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New ZWO AM5 Harmonic Drive Mount

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#551 rgsalinger

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Posted 21 June 2022 - 10:57 PM

The ASCOM issue is irrelevant and shows that the reviewer doesn't understand ASCOM.  https://ascom-standa...FAQs/DevHub.htm is the replacement for POTH which got around exactly this problem for years and years. 

 

Other than that, I find the review incredible. I am distrustful of anything posted on Fakebook. I personally have not ordered one of these and wouldn't until I see some reviews by people that I know are credible. Frankly, seeing finished products where one has no idea of the quality of the underlying data and/or the processing expertise needed to obtain the results, is just not something that anyone should be impressed by. 

 

If I wanted to review a mount I would do it here or on other sites that have people who know mounts. I would provide logs and raw data. Without that kind of review, I'm not ordering one.

 

Still, if you don't own a mount, like the 30 lb capacity limit and understand the well known guiding issues, it would certainly be tempting to give one a try. Since I already own 4 mounts, I'll wait until I can see that one of the harmonic mounts is a good replacement for one of the other ones. 

 

I wouldn't buy the ZWO version if there was even a whiff that it tied me into their appliance. Why bother with ZWO, when credible manufacturers like iOptron who have US based support are selling the same product at the same price? Think carefully about support when choosing a vendor. Mounts last a long time and so support is much more important than it is with guide cameras. 

 

Rgrds-Ross


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#552 charles.tremblay.darveau

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Posted 21 June 2022 - 11:08 PM

Hi all, thought I'd jump in here as I am the YouTube reviewer Astro With RoRo. I also personally know the FB text reviewer and we have talked quite a bit about the mount and our feelings on it before posting to make sure that my views was not too distant from his own experience.

 

As I called out in the video, the guiding numbers I got and mention are higher than you would see if you were in a field / open space. I had only 2 days with the mount, and limited time under the skies during this 2 days so was stuck to imaging from my apartment balcony. The seeing is poor compared to skies you can get away from the city & I have buildings near me that can cause interesting seeing/wind movements which amplify guiding numbers somewhat. In general Prasun and I agree that the mount will perform solidly so long as you are able to guide it at sub 1.5s intervals as I mention in the conclusion. If you are not able to do this, then yes this mount is probably not for you. The mount can definitely hold a good payload (as you can see through Prasun's setup) and with fast guide exposures you can get some nice looking stars (note he uses a 174 for guiding and he did not think a 120 or 290 could OAG fast enough). I was disappointed to see the star trails in my wide focal length images, but I think Prasun's image shows that with time, tweaking of settings, the right environment, etc, you can absolutely obtain very good images from the AM5.

 

I don't want to take away from what ZWO has created here, it's a great piece of hardware that competes well with many other harmonic mounts. I do think they were being greedy to think that not releasing proper integration with non-ASIAIR hardware wouldn't come back to bite them. With time this should be resolved though and after that this mount, just like many others will serve many users well over the coming years.

 

Happy to answer any other questions I can.

Again, thanks for all your hard work. This is a very valid data point and curious what other people's mount will also look like. If you play with the AM5 again, let us know if you can replicate those 5" spikes. Curious if those are intrinsic to the mount or due to external factors. Cheers,


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#553 licho52

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Posted 21 June 2022 - 11:24 PM

Hi all, thought I'd jump in here as I am the YouTube reviewer Astro With RoRo. I also personally know the FB text reviewer and we have talked quite a bit about the mount and our feelings on it before posting to make sure that my views was not too distant from his own experience.

 

As I called out in the video, the guiding numbers I got and mention are higher than you would see if you were in a field / open space. I had only 2 days with the mount, and limited time under the skies during this 2 days so was stuck to imaging from my apartment balcony. The seeing is poor compared to skies you can get away from the city & I have buildings near me that can cause interesting seeing/wind movements which amplify guiding numbers somewhat. In general Prasun and I agree that the mount will perform solidly so long as you are able to guide it at sub 1.5s intervals as I mention in the conclusion. If you are not able to do this, then yes this mount is probably not for you. The mount can definitely hold a good payload (as you can see through Prasun's setup) and with fast guide exposures you can get some nice looking stars (note he uses a 174 for guiding and he did not think a 120 or 290 could OAG fast enough). I was disappointed to see the star trails in my wide focal length images, but I think Prasun's image shows that with time, tweaking of settings, the right environment, etc, you can absolutely obtain very good images from the AM5.

