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Equipment Discussions >> Mounts

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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: Has anyone here used an Paramount MX and an AP900? new [Re: frolinmod]
      #5201619 - 05/02/12 11:16 AM

Do both axis use belts or just Declination axis? It would make more sense if the belt is only for Dec axis to eliminate backlash and RA motor is always running in one diretcion therefore no backlash so there should not be a need for a belt on RA axis. Correct?

Peter


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Bowmoreman
Clear enough skies
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Reged: 09/11/06

Loc: Bolton, MA
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Peter in Reno]
      #5201628 - 05/02/12 11:21 AM

On the topic of belts... belt drive - done well - is usually BETTER than direct gearing in important aspects...

For example, with high-end audio turntable's, all the best are belt drive. Why? because belts better isolate rumble and high frequency physical disturbances/noise...

I can easily imagine the same phenomenon with mounts; the belts isolating/damping/smoothing out the higher order harmonics and noise from the motor and reduction gear(s) upstream of the belt.

With auto-tensioning, behavior variance as a function of stretch and/or temperature will be a non issue.

All the above is true only if it is done "right", which I'd have to believe they have.


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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Bowmoreman]
      #5201649 - 05/02/12 11:32 AM

I totally agree that using belt driven gears for mounts are great mainly to virtaully eliminate backlash. Backlash is the enemy for imaging. If Bisque has been using belt driven gears in their mount from day one and people have not complained about it, then I do not see a problem using belts in mounts. Like you said as long as it's well engineered. Probably PEC is not even needed.

Peter


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frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Bowmoreman]
      #5201674 - 05/02/12 11:46 AM

Quote:

Do both axis use belts or just Declination axis?



On all Paramounts both RA and DEC use timing belts. Tracking speeds are continuously variable on both axes. The mounts are intended to be used for more than just tracking sun, moon and stars. They can precisely track planets, comets, asteroids and satellites as well. Try putting your slew speed and acceleration up to maximum on an ME or MX sometime. It's like having an assembly line robot.


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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: Has anyone here used an Paramount MX and an AP900? new [Re: frolinmod]
      #5201706 - 05/02/12 12:05 PM

OK, thanks for providing valuable information about Paramount mounts. Sounds like great engineering work regarding to belt driven mounts.

Peter


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Joe Bergeron
Vendor - Space Art


Reged: 11/10/03

Loc: Upstate NY
Re: Has anyone here used an Paramount MX and an AP900? new [Re: saadabbasi]
      #5201718 - 05/02/12 12:11 PM

Quote:


Before the AP1600GTO was announced, I was ready to jump on an AP900. After the AP1600GTO, I've been slightly reluctant because it's fairly obvious it will be updated sooner or later.




A-P has stated that the currently available 900 mounts are the last that will be made. I think the upgrade will come sooner rather than later.


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blueman
Photon Catcher
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Reged: 07/20/07

Loc: California
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Joe Bergeron]
      #5201964 - 05/02/12 01:59 PM Attachment (51 downloads)

Though is is certain that the AP-900 will undergo a transformation, this does not take away from the mount as it is now. It is a great mount, compact, light weight and works very well.

Internally routed cables sounds like a good idea, but when cables are placed in a confined space and then twisted, then they will be more prone to failure over time. I think there have been problems with this with another brand mount. Still, I guess it would be nice.

More capacity would also be great, but if it is at the cost of more weight, well that would detract from the mount for me, I wanted the light weight as I am no longer a young man.

Then, increase price, hmm, well $8750 was already a lot of money, add the tripod or pier, counter weights and a polar scope and you are topping $10,000! The new mount may cost and additional $1200-1500 if the prices follow the AP-1600. This too is not always the best thing.

So, if you want a new AP-900, this is the time to act. But, remember this, if the new mount comes out soon and there are a lot of people wanting to upgrade, then there will be used AP-900 mounts for sale, same as the AP-1200! This is a good thing, maybe the prices will even be better?

