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Equipment Discussions >> Mounts

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Hilmi
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Ovision upgrade
      #5862288 - 05/15/13 01:52 PM Attachment (72 downloads)

I had earlier thought I had my PE under control for a while. Turns out that 360mm isnt exactly optimal for measuring PE. When I got my 8" RC scope I was getting nasty stars again. I measured the PE and this is what I got

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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5862291 - 05/15/13 01:54 PM Attachment (52 downloads)

I cant guide now since my ccd camera is dead and needs repair. So I figured its as good an excuse as any to get an ovision upgrade. I just got the excel sheet from them and here is the plot of the worm they are shipping to me. The Excel sheet was all in french. I am assuming this is the correct plot to look at. My french vocabulary consists of a couple dirty words and counting to 5 so couldnt figure out what they were going on about.

Im guessing this will let me image unguided till my ccd is back. Especially after I program the PEC. The installation instructions keep on telling you that it is easy to damage the worm. I hope I dont damage mine durring installation

Edited by Hilmi (05/15/13 02:15 PM)


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David Ault
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Reged: 09/25/10

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Re: Ovision upgrade new [Re: Hilmi]
      #5862426 - 05/15/13 03:15 PM

Hi Hilmi,

Congratulations on the new worm. Hopefully it works really well for you. Sorry to hear about your CCD though.

Any of the high precision brass worms can be easily damaged. I think the number one thing to look out for is making sure that the gears are meshed properly before any force is applied to the system. The steel worm wheel can easily notch or bend the brass causing irregularities in tracking.

Regards,
David


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EFT
Vendor - Deep Space Products
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Re: Ovision upgrade new [Re: Hilmi]
      #5864269 - 05/16/13 11:39 AM

Hard to say whether you will be able to do unguided or not and how long you will be able to go. In general, the G11, like most mounts, are not that great at unguided. You need to remember that the worm is not the only source of error in this case and, while the worm is very important, the graph is not all that clean and your ability to go unguided will depend on the image scale and the object brightness. If all it took to get the total error of the mount down to +/-4.5 arcsec was to add a higher precision worm, then that is what everyone would do and there would be no issue. Obviously, that is not the case.

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Hilmi
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Re: Ovision upgrade new [Re: EFT]
      #5864473 - 05/16/13 12:55 PM

I guess we will know once I get it installed. Stay tuned

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orlyandico
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Re: Ovision upgrade new [Re: Hilmi]
      #5864509 - 05/16/13 01:08 PM

My *cough* extensive studies of this issue seem to point to:

1) the worm is the source of most of the PE if it is > about 8" p-p

2) the motor gearbox contributes significant PE; we know on the CGEM it can be as high as 25" p-p (can be more than the worm fundamental) but for good-quality Japanese gearboxes the gearbox PE would be around 5" p-p

3) a really good gearbox would have perhaps 2" p-p

So at the end of the day, something like an Ovision worm with PEC applied would only have say 2" p-p of PE... but the gearbox PE is still there. I believe this is why some G11 users replace the regular motor with a Maxon.


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Startraffic
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Reged: 02/12/06

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Re: Ovision upgrade new [Re: orlyandico]
      #5864709 - 05/16/13 02:18 PM

Orly,
Maxons are now standard with Gemini-2, if you but the whole upgrade. In fact, they now a a newer Maxon motor that provides more torque than the old one.

Clear Dark Skies
Startraffic
39.138274 -77.168898


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Bart
Carpal Tunnel
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Reged: 05/28/06

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Re: Ovision upgrade new [Re: Startraffic]
      #5866564 - 05/17/13 08:04 AM

When did Losmandy start using the Maxon motors as regular OEM parts?

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Raginar
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Re: Ovision upgrade new [Re: Bart]
      #5866780 - 05/17/13 10:22 AM

It's been in the last 6 to 9 months. They're nice motors; very loud though.

