¿ªÔÆÌåÓý

Date

Re: Gemini 2 unit resets to default??

 

¿ªÔÆÌåÓý

I think you mean piqued ¡­

?

David

?

From: [email protected] [mailto:[email protected]] On Behalf Of Greg via Groups.Io
Sent: 04 October 2019 03:39
To: [email protected]
Subject: Re: [Losmandy_users_io] Gemini 2 unit resets to default??

?

?Brian no I have no problem with torque. It just peeked my interest.


Re: Gemini 2 unit resets to default??

 

?Brian no I have no problem with torque. It just peeked my interest.


Re: Gemini 2 unit resets to default??

 

¿ªÔÆÌåÓý

I've run my systems on 12v power for years... but recognize that "12v" is a bit of a colloquialism (12v power is seldom *actually* 12 volts). ?A fully charged lead acid battery is always delivering over 13 volts ... e.g. 13.8v for a new lead-acid battery at full charge. ?After a few years the same battery maybe only charges up to 13.4 volts.... (give or take). ?But if a lead-acid battery wont charge to better than 13 volts... it's probably time to think about replacing it. ?It might be fair to say that your "12v" battery is supplying somewhere around 13.5?? ?The best way to know is to use a meter to test it.

I've never had an issue with my mount... but somewhat recently I made some changes.

1. ?I switched from lead-acid (which weighs a ton) to Lithium packs (much lighter). ?But the problem is the Lithium packs (not sure if it's just my particular model or if this is generally a "a thing" with Lithium batteries) is that when FULLY charged, they just barely supply 12v (I've measured it at just 11.9) and as they drain, it can drop to around 10.8. ?But it's Lithium... so I can run them down to empty.

2. ?I bought a new optical tube and this optical tube weighs in at 45 lbs. ?By the time you add other accessories (cameras, finder scope, etc.) it's a bit over 50 lbs (I have 53 lbs of counterweight). ?

So I'm thinking ... maybe upping the voltage a touch wouldn't be such a bad idea even though I have never had an issue.

So I bought one of these:

SMAKN Waterproof DC/DC Converte 12V (9V-13V) Step UP to 15V/15A 15V 15A 225W Power Supply Module
by SMAKN: https://www.amazon.com/dp/B00UYCU0A4/ref=cm_sw_em_r_mt_dp_U_RWMLDbWJSB04N

I do not believe in using the "cigarette lighter" style plug -- the only electric receptacle that was actually designed so that thing you plug into can self-eject. ?I'm thinking I want something that has a better connection. ?I converted to Anderson "Power Pole" style plugs (I've been converting my friends over to these things one by one... and everyone loves them). ?I can't take credit for this discovery... I'm told HAM radio operators have been using them for years.

Keep in mind that the "Gemini" controller (the electronics) is TOTALLY happy with 12v power. ?You will not improve reliability of the electronics by upping the voltage (that will just get converted right back down to whatever the voltage is that runs the Gemini internally ... I'm not sure if it's a 5v system or a 3.3v system and possibly someone here can answer that, but I suspect the boards in the Gemini do not run on 18 volts.

When I bought my Losmandy StarLapse ... it was either Scott or Tanya (probably Tanya) who told em that the StarLapse (they no longer make this system) is actually the RA motor from the GM8 mount ... but modified to attach to a photo tripod. ?Also since it's just an RA drive, it doesn't use a Gemini... it has it's only small box that lets you set the direction and drive rate. ?Anyway, they told THAT system runs on ANYWHERE from 7 - 18 volts (quite a range) and that the ONLY thing you get from running a higher voltage is more torque at the motors ... and this assumes you have a load heavy enough to where having the torque is an advantage. ?If you don't have a heavy load ... you don't need the torque.

When I bought my heavier scope... I adjusted the max slew speed to 600 (down from the 800 which I think was the factory default).