But I have to say, I really like the AP-900. It is overall an easier mount for me to handle over my MI-250, which is also a great mount, just bigger and heavier.
Blueman
Quote:

Quote:


Before the AP1600GTO was announced, I was ready to jump on an AP900. After the AP1600GTO, I've been slightly reluctant because it's fairly obvious it will be updated sooner or later.




A-P has stated that the currently available 900 mounts are the last that will be made. I think the upgrade will come sooner rather than later.




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Joe Bergeron
Vendor - Space Art


Reged: 11/10/03

Loc: Upstate NY
Re: Has anyone here used an Paramount MX and an AP900? new [Re: blueman]
      #5202035 - 05/02/12 02:33 PM

Yes, if I controlled a fabulous fortune I would order a 900 mount right now.

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frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Joe Bergeron]
      #5202064 - 05/02/12 02:51 PM

Quote:

Internally routed cables sounds like a good idea, but when cables are placed in a confined space and then twisted, then they will be more prone to failure over time. I think there have been problems with this with another brand mount. Still, I guess it would be nice.



Through the mount wiring is indeed a very nice feature. I've never had any trouble with running cables through the mount nor with cable twisting or cable failure over time. Still, nobody likes having a lot of cables. These days I've reduced the number of extra added cables going through my mount to just two: one 14AWG 12V power and one USB2 data. I have a HitecAstro Mount Hub Pro on the mount to which everything else connects including dew heaters, focuser, rotator, camera and the mount itself. I have just a single USB2 cable running from the back of the mount to my computer. No cable clutter. If you haven't taken a look at the Mount Hub Pro, you might want to think about doing so.


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Christopher Erickson
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Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: Has anyone here used an Paramount MX and an AP900? new [Re: saadabbasi]
      #5202451 - 05/02/12 06:20 PM

Quote:

Thanks, orlyandico.

Before the AP1600GTO was announced, I was ready to jump on an AP900. After the AP1600GTO, I've been slightly reluctant because it's fairly obvious it will be updated sooner or later.

Considering that, I just feel I should get the most bang for my buck that I can. If I purchase the AP900 now I miss out on (potentially) through-the-mount cabling, an increase in payload, an option to have absolute encoders etc.

I feel these are significant improvements, especially if the "new" AP900 retains the current size.

The problem now becomes how long do I wait?. There's no info when the 'upgraded' AP900 will be produced. I have to wait till the end of the year to get enough cash. If however, the new AP900 still isn't announced, I'll probably have to go with PMX.

The PMX, as the AP900 stands, offers more payload, through-the-mount cabling, and it comes with a lot of extras (software, 2 x counterweights, saddle) - with no decrease in precision as compared to AP900 (at least that's what I perceive. I don't know if that is actually true, but considering the rave reviews of the PMX and the PME, it seems Bisque knows what they're doing).

I know that a computer is required all the time, but I need to have a computer 99% of the time anyway because of my CCD camera.

So, now, only one concerns remains - will Software Bisque still support this mount 10-15 years down the line?





Two more considerations concerning Astro-Physics:

1. They are honest and up-front about new products, future products, current products and old products. Most manufacturers are not willing to do that because it gives their competitors an advantage over them. AP clearly considers customer relations to be much more important than competitive strategies.

2. They (and Televue) support older products way above and beyond any other manufacturers. No reason to be afraid of a discontinued or older AP mount. It will be supported for many, many years.


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Christopher Erickson
Carpal Tunnel
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Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Peter in Reno]
      #5202496 - 05/02/12 06:41 PM

Quote:

I totally agree that using belt driven gears for mounts are great mainly to virtaully eliminate backlash. Backlash is the enemy for imaging. If Bisque has been using belt driven gears in their mount from day one and people have not complained about it, then I do not see a problem using belts in mounts. Like you said as long as it's well engineered. Probably PEC is not even needed.

Peter




I like timing-belt drive systems but it is important to note that about 98% of all telescope axis backlash comes from the interface between the worm gear and the worm wheel and that is not solved by a timing belt drive between the axis motor and the worm gear.