 

I don't want to take away from what ZWO has created here, it's a great piece of hardware that competes well with many other harmonic mounts. I do think they were being greedy to think that not releasing proper integration with non-ASIAIR hardware wouldn't come back to bite them. With time this should be resolved though and after that this mount, just like many others will serve many users well over the coming years.

 

Happy to answer any other questions I can.

 

Thanks for the review, it was helpful and you were not afraid to show the real results and even the nasty spikes on the guiding graph.  This also doesn't take away from ZWO as I think they were courageous to introduce this new and promising technology and any disappointment is due to our elevated expectations (which were a bit inflated given the SCT user's numbers).



#554 BlakPhoenix

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Posted 21 June 2022 - 11:47 PM

Again, thanks for all your hard work. This is a very valid data point and curious what other people's mount will also look like. If you play with the AM5 again, let us know if you can replicate those 5" spikes. Curious if those are intrinsic to the mount or due to external factors. Cheers,

We are planning a side by side of the AM5 and my RST-135E (with runs where the encoder is both on and off) once the weather clears again to gain more data and look further into these items. Will be sure to share this out (and will attempt to show raw logs for both too so the experts can weigh in).

 

The ASCOM issue is irrelevant and shows that the reviewer doesn't understand ASCOM.  https://ascom-standa...FAQs/DevHub.htm is the replacement for POTH which got around exactly this problem for years and years. 

 

Other than that, I find the review incredible. I am distrustful of anything posted on Fakebook. I personally have not ordered one of these and wouldn't until I see some reviews by people that I know are credible. Frankly, seeing finished products where one has no idea of the quality of the underlying data and/or the processing expertise needed to obtain the results, is just not something that anyone should be impressed by. 

 

If I wanted to review a mount I would do it here or on other sites that have people who know mounts. I would provide logs and raw data. Without that kind of review, I'm not ordering one.

 

Still, if you don't own a mount, like the 30 lb capacity limit and understand the well known guiding issues, it would certainly be tempting to give one a try. Since I already own 4 mounts, I'll wait until I can see that one of the harmonic mounts is a good replacement for one of the other ones. 

 

I wouldn't buy the ZWO version if there was even a whiff that it tied me into their appliance. Why bother with ZWO, when credible manufacturers like iOptron who have US based support are selling the same product at the same price? Think carefully about support when choosing a vendor. Mounts last a long time and so support is much more important than it is with guide cameras. 

 

Rgrds-Ross

Thanks Ross, always looking to expand my knowledge and understanding. The owner mentioned to me that the ASCOM hub attachment also did not work correctly for them, with incorrect slews/instructions not working and errors being thrown. Certainly using the direct driver you also cannot multi-connect as I mentioned in the video. To me this means that even the hub route requires some update to software to allow it to run properly, but I may be wrong here. The direct ASCOM driver does work perfectly well then you are connected directly though. Completely agree with your comments around lack of wider integration though.


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#555 Zambiadarkskies

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Posted 22 June 2022 - 02:38 AM

Hi all, thought I'd jump in here as I am the YouTube reviewer Astro With RoRo. I also personally know the FB text reviewer and we have talked quite a bit about the mount and our feelings on it before posting to make sure that my views was not too distant from his own experience.

 

As I called out in the video, the guiding numbers I got and mention are higher than you would see if you were in a field / open space. I had only 2 days with the mount, and limited time under the skies during this 2 days so was stuck to imaging from my apartment balcony. The seeing is poor compared to skies you can get away from the city & I have buildings near me that can cause interesting seeing/wind movements which amplify guiding numbers somewhat. In general Prasun and I agree that the mount will perform solidly so long as you are able to guide it at sub 1.5s intervals as I mention in the conclusion. If you are not able to do this, then yes this mount is probably not for you. The mount can definitely hold a good payload (as you can see through Prasun's setup) and with fast guide exposures you can get some nice looking stars (note he uses a 174 for guiding and he did not think a 120 or 290 could OAG fast enough). I was disappointed to see the star trails in my wide focal length images, but I think Prasun's image shows that with time, tweaking of settings, the right environment, etc, you can absolutely obtain very good images from the AM5.

 

I don't want to take away from what ZWO has created here, it's a great piece of hardware that competes well with many other harmonic mounts. I do think they were being greedy to think that not releasing proper integration with non-ASIAIR hardware wouldn't come back to bite them. With time this should be resolved though and after that this mount, just like many others will serve many users well over the coming years.

 

Happy to answer any other questions I can.