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Joe C
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Re: Ovision upgrade new [Re: orlyandico]
      #5866862 - 05/17/13 10:58 AM

You are correct that with PE applied, a very low P-P with the Ovision is seen. However, the Maxon now High Torque motors are only for added torque to handle additional moment arms and loads with a bit more ease. The gearboxes are completely different and are at times upgraded to Mclennan gear boxes that have metal rather than plastic gears and tend to be a bit more precise.

Quote:


So at the end of the day, something like an Ovision worm with PEC applied would only have say 2" p-p of PE... but the gearbox PE is still there. I believe this is why some G11 users replace the regular motor with a Maxon.




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orlyandico
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Re: Ovision upgrade new [Re: Joe C]
      #5867284 - 05/17/13 02:17 PM

Hmmm.. well thing is you can buy Maxons with Maxon gearboxes. I have some Dunker servo motors and the gearboxes are really tight. Dunker (German) and Maxon (Swiss) make really, really nice motors and gearheads.

I used to believe that Astro-Physics used Maxon gearboxes, but it seems that they manufacture their own gearhead reducers, although they do use Maxon motors.

If Losmandy is using Maxon motors but the same old gearboxes, you'd get better responsivity (less cogging) but the gearbox PE wouldn't change.

And yes, thanks for mentioning the Maclellan gearboxes. That was at the tip of my fingers but I conflated them with the Maxon motors.


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Hilmi
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Re: Ovision upgrade new [Re: orlyandico]
      #5867309 - 05/17/13 03:02 PM

I actually read a test somebody once did. I cant recall the link. Basically changing out the gearbox brought down the G11 PE by 1 arc second. So for the sake of example that ovision test run is +/- 4 arcseconds it can go down to +/- 3 with upgraded gearboxes. This is about as low as can reasonably be expected at this price point. Im thinking of getting the gearboxes myself if only to cut down on the unbearably loud noise.

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JSeay86
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Reged: 04/26/09

Loc: Tulsa, OK
Re: Ovision upgrade new [Re: Hilmi]
      #5867642 - 05/17/13 04:36 PM

Hi Hilmi,

Congrats on the Ovision worm, your graph looks very similar to mine. My Ovision worm is also about +/- 4 arcsec peak to peak. I noticed significant improvements after the change. With a little care during the install you should be fine. Of course, remove all scopes from the mount, and use a gauge block or similar to get each side of the worm the same distance from the flat on the housing that surrounds the larger ring worm gear.

I noticed some chatter and play in the stock gearboxes, and I am now in the middle of a McLennan gearbox and high torque motor conversion. This was not as straightforward as I had hoped, but the newer gearboxes feel MUCH smoother and I enjoy the tinkering. The conversion required several modifications:

- Reaming out the ID bore of the motor pinion supplied with the McLennan gearbox (stock pinion gear is for 3mm motor shaft, and the shaft size of the new high torque motors is 0.125 inches)

- Enlarging the mounting holes on the McLennan gearboxes. I used a 3.95mm diameter drill bit here.

- Expanding the screw holes on the gear box covers to fit the new motor position (slightly different).

- I ordered new Oldham style couplers from Ruland that fit the new gearbox output shaft and also the worm gear shaft. I have read about the Ruland coupler conversion but I don't think that it has much effect on the end performance. The Oldham style should be fine in my opinion. I have the Ruland part numbers for the couplers if anyone needs them.

- Finally, I installed a small stainless steel shim between the M2.5 mounting screws and the screw slot on the new high torque motors. The other option is to drill and tap the gearboxes to accommodate 4-40 screws like those used with the stock Losmandy gearboxes. I chose the shims instead to avoid opening up the gearboxes to drill and tap.

I will be testing everything over the next several weeks and report the results.

Also, follow the link below. I think this is the website for the gearbox conversion you are referring to.

G11 Gearbox and Coupler conversion

Edited by JSeay86 (05/17/13 04:42 PM)


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Hilmi
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Re: Ovision upgrade new [Re: JSeay86]
      #5867652 - 05/17/13 04:42 PM

You mind posting a photo tutorial along with links for shopping? There is a website out there with steps, but it sounds a bit different from what you are doing.