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Christopher Erickson
Carpal Tunnel
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Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Christopher Erickson]
      #5202526 - 05/02/12 06:58 PM

I should have added that in my day-job, "backlash" is generally-defined as the play in the worm drive.

"Hysteresis" is generally-defined as the play in the drive train between the motor and the worm drive.


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Stew57
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Reged: 05/03/09

Loc: Silsbee Texas
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Christopher Erickson]
      #5202605 - 05/02/12 07:32 PM

Backlash can be compensated for but Hysteresis is trouble. My lowly cgem has an 8/3 pe error that is 75% of the 1st harmonic. No way for PEC to correctn for it when PEC is only corrects for 1 worm rotation on that mount. A belt drive would have eliminated that problem.

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orlyandico
Post Laureate
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Reged: 08/10/09

Loc: Singapore
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Stew57]
      #5202616 - 05/02/12 07:40 PM

Mark, actually that 8/3 is inside the cheapo Igarashi gearhead. Replacing the spur gear between the gearhead output shaft and the worm shaft with a belt would do nothing to fix that.

(this is the reason why A-P uses Maxon motors.. you can't get rid of backlash in the gearhead, but you can reduce it)


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Peter in Reno
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Re: Has anyone here used an Paramount MX and an AP900? new [Re: orlyandico]
      #5202780 - 05/02/12 09:22 PM

I am a little confused. Why would Maxon motors reduce backlash?

I have read that A-P motors are from Switzerland but did not know that they were Maxon motors. I have read great things about Maxon motors.

Peter


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orlyandico
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Loc: Singapore
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Peter in Reno]
      #5203091 - 05/03/12 02:37 AM

the CGEM problem is a not-high-quality gearbox.

if the gearbox has loose tolerances then there will be backlash and periodic error caused by the gearbox itself.

e.g. when reversing direction you need to take up the slack within the gearbox itself, before you can take up the slack in the worm-to-worm-wheel interface.

obviously the more money you put in the motor gearbox, the less backlash there will be in the gearbox itself.

maxon also produces coreless servo motors that do not "cog."

cogging of the motor due to the armature poles limits the minimum movement the motor can execute.


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Bowmoreman
Clear enough skies
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Reged: 09/11/06

Loc: Bolton, MA
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Peter in Reno]
      #5203176 - 05/03/12 07:02 AM

Quote:

I am a little confused. Why would Maxon motors reduce backlash?

I have read that A-P motors are from Switzerland but did not know that they were Maxon motors. I have read great things about Maxon motors.

Peter




The Maxons in my MI 250 are great.

Belts virtually eliminate the hysteresis upstream of the worm... Not backlash tween worm and the final gear...


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orlyandico
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Reged: 08/10/09

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Re: Has anyone here used an Paramount MX and an AP900? new [Re: Bowmoreman]
      #5203315 - 05/03/12 08:52 AM

Dave - only true if the belt drive is directly driven by the motor via a high reduction. If there is a gearhead reduction on the motor itself, you would still have backlash inside the gearhead (which of course could be minimized by buying an expensive motor + gearhead).

To put this into perspective, a typical Maxon coreless motor with a 10:1 (range) high-end gearhead is $400 plus.

There's a reason these motors don't find their way into the CGEM's of the world...


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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: Has anyone here used an Paramount MX and an AP900? new [Re: orlyandico]
      #5203555 - 05/03/12 11:14 AM

YouTube video of MX Worm Block Assembly. You will see drive belt in the video.

http://www.youtube.com/watch?v=ARKTL9XlSV4

Peter


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frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: Has anyone here used an Paramount MX and an AP900? new [Re: Peter in Reno]
      #5203604 - 05/03/12 11:41 AM

Here's another video of the Paramount MX tracking a satellite:

http://www.youtube.com/watch?v=1b3GKy_sAr0

One of those pretty flashing types.


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