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I added bearings and belleville washers per Michael Herman's suggestion to my GM811 (no spring loaded worms). Tonight I wanted to test things out but clouds started to roll in while I struggled getting things set up. When I first started to move the DEC, it stalled. I remembered I needed to adjust the worm while at colder temperatures outside (currently 35degF) instead of the 70degF I did while installing the bearings. So I took off my telescope, weights, and motors and adjusted the DEC and RA worms per Losmandy's YT video. Put things back together and I still had stalls in DEC. I thought it was balanced but might have been out of balance(but not by much). While slewing DEC, looking at the Gemini 2 hand unit the balance showed a PWM of up to 40% and one side of the Y bar going orange or red. The other side bar would extend slightly but not change color. It could have been my cabling, as I just changed my set up to have all usb cables going to a hub and power cables going to a hub. Both hubs are located on the telescope dovetail. I'm going to be organizing this tonight in order to not get any cable drag when moving DEC or RA. I should also note that my battery supplies 15V DC to the mount so I don't think that would be an issue, but maybe it is.
So worm adjustment, balance, and cable drag or a combination of the three are what I think were my sources of DEC stall, but is there others?
Do Losmandy users take the telescope, counterweights/bar, and motor off when adjusting the worm or does this just make it easier? It was way easier for me to feel when the worm would freely move if the scope, weights, and motor were off.
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Taylor - it's most likely due to the worm and worm gear binding. the other things you mention or possible contributors but unlikely to stall the axis (unless you obviously?see a cable that is taut). if you are even close to balance, it should be fine.
I remove everything when I adjust the worm mesh.?
How old is your mount? do you have the spring-loaded worms?
On Fri, Feb 28, 2020 at 9:13 PM taylor waber < taylorwab@...> wrote: [Edited Message Follows]
I added bearings and belleville washers per Michael Herman's suggestion to my GM811 (no spring loaded worms). Tonight I wanted to test things out but clouds started to roll in while I struggled getting things set up. When I first started to move the DEC, it stalled. I remembered I needed to adjust the worm while at colder temperatures outside (currently 35degF) instead of the 70degF I did while installing the bearings. So I took off my telescope, weights, and motors and adjusted the DEC and RA worms per Losmandy's YT video. Put things back together and I still had stalls in DEC. I thought it was balanced but might have been out of balance(but not by much). While slewing DEC, looking at the Gemini 2 hand unit the balance showed a PWM of up to 40% and one side of the Y bar going orange or red. The other side bar would extend slightly but not change color. It could have been my cabling, as I just changed my set up to have all usb cables going to a hub and power cables going to a hub. Both hubs are located on the telescope dovetail. I'm going to be organizing this tonight in order to not get any cable drag when moving DEC or RA. I should also note that my battery supplies 15V DC to the mount so I don't think that would be an issue, but maybe it is.
So worm adjustment, balance, and cable drag or a combination of the three are what I think were my sources of DEC stall, but is there others?
Do Losmandy users take the telescope, counterweights/bar, and motor off when adjusting the worm or does this just make it easier? It was way easier for me to feel when the worm would freely move if the scope, weights, and motor were off.
-- Brian?
Brian Valente portfolio
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Hi Taylor,
Sorry to read you're finding some trouble.
Here are some suggestions to resolve the axis that is binding:
Remove the motor from that axis and run the system as though it were attached.??
If you see no reported stalls, the motor and it's cable are ok.
Now remove the gearbox from the mount and from the Oldham coupler to the worm, and just rotate the output shaft of the gearbox.? If that seems smooth, your gearbox seems fine.
Now you are down to the worm itself. Usually you cannot reach in to turn the worm drive or Oldham coupler, but often you can find a small length of rubber tube, as I find at automotive parts stores like rubber gas line ...anyway, try finding some rubber tube to fit over the worm shaft.?
Alternatively, if you can reach the OD of the worm you can rotate it with your finger.? If you can't move the worm by hand, it is commonly too tight against the ring gear. I've seen the spring loaded worm be too tightly pressed by its spring too. The stock spring is composed of a very heavy wire.? When it is deeply compressed by its adjustment bolt, it can also jam up the worm or make the motor really work hard.??
Anyway, when adjusted correctly, the worm should rotate fairly easily by hand.