In addition to the G11 mount ... I also own a GM8. ?The GM8 has my TeleVue refractor on it. ?It uses the 7 lb counterweight (even with cameras). ?So I figure I'm probably not in much danger of overloading the thing. ?I didn't bother to up the voltage or slow the slewing rate.



On Oct 3, 2019, at 4:00 PM, Brendan Smith <brenatlilydale@...> wrote:

?(¡°What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?¡±)

Greg.....not sure what your asking but in relation to motor torque you can enter the web interface/servos page and increase motor tracking power percentage. ?Leave slew percentage at default. This allows more energy to the appropriate servo for tracking, lessens stall occurrences. ?Don¡¯t go mad with % changes, just a few % and retest.?


Other than that the system runs on 12 V ok.?

You stated ¡° the battery did not solve this¡±....I¡¯m confused ....is there an issue here. ?Maybe your own thread?
--
Brendan


Re: Gemini 2 unit resets to default??

 

(¡°What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?¡±)

Greg.....not sure what your asking but in relation to motor torque you can enter the web interface/servos page and increase motor tracking power percentage. ?Leave slew percentage at default. This allows more energy to the appropriate servo for tracking, lessens stall occurrences. ?Don¡¯t go mad with % changes, just a few % and retest.?


Other than that the system runs on 12 V ok.?

You stated ¡° the battery did not solve this¡±....I¡¯m confused ....is there an issue here. ?Maybe your own thread?
--
Brendan


Re: Gemini 2 unit resets to default??

 

The converters are a nice idea.

I make these input polarity protected units for Gemini-2 (the 5.5mm DC input) and a slightly different one for Gemini-1(the DIN power input socket).? I use them at home for my 3 Gemini units. The input DC voltage can be any polarity so in field use you cannot damage the Gemini by a mistake in the dark.

It pumps ~12V DC input, to the correct polarity 17V output (adjustable internally) to the Gemini unit.? It has also has an output voltage and output current meter on it, so I know if there is a motor or gear jam issue by unusual current above normal.? It acts like a power dashboard for my Gemini units.? It aids in worm adjustment also by showing if the worm is jamming.?

With the voltage booster I also provide a? 115VAC to DC 12V 5amp unit. Also, a simple cigarette lighter cord unit can provide field power ~12V, and this gets pumped to 17V for better DC motor torque. I have the cigarette adaptor cords too.??

Anyway, let me know privately if interested.?

All the best,
Michael

On Thu, Oct 3, 2019, 10:03 AM Brian Valente <bvalente@...> wrote:
Hi Greg

>>What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?

The Gemini operates best at between 15-18v.?

I sometimes use the Losmandy AC adapter (15v) or a voltage upconverter (something like??)

Do you feel like you're not getting enough torque??



On Thu, Oct 3, 2019 at 9:49 AM Greg via Groups.Io <gregmorris425=[email protected]> wrote:
I just changed the battery in my gemini 2 mini and I used my gps module from losmandy when I powered it back up and it reset time and date pretty quick.? I did this because I'm using a TP-link and my ip address on one startup is 192.168.0.111 and the next time may be 192.168.0.100 which affects connecting. The battery did not solve this. I have 3.2 volts according to a meter and the web interface. ( Which is really really cool). What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?


Greg



--
Brian?



Brian Valente
portfolio


Re: Gemini 2 unit resets to default??

 

Hi Greg

>>What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?

The Gemini operates best at between 15-18v.?

I sometimes use the Losmandy AC adapter (15v) or a voltage upconverter (something like??)

Do you feel like you're not getting enough torque??



On Thu, Oct 3, 2019 at 9:49 AM Greg via Groups.Io <gregmorris425=[email protected]> wrote:
I just changed the battery in my gemini 2 mini and I used my gps module from losmandy when I powered it back up and it reset time and date pretty quick.? I did this because I'm using a TP-link and my ip address on one startup is 192.168.0.111 and the next time may be 192.168.0.100 which affects connecting. The battery did not solve this. I have 3.2 volts according to a meter and the web interface. ( Which is really really cool). What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?


