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Equipment Discussions >> Mounts

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Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: Why me? new [Re: EFT]
      #5384331 - 08/24/12 11:00 AM

Ed
Perhaps the initail ramp up slew speed is too fast for the inertia involved for the spring loaded worm.


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Why me? new [Re: Stew57]
      #5384340 - 08/24/12 11:05 AM

Quote:

Ed
Perhaps the initail ramp up slew speed is too fast for the inertia involved for the spring loaded worm.




That is a possibility depending on the pitch of the gear teeth. From his descriptions though, it sounds like it is not slewing at all at certain speeds which would suggest a different problem.


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neilson
professor emeritus


Reged: 08/22/10

Re: Why me? new [Re: Starhawk]
      #5384357 - 08/24/12 11:12 AM

Hi Guys,
Last night I had sent an email to Craig Weatherwax the owner of OPT where I bought this. He has helped me when Meade wouldn't return my calls at first. I have kept him posted. I explained all the adjustments Carlos had me doing, and my willingness to help. I pretty much stated that this mount might with more adjusting barely work in visual but will never work for AP. Much less reach the published 40lbs. I stated why would I want to use polar for visual, thats what Alt/Az is for.
His reply was "It sounds like Carlos is going over the top to try to help you resolve the issues with the LX80 mount." Then he went on to tell me he is leaving for China today and is referring me to one of his salesman to handle this.
Does anyone know if Meade has some kind of indoor false sky set up for testing.
As for your opinion as to if I am getting the run around to wear me down. Yes, its looking that way to me too. But they don't realize I won't go away until either they can make this mount work or admit it wont. And make other arrangements for me. Because I am not going to be stuck with a mount and OTA that wont work together.
neilson


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neilson
professor emeritus


Reged: 08/22/10

Re: Why me? new [Re: EFT]
      #5384411 - 08/24/12 11:44 AM

Hi,
I set up the mount with the ota and weights pointing east and west (horizontal)unlock the RA clutch completely and balance level. Then push down on each side to make sure I feel the same pressure and that it returns to level again.
I loosen the DEC clutch and slide the ota forward and back until it stays level. With diagonal and eyepiece installed.
I am very picky about making sure the mount is level and balanced perfect with the options I'm going to use. I use a real level thats more accurate than a bubble level. In fact both bubble levels were installed cockeyed in different directions on the mount and tripod. I removed them and reinstalled them correctly.
The problem is at 45deg from top the mount feels more weight because its wanting to go horizontal to level itself. And the motor is acting week at lower speeds like the low speeds used in tracking when at 45 deg. The wormblock is tight enough now so it doesnt kickout and disengage easily anymore. Now it requires a reasonable amout of force to cause it to disengage. I am going to call Carlos shortly and let him know how it went.


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jrcrillyAdministrator
Refractor wienie no more
*****

Reged: 04/30/03

Loc: NE Ohio
Re: Why me? new [Re: neilson]
      #5384428 - 08/24/12 11:51 AM

Quote:

Hi,
I set up the mount with the ota and weights pointing east and west (horizontal)unlock the RA clutch completely and balance level. Then push down on each side to make sure I feel the same pressure and that it returns to level again.




If it's balanced, it'll stay anywhere you put it. If it moves back to level when you release it, it isn't balanced.


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neilson
professor emeritus


Reged: 08/22/10

Re: Why me? new [Re: jrcrilly]
      #5384533 - 08/24/12 12:43 PM

Your absolutely correct. But I know how to balance a mount. I was upset at the question. I have an Lxd 75 SN10, Lx3 10" LX200ACF 10" and this LX80 10" as well as other telescopes. I know how to balance a mount correctly and have done it a thousand times over the years. It doesnt go back to level I put it there and make sure it stays. I push down each side to see if I feel the same pressure and set it at 45deg each way. I just didnt want to write this whole process. I'm still upset this didnt work last night, then the email from OPT then asked if I know how to balance a mount.
But this did make me realize one thing. I was testing this on Arcturus which happens to be at 45deg. so for some reason I started thinking that it might be under more load there. I didnt have time to test any other stars due to clouds so Its probably doing this no matter where I point.
Therefore forget the 45 deg thing. And although I was upset at the question of balancing a mount it did make me realize that this is probably happening at all stars and I feel real stupid for coming up with that greater load at 45deg.thing. So thanks for asking and thanks for correcting me. I should of known better. I'm just looking for some reason for this and I'm pretty sure its from the motors inability to push the otas weight at low speeds against the rotation of the sky.
neilson