It can happen that a worm bearing is not lined up right, and you should feel for any tight spots when you rotate the worm by hand.??
Then, reassemble the Oldham coupler and gearbox back on.? When you rotate the gearbox you should look for any movement of the center plastic Oldham part.? Try to make that part only rotate, not slide on its mating metal parts.? Rotating only minimizes PE.? To optimize that, the gearbox position must be adjusted.??
Once the gearbox is lined up, and the Oldham parts locked down, add on the motor and it will run smoothly.
All the best, Michael
On Fri, Feb 28, 2020, 9:16 PM Brian Valente < bvalente@...> wrote: Taylor - it's most likely due to the worm and worm gear binding. the other things you mention or possible contributors but unlikely to stall the axis (unless you obviously?see a cable that is taut). if you are even close to balance, it should be fine.
I remove everything when I adjust the worm mesh.?
How old is your mount? do you have the spring-loaded worms?
On Fri, Feb 28, 2020 at 9:13 PM taylor waber < taylorwab@...> wrote: [Edited Message Follows]
I added bearings and belleville washers per Michael Herman's suggestion to my GM811 (no spring loaded worms). Tonight I wanted to test things out but clouds started to roll in while I struggled getting things set up. When I first started to move the DEC, it stalled. I remembered I needed to adjust the worm while at colder temperatures outside (currently 35degF) instead of the 70degF I did while installing the bearings. So I took off my telescope, weights, and motors and adjusted the DEC and RA worms per Losmandy's YT video. Put things back together and I still had stalls in DEC. I thought it was balanced but might have been out of balance(but not by much). While slewing DEC, looking at the Gemini 2 hand unit the balance showed a PWM of up to 40% and one side of the Y bar going orange or red. The other side bar would extend slightly but not change color. It could have been my cabling, as I just changed my set up to have all usb cables going to a hub and power cables going to a hub. Both hubs are located on the telescope dovetail. I'm going to be organizing this tonight in order to not get any cable drag when moving DEC or RA. I should also note that my battery supplies 15V DC to the mount so I don't think that would be an issue, but maybe it is.
So worm adjustment, balance, and cable drag or a combination of the three are what I think were my sources of DEC stall, but is there others?
Do Losmandy users take the telescope, counterweights/bar, and motor off when adjusting the worm or does this just make it easier? It was way easier for me to feel when the worm would freely move if the scope, weights, and motor were off.
--
Brian?
Brian Valente portfolio
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Taylor,
What power supply are you using?
toggle quoted message
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On 29 Feb 2020, at 4:11:27 pm, taylor waber < taylorwab@...> wrote:
I added bearings and belleville washers per Michael Herman's suggestion to my GM811. Tonight I wanted to test things out but clouds started to roll in while I struggled getting things set up. When I first started to move the DEC, it stalled. I remembered I needed to adjust the worm while at colder temperatures outside (currently 35degF) instead of the 70degF I did while installing the bearings. So I took off my telescope, weights, and motors and adjusted the DEC and RA worms per Losmandy's YT video. Put things back together and I still had stalls in DEC. I thought it was balanced but might have been out of balance(but not by much). While slewing DEC, looking at the Gemini 2 hand unit the balance showed a PWM of up to 40% and one side of the Y bar going orange or red. The other side bar would extend slightly but not change color. It could have been my cabling, as I just changed my set up to have all usb cables going to a hub and power cables going to a hub. Both hubs are located on the telescope dovetail. I'm going to be organizing this tonight in order to not get any cable drag when moving DEC or RA.?
So worm adjustment, balance, and cable drag or a combination of the three are what I think were my sources of DEC stall, but is there others?
Do Losmandy users take the telescope, counterweights/bar, and motor off when adjusting the worm or does this just make it easier? It was way easier for me to feel when the worm would freely move if the scope, weights, and motor were off.?
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I ain't touchin mine.
It's perfect!
--
SonnyE
(I suggest viewed in full screen)
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Hi Taylor,
Are you running the classic 2-piece worm bearing blocks or OPWs? The trick here is to have the Gemini run the mount all the way around the worm wheel watching current draw on a COLD acclimated mount and adjusting to minimize current draw until you see minimal changes in current in both directions all the way around the worm wheel of both RA and DEC. Don't worry about the excessive backlash at room temperature, you don't use the mount at room temperature, if you have adjusted in the cold all will be right when the mount is used in the cold.?
