that is when I damaged this sprocket. You can watch the set screw locations on the brass part and the sprocket part move out of sync with each other (large backlash). I will rearrange all my stuff in the rocker of the UC or move it to outside the scope so there is no danger of any impact. Hopefully I can get a replacement part to restore my scope's operation.? I am really liking my new camera. Here is my last photo before I broke the sprocket.?  Richard
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Oops, I broke my sprocket
Gary, I broke my sprocket while attempting to remove my backlash.? I over tightened the set screw and broke the sprocket. Any advice--can Bill sell me a new sprocket? 
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Re: [>|ServoCAT] New camera-more power through my powered ground board
Gary, ? Will do. ? Richard ? ? be sure to use 2 diodes so that neither backfeeds the other.?
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------ Original Message ------Date 11/5/2023 4:30:44 PM Subject Re: [ServoCAT] New camera-more power through my powered ground board Gary,
I will try your suggestion of a diode switched LiFePo battery. ?I love fault tolerance designs!
Richard
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Re: New camera-more power through my powered ground board
be sure to use 2 diodes so that neither backfeeds the other.?
------ Original Message ------
Date 11/5/2023 4:30:44 PM
Subject Re: [ServoCAT] New camera-more power through my powered ground board
Gary,
I will try your suggestion of a diode switched LiFePo battery. ?I love fault tolerance designs!
Richard
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Re: New camera-more power through my powered ground board
Gary,
I will try your suggestion of a diode switched LiFePo battery. ?I love fault tolerance designs!
Richard
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Re: New camera-more power through my powered ground board
Richard,?
I don't know if you have my PGB or not - I believe you do (and you would if it is an Obsession 18UC). I think Mickey has a different one supplied by StarStructure.?
The spring pressure on the redundancy plate is critical - and over time the screw has been known to loosen up (the center screw that provides that pressure). I'd check that out.?
The brushes are phosphorus bronze. They can corrode a bit over long periods of time especially if near salt air. But generally just removing them (that same screw above) and cleaning them once every other year should do a perfectly fine job. I'd remove the bushings and put a pencil eraser in and run it around a few times to clean the contact plate as well. NOTE that we did have issues with those bushings NOT being installed correctly. We've had more than a few that the brushes were cocked due to the hole being non-perpendicular to the floor. If that is the case I'd recommend drilling those holes (BE CAREFUL NOT TO GO FURTHER THAN THE DEPTH OF THE HOLE) with a 13//32" drill bit to allow them to readjust as needed.?
Note you are drawing more current than it was designed for. The system nominally, w/o all the extra hardware you have, would see an average current of about 400mA when tracking and supplying the ServoCAT and a DSC... and a peak (and very brief) current w/ both axes slewing of maybe 2.5 - 4A depending on the scope size and more importantly depending on how well the scope was built re static friction (and believe you me - it can be a substantial difference with some scopes - HUGE frictional forces I've seen). So if you are averaging as much as 4A you're peaking closer to 8 probably.?
You might consider just putting a LiFePO4 battery inside the scope... you could either have it run everything or you could have it diode isolated to automatically power the system if there is a momentary interruption. if you do that it should never 'stop' as it would ride through the very brief interruption. I'd use high current shottky diodes to do this as they can be found with a Vf of about 0.4V. By isolating you won't run it down - and would just need to top it off once a month or so.?
Also if you remove that screw - I'd suggest you get a #2 pencil and shave off some wood chips - stuff them in to the hole so that it has a good purchase when reinserted. Otherwise it will be looser and it could unscrew as mentioned above.
Gary?
fantastic shot - can you show it WITH the stars? I'd be curious to see that as well.?
------ Original Message ------
Date 11/5/2023 10:57:08 AM
Subject Re: [ServoCAT] New camera-more power through my powered ground board
Mickey,
The Eagle4S has power distribution and measures voltage and current for each port. ?It also has a sky quality meter. ?It runs all my software: ?MallincamSky, Stellerarium, play, my VB.net software and database, ASCOM drivers, Eagle Manager X and I connect with MS remote desktop. ?