Greg



--
Brian?



Brian Valente
portfolio


Re: Gemini 2 unit resets to default??

 

¿ªÔÆÌåÓý

I just purchased a waterproof 12V -> 18V DC-DC converter from eBay with a ?8A rated capacity ¨C works fine.? They¡¯re still selling them for about USD20 or so (see eBay item number 162987841478).

?

I couldn¡¯t begin to make one for that price!!!

?

David

From: [email protected] [mailto:[email protected]] On Behalf Of Greg via Groups.Io
Sent: 03 October 2019 17:49
To: [email protected]
Subject: Re: [Losmandy_users_io] Gemini 2 unit resets to default??

?

I just changed the battery in my gemini 2 mini and I used my gps module from losmandy when I powered it back up and it reset time and date pretty quick.? I did this because I'm using a TP-link and my ip address on one startup is 192.168.0.111 and the next time may be 192.168.0.100 which affects connecting. The battery did not solve this. I have 3.2 volts according to a meter and the web interface. ( Which is really really cool). What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?


Greg


Re: Gemini 2 unit resets to default??

 

I just changed the battery in my gemini 2 mini and I used my gps module from losmandy when I powered it back up and it reset time and date pretty quick.? I did this because I'm using a TP-link and my ip address on one startup is 192.168.0.111 and the next time may be 192.168.0.100 which affects connecting. The battery did not solve this. I have 3.2 volts according to a meter and the web interface. ( Which is really really cool). What is the best thing to get to increase voltage to the gemini to improve the torque if you guys dont mind me asking here?


Greg


Re: Gemini 2 unit resets to default??

 

Magnus....

what does the web interface indicate as battery voltage?

Timothy summed it all up. ?I¡¯ve seen bad batteries out of the packaging. ?There are quit a few ¡°fake batteries¡± out there. ?Buy from reputable source, mouser, dogikey, arrow, RS


--
Brendan


Re: Gemini 2 unit resets to default??

 

¿ªÔÆÌåÓý

Hi Magnus,

There¡¯s a known bug in the clock chip (this isn¡¯t something that Losmandy can fix with a firmware update). ?When the battery is changed and it loses the date & time, it starts in a state that causes it to drain power rapidly UNTIL you set the date/time (and then everything is normal again).

There are a few techniques to change the battery to avoid this.

1) ?Replace the battery with the unit powered off. ?Once the new battery is installed, immediately power up the Gemini and set the date/time. ?

BTW, you do not need to have the Gemini connected to the mount when you do this. ?So if the mount is in an observatory but you¡¯d rather do this inside where it¡¯s warm ¡­ just disconnected RA/Dec cables, remove the Gemini module from the mount and bring it in to change it. ?It will likely complain that the motors aren¡¯t working but¡­ this wont affect your ability to set the date and time (and you know the reason the motors aren¡¯t responding is because they aren¡¯t connected.

2) ?Replace the battery while the unit is powered on (running on 12v power). ?Take care here to not touch any of the exposed electronics, ?But since the unit technically never lost power it will still have the date/time set.

I typically just do method #1 and I always immediately re-order a spare battery (I find local stores tend to not have these sizes so I never want to get caught with a dead battery and no spare).

Scott has a YouTube video where he shows how to swap the battery. ?He uses a simple piece of scotch tape so that when he lifts the battery retaining spring he can just pull on the tape and the battery comes out easily.



As for voltage¡­

The mount runs on 12v-18v power. ?The electronics are completely happy with 12v power. ?BUT¡­ if you run the mount on higher voltage then you get more torque to the motors (especially useful if you have a heavy load). ?If you are running a light load ¡­ go ahead and stick with 12v power. ??


Clear Skies,
Tim

On Oct 1, 2019, at 4:09 PM, Magnus Larsson <magnus@...> wrote:

Hi!

OK, not sure I did that. So I'll do it again. But: I don't see what difference that does.... setting the time and so on, when changing battery?