Also having difficulty getting hold of the gearboxes. The sites that seem to provide them for international shipping are quoting a 60 days lead time.

Same goes for the pinion puller. Could you post a link to where you got yours?

Edited by Hilmi (05/17/13 04:45 PM)


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JSeay86
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Reged: 04/26/09

Loc: Tulsa, OK
Re: Ovision upgrade new [Re: Hilmi]
      #5867655 - 05/17/13 04:44 PM

Hi Hilmi,

I just updated the prior post with a link to the website you are referring to I believe. I am out of the country right now, but I can take some images when I return home outlining some of the steps required for the gearbox conversion.


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JSeay86
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Reged: 04/26/09

Loc: Tulsa, OK
Re: Ovision upgrade new [Re: JSeay86]
      #5867665 - 05/17/13 04:48 PM

THIS might also be the website you are referring to for the gearbox conversion. He does not mention having to ream out the pinion gears, so I think the older McLennan gearboxes or Losmandy motors used a slightly different size.

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wolfman_4_ever
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Reged: 07/15/11

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Re: Ovision upgrade new [Re: JSeay86]
      #5867963 - 05/17/13 07:19 PM

A TDM would take care of that PE as well as your headaches. I can jack up my ra adjustments with a 60+ p2p pe and the TDM knocks it down to below 1.

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Hilmi
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Re: Ovision upgrade new [Re: wolfman_4_ever]
      #5868640 - 05/18/13 01:57 AM

I had seriously considered the TDM and this was my conclusion:

TDM up sides:
-Fixes tracking issues with one device with high level of precision
-One purchase to eliminate all the issues
TDM Downside":
-Costs a lot
-Adds more wires to an already complex set up
-Lose access to polar scope unless you are willing to disassembel and re-assemble everything on a regular basis

Upgrading gears and worm upside
-Fixes the root of the problem, therefore even if I add a TDM to this set up later, I will get even better performance
-Will reduce the noise from the plastic gearbox
-Costs far less

Downsides:
-Needs tinkering to get right (especially gearbox upgrade)
-Warranty implications??? <-Mine is out of warranty.


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orlyandico
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Re: Ovision upgrade new [Re: Hilmi]
      #5868750 - 05/18/13 04:16 AM

The TDM will also fix PE problems regardless of whether you are east- or west-heavy. This would make balance less problematic / critical.

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Jesus Munoz
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Re: Ovision upgrade new [Re: orlyandico]
      #5869414 - 05/18/13 02:01 PM

Quote:

The TDM will also fix PE problems regardless of whether you are east- or west-heavy. This would make balance less problematic / critical.




What is TDM?


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Hilmi
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Re: Ovision upgrade new [Re: Jesus Munoz]
      #5869486 - 05/18/13 02:45 PM

It is an encoder that measures pe on the axis and corrects for it in real time via guide port. A bit expensive bit rhe price has come down a bit.

Edit: TDM is short for Telescope Drive Master


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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5870678 - 05/19/13 02:56 AM

I just placed my order for 2 gearboxes from RS Components. They expect the gearboxes to arrive in 10 days time. Local custom is for shops to over promise and under deliver, so I will assume they will take 2 weeks to deliver. I have also ordered a pinion puller and some brass tubing from eBay. One ships from the US and the other from UK so I guess the US shipment will be late due to the new postal security checks. So overall I think I will have everything needed to upgrade the gearboxes in 3 weeks time. I'll see how it goes from there.

I'm not sure how I will ream the pinion as my Dremel Bits are metric. I have a Dremel press attachment, so I should be able to drill straight down, but I'm not sure how to secure the gear so it doesn't slide or rotate without damaging it. I guess one way to do that would be to make a hole on a piece of wood to place the gear in. I guess the hole should be a tight fit but not so tight as to damage the gear teeth.