?The issue is the eccentricity of the worm wheel and the large bearings in the worm wheel, the variables stack? you up and you must adjust for the worst case stacking of these variables to avoid / minimize drag which causes the lag messages. My suggestion if you are an imager is to get the mount upgraded, it is the best thing for these mounts.?
--
Chip Louie - Chief Daydreamer Imagination Hardware
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That approach works fine if you¡¯re in USA ¨C shipping a G11 from UK to CA and back makes that a very un-economic option (never mind the argument with customs when it gets back to UK) ¨C much as I¡¯d love to upgrade to tucked in motors, OPW etc. ? I wish that Scott would release the machining specification for DIYing this conversion and sell the parts as a kit ¡ ? AFAICT it¡¯s a small amount of machining that would be needed ¨C I suspect mostly drilling and tapping a couple of holes ¨C not something to do with a hand-held drill ¨C but if you have a vertical mill ¡ ? David
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From: [email protected] [mailto:[email protected]] On Behalf Of Chip Louie
Sent: 01 March 2020 17:39
To: [email protected]
Subject: Re: [Losmandy_users_io] Likely causes of DEC stall? ? Hi Taylor,
Are you running the classic 2-piece worm bearing blocks? The trick here is to run the mount all the way around watching current draw on a COLD acclimated mount and adjusting to until you see minimal changes in current in both directions all the way around the worm wheel. The issue is that the eccentricity is a combination of the worm wheel and the large bearings in the worm wheel, they stack and you must adjust for the worst case stack of variables to avoid a lag. My suggestion is to get the mount upgraded, it is the best thing for these mounts.
--
Chip Louie - Chief Daydreamer Imagination Hardware
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Hi David,?
For folks not here in the US the adjustment as I described works fine but requires a way to monitor current draw. A bench supply is good or any of the small inexpensive meters will do inline for the Gemini power cord.?
The spring loaded OPWs resolve the issue once and for all, everything else is still a compromise and requires seasonal adjustment.
--
Chip Louie - Chief Daydreamer Imagination Hardware
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Brian ¨C Thank you, I bought my mount ~Oct 2018 and it does not have spring loaded worms. I think it would be useful to add to the OPW adjustment to say do this during imaging temperatures and also slew the mount 360 deg in order to see if there are any spots that it binds, or in Chip¡¯s recommendation, if there are any spots where the power draw is high.
?
Michael ¨C Thanks as always for the detailed response! I¡¯ll be giving this a shot tonight, as the forecast is cloudy.
?
Paul ¨C I have a 12V DC battery with a DC-DC boost converter to 15V DC to the Gemini 2 unit.
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Sonny- So glad you ironed out your issues! Hopefully I¡¯ll be next!
?
Chip ¨C I¡¯m running OPW (not spring-loaded). Thanks! I¡¯ll definitely run the mount all the way around to see if there¡¯s any binding. Could I watch the current draw on the Gemini unit? Or should I hook up a multimeter? (mine was about $35 off amazon so I hope it¡¯s of quality)
?
ALL ¨C Would you expect worm adjustment to change when transporting the mount to a dark location? I feel that the small thumb screws, to adjust the worm distance, stick out so much that I could bump them in moving and it would adjust the worm. I might 3D print some small covers and Velcro them to cover these during transport. Also upgrading to the spring-loaded worms would solve this issue entirely so I might do that.
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Hi Taylor,
I don't know your level of electronics but you probably cannot get a good current measurement with what you have. You could buy one of Michael Herman's magic power cord boxes which steps up voltage and has a digital display that shows volts or amps. For most folks that thing is a lifesaver and they are cheap. You could also order the parts from DigiKey eBay or Amazon and build one but probably not as good as Michel's box. When you get the lag errors you can usually hear the servo motors dragging or slowing, if you stop the mount immediately at that point you can also feel there is zero backlash on the axis with the problem. This will tell you your adjustment os off, you MUST set backlash on a COLD mount for the worm to have correct backlash under your cold working conditions or when the mount is cold it will have no backlash and drag/lag.?
.?