Rowan, thanks for taking the time to make the Youtube review.  I found it very well done - like all your Youtube work.  You asked if people would be interested in more reviews and a comparison with your RST.  Definitely!  


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#556 arbit

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Posted 22 June 2022 - 04:45 AM

Just a data point re the iOptron HEM27. It is different in that it has a worm on the dec, so its a hybrid rather than a pure SWG drive like the AM5, RST etc.

As per the manual, it needs balancing in Dec, except it has to be done with the OTA vertical, which sounds painful :-)



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#557 Northernguy

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Posted 22 June 2022 - 07:23 AM

 

 

I wouldn't buy the ZWO version if there was even a whiff that it tied me into their appliance. Why bother with ZWO, when credible manufacturers like iOptron who have US based support are selling the same product at the same price? Think carefully about support when choosing a vendor. Mounts last a long time and so support is much more important than it is with guide cameras. 

 

Rgrds-Ross

I have the AM5 on order, but am waffling. I do need a mount with greater weight capacity than what I have currently, although I am very happy with my CEM26, for when I use it with a load that it is comfortable with. However, compared to the AM5, I don't see a similar priced/similar capacity mount from iOptron? What are you thinking of, that might be a comparator?

Have to decide if the superior capacity to overall weight ratio of a strain-wave mount like the AM5 is worth the bother of the PE and software issues. 



#558 arbit

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Posted 22 June 2022 - 08:04 AM

I have the AM5 on order, but am waffling. I do need a mount with greater weight capacity than what I have currently, although I am very happy with my CEM26, for when I use it with a load that it is comfortable with. However, compared to the AM5, I don't see a similar priced/similar capacity mount from iOptron? What are you thinking of, that might be a comparator?
Have to decide if the superior capacity to overall weight ratio of a strain-wave mount like the AM5 is worth the bother of the PE and software issues.

Ioptron has just announced the HEM27. However, as mentioned in my post just before yours, its a hybrid, not a pure SWG.

In practical terms, that means some Dec backlash and the need to balance in Dec. Also it operates only above 15 degrees latitude.

Of course, they have solid experience in mounts, and their software is well tested.

For me, the Dec balancing and latitude restriction rule it out. YMMV.

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#559 dciobota

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Posted 22 June 2022 - 09:49 AM

Personally, the am5 is the mount for me.  Rowan's results are not surprising for a mount that has non perfect sinusoidal error.  This is why faster guiding is recommended.  And an rms error of 0.8 is right in the range zwo mentioned their guiding accuracy would be (I think they advertise 0.6-0.8).  I'll wait further testing from Rowan after he tweaks the guiding parameters a bit  I'm also curious about performance comparisons against the rst135e without the encoders turned on.

 

Btw, for those of you that assume that zwo is tying into their asiair ecosystem, as far as I know they use standard indi drivers there.  So I'm pretty sure that other indi based apps would work just as well.  Yes, it is a shame they didn't test the ascom driver more thoroughly.  But it's a software issue, nothing to do with the mount itself.  How many times has qhy screwed up (and still does occasionally) their drivers, and they've been in the camera business for over a decade?  I'm cutting zwo some slack on this.  I'm sure the fixed ascom driver won't take long, probably even before most of us get our mounts.  ;-)

 

All in all, I don't see any zwo "broken promises".  Many on facebook and even on here have hyped up the mount to where people were expecting (and actually demanding) much better performance than zwo advertised.  So now those folks are a bit disappointed from just one data point.  Let's wait for others who have received their mounts to chime in.

 

Btw Ross, zwo is planning (and may already have it operational) a US based distribution and repair center.  I strongly considered ordering my mount directly from China, because of this, but I still prefer to deal with a US based reseller.  More peace of mind.  Maybe in the future this won't make a difference anymore.

 

I also want to add, maybe those of you dropping your orders will be good for me; maybe I'll advance far enough in the queue to be in on the end of June deliveries.  ;-)


Edited by dciobota, 22 June 2022 - 09:51 AM.