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Hilmi
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Re: Ovision upgrade new [Re: JSeay86]
      #5870835 - 05/19/13 07:43 AM

Quote:

Finally, I installed a small stainless steel shim between the M2.5 mounting screws and the screw slot on the new high torque motors. The other option is to drill and tap the gearboxes to accommodate 4-40 screws like those used with the stock Losmandy gearboxes. I chose the shims instead to avoid opening up the gearboxes to drill and tap.




I'm a bit confused about this step, especially when I looked at some online directions that said the following about the same step.
Quote:

As the new screws are slightly undersized, put a wrap or two of tape around them where they fit through the motor housing.
The motor is in a very slightly different position, so only tighten the gearbox cover screws after you have fitted the motor.




So I figure a picture is worth a thousand words. What exactly is it you are talking about? I'd like to understand before I place my order for the screws.


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Geo.
Carpal Tunnel
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Re: Ovision upgrade new [Re: orlyandico]
      #5870978 - 05/19/13 09:33 AM

Quote:

2) the motor gearbox contributes significant PE; we know on the CGEM it can be as high as 25" p-p (can be more than the worm fundamental) but for good-quality Japanese gearboxes the gearbox PE would be around 5" p-p




Orly, any idea of what reduction Celestron is using for the CGEM?


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orlyandico
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Re: Ovision upgrade new [Re: Geo.]
      #5871307 - 05/19/13 12:41 PM

Hi George, do you mean the gearhead reduction? it's 57.xxxx (some weird irrational ratio) in the Igarashi gearbox.

Hilmi - do not try to ream out the holes with your dremel drill press!!!!!! get someone with a LATHE to do the reaming for you.

Trust me, I tried reaming out the 5mm holes in my AP600's spur gears to 6mm myself. The holes came out not perfectly square and it increased the periodic error. I had to buy new spur gears from AP (good thing they still sell parts for a 25-year old mount!)


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Hilmi
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Re: Ovision upgrade new [Re: orlyandico]
      #5871340 - 05/19/13 01:02 PM

1 mm of reaming is a lot to. I was going to attempt 0.2 mm. The bit should self center if done 0.1mm at a time. I have had very little success finding a high precision machine shop in Oman. All the shops I found deal with heavy industrial equipment. I once paid $500 to get a pier plate adapter made and they got it all incorrect even though I gave them cad blue prints.

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JSeay86
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Reged: 04/26/09

Loc: Tulsa, OK
Re: Ovision upgrade new [Re: Hilmi]
      #5872704 - 05/19/13 10:27 PM

Orlandico is right, do not use the Dremel tool to ream out the pinion. Luckily I work with an experienced machinist that helped me out a bit with this. I used a low melting point alloy, and made a small casting with the pinion gear in the middle. This conforms to the gear teeth and holds the pinion gear during the reaming process. Then, I reamed out the pinion with a 0.125" straight reamer. You are only reaming out 0.175 mm. This was done on a mill, and I rotated the spindle slowly by hand, and lubricated the bit with a little 3 in 1 oil.

I will get a picture of the spacers that I used for the M2.5 screws. This was my alternate to the tape mentioned above, and it will hold everything square.

Tomorrow I will take some pictures of everything and post with more details.

Edited by JSeay86 (05/19/13 10:32 PM)


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orlyandico
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Re: Ovision upgrade new [Re: JSeay86]
      #5872814 - 05/19/13 11:23 PM

Hilmi, maybe you can pay someone to do the reaming-out for you.

I know the bit will "probably self-center" but if it doesn't... or it's not precise... you'll lose whatever benefits you hoped to gain from the Maclellan gearbox. We're talking about 1" to 2" levels of precision here.

EDIT: please see my post in your other thread. I would be more comfortable with that route (hand-ream the hole with an actual reamer, of the correct diameter).


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JSeay86
sage


Reged: 04/26/09

Loc: Tulsa, OK
Re: Ovision upgrade new [Re: orlyandico]
      #5874465 - 05/20/13 07:09 PM

Alright, finally got around to taking some images.