--
Chip Louie - Chief Daydreamer Imagination Hardware
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Hi Taylor
with those additional details, i would say your DEC worm is binding, particularly since you've been inside the gear and customizing it, it seems like the likely cause. I don't know much about Michael's belleville customization, so he may have input here.
If your electronics and battery were good before, they are probably still fine
Brian
On Fri, Mar 6, 2020 at 9:37 AM taylor waber < taylorwab@...> wrote: Brian ¨C Thank you, I bought my mount ~Oct 2018 and it does not have spring loaded worms. I think it would be useful to add to the OPW adjustment to say do this during imaging temperatures and also slew the mount 360 deg in order to see if there are any spots that it binds, or in Chip¡¯s recommendation, if there are any spots where the power draw is high.
?
Michael ¨C Thanks as always for the detailed response! I¡¯ll be giving this a shot tonight, as the forecast is cloudy.
?
Paul ¨C I have a 12V DC battery with a DC-DC boost converter to 15V DC to the Gemini 2 unit.
?
Sonny- So glad you ironed out your issues! Hopefully I¡¯ll be next!
?
Chip ¨C I¡¯m running OPW (not spring-loaded). Thanks! I¡¯ll definitely run the mount all the way around to see if there¡¯s any binding. Could I watch the current draw on the Gemini unit? Or should I hook up a multimeter? (mine was about $35 off amazon so I hope it¡¯s of quality)
?
ALL ¨C Would you expect worm adjustment to change when transporting the mount to a dark location? I feel that the small thumb screws, to adjust the worm distance, stick out so much that I could bump them in moving and it would adjust the worm. I might 3D print some small covers and Velcro them to cover these during transport. Also upgrading to the spring-loaded worms would solve this issue entirely so I might do that.
-- Brian?
Brian Valente portfolio
|
Hi Taylor,
I find my DEC Stalled messages from one of 2 causes:
a. The DEC axis is not balanced.? This means the load is not in the dovetail saddle at the right position. Especially if it was balanced and I added a few shield (weights the front too much) or my deep sky camera (weights the back too much) To check this best: ? ?Always first install a 1/4-20 bolt in the front of the dovetail (should be a threaded hole there) so the scope can't slip out into the ground. ? ?Next, rotate your RA til the scope and counterweights are horizontal. This removes all weight from the clutch disk and the axis will freely spin. ? ?Then loosen the DEC clutch and this will cause the scope to flip up or down if not balanced (be ready to catch it!!!!).? ? ?Then carefully adjust the scope in the dovetail or else move other weights around (there are sliding weight systems for SCTs anyway).? Before I move my scope I put it back at CWD... because if horizontal there can be a lot of friction with the dovetail edges.??
b. The DEC worm is getting stuck. The Belleville washer you put in cannot make the worm get stuck. It's only a spring that keeps the worm from side to side motion.? So worm binding is most likely the worm pushed into the ring gear too tightly, or a speck of something (dust/sand) is jamming it.? So first try spraying in some lube (lithium grease, perhaps, or WD40?) and use a spark plug feeler gauge to slightly increase the worm to ring gear gap.? Always carry a set of US sized Allen wrenches if you go out to the field (or back yard!), because this adjustment is so common.??
Chip thinks the binding between the ring and worm is temperature related...as it surely can be. But the major parts that expand and contract radially from the DEC center are all aluminum.? I was hoping the expansion and contraction would scale so the gap would remain constant.? But as Chip also pointed out, if the ring gear is not perfectly centered, or one of the cylindrical needle bearings slightly higher, it will push the ring gear toward the worm gear at a certain high spot in the 360 degree rotation if the ring gear. So as Chip says, run your axis around 180 degrees clockwise, the back and 180 degrees Counterclockwise to be sure there are no high binding spots.
All the best, Michael
On Fri, Mar 6, 2020, 12:32 PM Brian Valente < bvalente@...> wrote: Hi Taylor
with those additional details, i would say your DEC worm is binding, particularly since you've been inside the gear and customizing it, it seems like the likely cause. I don't know much about Michael's belleville customization, so he may have input here.
If your electronics and battery were good before, they are probably still fine
Brian
On Fri, Mar 6, 2020 at 9:37 AM taylor waber < taylorwab@...> wrote: Brian ¨C Thank you, I bought my mount ~Oct 2018 and it does not have spring loaded worms. I think it would be useful to add to the OPW adjustment to say do this during imaging temperatures and also slew the mount 360 deg in order to see if there are any spots that it binds, or in Chip¡¯s recommendation, if there are any spots where the power draw is high.