I'll measure the batter too,? soon as I can.


Magnus


Den 2019-10-01 kl. 20:31, skrev Brendan Smith:
Magnus when you changed the battery did you immediately set DTG.?



Cam you now measure the battery thru web interface is it above 3.0v?


Gemini units are very pernickety about backup battery voltage for sure this is your problem. Have even heard of new old batteries being used that were below voltage out of the packet, so also maybe check them with a multimeter.?
--
Brendan


Re: Gemini 2 unit resets to default??

 

magnus there's a setting for how gemini boots, "ask if possible" is one of the options. sounds like it's switched to something else

as brendan points out, if it's losing the values you put in, it's backup power related (i.e., the internal battery)

yes, it's good to have 15v for gemini ;)

Brian


Re: Gemini 2 unit resets to default??

 

¿ªÔÆÌåÓý

Hi!

OK, not sure I did that. So I'll do it again. But: I don't see what difference that does.... setting the time and so on, when changing battery?

I'll measure the batter too,? soon as I can.


Magnus


Den 2019-10-01 kl. 20:31, skrev Brendan Smith:

Magnus when you changed the battery did you immediately set DTG.?



Cam you now measure the battery thru web interface is it above 3.0v?


Gemini units are very pernickety about backup battery voltage for sure this is your problem. Have even heard of new old batteries being used that were below voltage out of the packet, so also maybe check them with a multimeter.?
--
Brendan


Re: Gemini 2 unit resets to default??

 

Magnus when you changed the battery did you immediately set DTG.?



Cam you now measure the battery thru web interface is it above 3.0v?


Gemini units are very pernickety about backup battery voltage for sure this is your problem. Have even heard of new old batteries being used that were below voltage out of the packet, so also maybe check them with a multimeter.?
--
Brendan


Gemini 2 unit resets to default??

 

Hi!

I've said this before in this forum, but then it was summer and no astro activity. Now it is fall and I'm up and running again. And this happens on and off - for me, quite unpredictable: When I turn the mount on, it does NOT give me the menu to choose startup mode (COld, Warm, Restart) but just boots. And when I check, the valuyes I'd set are reset to default: speed to 800 (I set it 500), limits to default (and this is really bad, since then automated meridian flips won't work).?

I'm running the unit on 12V, I know there have been discussion on that and a 15 V step-up converter is more or less on it's way. I change battery in the spring, not much used since then. So what could it be??

Magnus


Russell Jancic Passed away.

 
Edited

On the losmandy Facebook page a post that Russell passed away from a long illness. ?My condolences to his family, Scott and all at Losmandy.



Russell was Scott¡¯s right hand man a person of many talents who has helped many in these forums and repairing their units back at Losmandy.?

I didn¡¯t know him well he helped me personally enormously, he has a big legacy. ?Goodbye Russell?
--
Brendan


Re: Quite sticky mount

 

¿ªÔÆÌåÓý

Wow!.. Wish my G11 had one of those RA Washers!

?

Derek

?


From: [email protected] [mailto:[email protected]] On Behalf Of John Kmetz
Sent: Sunday, September 29, 2019 9:57 PM
To: [email protected]
Subject: Re: [Losmandy_users_io] Quite sticky mount

?

Franco,

To insert the washer, you will need to completely remove the RA lock knob while being careful of the order of the washers and bearings underneath. Pics attached.

Then you can slide out the upper RA assembly and shaft, then insert the clutch washer and reassemble in reverse order.

Best Regards,

John

?

Virus-free.


Re: Modeling mount

 

Luis,

Yes the purpose of the EQmod group program PECprep.exe is to analyze the Unguided PE data, by the method called FFT, and this tells the owner the exact frequencies present in the RA drive.? That program has a top menu selection for G11 and GM8 also...and many other mounts.? The program originally was designed for the Synta EQ6, but was nicely expanded by the authors to cover many popular mounts.