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#560 chimerasaurus

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Posted 22 June 2022 - 09:57 AM


Btw, for those of you that assume that zwo is tying into their asiair ecosystem, as far as I know they use standard indi drivers there.  So I'm pretty sure that other indi based apps would work just as well.  Yes, it is a shame they didn't test the ascom driver more thoroughly.  But it's a software issue, nothing to do with the mount itself.  How many times has qhy screwed up (and still does occasionally) their drivers, and they've been in the camera business for over a decade?  I'm cutting zwo some slack on this.  I'm sure the fixed ascom driver won't take long, probably even before most of us get our mounts.  ;-)

 

That would be interesting because AM5 support in INDI appears to be just LX200 with no actual input from ZWO:

 

Add entry for ZWO AM5 as LX200 Autostar compatible mount. This is a guess at this point, it could require tweaking

 

Which means their "support" for a larger ecosystem is basically just hoping stuff works. It's also interesting, to me at least, they haven't contributed to the INDI project, which they're likely using for the ASIAIR.


Edited by chimerasaurus, 22 June 2022 - 09:59 AM.


#561 rgsalinger

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Posted 22 June 2022 - 10:13 AM

ZWO has some sort of repair center for cameras already in "operation". I've documented my experience with them trying to get a camera fixed elsewhere on the site. To summarize, it was a nightmare compared with getting my CEM120EC2 lubed and upgraded a year ago. So, I have a practical real world data point about ZWO and iOptron. 

 

Once you get outside the USA, it's can be another matter entirely. Altair Astro handles iOptron mount repairs in Europe, FWIW. That's still better than ship it to China. It can, though, be fun to be a pioneer. Some pioneers got to Oregon just fine. I bought my CEM120EC2 and was ridiculed for the choice. That mount has performed every bit as well as my recently departed Paramount MX+ for over 4 years now (serial number 14). Still, I see the selection calculus here differently. 

 

I'll have to wait and see how important the choice of using a DEC worm/gear arrangement turns out to be. Balanciing DEC is not likely to be a problem and the latest belt drive mounts show little of no backlash. It's really hard to have much if any backlash in a belt driven spring loaded mount. Paramounts have worked exactly this way basically forever.

 

What I know is that we have an offering of a 9 pound mount from a company experienced in building and servicing mounts versus a company that makes cameras and some other odds and ends. If I move to Peru, I'll worry about latitude. And for 3200 bucks you get an encoder version of the mount which is not even offered yet by ZWO. iOptron can do this because it's the same technology that they use in all the EC mounts.

 

FWIW, the ASCOM driver issue with the AM5 is irrelevant. Just use the ASCOM device hub to get around the issue. At least, unlike indi drivers, it's supported by the vendor. That's a good thing when you have a problem. There's not much fun for most people delving into the mysteries of Linux distros in order to solve a cryptic error message. That was precisely the experience that I had and the iOptron driver was way behind the ASCOM driver in terms of what methods it supported. 

 

Rgrds-Ross


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#562 dciobota

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Posted 22 June 2022 - 10:15 AM

I honestly don't know if the lx200 protocol is all that is needed or not to operate the mount.  Someone will have to test it.  But as far as I understand indi, multiple device access to indi drivers is not an issue as it is with ascom drivers.  So that's what I was referring to.  I could be wrong but I don't see why zwo would write a non indi compliant driver in linux just for the asiair.  Perhaps they need to publish their zwo indi driver they developed, or maybe the plain lx200 driver is what they use also.



#563 chimerasaurus

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Posted 22 June 2022 - 10:18 AM

I’d be surprised if the mount didn’t have LX200 plus other methods that a custom driver could wrap.

I have dug into the source for iOptron mounts too and the INDI driver is leaps and bounds less horrible, but that’s just another topic altogether.

#564 dciobota

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Posted 22 June 2022 - 10:37 AM

Hi Ross,

 

My comment was simply a correction about zwo not having a repair center in the USA.  Looks like they do, and you've had a bad experience.  Understandably, you now prefer ioptron products.  But I'd rather this thread not be about vendor bashing or praising, just an analysis of the mount based on the available data.

 

As far as belt driven worm drives in dec, well, no one is comparing a product like the hem27 to an ap mount, I'm sure.  And the encoder version of the hem27, while nice, is over $1000 more than the non encoder (and am5).  Different class of product imo.  If you follow the hem27 thread you will noitice quite a few comments on how the dec unit on the hem27 is similar to other iptron mounts that have had backlash issues.  So it is a valid concern.  Belt driven worm gears look good on paper but the reality is unless you have the kind of quality control and machining AP mounts have, you are liable to have issues in that area.  It's just how it is. 

 

The beauty of the am5 for me is to just slap my equipment on it, turn it on and it just does the job.  Not fiddling with balance, counterweights and such.  I love simplicity and minimalism in design, and that's one thing that appeals to me with the am5.  