?
Michael ¨C Thanks as always for the detailed response! I¡¯ll be giving this a shot tonight, as the forecast is cloudy.
?
Paul ¨C I have a 12V DC battery with a DC-DC boost converter to 15V DC to the Gemini 2 unit.
?
Sonny- So glad you ironed out your issues! Hopefully I¡¯ll be next!
?
Chip ¨C I¡¯m running OPW (not spring-loaded). Thanks! I¡¯ll definitely run the mount all the way around to see if there¡¯s any binding. Could I watch the current draw on the Gemini unit? Or should I hook up a multimeter? (mine was about $35 off amazon so I hope it¡¯s of quality)
?
ALL ¨C Would you expect worm adjustment to change when transporting the mount to a dark location? I feel that the small thumb screws, to adjust the worm distance, stick out so much that I could bump them in moving and it would adjust the worm. I might 3D print some small covers and Velcro them to cover these during transport. Also upgrading to the spring-loaded worms would solve this issue entirely so I might do that.
--
Brian?
Brian Valente portfolio
|
I have also seen binding caused by a marred ring gear ¨C how it happened I don¡¯t know and the owner claimed not to know either. ? I didn¡¯t have any files fine enough to fettle that damage ¨C a 0.5mmt thick dremel disc was also too coarse. ? D. ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Michael Herman
Sent: 06 March 2020 21:27
To: [email protected]
Subject: Re: [Losmandy_users_io] Likely causes of DEC stall? ? Hi Taylor, I find my DEC Stalled messages from one of 2 causes: a. The DEC axis is not balanced.? This means the load is not in the dovetail saddle at the right position. Especially if it was balanced and I added a few shield (weights the front too much) or my deep sky camera (weights the back too much) To check this best: ? ?Always first install a 1/4-20 bolt in the front of the dovetail (should be a threaded hole there) so the scope can't slip out into the ground. ? ?Next, rotate your RA til the scope and counterweights are horizontal. This removes all weight from the clutch disk and the axis will freely spin. ? ?Then loosen the DEC clutch and this will cause the scope to flip up or down if not balanced (be ready to catch it!!!!).? ? ?Then carefully adjust the scope in the dovetail or else move other weights around (there are sliding weight systems for SCTs anyway).? Before I move my scope I put it back at CWD... because if horizontal there can be a lot of friction with the dovetail edges.?? b. The DEC worm is getting stuck. The Belleville washer you put in cannot make the worm get stuck. It's only a spring that keeps the worm from side to side motion.? So worm binding is most likely the worm pushed into the ring gear too tightly, or a speck of something (dust/sand) is jamming it.? So first try spraying in some lube (lithium grease, perhaps, or WD40?) and use a spark plug feeler gauge to slightly increase the worm to ring gear gap.? Always carry a set of US sized Allen wrenches if you go out to the field (or back yard!), because this adjustment is so common.?? Chip thinks the binding between the ring and worm is temperature related...as it surely can be. But the major parts that expand and contract radially from the DEC center are all aluminum.? I was hoping the expansion and contraction would scale so the gap would remain constant.? But as Chip also pointed out, if the ring gear is not perfectly centered, or one of the cylindrical needle bearings slightly higher, it will push the ring gear toward the worm gear at a certain high spot in the 360 degree rotation if the ring gear. So as Chip says, run your axis around 180 degrees clockwise, the back and 180 degrees Counterclockwise to be sure there are no high binding spots. ? On Fri, Mar 6, 2020, 12:32 PM Brian Valente <bvalente@...> wrote: Hi Taylor with those additional details, i would say your DEC worm is binding, particularly since you've been inside the gear and customizing it, it seems like the likely cause. I don't know much about Michael's belleville customization, so he may have input here. If your electronics and battery were good before, they are probably still fine ? On Fri, Mar 6, 2020 at 9:37 AM taylor waber <taylorwab@...> wrote: Brian ¨C Thank you, I bought my mount ~Oct 2018 and it does not have spring loaded worms. I think it would be useful to add to the OPW adjustment to say do this during imaging temperatures and also slew the mount 360 deg in order to see if there are any spots that it binds, or in Chip¡¯s recommendation, if there are any spots where the power draw is high. ? Michael ¨C Thanks as always for the detailed response! I¡¯ll be giving this a shot tonight, as the forecast is cloudy. ? Paul ¨C I have a 12V DC battery with a DC-DC boost converter to 15V DC to the Gemini 2 unit. ? Sonny- So glad you ironed out your issues! Hopefully I¡¯ll be next! ? Chip ¨C I¡¯m running OPW (not spring-loaded). Thanks! I¡¯ll definitely run the mount all the way around to see if there¡¯s any binding. Could I watch the current draw on the Gemini unit? Or should I hook up a multimeter? (mine was about $35 off amazon so I hope it¡¯s of quality) ? ALL ¨C Would you expect worm adjustment to change when transporting the mount to a dark location? I feel that the small thumb screws, to adjust the worm distance, stick out so much that I could bump them in moving and it would adjust the worm. I might 3D print some small covers and Velcro them to cover these during transport. Also upgrading to the spring-loaded worms would solve this issue entirely so I might do that.
