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Losmandy SAIA stepper motors

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#1 gnowellsct

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Posted 21 July 2010 - 12:39 PM

I knew that these motors were a big step up from the old Hursts, but last week we had extraordinary seeing and I did extensive observing in the FS128 at 475x (95x per inch!). I even had the 3.5XW barlowed 2x for a while to observe at 594x. But truth be told 300x was just as good as 475x.

Anyhow the point of this post: Here I've got this long f/8.1 FS128 on a G11 with its standard saddle plate, and if you were ever going to get stepper vibration it would be with a longish refractor at high power.

I didn't see any at all, so the SAIA motors get a thumbs up for passing a rigorous test.

I've heard of folks pushing their refractors up to crazy high mags, I've tried it on my 4" but views get too dim. With Jupiter and a 5", the views can be pretty good. It'll probably be two or three years before I have seeing that steady again.

regards
Greg N

#2 urbanMark

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Posted 21 July 2010 - 12:50 PM

Thanks Greg - good to know. I run a 152ED on my G11 (w/ Gemini, servos not steppers) - but seeing rarely supports that kind of mag in my area. The G11 does great with this OTA btw - though I do use a long saddle/dovetail.

My Gemini is presently dead - and new boards won't be available for a while, so I have a stepper system being sent to me courtesy a fellow member of the Losmandy User's group! I'm pretty sure it is the stock steppers, but it will be interesting to see if I can detect any stepping vibration with the longer OTA and high mags.

#3 gnowellsct

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Posted 21 July 2010 - 01:03 PM

so I have a stepper system being sent to me courtesy a fellow member of the Losmandy User's group! I'm pretty sure it is the stock steppers, but it will be interesting to see if I can detect any stepping vibration with the longer OTA and high mags.


The "stock steppers" since about 2002 have been SAIA. So if your friend is sending you motors on a newer stepper version, SAIA is what you'll get.

If you remove the motor covers you can see the brand on the side of the motors. We actually have pics in PHOTOS of Losmandy Yahoo.

If you end up with Hurst steppers, for $50 you can switch out just the RA, but I admit that when I did it, I changed both motors.

There is a "motor upgrade" for the servo go-to series. Those are the Maxons which are better protected against servo burn out. The servos of course show no vibration at all.

regards
Greg N

#4 urbanMark

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Posted 21 July 2010 - 06:54 PM

Thanks Greg - the stepper setup is just to get me by until Losmandy starts selling Gemini boards again (currently in a re-design, expected new boards in Aug or Sept, or so they claim...my guess is it will drag on a bit).

Once I have the new Gemini board I'm going to look at upgrading servos, gear boxes, worm block, etc. As you know, these are great mounts and they are way less expensive than the next best thing - so it is easy to justify spending a few bucks. I just read where a guy bought a $12,500 TEC160FL over a $8,500 TEC160ED because the FL worked better on his G11 and it was cheaper to spend $4,000 more on the scope than ~$6,000 to upgrade his G11 to an AP900! I guess he could have spent $5,000 and upgraded to a MI-250, but that's still more money, and I don't know of any mounts I'd pick in between the G-11 and the MI-250.

#5 gnowellsct

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Posted 21 July 2010 - 11:45 PM

Thanks Greg - the stepper setup is just to get me by until Losmandy starts selling Gemini boards again (currently in a re-design, expected new boards in Aug or Sept, or so they claim...my guess is it will drag on a bit).

Once I have the new Gemini board I'm going to look at upgrading servos, gear boxes, worm block, etc. As you know, these are great mounts and they are way less expensive than the next best thing - so it is easy to justify spending a few bucks. I just read where a guy bought a $12,500 TEC160FL over a $8,500 TEC160ED because the FL worked better on his G11 and it was cheaper to spend $4,000 more on the scope than ~$6,000 to upgrade his G11 to an AP900! I guess he could have spent $5,000 and upgraded to a MI-250, but that's still more money, and I don't know of any mounts I'd pick in between the G-11 and the MI-250.



The AP900 is not a $6k mount. By the time you get the counterweights, a saddle plate, an ATS pier, and the rest of the stuff (such as the polar scope), you're just north of $10k.

Another way of stating it: my ap900QMD was purchased used for $3250. By the time I had an ATS pier, counterweights, saddle plate (none of that was included), upgraded the polar scope, and sent the mount back for the dec upgrades and gotten the azimuth and altitude upgrades, I was somewhere near $6.5k for this non-go-to version of an AP900.

I love it, by the way. Very good performer for the C14. But I didn't ditch my G11 and I'm glad I didn't.

regards
Greg N

#6 gillmj24

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Posted 22 July 2010 - 12:30 AM

I think e meant a $6k difference between the g11 and the ap900 which sounds pretty close.

#7 urbanMark

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Posted 22 July 2010 - 01:48 AM

Yep - "~$6,000 to upgrade his G11 to an AP900" is what I wrote, and that is not far off your figures. If a used G11 w/ Gemini fetches $2500 or there about, that is $8,500 for the AP900, which depending on accessories, version, used/new, etc seems about right.

#8 peleuba

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Posted 22 July 2010 - 08:34 AM

I just read where a guy bought a $12,500 TEC160FL over a $8,500 TEC160ED because the FL worked better on his G11 and it was cheaper to spend $4,000 more on the scope than ~$6,000 to upgrade his G11 to an AP900!