 

But everyone has their own criteria for choosing or not choosing a particular mount.  I certainly am not telling you what to buy, just commenting on the technical aspects of this mount and reported performance so far.


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#565 dciobota

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Posted 22 June 2022 - 10:40 AM

I’d be surprised if the mount didn’t have LX200 plus other methods that a custom driver could wrap.

I have dug into the source for iOptron mounts too and the INDI driver is leaps and bounds less horrible, but that’s just another topic altogether.

That's very possible.  I'd be very interested in seeing someone test the mount with an app like Ekos and the lx200 driver.  And I would certainly hope zwo publishes their implementation.

 

I don't know much about ascom drivers, can they be reverse engineered?  I'm wondering if someone could find out whether there is more to the ascom driver than a plain lx200 protocol.



#566 cddestins

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Posted 22 June 2022 - 10:57 AM

Hi! what length for the 3/8-16 unc screw please? 14 mm it’s good for am5 o need more? Thank you!

#567 jimhoward999

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Posted 22 June 2022 - 11:24 AM

Based on the spec sheets and reviews I have read, the AM5 stated periodic error of ±20 arcseconds is smaller than any other Harmonic drive mount on the market or announced, regardless of price. 

 

Encoders and software may compensate in other mounts, but in terms a raw numbers I think the AM5 is the lowest.

 

Am I right on that?



#568 arbit

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Posted 22 June 2022 - 11:37 AM

Based on the spec sheets and reviews I have read, the AM5 stated periodic error of ±20 arcseconds is smaller than any other Harmonic drive mount on the market or announced, regardless of price.

Encoders and software may compensate in other mounts, but in terms a raw numbers I think the AM5 is the lowest.

Am I right on that?

I just read on the Nyx thread that Pegasus in an email has indicated it is specced at +-15, so that's probably the best. But its pretty close.

A lot of the early AM5 mounts seem to be in the range of 4as min to 18 as max p2p (over the complete cycle) as per the individual sheets shown. If those are not outliers it's decent for the target market.

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Edited by arbit, 22 June 2022 - 11:54 AM.


#569 DeepSky Di

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Posted 23 June 2022 - 05:08 PM

Here's the first actual review that I have seen, from Astro with RoRo. https://youtu.be/EOpemZB64EA

 

An unexpected issue - he said it can connect to NINA or PHD2 but not both at the same time, and this is being worked on. He doesn't have an ASIAIR and can't comment on how they work together. 



#570 Mike Sandy

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Posted 23 June 2022 - 09:18 PM

There are other AM5 reports coming out now on Facebook.  Results seem to vary greatly - some better than others.  Could vary with the user, or just the hardware lottery.  
 

I’ve been thinking about these drives some more, and looking at some of the drive error charts.  I don’t believe these mounts have any type of clutch. If that’s true, it means the orientation of the RA flex spline will always be consistent with respect to the circular spline - which is fixed with respect to the mount body.  That seems to mean that the mount will always track with the teeth meshing through only 180 degrees of motion (okay, maybe a bit more).  Why is that important - you ask?  When I look at some of the drive error charts the error varies significantly over the full 360 degree rotation.  The one chart I’m thinking of showed 15.9” peak to peak as the max error, but it only occurred over about 120 degrees of rotation.  The rest of the error looked more like 10” peak to peak.  If you could cherry pick (meaning adjusted the drive orientation to operate in the lowest part of the error) you might be able to see even smaller errors for the part of the drive rotation that you use.  Not every chart showed that kind of variation in the error measurement - and it may not be possible to adjust the drive orientation.  That said, there are things to learn with these drives - we can’t just apply what we know about traditional mounts.  

So am I crazy (never a good question to ask)?  Does this even make sense to anyone else?



#571 arbit

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Posted 23 June 2022 - 10:19 PM

There are other AM5 reports coming out now on Facebook. Results seem to vary greatly - some better than others. Could vary with the user, or just the hardware lottery.

I’ve been thinking about these drives some more, and looking at some of the drive error charts. I don’t believe these mounts have any type of clutch. If that’s true, it means the orientation of the RA flex spline will always be consistent with respect to the circular spline - which is fixed with respect to the mount body. That seems to mean that the mount will always track with the teeth meshing through only 180 degrees of motion (okay, maybe a bit more). Why is that important - you ask? When I look at some of the drive error charts the error varies significantly over the full 360 degree rotation. The one chart I’m thinking of showed 15.9” peak to peak as the max error, but it only occurred over about 120 degrees of rotation. The rest of the error looked more like 10” peak to peak. If you could cherry pick (meaning adjusted the drive orientation to operate in the lowest part of the error) you might be able to see even smaller errors for the part of the drive rotation that you use. Not every chart showed that kind of variation in the error measurement - and it may not be possible to adjust the drive orientation. That said, there are things to learn with these drives - we can’t just apply what we know about traditional mounts.

