Re: I put a G11 gearbox in the freezer...
I have imaged at ~25F without any major issues but I am running at 15.2 volts.
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Do The Gemini High Torque Servo Motor Have Gears?
As the title says.? Do they have gears?
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Re: I put a G11 gearbox in the freezer...
Hi David
Have you used your mount at these temps or is it the freezer experiment?? ??
One of the best things you can do is increase the voltage towards the higher end, 15-18v. you can also reduce your slew speed (btw, these are the same recommendations as astro physics).?
We have many losmandy mounts in the wild operating at cold temps. We get inquiries on the Gemini, the hand controller, power sources, battery life, etc. but i have yet to hear of an issue regarding the gearbox or motor performance?
Brian
Here's the thing - I get all the worm backlash stuff, but for Dec, the stiff grease could cause issues with the reversals (Stiction is a term that comes to mind :)).
By the way - I see the decreased performance in Dec. with decreasing temps.
Here's what I'm gonna try when I get a chance.? Flush all the grease out of the Dec gearbox and put in a light oil.?
There is not much need for grease in these gearboxes (low load when guiding - arguably high when slewing) as the teeth are (I think) involute (I only eyeballed them once) which have a rolling contact.
A bit of grease will help with backlash, but it it gunks up under low temps, then - well - it kinda has the reverse effect.
I tend to write in fractured - hyphenated - parenthetical - sentences - so sorry in advance.
Thoughts on gearbox grease?
-- Brian?
Brian Valente portfolio
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Re: I put a G11 gearbox in the freezer...
So how do you replace the grease without destroying the gearbox??
I think stiction is minimal.?
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Re: I put a G11 gearbox in the freezer...
Here's the thing - I get all the worm backlash stuff, but for Dec, the stiff grease could cause issues with the reversals (Stiction is a term that comes to mind :)).
By the way - I see the decreased performance in Dec. with decreasing temps.
Here's what I'm gonna try when I get a chance.? Flush all the grease out of the Dec gearbox and put in a light oil.?
There is not much need for grease in these gearboxes (low load when guiding - arguably high when slewing) as the teeth are (I think) involute (I only eyeballed them once) which have a rolling contact.
A bit of grease will help with backlash, but it it gunks up under low temps, then - well - it kinda has the reverse effect.
I tend to write in fractured - hyphenated - parenthetical - sentences - so sorry in advance.
Thoughts on gearbox grease?
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Re: I put a G11 gearbox in the freezer...
On Wed, Feb 24, 2021 at 05:43 PM, davidfenster@... wrote:
I have always had decreasing mount performance (guiding that is) as the temps dropped, so I thought I'd try an experiment.
I put a brand new gearbox in the freezer - and guess what - the grease turns to sludge and the gearbox is hard to turn.
Now - the motors probably have enough torque to overcome this, but I wanted to throw this out there to see if anyone else has done this.
A ton of talk on these forums about grease for the worm gears - perhaps it's time to discuss the grease used in the gearboxes.
I might be way off base, but try it - - put a gearbox in the freezer for a couple of hours and let me know what you think.
Dave Fenstermacher
Woodbridge, VA
Dave,? The gearbox is not the problem if you have a straight 2+piece worm block. The problem is material shrinkage when cold which reduces backlash even causes stalls. The solution I have been preaching is to set backlash on a cold acclimated mount. This make the backlash in a warm condition excessive but personally I don't image in the daylight.? -- Chip Louie Chief Daydreamer Imagination Hardware?
? ?Astropheric Weather Forecast - South Pasadena, CA?
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Re: I put a G11 gearbox in the freezer...
I placed a damaged gear box in the freezer (-5F) for about 40 minutes and the grease got real stiff.? I don't think it would cause issues.? The servo's have enough torque.
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Re: New owner of Used Titan
Mike,
You can get them to make an extension but it will not be cheap.? The extension is basically a longer MAL, takes all the same machining and holes needed on both ends and requires the base and recessed section to use the fasteners to the MAL.?
--
Chip Louie Chief Daydreamer Imagination Hardware?
? ?Astropheric Weather Forecast - South Pasadena, CA?
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Re: New data cable for Gemini 1... an option to try first.
Well, it looks like the cable is good.
At least the cable checks out continuity wise.
Hopefully the new USB adapter will be here tomorrow and that'll fix it.
If not, I'll get a hold of you Michael off line and see about sending it up to you.
Thanks
Jim
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I put a G11 gearbox in the freezer...
I have always had decreasing mount performance (guiding that is) as the temps dropped, so I thought I'd try an experiment.