As mentioned above, there are several things that you need to do for the McLennan gearbox conversion, and the details below correspond to a McLennan conversion using the new Losmandy high torque servo motors. The McLennan gearboxes that I ordered can be found HERE. Ok, the primary steps are as follows:

1. Ream out the pinion gear that comes with the McLennan gearbox so that it fits the output shaft of the new high torque servos. The ID bore of the supplied pinion is 3.0 mm, and the output shaft of the high torque servos is 0.125" (3.175mm). Here I used a 0.125" diameter straight reamer bit. Do this step on either a mill or lathe, and take care to keep the bit square to the pinion bore, as orlyandico stated, and take care not to damage the teeth of the pinion gear!. This step is the trickiest.

Once this is done, install the pinions onto the motors using the pinion spacer tool supplied with the McLennan gearbox (0.9mm spacing), and Loctite. After doing some research, I chose to use Loctite 680. Install and let dry for 24+ hours.

2. Enlarge the mounting holes on the new McLennan gearboxes (the holes for mounting the gearbox to the mount body), so that they fit over the threaded rods that stick out on the G11 mount. I used a 3.95 mm diameter drill bit here.

3. The output shaft of the new McLennan gearboxes is a different size than the stock Losmandy gearbox, so you can either use the existing Oldham style motor couplings with some slight modifications, or you can order new couplers that fit the new shaft.

You can use your stock Oldham couplers, and follow the steps listed HERE, OR you can order Ruland style couplers to replace the Oldhams, OR you can order new Oldham style couplers that fit the new shaft. I chose the last option, and here are the part numbers you need to order from the Ruland website:

-2 each of Part #: OD8/13-AT
-2 each of Part #: MOST13-4-A
-2 each of Part #: OST8-4-A

Once assembled, these will fit both the 4mm output shaft of the McLennan gearbox and also the 0.25" shaft of the worm gear, and the complete couplers have roughly the same exterior dimensions (length and OD) as the original Oldham couplers from Losmandy.

4. Elongate the mounting holes on the stock gearbox covers to accomodate the slightly different mounting location of the motors.

5. The motor mounting holes in the McLennan gearboxes are m2.5 thread, and the stock Losmandy gearboxes are threaded for 4-40 screws. 4-40 screws are supplied with the new high torque servos. Here you have 2 options:

a. Drill and tap the McLennan gearboxes to 4-40 thread. If you choose this option then it would be best to remove the plate on the gearbox that you are needing to tap. This will prevent you from getting any small pieces of metal & shavings (from the drilling/tapping process) inside the gearbox housing.

b. Don't tap the new gearboxes, leave as M2.5 thread. Order M2.5 x 16mm screws to mount the gearboxes. Then, you will need some sort of shim to fit between the M2.5 screws and the mounting screw holes on the high torque servos (which are meant for 4-40 screws) to keep everything tight, as the M2.5 screws will just fit loosely in the mounting holes because their OD is too small. I would not just use tape, I chose to order some stainless steel spacers here that were close to the finished size I needed. Part numbers below for screws and spacers from McMaster Carr.

- 92321A014 (stainless steel unthreaded spacers)
- 92290A065 (SS Socket head cap screw, M2.5 x 16mm, 0.45mm pitch)

The ID bore of the spacers will have to be very slightly enlarged with a drill bit to fit the screws. Also, the OD will have to be turned down very slightly to fit snugly into the mounting holes on the high torque servos. I intentionally ordered the length oversized here, so that you can mount the spacers into a drill bit chuck for these modifications. For turning down the OD, I mounted the spacer in a drill bit chuck and spun it against some fine grit sandpaper. Finally, you will need to take the length down on the spacer to fit properly in the mounting holes on the servo motor.

Here is an image of the mounting holes on the high torque servo motors without spacers:



and here is an image of the mounting holes with spacers installed:



The M2.5 screws fit tightly into the spacers to keep everything square, and the spacers fit snugly into the mounting holes on the motor.