So am I crazy (never a good question to ask)? Does this even make sense to anyone else?

Been wondering about that myself.

The range of PE seems to vary though. If I remember the various charts correctly, the range is 4-15 in one mount, and 12-22 in another. Wonder if its at all possible to link the imaging to where it is in the phase angle (have I got that term right?)

There's definitely a learning curve here on how to mount, guide etc. I do expect that a lot of users will start by using the classic approach and be disappointed. Will have to see results once some optimization has been done, I suppose.

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#572 OzAndrewJ

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Posted 23 June 2022 - 10:40 PM

Gday Mike

For your request to work, the "clutch" would need to be between the outer rigid ring gear

and the main housing, and that is currently very solidly fixed.

It would be feasible to make that joint a user adjustable fit ( probably costly )

but it would not be something you would do under load, like a normal clutch.

I suspect these mounts are going to give very different error curves based on

how they are loaded, both in total mass, and amount of axial "torque" applied

to the spline as it rotates.

Just needs lot more data from lots more mounts to see what drops out.

 

Andrew Johansen Melbourne Australia



#573 Mike Sandy

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Posted 24 June 2022 - 12:07 AM

Hi Andrew - good to hear I’m not the only crazy out there.  I’m not wanting a clutch at all - that would add back in variability and you wouldn’t know where the “bad” part of the mesh was.  I’m thinking you rotate the strain wave attachment in the mount so that the least error section (you said phase angle - which I think is correct) of the mesh is positioned such that it is in the active portion of the mounts rotation.  Since the mount shouldn’t ever rotation through the lower 180 degrees of motion - position the rough part of the mesh down there.  
 

A ton of questions pop up:

1) Can you rotate the position of the drive in the mount?  
2) Can you identify where the “good parts” of the mesh are physically to know the best orientation?  
3) Would the error change with load such that it just wouldn’t matter (your point about load)

 

i’m thinking the OEM likely has the best shot at optimizing the performance of each drive in the mount doing something like this, but that is exactly the kind of manual testing and specialized unit specific assembly that is likely not possible at this price point.  Not sure it would make that much of a difference either.  The more people get their hands on these, and the more companies start to spend some engineering on them, I think we’ll see improvements other than just encoders.  


Edited by Mike Sandy, 24 June 2022 - 12:09 AM.


#574 OzAndrewJ

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Posted 24 June 2022 - 01:06 AM

Gday Mike

good to hear I’m not the only crazy out there

I prefer the term "ratbag theorist" lol.gif

 

Can you rotate the position of the drive in the mount?

The ones i have seen would appear to have a 6 to 12 bolt fixing pattern

but there are so many different models, you would need to see the exact unit being used,

and what the vendors have done in order to fit them.

 

Can you identify where the “good parts” of the mesh are physically

No idea. You would need to use a lab test of some sort, but i suspect it will all be moot

as i believe testing would be way more complicated than that for a

standard worm supported on a rigid axle. The lack of an "axle" in these drives adds a large new

unknown to how it works.

re
 

Would the error change with load such that it just wouldn’t matter

Based on the (limited) data i have seen so far, i suspect loading will have a very large effect

on how the output axis works, both for RA PE and DEC swash.

I havent seen much unguided data where people have played with loading

and as i mentioned earlier in the thread, i have never seen any papers yet on how these drives

work ( at the arcsec level ) when driving an unbalanced cantilevered load

 

Andrew Johansen Melbourne Australia



#575 Clouzot

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Posted 24 June 2022 - 01:31 AM


I suspect these mounts are going to give very different error curves based on

how they are loaded, both in total mass, and amount of axial "torque" applied

to the spline as it rotates.

I'm pretty sure this has been discussed at length in the RST-135 thread, even including some valuable input from our own antipodal "ratbag theorist" grin.gif

Anyway, there was even a link to an academic paper analyzing, in the context of strain wave reducers, the PE dependency on the actual load and angle. That was one of the reasons why programmable PEC wouldn't be an option  (now where is that one paper...)


Edited by Clouzot, 24 June 2022 - 12:08 PM.

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