If the only large frequency is the worm period (on a G11 this is ~240 sec or 4 minutes.? On a GM8 that is 480 sec or 8 minutes), that is what is desired, and the PE value will be shown (in arcsec peak to peak and RMS).? You desire the PE to be under 2 arcsec RMS for a G11, or under 4 arcsec for a GM8.? The reason is that with the identical worm it should be double that for a GM8, because it's RA ring gear is half the diameter of the G11 ring gear.??

Some people have achieved ~1 arcsec RMS with their G11, or about 2 arcsec with their GM8.? It required a Losmandy precision brass worm, and usually (not always) a Losmandy OPW and a high grade ABEC5 or ABEC7 worm bearings, and a Belleville spring washer.??

The program can also tell you about frequencies unique to different drive gears. That way you can identify a problem mechanical component.? The nice part if the Losmandy system is that RA and DEC components are interchangeable, do you can run experiments to find the best parts for the RA drive.

Astronomy is very demanding on equipment...and people.? ?Early astronomers included Gauss, who invented the normal distribution to try and understand the varied data he was getting from other people.? Another was Albert Michelson, who used spectroscopy to (dis)prove the theory of the luminiferous ether, leading instead to the Lorentz equation and finally the theory of relativity.? It is an amazing miracle that our amateur equipment can be made so well that we can expect near perfect tracking from modestly expensive mounts.? We are all seeking perfection and it usually takes extra effort, or extra money, to get closer to it.

Very best,
Michael

On Mon, Sep 30, 2019, 3:16 PM Luis Barneo <lbarneo@...> wrote:
I had download your document some months ago. Your advise is unchecked? "Precision Pulse guide" and "Sync performs Additional Align". My telescope is in an horizontal position, the "Western Goto limit (from CWD) should be 0 or 90.00? What is the utility?of EQMOD software? To analize PEC?

El lun., 30 sept. 2019 a las 22:21, Michael Herman (<mherman346@...>) escribi¨®:
Luis,

Here is a write-up I did for connecting the Gemini 1 to a PC.? There may be some info in there you can use.

The question of remote operation is coming up in this group nowadays.? However, I can't comment on the best ways to do that. Perhaps other owners can speak about how they are doing this. They may have a Gemini-2 and this newer version may make it easier.? I don't have one yet!

Very best,

Michael

On Mon, Sep 30, 2019, 10:58 AM Luis Barneo <lbarneo@...> wrote:

Thanks Michael,

1.????? How does I save the model to my PC? I usually Warm Restart with the hand controller deluxe and synchronized some stars and not realized the aligment of these stars because I did it in a previous session and the mount put the star almost in the center of the camera ST-402 (FOV of 8.9 x 13.4 arcmin). After, I connect TheSkyX Prof to find the stellar objects that are not in the Gemini catalogs (asteroids, small stars,¡­) and works with the camera, focus, etc.


2.????? My small observatory is in the mountain wihout internet. For the correct time I tried to connect the PC with a GPS through Geminitelescope.net and gave the correct position, time and altitude. I don¡¯t? know if these data collected by Geminitelescope.net is transmitted to the mount that are a little difference of the data that appears when I warm ?with the hand controller (position, time), and cause or not a disturbing to the mount . For this reason, I¡¯m afraid to control the mount with the Geminitelescope.net.


El lun., 30 sept. 2019 a las 17:12, Michael Herman (<mherman346@...>) escribi¨®:
Luis,

In theory, once you build your model, you should save it to your PC and not need to ever cold boot again.? Only do warm boot to load in the last model saved inside the Gemini1 SRAM chip.

I say save it to your PC because if your backup battery dies, the Gemini 1 will lose the settings.
You can then upload the saved file after changing the battery.

Be sure to turn off settings in the Gemini.net applet that can affect the model.
That is on the advanced panel, upper right checkbox for "Synch performs additional Align".? You don't want that!

Then, just Synch on a known star every time you do the wam boot. ?

And always park your system to a known position like CWD. ?