Edited by JSeay86 (05/20/13 07:22 PM)


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JSeay86
sage


Reged: 04/26/09

Loc: Tulsa, OK
Re: Ovision upgrade new [Re: JSeay86]
      #5874476 - 05/20/13 07:12 PM

Please let me know if anything is unclear from the post above, there is a lot of info buried in there. Here is an image of the new gearboxes installed on the mount. I am awaiting my Loctite to arrive in the mail so that I can install the pinions (local hardware stores didn't have the right kind). It will arrive tomorrow, and I should have everything bolted on and ready to test on Wednesday night. I'll report back.



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Hilmi
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Loc: Muscat, Sultanate of Oman
Re: Ovision upgrade new [Re: JSeay86]
      #5874980 - 05/20/13 11:45 PM

Clear as can possibly be. I think the simpler option would be to get the gearbox rethreaded though. Making those spacers sounds complicated if you dont have access to a lathe machine

I appreciate the work you have done with that write up


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GeHe
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Reged: 08/06/11

Loc: Germany
Re: Ovision upgrade new [Re: Jesus Munoz]
      #5877400 - 05/22/13 03:45 AM

hi hilmi ,
i have the ovision-worm in my Losmandy g11 , additionally , since this week wit TDM , see the graf in this treat :

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5875889/page...


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Hilmi
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Re: Ovision upgrade new [Re: GeHe]
      #5877416 - 05/22/13 04:26 AM

Those are very nice results. I will keep you posted once my gear arrives.

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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5885034 - 05/26/13 02:41 AM

9 Days after the Package was shipped from Ovision in France and the Colissimo web page is saying "Your parcel is getting ready to leave the country of origin" This update was on the 23rd and no update since then. So I am assuming my Ovision worm has still not left France. I am proud to say that I no longer consider my countries Postal service the worst in the world, looks like the French have outdone us!

Edit: I retract the above statement, we still hold the position of worst postal service in the world. I called the post office and the package has finally arrived. Perfect timing too as I wanted to do this upgrade before I went camping next weekend.

Edited by Hilmi (05/26/13 03:17 AM)


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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5885131 - 05/26/13 05:43 AM

Got the package and started installing it during lunch break, didn't finish the job as I am supposed to meet somebody in the office soon. Here are my observations so far.

-The worm gear was packaged in an inflated nylon bag which was then covered in foam peanuts which was then in a small box which was then covered in more foam peanuts then the outer box. Although the outer box was crushed, the interior box was in perfect condition. Packaging gets 10/10 for protecting such a delicate item.

-If you have the OPWB installed in both axis as some people have done, you will need to get hold of some screws and parts to install the new worm block. This is due to the fact that the new worm block does not fit into the OPWB cradle. It also requires some parts from the standard worm block, those parts being the cover and the Oldham Coupler.

-The Ruland coupler that comes with the OPWB will not work with the Ovision worm block, there isnt enough space between the gear box and the worm block. You need to move the Ruland Coupler to the Dec axis and take the Oldham coupler from the Dec axis and install it on the RA with the Ovision worm and worm block.

-The worm seems to be very well machined and it moves very smoothly on the bearings when turned by hand. I also found it much easier to pop into place than the OPWB. On the downside, for some reason, I found it very fiddly to get the screws into the screw hole when I tried to screw it on. I can't explain why that is the case.

Further info coming soon as I finish the install. Will probably post PE figures tonight or tomorrow night.


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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5885876 - 05/26/13 04:54 PM

OK, the first run I did of PEMPro reported a Peak to Peak PE of 3.75 Arc Sec. I suspect something is wrong though because my first worm period looked funny. I must have bumped into the mount. I am rerunning it now to validate. The curve generated from the first run looks very smooth. I'll post the second one once I have finished collecting the data. I'll keep you posted.

And before anybody asks. I did run the calibration wizard, twice just to be sure. Anyway, by the end of this second run I will know for sure


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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5885909 - 05/26/13 05:15 PM Attachment (24 downloads)

OK, here is my second test. This is unbelievable for me. The mount PE has gone down to less than 30% its original PE! I cant wait to see what I will end up with once I also install the gearboxes.

