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Re: High worm torque

 

?For those who care. My major problem with high torque was the wave-washer. It had an OD of 51.01 mm and the bore of housing is 50.80 mm. An interference that when assembled restricting shaft rotation. This was depicted by large scrapes on the shaft. The strange thing is the scrapes were only on one side, which would indicate I may also have some of the same problems Eric had. This could not be confirmed because a dial indicator read less than 0.0005 inches run out, which is the limit of accuracy of my setup. I ground down the OD of the washer, but, the easiest thing is just put it next to the knob. I would like to have an assembly drawing but can¡¯t find one. Also, do the blocks that hold the shaft bearings come off? I posted an image, look in photostream or Chris Strang.
Eric, thanks for the thought.

Chris

?
Re: High worm torque

 

Hi Chris,?

Hope your wife has a speedy recovery.

Eric
Re: High worm torque

 

Thanks Eric for the follow-up note. I will look at it when I can, my wife is very ill in the hospital and my astronomy is on the back burner. I have the precision tools and skill to make the repairs if I can find the problem. I started this ¡°topic¡± by asking if the clutch should influence the worm torque, and the answer is no. As I remember, there was no indicators of rubbing and the worm turn the shaft nicely with low clutch loading, but I will recheck as to your suggestion.

Chris

?
Re: Does anyone know what would cause a Zig-Zag star trail in photos?

 

Best not to cross post between losmandy/Gemini yahoo forums. especially since the photos are on the other group forum.?? Obviously there is some worm zig zag but I'm not the best at actual operational adjustments to comment, others will...probably best on other forum.

Also best to use a signature or name at end of post for others to address you when replying, it just good etiquette.? Don't fret your not the first or last ever to do this..

regards

Brendan
Re: Does anyone know what would cause a Zig-Zag star trail in photos?

[email protected]
 

Dragging cable?

Regards,

Charlie
Does anyone know what would cause a Zig-Zag star trail in photos?

 

See photo section for 2? posted 3 min exposures, one guided using PHD and one un-guided
Re: High worm torque

 

Hi Chris,?

Clutch loading is the same problem I had. ?My DEC axis became stiff when the clutch was tightened. My top bearing housing was not installed straight (you can see evidence of this on my DEC Shaft).?

http://www.ericchesak.com/Galleries/Astro-Images/GM8-4/i-KD9QSXB/A

If you're still having issues, I'd encourage you to try this:

-Remove the motor and worm/bearings - the axis should rotate freely
-Tighten the clutch - if the axis stiffens you likely have an alignment problem (provided the bearings are good and all surfaces are properly greased).
- Also check the shaft for wear or bearing marks

I believe this to be a fairly common problem. ?Mine was out only about 4-5 thousands of an inch and it caused serious problems with a stiff axis, as the clutch was tightened. This distance is not readily visible (a couple sheets of paper thick) but can significantly affect the performance. With the housings properly aligned, it's smooth as glass.

Eric
Re: High worm torque

 

Thanks Eric for the note. My problem appears to be different from yours. It is/was totally related to clutch loading. With low clutch pressure they could be easily rotated by hand, very low torque and extremely smooth. In my second post I explained my repair (luck) of the RA drive, but not the dec. With this new knowledge I will disassemble the dec. drive one more time for an interference or incorrect assembly. By the way Paul, after the RA reassembly the RA high torque problems are gone and no¡°high load¡±reports displayed for any RA position (vertical or horizontal) or movement.

Chris
Re: High worm torque

 

Hi Chris,?

This sounds precisely like the problem I had with my GM8. ?It's possible one of the bearing housings is misaligned with the main bore. ?When this is the case, as the clutch is tightened, the system is pulled further out of alignment creating binding. ?I outlined some procedures to check the alignment by using feeler gauges. ?



If you pull the worm, check for binding with and without the clutch tightened. ?This is a fairly definitive test. ?I'd be happy to answer questions as you look into it.

Best,?

Eric
Re: GM811G AP Questions

 

Hi Bill,

The GM811G is just a G11G bottom with a GM8 top. So the tracking will be just as good if not better than the G11G because the RA axis does all the work once you are on an object and the G11G base is more than capable of carrying a 60lb. payload and in this application Losmandy has underrated the drive to fit a spot in the new mount lineup.?

Chip?
GM811G AP Questions

Bill Long
 

¿ªÔÆÌåÓý

Hello all,


Brand new to the group, and I am looking for some data on the GM811G mount. Specifically, I am looking for information on how it has been working for Astrophotography. How is the Periodic Error? How has guiding/tracking been? Any quirks I should know of, in terms of balancing, etc? Currently I use an AP1100 GTO mount, but was looking for a lighter weight companion. The GM811G with the LW Tripod (already own the HD Tripod; my AP1100 rides on that beast) fit the bill in terms of weight, and also has a fantastic 50 lb rated AP capacity. Also helps that it is made here in the USA. :)


Any info would be great.
Re: High worm torque

 

Hi Chris,

I think your report makes some sense...