I have considered changing the contact design away from dissimilar metals. ?If you remember the channel selector on TVs built in the 1960s they always used silver plated contacts on both the leaf spring and the circuits since silver oxide is conductive. ?But for large DC current it is better to use another metal to avoid silver migration. ?I am thinking of plating both the springs and plate with a noble metal—perhaps gold.
Richard
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Re: New camera-more power through my powered ground board
Mickey,
The Eagle4S has power distribution and measures voltage and current for each port. ?It also has a sky quality meter. ?It runs all my software: ?MallincamSky, Stellerarium, play, my VB.net software and database, ASCOM drivers, Eagle Manager X and I connect with MS remote desktop. ?
I have considered changing the contact design away from dissimilar metals. ?If you remember the channel selector on TVs built in the 1960s they always used silver plated contacts on both the leaf spring and the circuits since silver oxide is conductive. ?But for large DC current it is better to use another metal to avoid silver migration. ?I am thinking of plating both the springs and plate with a noble metal—perhaps gold.
Richard
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Re: New camera-more power through my powered ground board
Excellent image Richard. As for the ground board contacts buried in the bottom. Every year since I had the problem you describe, (losing power) I disassemble the scope and remove those little copper contacts from the underneath of the ground board, clean the contacts and make sure the stings have plenty of spring left in them. No need to data log, I guarantee you the contacts need cleaning. ? So are you using the EagleS4 instead of a separate stand alone router for your remote control Wi-Fi?
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On Nov 4, 2023, at 9:06 PM, Richard <rmille64@...> wrote:
?All, I now have a bunch of gear on my UC18.? A Win10 PC with an I3 processor (Eagle4S pulls one amp just for itself), a motorized focuser, Mallincam DS10CTEC, Pegasus USB 3 Hub, dew heater, filter changer, and the ServoCAT gear.? My average current draw is 2 to 3 amps out of the battery.? I have a 10 amp 12 volt DC-DC converter in the rocker next to the ServoCAT electronics that powers all my gear. After a few hours the Eagle4S turned off as the temperature approached freezing--I had plenty of power reserve left in my 55-amp hour battery.? I replaced the battery with the AC to DC power supply I bought from Gary for the powered ground board. Worked for a few hours then the Eagle4S shut off again. I am thinking it is time to do some maintenance on my rotating contacts on the powered ground board.? I need to data log my input voltage variation to help troubleshoot.?? Anyway, while I still had several hours of operation, I got a photo of the Pacman and a few other targets. Richard <NGC281.jpg>
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New camera-more power through my powered ground board
All, I now have a bunch of gear on my UC18.? A Win10 PC with an I3 processor (Eagle4S pulls one amp just for itself), a motorized focuser, Mallincam DS10CTEC, Pegasus USB 3 Hub, dew heater, filter changer, and the ServoCAT gear.? My average current draw is 2 to 3 amps out of the battery.? I have a 10 amp 12 volt DC-DC converter in the rocker next to the ServoCAT electronics that powers all my gear. After a few hours the Eagle4S turned off as the temperature approached freezing--I had plenty of power reserve left in my 55-amp hour battery.? I replaced the battery with the AC to DC power supply I bought from Gary for the powered ground board. Worked for a few hours then the Eagle4S shut off again. I am thinking it is time to do some maintenance on my rotating contacts on the powered ground board.? I need to data log my input voltage variation to help troubleshoot.?? Anyway, while I still had several hours of operation, I got a photo of the Pacman and a few other targets. Richard 
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Re: Suddendly developed backlash on the Alt
Richard, Thanks for the tip
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On Nov 3, 2023, at 2:38 PM, Richard <rmille64@...> wrote:
? Mickey, ? Good to know.? BTW, a quick way to test for backlash is the ServoCAT spiral search where it becomes obvious. ? Richard
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Re: Suddendly developed backlash on the Alt
Was this backlash from an Obsession Classic or Ultra Compact??
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Re: Suddendly developed backlash on the Alt
Note that the spiral search function is really tightly designed and coded.... and that it does take backlash compensation in to account. So indeed if you don't adjust the backlash compensation (the users responsibility as it has to be done in situ) you'll see less than an ideal pattern.