That's the theory. ?

In practice:

Some programs like Plate Solver programs do not know about the Gemini model and using both is reported to mess up pointing.? So if you are using plate solving, after the first Synch, ?try leaving the Gemini model at all zeros.? See if that fixes the issue. ?

Sometimes my model parameters are messed up. Perhaps I added a bad alignment point.? Or some other thing has happened.? In that case, I build a new model.

There is a chip in the Gemini1 made by Epson. It is called an RTC real time clock chip.? Some people have said that can lose or gain time and so you must reSynch your time.? There is a simple way to do that in ,... I think it's on the Telescope panel. ?

?

Making a good model:

The manual says: add 3 align points on one side of the meridian, then add 3 on the other side of the meridian.? That is, do 3 align points either East (or West) followed by 3 on the other side West (or East).

Have fun, and hope your system stays Aligned!

Best,?
Michael












On Mon, Sep 30, 2019 at 2:25 AM Luis Barneo <lbarneo@...> wrote:

I suppose that is not a true new topic about the Losmandy mount: how often is advisable to realize the modeling of the mount? Every time when I open in warm restart, only warm or could start? My mount is a Losmandy G11 Gemini1 level4 in a permanent pier.


Luis

--
Michael Herman
mobile: 408 421-1239
email: mherman346@...


Re: Modeling mount

 

I had download your document some months ago. Your advise is unchecked? "Precision Pulse guide" and "Sync performs Additional Align". My telescope is in an horizontal position, the "Western Goto limit (from CWD) should be 0 or 90.00? What is the utility?of EQMOD software? To analize PEC?


El lun., 30 sept. 2019 a las 22:21, Michael Herman (<mherman346@...>) escribi¨®:
Luis,

Here is a write-up I did for connecting the Gemini 1 to a PC.? There may be some info in there you can use.

The question of remote operation is coming up in this group nowadays.? However, I can't comment on the best ways to do that. Perhaps other owners can speak about how they are doing this. They may have a Gemini-2 and this newer version may make it easier.? I don't have one yet!

Very best,

Michael

On Mon, Sep 30, 2019, 10:58 AM Luis Barneo <lbarneo@...> wrote:

Thanks Michael,

1.????? How does I save the model to my PC? I usually Warm Restart with the hand controller deluxe and synchronized some stars and not realized the aligment of these stars because I did it in a previous session and the mount put the star almost in the center of the camera ST-402 (FOV of 8.9 x 13.4 arcmin). After, I connect TheSkyX Prof to find the stellar objects that are not in the Gemini catalogs (asteroids, small stars,¡­) and works with the camera, focus, etc.


2.????? My small observatory is in the mountain wihout internet. For the correct time I tried to connect the PC with a GPS through Geminitelescope.net and gave the correct position, time and altitude. I don¡¯t? know if these data collected by Geminitelescope.net is transmitted to the mount that are a little difference of the data that appears when I warm ?with the hand controller (position, time), and cause or not a disturbing to the mount . For this reason, I¡¯m afraid to control the mount with the Geminitelescope.net.


El lun., 30 sept. 2019 a las 17:12, Michael Herman (<mherman346@...>) escribi¨®:
Luis,

In theory, once you build your model, you should save it to your PC and not need to ever cold boot again.? Only do warm boot to load in the last model saved inside the Gemini1 SRAM chip.

I say save it to your PC because if your backup battery dies, the Gemini 1 will lose the settings.
You can then upload the saved file after changing the battery.

Be sure to turn off settings in the Gemini.net applet that can affect the model.
That is on the advanced panel, upper right checkbox for "Synch performs additional Align".? You don't want that!

Then, just Synch on a known star every time you do the wam boot. ?

And always park your system to a known position like CWD. ?



That's the theory. ?

In practice:

Some programs like Plate Solver programs do not know about the Gemini model and using both is reported to mess up pointing.? So if you are using plate solving, after the first Synch, ?try leaving the Gemini model at all zeros.? See if that fixes the issue. ?