In the case of the high load weights, the weight of these (x sine and x cosine of the downward angle) ?are acting the same as having the DEC and RA clutches tightened.? In a way, the load is pre-loading the clutch disk.? So a high weight would cause the same behavior as tightening your clutch knobs (at least in CWD position... moving the scope around in RA and DEC would change those angles and the sine and cosine values).

Also, if the low scope+counterweight load and low clutch knob force somehow allowed the Ring Gear to ride up and therefore engage the worm off center-to-center, it would have looked (to the worm) like you had pushed the worm-to-ring gear space too close so you'd get "Lags" or "Stalled" issues. ?

Again,... I don't know what mechanically could cause the Ring gear to go off its lowest position and suggest you call Losmandy to find out why. ?

All the best and good luck,

Michael




On Sat, Sep 23, 2017 at 11:34 AM, christystrang@... [Losmandy_users] <Losmandy_users@...> wrote:
?

Thanks Michael & Paul. The mystery goes on. Last night I was trying to evaluate a homemade ¡°on-axis-guider" I made from a Meade flip mirror. With clutch pressure set as low as I could I kept getting ¡°high drive load¡± reports (system well balanced in all three planes). I tell myself never work on a mount in the dark but I did, not because of the reports but I had conservatively set the backlash too loose for auto guiding. I removed the motors and began adjusting RA backlash. To my SURPRISE after adjusting backlash and the clutch, the worm torque was well within limits. The only thing different from the many previous tries is that there was a full load ( 20# scope/camera + 19# weights) on the RA axis. I had NO SUCH LUCK with dec. The RA reports were gone.

Chris




--
Michael Herman
mobile: 408 421-1239
email: mherman346@...
Re: High worm torque

 

Thanks Michael & Paul. The mystery goes on. Last night I was trying to evaluate a homemade ¡°on-axis-guider" I made from a Meade flip mirror. With clutch pressure set as low as I could I kept getting ¡°high drive load¡± reports (system well balanced in all three planes). I tell myself never work on a mount in the dark but I did, not because of the reports but I had conservatively set the backlash too loose for auto guiding. I removed the motors and began adjusting RA backlash. To my SURPRISE after adjusting backlash and the clutch, the worm torque was well within limits. The only thing different from the many previous tries is that there was a full load ( 20# scope/camera + 19# weights) on the RA axis. I had NO SUCH LUCK with dec. The RA reports were gone.

Chris
Re: FS: Gemini-1 and deluxe hand controller

 

Keep testing in daytime Magnus... conect and disconnect...power up and down.? If you've still got trouble, you will see it.? If not, you are probably assured for the night.??

Once I had intermittent trouble with the handbox I also cleaned the board, sickets, and connectors with alcohol swabs and the trouble has gone away...now several years.??

There is a battery in the Gemini1 of course, and voltage and moisture drive corrosion.? So on finding a small beetle inside my Gemini1 once, I cut some heavy felt cloth and stuffed it around the open areas of the Gemini1 around the hand controller socket, and around the RS232 and other sockets.? ?I tried to block as much moisture and bugs crawling in as possible.? ?I'm not sure it solved the moisture issue but it did prevent bugs from crawling in...? corrosion concern is also a reason to remove the 12-18V DC voltage from an outdoor unit when not using it.??

Stay well,?
Michael?





On Sep 23, 2017 08:17, "jfev5mnsvqiyzpq756wvokt55jve7sbg2esr5mip@... [Losmandy_users]" <Losmandy_users@...> wrote:

?

Hi!

I tried cleaning, and there might have been some small something close to the connectors btw HC-connector and the Gemini PCB. I cleaned with alcohol. After that, it worked a full night, so it might have helped..... but it is tricky when it is an intermittent behavoir. I'll keep trying - keeping fingers crossed...

Magnus
Re: FS: Gemini-1 and deluxe hand controller

[email protected]
 

Hi!

I tried cleaning, and there might have been some small something close to the connectors btw HC-connector and the Gemini PCB. I cleaned with alcohol. After that, it worked a full night, so it might have helped..... but it is tricky when it is an intermittent behavoir. I'll keep trying - keeping fingers crossed...

Magnus
Re: Great mount

 

Hi Keith,

Hmm, this is a difficult question to answer. From a mechanical POV the new Losmandy OPW design appears to be virtually identical to the old design in terms of worm bearing block alignment, it is for all intents and purposes functionally identical. The only difference is that the gearbox is attached directly to the plate under the mount's large worm wheel instead of floating with the OPW as in the original Losmandy OPW design.?