I put a brand new gearbox in the freezer - and guess what - the grease turns to sludge and the gearbox is hard to turn.
Now - the motors probably have enough torque to overcome this, but I wanted to throw this out there to see if anyone else has done this.
A ton of talk on these forums about grease for the worm gears - perhaps it's time to discuss the grease used in the gearboxes.
I might be way off base, but try it - - put a gearbox in the freezer for a couple of hours and let me know what you think.
Dave Fenstermacher
Woodbridge, VA
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Re: New data cable for Gemini 1... an option to try first.
Well, it looks like the cable is good.
At least the cable checks out continuity wise.
Hopefully the new USB adapter will be here tomorrow and that'll fix it.
If not, I'll get a hold of you Michael off line and see about sending it up to you.
Thanks
Jim
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Re: Gemini 2: Polar alignment
Rahul,
If you are shooting with a wide field scope (80mm f/6 refractor, or f/4 reflector maybe) your polar scope with? alignment and autoguiding might be ok. Certainly to start getting experience it's ok.? A long FL scope will require very good polar alignment by drift usually.
But to get the best image sharpness, you'd be better off doing a "drift" alignment.? You can read about that elsewhere.? The same free PHD2 program used for autoguiding has a nice drift alignment tool.? Try that method and you will get to perfect polar alignment for imaging.
Just take it a bit at a time.? ?There are many facets to master in deep sky long exposure imaging.? Each skill must be mastered.??
Michael
On Wed, Feb 24, 2021, 3:50 PM Rahul < trwway@...> wrote: [Edited Message Follows]
I have a G11G and G2 GoTo. I have never fussed about getting perfect polar alignment as till now it was all about visual observing. However decided to try imaging for a change.
So far what I have been doing:
1) Polar align mount using polar scope.
2) Cold start every time as I don't have a permanent setup. However lately what I have started to do is plunk down the tripod at same spot so maybe I could do away with cold start & rely on warm start instead.
3) Park mount in CWD position.
4) Then align using 1 or two bright stars. This usually gets me close the star though never centered in eye piece (wide field) which for me was OK for visual observing.
I do this from my backyard & like any other suburban location don't have unhindered views of sky in any direction.
For imaging I still plan on doing above steps however wondering what else do I need to do to get #3 right every time so that star(s) is centered in eye piece ?
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Re: New owner of Used Titan
Tanya had mentioned when I ordered the MAL that they¡¯ve made special adapters before. ?I¡¯ll have to follow up on that question. I was curious if others know of other solutions. ?Sometimes, especially when all the major mount manufacturers taxed in meeting the latest demand, special orders are done when time is available. ?So if someone has already figured an alternative resource that may be faster.
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Gemini 2: Polar alignment
I have a G11G and G2 GoTo. I have never fussed about getting perfect polar alignment as till now it was all about visual observing. However decided to try imaging for a change.
So far what I have been doing:
1) Polar align mount using polar scope.
2) Cold start every time as I don't have a permanent setup. However lately what I have started to do is plunk down the tripod at same spot so maybe I could do away with cold start & rely on warm start instead.
3) Park mount in CWD position.
4) Then align using 1 or two bright stars. This usually gets me close the star though never centered in eye piece (wide field) which for me was OK for visual observing.
I do this from my backyard & like any other suburban location don't have unhindered views of sky in any direction.
For imaging I still plan on doing above steps however wondering what else do I need to do to get #3 right every time so that star(s) is centered in eye piece ?
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Re: Weird tapping noise from RA gearbox or motor. Please, watch a movie.
On Tue, Feb 23, 2021 at 09:31 AM, Sebastian Kotulski wrote:
Hello.
Help me to diagnose an issue with a RA axis drive. I have never heard such tapping noise before. Is it a gearbox or motor failure. The mount slews as usual but when it stops I can hear this weird knocking noise.?
Please, watch the movie in the link below, and help me to diagnose the problem.