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: Why me? new [Re: jrcrilly]
      #5384579 - 08/24/12 01:13 PM

Neilson
You stated that it would not keep up with Arcturus I know the rule of thumb is to make the Ra east heavy just slightly try making the RA just slightly heavy to the west and see if it tracks better. are you noticing any Dec movement or just in RA? When we use the LX55 we balance for the side of the meridian we are shooting on in which is not that bad we set up a run for couple hours then have another object schedule in the same side of the meridian.We have so much flex in the tripod I have a LX200 10" field tripod that we need to make adapter plate to carry the LX55 mount head that would make it more steady. Fake indoor star sounds great a fiber optic star on a long all thread to give it motion sounds like a cool DIY project. if everything could be worked out? Look at the first post I do like having the duel dovetails it makes balancing so easy get you OTA close and adjust the guide scope on the top rail to finish up.

mmalik
I'm planning on doing a 5min, 8min, 10min run when the weather gives me a break.I have had clouds the last two weeks other than one day just after a rain, and would have had to install windshield wipers on OTA the dew was so heavy and it just wouldn't be a fair test. But a long exposure in on the to do list I promise.

Mark
I was thinking about the CGEM DX Mount & Tripod but reading CN forums what up with hard reset with out warning. the mount is on sale right now but I don't want to buy a more expensive problem, the design is old school GEM so should have less problems. It does how ever looks like the knobs would grab cables. Just not sure about the CGEM DX I did go and look at one at Astronomics a few week back, and liked how beefy the whole set up looks. I have read how folks are using shorties and getting lighter weights to get it balanced. I do want something that would handle a 8" or 10" RC (future purchase) and be able to take 10min sub. I have been kicking tires just a little gun shy right now.


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Lee Jay
Pooh-Bah
*****

Reged: 02/27/08

Loc: Westminster, CO
Re: Why me? new [Re: neilson]
      #5384591 - 08/24/12 01:26 PM

Quote:

I'm just looking for some reason for this and I'm pretty sure its from the motors inability to push the otas weight at low speeds against the rotation of the sky.
neilson




I can't even imagine this being a problem. From the point of view of the motor, the inertia of the OTA and balance weight is virtually zero (I did do the math). The energy to keep it going is exactly zero. The motor is primarily overcoming its own inertia, and the running power is just bearing drag (which can be affected by weight, but it should still be extremely small as well because the speed is exceptionally slow). I can't see how the motors could be a limitation unless you've got gear binding. Gear torque on the low-speed worm can be significant, but not motor load.


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Why me? new [Re: neilson]
      #5384592 - 08/24/12 01:26 PM

It was not my intention to be insulting with the question at all. I was not questioning your ability to balance the mount. I was questioning the mount's ability to be balanced since this is a problem I see with many mounts.

Even the weakest motors can move an axis that is well balanced. Using stronger motors or applying greater power simply to overcome misbalance is not the way to do things since it puts unnecessary stress on components. If the mount will not move at all at certain speeds and it is not a balance issue, then it is most likely that the motors are unable to overcome either their own resistance or the resistance of the gears to move. This can be an issue with servo motors and how they are regulated. In general, with a servo system, the controller will continue to ramp up the power to the motor until it breaks free. This often results in a momentary jerk forward before returning to the set speed. Of course, the control board can be programmed or designed to only apply power up to a certain point and then stop in order to avoid damaging components. If that point is too low to supply the initial torque necessary to get everything moving, then the motor will never move.

This all comes back to why I asked about how you were balancing the mount and whether the mount can be well balanced. If the axes are too stiff to allow you to balance the mount well, and the motors are not supplied with enough power to over come misbalance, but not enough to cause damage to the components, then balance could in fact be the cluprit due to the design limitations of the mount and electronics. Not having played with one of these mounts myself yet, I don't know all of the characteristics of the mount in its different configurations. However, especially considering the dual Alt/AZ-GEM design, a problem like this would not surprise me. But it root cause is not your inability to balance the mount but the mount's possible inability to be balanced and the inability of the design to overcome that issue.