What this means is that as the new OPW worm mesh/gap is adjusted there is a slight misalignment introduced between the gearbox output shaft axis and the worm gear axis. Scott will tell you this is not important as the Oldham couplers allow for this very slight misalignment between the worm and gearbox shafts. But the Oldham is not?homokinetic, if there is misalignment between the shafts there will also be velocity changes introduced. This is where the original Losmandy OPW design was a better design, it had no misalignment so there was a smoother transmission of movement between the gearbox and worm gear. That said the velocity differences are very small and may not be detectable.?

Chip
?? ??
?
Re: High worm torque

 

Hi gang,

That is a good question and I'm surprised to find that reported -- on one system let alone 2 systems!

I have not observed that on my GM8 or CG11 systems (yet). ?

I think that is not supposed to be happening and you should call Losmandy to discuss it. ?

The ring gear must ride on some bearing.? If that height is changing, the bearing is flexing and allowing the movement.? I thought that was nearly impossible (though every solid thing has elastic properties if forced strongly enough). ?

------------------------- I thought the system works like this --------------------------

The Ring Gear is the large flat gear with teeth all around its circumference.? That is driven by the worm gear. ??
? I'll sketch it like this: ? ??
? ? ? ? ?))))||||||((((?

I will sketch the center of the ring gear teeth like this:

? ?))))||||||(((( ? ?<- center here ? ??

?the Ring Gear is always driven by the worm, which I will sketch like this: o ?.

For proper functioning, without jamming, the center of the worm gear must closely match the center of the worm gear axis. ?
The worm gears in mounts like the Losmandy (or Orion Atlas/Synta EQ6) has a smaller diameter than what would be the diameter of the ring gear teeth.? So the worm gear, if represented by a circle ?o ?must have its center at the same center of the ring gear.

))))||||||(((( ?o ? <- ring gear and worm gear both centered here

The plate on top which I sketch as this ?________?? holds the DEC axis, or the telescope:

________ ? ?telescope on top of that if DEC axis, ?or DEC axis assembly if this is the RA axis. ?
________ ? ?clutch plate on top is this line ___
))))||||||(((( ?o ? <- ring gear and worm gear both centered here
? ? ?| ? ?| ? ? ? ? ??
? ? ?| ? ?| ? ? ? ? ? ?this rod represents either the counterweight rod axis or the RA polar scope axis
? ? ?| ? ?|

If your ring gear is able to move vertically when you tighten your Clutch knob, then the ring gear center will be shifting with regards to the worm gear.? This is not supposed to happen. ?

In the Orion Atlas, the ring gear sits on a large roller bearing, designed for automobile axles.? In the Losmandy systems, I am not sure what that sits on.? It is likely a flat needle bearing. ?

In the Orion Atlas, you can adjust the ring gear height using plastic shims.? You do that until the ring gear center is very close or exactly on the center of the worm axis. ?

On the Losmandy systems, there is no adjustment provided that I know of. ?
You have essentially no adjustment possible on the height of the worm gear because that height is machined into the Worm Bearing blocks that hold the worm. ?
You can only adjust the worm gear to ring gear tooth spacing (horizontally in my sketch). ??
So I'd call Losmandy and report this problem.

------------------------------

There was a report on-line from Michael Siniscalchi, who found his ring gear plate got distorted, so he needed to file it down flat.? I wondered if his system somehow got far overtightened by the clutch knob and somehow distorted the plates.? Here is the website:



Possible solution?

You should not need to really torque down hard on the Clutch knobs to get the clutch disk to hold the upper axis.? If that is slipping, and you need to really overtighten the clutch knob, you could be distorting the ring gear surface with too much force down the axis (vertical in my sketch). ? These clutches slip from lubricant that diffuses on to their surfaces (from the internal lubricated bearings) and these need to be cleaned with oil solvent, or....

I do have some high friction clutch disks which resist oils and moisture. ?
I have these in sizes for the GM8, G11, and CG11, that reduce the clutch force needed to get a strong grip between the ring gear surface and the upper axis (telescope or DEC axis). ?
If you want to try them and see if they eliminate the problem, let me know.

Best,
Michael
??

On Fri, Sep 22, 2017 at 4:22 PM, Paul Homer phomer60@... [Losmandy_users] <Losmandy_users@...> wrote:
?

Peter, Chris,


There is something wrong somewhere, there should be no relationship between how hard the clutches are tightened and the motor drive.

Regards

Paul

On 23 Sep 2017, at 9:13:58 am, Peter Van Nijnatten pvnijn66@... [Losmandy_users] <Losmandy_users@yahoogroups.com> wrote:


Of course I mean G11 ?