Sebastian
That sounds awful, adjust your servo motor to gearbox they are too tight. You should adjust the servo motor to gearbox backlash, you do this by loosening the cap screws on the servo motor and moving the motor to minimize the noise you hear. then recheck for that knocking. If you still have the knocking check the Oldham coupler grub screws, there are 4 of them and if there are flats on your gearbox and worm one of the grub screws should to be on the flat. The grub screws should be snug not gorilla tight and the plastic part of the coupler should be fully compressed, no gaps visible. Also verify that the worm has no movement between the bearings and cannot move back and forth on the worm shaft axis, check this by moving the RA back and forth checking for worm movement, this must be ZERO! If you still hear the noise you may have a dirty sticking worm bearing, most likely the worm bearings given the sound and location, the bearings are consumable parts, do not try to save them by cleaning it is a waste of time and the bearings are cheap. Replace them all at once with high quality stainless steel ABEC5 or better precision bearings - R4ZZ is the size. McMaster Carr sells them at a reasonable price and they are excellent quality.? I have also heard this sound under two other conditions. Very over tightened clutches causing too much drag on thrust bearings, you get a slip stick effect which is bad for smooth movement. The Porter Slip clutches are reliable when the plastic clutch discs are fresh and clean. But over time due to use of the wrong lube and or too much lube the clutch discs get oiled and they slip causing people to over tighten them and you get the creaking noises when the RA is driven at tracking speeds. This happens on the DEC axis too but because the DEC is never driven at tracking speeds you never hear it. Has the mount been disassembled for cleaning and lubrication using SuperLube with Teflon? If not or you have no idea what I'm talking about get someone in you club to help you who knows the Losmandy mounts. Short of that look for YouTube videos on how to do this. Using the wrong lubricant and/or too much of even the right lubricant is not a good thing. You cannot reliably diagnose this issue by loosening the clutches and rechecking, sometimes the bearings are dirty and causing this slip-stick issue but sometimes it can give you an indication you need to have a look at the bearing and lube condition.? I have also heard this when I under tightened the clutch with Michael Herman's high friction clutch discs. I tend to use minimal clutch tightness with the high grip discs because they are so good. But if the load is not well balanced and there is any slippage the clutch discs will creak if there is any slipping movement at all of the RA and DEC. If you don't have M.H. clutch discs this is not your issue.?? I doubt the problem is in the servo motor, the knocking is too slow speed, not like in the other guy's video which is fast and related to the input speed of the servo motor which indicates the gearbox has an issue. ? -- Chip Louie Chief Daydreamer Imagination Hardware?
? ?Astropheric Weather Forecast - South Pasadena, CA?
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Re: Used GM-8 Guiding Help
Thanks Brian,
I'll try to slow my brain down but no promises hah! Will look in to a different power supply. Lately I have been doing pier side west and bias weight east (I believe since you made that comment before). I'll update again once I feel I've done some testing worthy of critique/input, who knows maybe even a success story. The main thing is knowing that this is still odd behavior and likely mechanical, I wasn't sure if this was something a good PEC would fix but it doesn't sound like it
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Re: Used GM-8 Guiding Help
Hi Nick
that's 2001 vintage mount
I would not recommend a jump starter type power supply, they are designed for a different application.?
you really just want something that is 3-5amp output min and 12-18v, preferably 15-18v.?
I think you are trying too many things at once. For now, i suggest focusing on one side of the mount, maybe pier side west, and bias the weight east, and just focus on the RA performance with default PHD settings.?
?
Thanks Brian,
Serial number is: HGM301077076, maybe '01, '07, or '10?
I listened to the slewing and I really can't hear any rough spots. When changing to the HP worm I also rotated the worm by hand for the full rotation of the worm wheel (more than once), there was a small area (maybe 20-30 deg of rotation) where it was harder to turn. I adjusted until this area was easier to turn but not so much that all other areas were too sloppy. I also put this area at the top to try and avoid getting to it all together during operation and always slew to CW down at the end of the session to keep the area used on the worm wheel consistent. I also balance slightly east biased to help with any slop.
I did end up ordering new gearboxes last night and will install them and try again once they arrive. At this point I'm doubtful it will be the magic piece of the puzzle, but hey I can dream for now. I noticed my ASI120MM camera can act a little funny with PHD2, not sure if this could also be an issue. I just discovered the "simulator" option for PHD2 camera, I may play with this see if results are similar. Another idea, I did modify a "PC to printer" cable (RJ22 to USB using FTDI), basically I just had to swap Rx and Tx, and I did use a new RJ22 connector with a RJ22 crimper. Everything seems to work fine so I don't think this is the issue? Last, I have a fairly cheap 120v -> 12-24v adj. power cord, not sure if this could be the issue? Plugging it in now I will say I hear "clicking" in the box...maybe I should try using a jump starter I have instead just to rule it out?
Sorry for all the info, at this point I'm just trying to rule everything I can out!?
-- Brian?
Brian Valente portfolio
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Re: New owner of Used Titan
Congratulations Mike!
I don't know if the extensions made for the other mounts can work for the Titan.
But I know who does, Call Losmandy. I bet Tanya knows what fits what.
Manufactured by:
Hollywood General Machining, Inc.