Sometimes my model parameters are messed up. Perhaps I added a bad alignment point.? Or some other thing has happened.? In that case, I build a new model.

There is a chip in the Gemini1 made by Epson. It is called an RTC real time clock chip.? Some people have said that can lose or gain time and so you must reSynch your time.? There is a simple way to do that in ,... I think it's on the Telescope panel. ?

?

Making a good model:

The manual says: add 3 align points on one side of the meridian, then add 3 on the other side of the meridian.? That is, do 3 align points either East (or West) followed by 3 on the other side West (or East).

Have fun, and hope your system stays Aligned!

Best,?
Michael












On Mon, Sep 30, 2019 at 2:25 AM Luis Barneo <lbarneo@...> wrote:

I suppose that is not a true new topic about the Losmandy mount: how often is advisable to realize the modeling of the mount? Every time when I open in warm restart, only warm or could start? My mount is a Losmandy G11 Gemini1 level4 in a permanent pier.


Luis

--
Michael Herman
mobile: 408 421-1239
email: mherman346@...


Re: GM8 DEC backlash

 

Sorry that nutty Google is playing new games with my documents.

I'll try and attach the file here again.

Hope it works. If not, send me an email and I'll send it?to you directly.

Best,
Michael

On Mon, Sep 30, 2019, 1:38 PM Brian Valente <bvalente@...> wrote:
michael this doc that begins with ""

it says I need to request access for it?

On Mon, Sep 30, 2019 at 1:27 PM Michael Herman <mherman346@...> wrote:
Here are two documents.? One is about GM8 PE testing.? The other is about fixing the worm lateral containment.? Perhaps there are clues in that to help you solve your GM8 issue.? ?

All the best,
Michael


On Mon, Sep 30, 2019, 7:44 AM Michael Herman via Groups.Io <mherman346=[email protected]> wrote:
Matthieu,

4 secs seems very long.

I don't think the gearbox itself is a cause, but there is an Oldham coupler that links the gearbox to the worm. Sometimes the metal ends of that coupler can work loose. Usually it's easy to tighten the tiny setscrews that hold those coupler ends to their metal shafts using an Allen hex key wrench. I think the size is 0.050 inch (and is included in sets of American size hex key wrenches by Bondhus).

The movement of the worm toward the ring gear is easy, by design of the worm blocks. ?

The difficult element is the locking of the worm between the worm blocks, but it can be done. It is easier to add in a Belleville spring washer to the place behind the far bearing (far end of the worm, away from the coupler), that will always keep pressure on the bearing and the worm.

My GM8 has essentially no backlash in either axis with these adjustments.? I leave no gap between the worm and ring gear. ?

I am surprised your RA does not have the problem, but perhaps because RA is always driven at some rate (Sidereal or solar or lunar, perhaps). ?

Let me know if you need parts like the spring washers.? I'll send you a PDF about my GM8 results.

Best,
Michael

On Mon, Sep 30, 2019 at 5:50 AM Matthieu Andre <matthieu.andre.mail@...> wrote:
Hi,

I have a GM8 from 2006 (no upgrades) and I was looking into decreasing the DEC backlash.
From my understanding, there are 3 main sources of backlash:?
-Worm to gear not tight enough
-Worm loose between its blocks
-Gearbox.

The first two can be addressed with careful alignment.
What about the gearbox? From my tests it seems I need at least 4 seconds at guide speed to clear the backlash between input and output. Does that seems right?
Could this duration be decreased by doing the backlash compensation at higher speed? I don't see this option in PHD2, and I have read that it is better to leave the Gemini backlash compensation off when guiding.

--
Michael Herman
mobile: 408 421-1239
email: mherman346@...



--
Brian?



Brian Valente
portfolio


Re: Upgrading from Half Hitch FTQ

scubaLee
 

Thank you everyone for super advice! I'll wait, work on selling my ftq, and consider the gm8.