Gary Myers
------ Original Message ------
Date 11/3/2023 2:38:33 PM
Subject Re: [ServoCAT] Suddendly developed backlash on the Alt
Mickey, ? Good to know.? BTW, a quick way to test for backlash is the ServoCAT spiral search where it becomes obvious. ? Richard
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Re: Suddendly developed backlash on the Alt
Mickey, ? Good to know.? BTW, a quick way to test for backlash is the ServoCAT spiral search where it becomes obvious. ? Richard
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Re: Suddendly developed backlash on the Alt
As it turns out my slippage was not the set screw (apparently Mike Zammit) uses blue loctite. The problem was silicone over spray from when I cleaned the Teflon pads.?
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On Nov 3, 2023, at 11:57 AM, wilson_buster <retsub@...> wrote:
?A couple more thoughts about set screws. It’s good to have a flat area for the set screws to make up to. Can’t remember the name but some set screws had serrations on the tip for a better grip. In previous shop work before Loctite came on the market we used double set screws if needed and there was enough thread depth to do so. BW?
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Re: Suddendly developed backlash on the Alt
A couple more thoughts about set screws. It’s good to have a flat area for the set screws to make up to. Can’t remember the name but some set screws had serrations on the tip for a better grip. In previous shop work before Loctite came on the market we used double set screws if needed and there was enough thread depth to do so. BW?
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Re: Suddendly developed backlash on the Alt
one more note on the subject: of necessity the set screws, when shipped, are dry (i.e. no locktite) of course since the roller is separate from the drive shaft. It has to be placed in situ. And I know a number of - let me state that a different way, only a few telescope makers actually put locktite on the set screw when they do place the roller on the shaft/scope.?
So be aware: there's a good chance if you've not done it - there's none there!?
Gary?
and NEVER use red locktite on any of the hardware! I used it internally on the gears/pulleys to ensure they wouldn't slip - but anything external should not use red. It is for the most part a PERMANENT bonding agent. I had one case where a user used it on an AZ roller - LOTS of it. I needed to work on something for him and to do that I needed to remove the roller. I could not, even with heat, get it off. I had to saw the roller/shaft!?
------ Original Message ------
Date 11/2/2023 11:25:21 AM
Subject Re: [ServoCAT] Suddendly developed backlash on the Alt
NOTE: Blue locktite has a quite low viscosity. Almost like water. And the tapped hole on the drive rollers is long. My recommendation, what I do myself, is I put locktite on the set screw (NEVER in the hole) and screw it in - remove it and repeat a number of times. This helps to ensure that the locktite is actually ON the set screw/internal threads at the bottom of its travels. If you do it once you're almost guaranteed to have none on it when its finally in place. Of course the bigger the roller - the more this is the case.
Gary Myers
------ Original Message ------
Date 11/2/2023 11:14:41 AM
Subject Re: [ServoCAT] Suddendly developed backlash on the Alt
I find that screw constantly loosens particularly on long drives across country.? Even blue Loctite did not keep it.? But that is the best I can do.? So I try to remember to test it by hand trying to rock it back an forth on the shaft.
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Re: Suddendly developed backlash on the Alt
NOTE: Blue locktite has a quite low viscosity. Almost like water. And the tapped hole on the drive rollers is long. My recommendation, what I do myself, is I put locktite on the set screw (NEVER in the hole) and screw it in - remove it and repeat a number of times. This helps to ensure that the locktite is actually ON the set screw/internal threads at the bottom of its travels. If you do it once you're almost guaranteed to have none on it when its finally in place. Of course the bigger the roller - the more this is the case.
Gary Myers
------ Original Message ------
Date 11/2/2023 11:14:41 AM
Subject Re: [ServoCAT] Suddendly developed backlash on the Alt
I find that screw constantly loosens particularly on long drives across country.? Even blue Loctite did not keep it.? But that is the best I can do.? So I try to remember to test it by hand trying to rock it back an forth on the shaft.
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Jack Huerkamp