Op 23 sep. 2017 01:12 schreef "Peter Van Nijnatten" <pvnijn66@...>:
I have a similar probleem.?I just got my new G12 two months ago.The clutches have to be fastened just right.? If they are too fast, the drive stalls. If too loos, ?they slip. All with a well balanced mount with less than 10 kg of scope + camera. Making series of 30 sec. images I sometimes still find some of the subs with small trails.

Peter?

Op 22 sep. 2017 19:13 schreef "christystrang@...?[Losmandy_users]" <Losmandy_users@...m>:
?

Subject: High worm torque

?

Hello, I have a GM8, current Gemini 2 (square). My question is¡± should the torque to turn the worm increase as the clutch pressure is increased¡±? I am told that it should not.?

1. With no clutch pressure and the motor removed the worm turns the worm-gear very smoothly with low torque.

2. As the clutch pressure is increased the required worm torque is too high.(the small backlash does not change).

3. If this is true, what should I do?

??????????????a. Is there something bad with the assembly?

??????????????b. Am I setting the clutch pressure to high?

Chris.?








--
Michael Herman
mobile: 408 421-1239
email: mherman346@...
Re: High worm torque

 

¿ªÔÆÌåÓý

Peter, Chris,

There is something wrong somewhere, there should be no relationship between how hard the clutches are tightened and the motor drive.

Regards

Paul

On 23 Sep 2017, at 9:13:58 am, Peter Van Nijnatten pvnijn66@... [Losmandy_users] <Losmandy_users@...> wrote:


Of course I mean G11 ?

Op 23 sep. 2017 01:12 schreef "Peter Van Nijnatten" <pvnijn66@...>:
I have a similar probleem.?I just got my new G12 two months ago.The clutches have to be fastened just right.? If they are too fast, the drive stalls. If too loos, ?they slip. All with a well balanced mount with less than 10 kg of scope + camera. Making series of 30 sec. images I sometimes still find some of the subs with small trails.

Peter?

Op 22 sep. 2017 19:13 schreef "christystrang@...?[Losmandy_users]" <Losmandy_users@yahoogroups.com>:
?

Subject: High worm torque

?

Hello, I have a GM8, current Gemini 2 (square). My question is¡± should the torque to turn the worm increase as the clutch pressure is increased¡±? I am told that it should not.?

1. With no clutch pressure and the motor removed the worm turns the worm-gear very smoothly with low torque.

2. As the clutch pressure is increased the required worm torque is too high.(the small backlash does not change).

3. If this is true, what should I do?

??????????????a. Is there something bad with the assembly?

??????????????b. Am I setting the clutch pressure to high?

Chris.?
Re: High worm torque

 

Of course I mean G11 ?

Op 23 sep. 2017 01:12 schreef "Peter Van Nijnatten" <pvnijn66@...>:

I have a similar probleem.?I just got my new G12 two months ago.The clutches have to be fastened just right.? If they are too fast, the drive stalls. If too loos, ?they slip. All with a well balanced mount with less than 10 kg of scope + camera. Making series of 30 sec. images I sometimes still find some of the subs with small trails.

Peter?

Op 22 sep. 2017 19:13 schreef "christystrang@... [Losmandy_users]" <Losmandy_users@yahoogroups.com>:
?

Subject: High worm torque

?

Hello, I have a GM8, current Gemini 2 (square). My question is¡± should the torque to turn the worm increase as the clutch pressure is increased¡±? I am told that it should not.

1. With no clutch pressure and the motor removed the worm turns the worm-gear very smoothly with low torque.

2. As the clutch pressure is increased the required worm torque is too high.(the small backlash does not change).

3. If this is true, what should I do?

??????????????a. Is there something bad with the assembly?

??????????????b. Am I setting the clutch pressure to high?

Chris.?
Re: High worm torque

 

I have a similar probleem.?I just got my new G12 two months ago.The clutches have to be fastened just right.? If they are too fast, the drive stalls. If too loos, ?they slip. All with a well balanced mount with less than 10 kg of scope + camera. Making series of 30 sec. images I sometimes still find some of the subs with small trails.

Peter?

Op 22 sep. 2017 19:13 schreef "christystrang@... [Losmandy_users]" <Losmandy_users@...>:

?

Subject: High worm torque

?

Hello, I have a GM8, current Gemini 2 (square). My question is¡± should the torque to turn the worm increase as the clutch pressure is increased¡±? I am told that it should not.

1. With no clutch pressure and the motor removed the worm turns the worm-gear very smoothly with low torque.

2. As the clutch pressure is increased the required worm torque is too high.(the small backlash does not change).

3. If this is true, what should I do?

??????????????a. Is there something bad with the assembly?

??????????????b. Am I setting the clutch pressure to high?

Chris.?
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