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blueman
Photon Catcher
*****

Reged: 07/20/07

Loc: California
Re: Why me? new [Re: neilson]
      #5384596 - 08/24/12 01:28 PM

Hi Neilson,
As I stated, you have shown great patience in my opinion.

If you want my opinion on this, give it up, the mounts are not ready for action and they need work. This kind of work should be performed before they are sold and not after by the purchaser.

Personally, I would return it and either buy another mount or save my money and buy a better mount. It would also be possible that I would wait for a few months to see if they ever work out the bugs on the LX-80 and LX-800 mounts and then buy another, if that seemed like a good idea at the time.

Nothing personal towards Meade, I have never been a fan of buying new products before they have been proven in the field to be dependable.
Blueman
Quote:

Hi Guys,
Last night I had sent an email to Craig Weatherwax the owner of OPT where I bought this. He has helped me when Meade wouldn't return my calls at first. I have kept him posted. I explained all the adjustments Carlos had me doing, and my willingness to help. I pretty much stated that this mount might with more adjusting barely work in visual but will never work for AP. Much less reach the published 40lbs. I stated why would I want to use polar for visual, thats what Alt/Az is for.
His reply was "It sounds like Carlos is going over the top to try to help you resolve the issues with the LX80 mount." Then he went on to tell me he is leaving for China today and is referring me to one of his salesman to handle this.
Does anyone know if Meade has some kind of indoor false sky set up for testing.
As for your opinion as to if I am getting the run around to wear me down. Yes, its looking that way to me too. But they don't realize I won't go away until either they can make this mount work or admit it wont. And make other arrangements for me. Because I am not going to be stuck with a mount and OTA that wont work together.
neilson




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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: Why me? new [Re: TALK2KEV]
      #5384599 - 08/24/12 01:30 PM

I just received a call back from Meade they are looking into this Latitude lock which was great to hear from Meade I hope they will send me a part and the latitude lock will be fixed
He said he would try to call back today but no later than Monday. I hope he will call back telling me the parts are in route.


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TALK2KEV
sage


Reged: 03/08/06

Loc: Oklahoma
Re: Why me? new [Re: TALK2KEV]
      #5384641 - 08/24/12 01:52 PM

Neilson
I know a guy that hes does a balance by hand then does a current test on the motors to fine tune the balance.To see how much power the motor is pulling. Just a thought


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neilson
professor emeritus


Reged: 08/22/10

Re: Why me? new [Re: TALK2KEV]
      #5384660 - 08/24/12 02:07 PM

Hi Guys,
I'm glad they are going to do something about your latitude lock problem Kevin.

As far as the RA problem goes when the mount is in Alt/Az it works fine but when I tilt it up to 28.58 degrees latitude for polar mode thats when it has the problems.
Also was mentioned that it should ramp up the speed until it starts moving to correct tracking. I agree it should but its not. That might solve this problem. Theres just too much drag when the mount/RA it tilted up for polar, or more than the motor can compensate for. All this is making more sense with all the input from ya'll today. Now I guess either the motor setup, or firmware to compensate, or reduce drag in the mount without reducing weight.
neilson


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neilson
professor emeritus


Reged: 08/22/10

Re: Why me? new [Re: TALK2KEV]
      #5384680 - 08/24/12 02:26 PM

Kevin,
I do look at the amp draw when slewing but the ring gears have a high and low spot so that effects the current readings and would make that difficult unless you happen to know where the high spot was at that time and avoid it. Although some ring gears arn't as bad as others. But with that said, yes If I am out of balance it's noticeable in the amp readings. And if that happens I do stop and re balance and re align. That's why I pay close attention to my balance in the beginning.
neilson


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Why me? new [Re: neilson]
      #5384710 - 08/24/12 02:50 PM

That is definitely one of the problems with the amp-draw/electronic balancing method. First, it assumes that any difference in the current draw is the result of imbalance at the end of the train between the motor and the OTA, when there are plenty of opportunties in between to cause additional drag on the system. In addition, the smaller the ring gear diameter and/or the less precise is it made and matched with the worm, the more likely it is to show rapid and significant variation in current draw making it difficult to really see what is happening. Realistically, it would require an average of the amp pull over some distance of slewing to really give you a good idea of the imbalance (and that assumes that you are seeing imbalance and not a problem in the gears themselves). At best, in this class of mount, the method may be useful for detecting gross imbalance, but for finer imbalance there is too much noise to make it very useful without a system that measures and averages the change in current draw over time. That's why I prefer a mount that turns as freely as possible with the clutch disengaged to start with.