--
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Quick update: I went out last night and slewed each axis full rotation, RA was fine, DEC had stalls. So I adjusted the worm at the location of the stall. Tried to rotate the DEC again and it could rotate all the way, but I could hear some whining(what sounded like the motor struggling) near another point, close to the last DEC stall point. So I went to adjust the worm again at this point. Before adjusting I tried to rotate the gears that rotate the worm just to see how tight it was. I couldn't move the worm at all, it was very tight. After adjustment, the DEC could slew all the way around without any stalls or odd motor sounds. I think I'll be good to go for tomorrow night!
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Good work, Taylor.? Glad you were able to trace and solve your problem.
It doesn't take very much adjustment error to pinch the worm at one slightly higher point on the worm wheel/ring gear.? The materials are very hard.? ?Ideally there are no high spots but... all mechanical systems have them.
There was a report long ago of some owner who thought these high spots could be polished out, using successively finer grits like you'd polish an engine cylinder.? But we are not supposed to do that with these (brass worm and anodized aluminum ring gear) parts.? You'd only wear down the worm, and potentially grind off the anodization of the ring gear. The underlying aluminum would be soft.??
Just keep it lubed, and adjusted as you did.
Congratulations,
Michael
On Mon, Mar 23, 2020, 5:26 PM taylor waber < taylorwab@...> wrote: Quick update: I went out last night and slewed each axis full rotation, RA was fine, DEC had stalls. So I adjusted the worm at the location of the stall. Tried to rotate the DEC again and it could rotate all the way, but I could hear some whining(what sounded like the motor struggling) near another point, close to the last DEC stall point. So I went to adjust the worm again at this point. Before adjusting I tried to rotate the gears that rotate the worm just to see how tight it was. I couldn't move the worm at all, it was very tight. After adjustment, the DEC could slew all the way around without any stalls or odd motor sounds. I think I'll be good to go for tomorrow night!
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Taylor,
While adjusting the distance of the worm to the main gear, check too if there might be a speck of sand or grit in the worm grease. This can cause binding. Also make absolutely sure that the worm is perfectly square to the main gear. Finally, do not press the worm too tightly against the main so that any minor unevenness between the two won't cause binding. You may also want to make sure there is no unevenness or binding after you tighten everything by manually spinning the worm till the main gear makes one full turn and feeling if there are any tight spots. If you feel any tight spot, loosen the worm a wee bit more till the tightness is gone.
Best regards,
John
On Tuesday, March 24, 2020, 8:26:22 AM GMT+8, taylor waber <taylorwab@...> wrote:
Quick update: I went out last night and slewed each axis full rotation, RA was fine, DEC had stalls. So I adjusted the worm at the location of the stall. Tried to rotate the DEC again and it could rotate all the way, but I could hear some whining(what sounded like the motor struggling) near another point, close to the last DEC stall point. So I went to adjust the worm again at this point. Before adjusting I tried to rotate the gears that rotate the worm just to see how tight it was. I couldn't move the worm at all, it was very tight. After adjustment, the DEC could slew all the way around without any stalls or odd motor sounds. I think I'll be good to go for tomorrow night!
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Michael Herman
Chip Louie
David C. Partridge