416 N. Varney St
Burbank, California?? 91502
747-283-1075?????? FAX: 747-283-1078
--
SonnyE
(I suggest viewed in full screen)
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Re: Used GM-8 Guiding Help
Thank Michael,
Just replied to your other message as well. This is Gemini 1 system. The power supply is rated for 10a, the clicking/ticking is coming from the power supply circuit board/black box constantly at roughly 6-8hz even when not plugged into the mount. From quick searches online most instances where people experience this the advice is "bad PSU, get a new one". I will try using my car jumper - it's Li-ion at 14v and capable of very high amps so that shouldn't be an issue.
I'm hoping between the power supply and new gearboxes I'll see good improvement - I think I butchered my gearboxes because the plastic housing was coming off and I had to DIY it and try to re-melt the plastic rivets and glue around the edges.
I'll update once I install new gearboxes and get a good testing day!
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Re: Used GM-8 Guiding Help
Nick,
Your ("cheap") power supply box is making a clicking sound?? Hmmmm.? I'd replace that with one rated at 5 amps and see if has a benefit.??
-------
The DC power into the controller (492? or Gemini?) drops the input voltage (12 to 18V for Gemini, 12 V only for 492) to about 5V (G-1 and 492) and then has capacitors to filter out noise from the "Vcc" going to the logic chips.? But the full voltage going in does go almost directly to the motors when the control logic switches the supply voltage to the motors.?
Once the motor gets powered it will cause an instant high inrush current to the motor, and this current must come from the power supply.? Perhaps the clicking is from the power supply trying to create the current.? If it can't, the voltage will momentarily drop down and maybe then it must turn its circuitry up and "click"??
Get a high current capable power supply.? I use a "5 amp" rated supply because I expect a new phenomenon: spec cheating.? It's a new thing of course, this millenium.? I only think it really needs a solid 2.5 amp supply so I "derate" the power supply by 2x.? ( Circuit designers also derate capacitors....if you need only 10 V for your circuit you buy a capacitor rated for at least 25V.? )
From my usage on 5 different Losmandy mounts, the motors should not need over 1.5 amp ever, and to know this I use an ammeter in line in a 17V power booster supply shown here.? The picture shows the current running a Gemini-2.? The 17V would power the DC motors.? Normally running sidereal rate RA and autoguiding (pulses the motors) takes DC average 0.2 to 0.35 amp (and 0.15 amp of that normally runs the Gemini 1 or 2 booted up but not running a motor).??
Taking high DC current like 0.5 amps or more is observed when: ?? ? ?the worm is jammed
? ?the scope load is unbalanced..(I added / removed a camera and did not rebalance...or something slipped in the dovetail [use a 1/4-20 bolt in your dovetail bottom so your gear cannot not fall out])
? ?fast slewing, and the gearbox can't go that fast (I have seen gearboxes with a max rotation rating).? (You can lower the slew speed in Gemini using it's digital motor speed settings.) ? ? ?a motor is defective.? (Once....worked but always drew 0.5 amps more than other motors.? )
? ?(Other thoughts: ? ?a gear is stuck...maybe in the gearbox ? ?a counterweight slipped?
? ?the Oldham coupler is trying to shift a lot and may stick? ? ? )
Best of luck uncovering the issue,
Michael
Thanks Brian,
Serial number is: HGM301077076, maybe '01, '07, or '10?
I listened to the slewing and I really can't hear any rough spots. When changing to the HP worm I also rotated the worm by hand for the full rotation of the worm wheel (more than once), there was a small area (maybe 20-30 deg of rotation) where it was harder to turn. I adjusted until this area was easier to turn but not so much that all other areas were too sloppy. I also put this area at the top to try and avoid getting to it all together during operation and always slew to CW down at the end of the session to keep the area used on the worm wheel consistent. I also balance slightly east biased to help with any slop.
I did end up ordering new gearboxes last night and will install them and try again once they arrive. At this point I'm doubtful it will be the magic piece of the puzzle, but hey I can dream for now. I noticed my ASI120MM camera can act a little funny with PHD2, not sure if this could also be an issue. I just discovered the "simulator" option for PHD2 camera, I may play with this see if results are similar. Another idea, I did modify a "PC to printer" cable (RJ22 to USB using FTDI), basically I just had to swap Rx and Tx, and I did use a new RJ22 connector with a RJ22 crimper. Everything seems to work fine so I don't think this is the issue? Last, I have a fairly cheap 120v -> 12-24v adj. power cord, not sure if this could be the issue? Plugging it in now I will say I hear "clicking" in the box...maybe I should try using a jump starter I have instead just to rule it out?
Sorry for all the info, at this point I'm just trying to rule everything I can out!?
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Chip Louie
Michael Herman