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neilson
professor emeritus


Reged: 08/22/10

Re: Why me? new [Re: EFT]
      #5384770 - 08/24/12 03:25 PM

This mount does have a small amount of drag with the clutch disengaged in RA but not the DEC. Its not much though.
I found the high spot on my ring gear and found a fairly smooth area and tested balance. My mount was perfect. I moved 1 weight about 1 or 1.5 inches outward and it was noticeable on the test.
I took readings with ota and weights and RA 0.48 amp draw. I removed the ota and weights and 2 sections of the bar and had both saddles on for balance and RA 0.43 amp draw. then with the clutch disengaged RA 0.41 amp draw. The weight of everything causes only 0.07 amp difference. I dont know if thats enough to cause these problems or not but a small refractor like many on this forum are using would probably just draw 0.44 amp.
When I recieved my mount it was drawing 0.58 amp with ota so the adjustments yesterday brought it down 0.1 amps.
neilson


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Why me? new [Re: neilson]
      #5384886 - 08/24/12 04:29 PM

It's good to know that the axes turn fairly easily. High spots on the the ring gear are not at all uncommon in this level of mount (or just about any mount in reality). That's part of what spring mounted worms are for.

I would say that the difference before and after you made the adjustments is fairly significant (15-20%) and certainly indicative of an adjustment problem that you were able to address with some success. It also brings into question the ability of the motors and motor board to overcome both imbalance and stiction and simple torque issues. If the mount was simply unable to slew at certain speeds in this case, it certainly suggests that insufficient power is being supplied to overcome the resistance of the motor and gears to move since it appears that the axis was well balanced and should have supplied little resistance itself.


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neilson
professor emeritus


Reged: 08/22/10

Re: Why me? new [Re: EFT]
      #5385021 - 08/24/12 06:16 PM

When I received my mount with the RA bearing loose I had tightened the bearing finger tight but on the snug side with my fingers before. Now I went and loosened it, then finger tightened it lightly. There is an extremely small amount of play now. I retested the amp draw but there was no improvement. I just wanted to make sure it wasn't causing problems.
neilson


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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: Why me? [Re: neilson]
      #5385062 - 08/24/12 06:47 PM Attachment (8 downloads)

Gday Neilson

Quote:

Also was mentioned that it should ramp up the speed until it starts moving to correct tracking. I agree it should but its not.




Just for info, and after reading most of this mornings threads,
how do you know its not "ramping" the speed.
At "tracking rates", unless you log the actual motor lines / encoders, to see whats happening, you cant tell.
( I'm not trying to be funny, just trying to understand whats going on )
Ie is it motors cant get it moving or is it motors arent trying???

Just for info, i have attached some plots i use to monitor/check this sort of stuff.
One shows an LX90 tracking in Polar with an Audiostar controller,
and how it deals with pulseguides via serial commands.
The other shows the way the motor PWM is applied in short bursts to get the motors moving.
The latter is for an ASII, but the Audiostar is similar.
I will make up a new one for the Audiostar, to show specifically what really happens.
There does appear to be a fairly complex motor control feedback loop in the motorcards.

As a lot of this process is controlled by the motor cards, you need to actually play with the real cards to see what happens, monitoring the firmware doesnt always help.
That said, there is a known bug where the motors wont always restart tracking immediately after a manual slew, esp short bursts via the hbx to centre something, but this doesnt sound like its your problem.

Andrew


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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: Why me? [Re: OzAndrewJ]
      #5385064 - 08/24/12 06:48 PM Attachment (7 downloads)

PartII
This is the motor starting routine


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