That "guy" is me. I put a lot of TLC into my G11 - new motors, DSC's, new clutch pads, complete disassemble cleaning and re-lube, new Belrebach Planet Triod and ATS Portable Pier. I simply did not have an appetite to spend more money on an AP900 class mount so that the TEC160ED would be properly mounted. I decided to go with a TEC160FL. Yuri was a dream to work with handling the exchange. The 160FL is several pounds lighter and about 6" shorter then the 160ED. It may seem small, but this made a noticeable difference in the way the G11 performed. And, perhaps more importantly, the 160FL is easier for me to take off the mount at 3am after a night of observing.


I guess he could have spent $5,000 and upgraded to a MI-250, but that's still more money, and I don't know of any mounts I'd pick in between the G-11 and the MI-250.



I looked at other options like the AP Mach1 and the MI-250. The G11 and the Mach1 are really in the same class. Mach1 can support a little more weight and is manufactured to a higher quality, but at the end of the day, these mounts have more in common for the visual observer then is different. My former TEC160ED would have rode basically the same on the Mach1 as it did on the G11. I was not really interested in the MI-250.

#9 gnowellsct

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Posted 22 July 2010 - 10:45 AM


That "guy" is me. I put a lot of TLC into my G11 - new motors, DSC's, new clutch pads, complete disassemble cleaning and re-lube, new Belrebach Planet Triod and ATS Portable Pier. I simply did not have an appetite to spend more money on an AP900 class mount so that the TEC160ED would be properly mounted. I decided to go with a TEC160FL. Yuri was a dream to work with handling the exchange. The 160FL is several pounds lighter and about 6" shorter then the 160ED. It may seem small, but this made a noticeable difference in the way the G11 performed.


The effects of moment arm/leverage are not often discussed in terms of mount performance, but it does make a *huge* difference.

To take another example, the Super Polaris is basically a mount for a four inch refractor or smaller.

But it easily handles a c8.

regards
Greg N

#10 urbanMark

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Posted 22 July 2010 - 12:28 PM

I guess the moral of the story is:

1. The G-11 is a great mount as is
2. For a little $ and some effort, you can make it even better.
3. If you need more mount than that, it is going to cost a large pile of cash!

BTW - speaking of moment arms and big refractors, anyone ever play with a bar between the optical tube (near the objective) and the counter weight shaft? I've seen a few photos of setups like this and always wondered how much improvement it provided.

(Paul - sounds like a great setup. Hard to argue with smaller and lighter with the same or better optical performance!)

#11 Jeroen

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Posted 22 July 2010 - 12:52 PM

Mark,

" 3. If you need more mount than that, it is going to cost a large pile of cash! "

That may be true on your continent, but here in Europe one can buy a fine GOTO mount for about 6000 Euros e.g. a Fornax 51 or a Gemini 42 Obs+ which can carry 40 kg and has an error of +/- 2.5 arcseconds (delivered with test certificate). No upgrading needed.

For comparison, a Losmandy G11 Goto (Gemini) costs about 4500 Euros without the costs of improvement.

Jeroen

#12 mclewis1

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Posted 22 July 2010 - 01:22 PM

BTW - speaking of moment arms and big refractors, anyone ever play with a bar between the optical tube (near the objective) and the counter weight shaft? I've seen a few photos of setups like this and always wondered how much improvement it provided.

Mark - It's called a Hargreaves strut. There are a few folks in the refractor forum who use them. Look for the the long fl achromat discussions. Steve Fisher is one of the guys who comes to mind right away.

#13 peleuba

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Posted 22 July 2010 - 04:20 PM

(Paul - sounds like a great setup. Hard to argue with smaller and lighter with the same or better optical performance!)


Trust me, I would rather not have spent an additional $4000 on the 160FL. But I wanted to stay at 6" of aperture and keep the G11. TEC is a great manufacturer with guaranteed 1/8 wave quality. I have toured the TEC facility and feel like a "friend of the firm" so-to-speak.

One last thing regarding #2 in your list. If the G11 is a recent vintage, you will not have to spend any money nor exert any effort; it will be fine as is. All the improvements I have done are now stock.

#14 urbanMark

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Posted 22 July 2010 - 09:11 PM

The "stock steppers" since about 2002 have been SAIA. So if your friend is sending you motors on a newer stepper version, SAIA is what you'll get.


UPS showed up today. Original Celestron branded system, Hurst motors. Plugged it in on the bench - you can feel and hear the RA motor pulse - will be interesting to see what that does with the scope. In any case, I am thrilled and grateful to have something to drive my mount while I wait for Losmandy to produce a replacement Gemini board.

BTW - what does the TVC button/display do?

#15 gnowellsct

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Posted 22 July 2010 - 09:48 PM

The "stock steppers" since about 2002 have been SAIA. So if your friend is sending you motors on a newer stepper version, SAIA is what you'll get.


UPS showed up today. Original Celestron branded system, Hurst motors. Plugged it in on the bench - you can feel and hear the RA motor pulse - will be interesting to see what that does with the scope. In any case, I am thrilled and grateful to have something to drive my mount while I wait for Losmandy to produce a replacement Gemini board.

BTW - what does the TVC button/display do?


If you have a celestron seies you might want to consider sending it to Losmandy for the second altitude lock screw. this is a routine upgrade--one of the very few that sends it back to the shop. It would leave you w/o a mount for a month or so. You can see what I'm talking about in the picture. There is only one altitude lock bolt. This was changed to two lock bolts and is more stable.

TVC is for controlling backlash in the Dec axis when imaging. See detailed explanation here:

http://www.company7....ron/cg11rv.html

Greg N

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#16 urbanMark

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Posted 22 July 2010 - 10:29 PM

Thanks - yep, I have the 2nd lock screw, and as far as I know I have every upgrade possible except an Ovision (or Scott's adjustable) worm block. I even have Robin Cassady counterweights which spiff it up a bit, though not as much as the young lady in the advert does.






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