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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5885936 - 05/26/13 05:26 PM Attachment (21 downloads)

And here is the tracking with PEC training. I am also now taking a single exposure of 240 Seconds (1 worm period) unguided. After I post that I am off to sleep and I will be dreaming of unguided imaging

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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5885958 - 05/26/13 05:45 PM Attachment (27 downloads)

OK, here is a test image, screen capture at 1:1 scale. The image scale is 0.6 Arcsec per pixel. Still not perfectly round, but I believe this level of star roundness is perfectly serviceable. It might even be due to collimation. I'll be testing that tomorrow.

I wonder if the gearbox upgrade (once it finally arrives) will get rid of the residual oval shape of the stars. If the mount continues to behave like this then I no longer have any regrets buying the G11 other than the time wasted troubleshooting.


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zytrahus
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Re: Ovision upgrade new [Re: Hilmi]
      #5885974 - 05/26/13 05:56 PM

Nice improvement Hilmi!

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Hilmi
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Re: Ovision upgrade new [Re: zytrahus]
      #5885990 - 05/26/13 06:09 PM Attachment (30 downloads)

what is reaIly impressive is that the stars look exactly like how the excel Sheet predicted they would

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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5888441 - 05/28/13 07:34 AM

OK, now I am confused. The PE has been revalidated with PEMPro and polar alignment has been validated as within 0.2 arc min yet My unguided images of lets say 8 min show far more streaking than can be explained via PE. Is this flex from the Vixen dovetail?

Last attempt showed stars that where more like a line rather than an oval


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blueman
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Re: Ovision upgrade new [Re: Hilmi]
      #5889068 - 05/28/13 02:18 PM

Quote:

OK, now I am confused. The PE has been revalidated with PEMPro and polar alignment has been validated as within 0.2 arc min yet My unguided images of lets say 8 min show far more streaking than can be explained via PE. Is this flex from the Vixen dovetail?

Last attempt showed stars that where more like a line rather than an oval




You are probably seeing flexure, either in the SCT or the mounting of the guide system. I am unsure whether you are using an OAG or not.
Blueman


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Hilmi
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Re: Ovision upgrade new [Re: blueman]
      #5889152 - 05/28/13 03:11 PM

Looks to have been user error. Today I updated the firmware to the correct version (last time I installed older firmware by mistake) and it seems to be tracking fine. This is unguided imaging as my guider is has gone for a bit of R&M.

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Hilmi
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Re: Ovision upgrade new [Re: Hilmi]
      #5889291 - 05/28/13 04:16 PM

Turns out it is possible to image unguided at long focal lengths on the G11. The following test image was done WITHOUT careful balancing of the mount, WITHOUT GUIDING and WITHOUT PEC. The image scale is aprox 0.6 Arc sec per pixel and this image was a single 4 minute (1 worm cycle) exposure without any processing other than stretching and in camera noise reduction. Please note that the Astrobin image is full resolution so it might take time to load the full image.



Edited by Hilmi (05/28/13 04:24 PM)


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WesC
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Re: Ovision upgrade new [Re: Hilmi]
      #5889571 - 05/28/13 07:13 PM

That looks pretty good!

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zytrahus
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Re: Ovision upgrade new [Re: WesC]
      #5889952 - 05/28/13 10:59 PM

very nice indeed!

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Hilmi
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Re: Ovision upgrade new [Re: zytrahus]
      #5890145 - 05/29/13 02:08 AM

I had a big smile on my face when I saw that picture. Too bad the clouds didn't allow me to do a longer test. I am planing to try again tonight.

The Mclennan gearbox is coming in tomorrow, but I will not be able to install it till next week as I am going camping this Friday and I doubt I will get enough time to modify the gearboxes in 1 day to fit the mount especially considering I am supposed to be shopping for my camping rations on Thursday after work.


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dawziecat
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Re: Ovision upgrade new [Re: Hilmi]
      #5890256 - 05/29/13 06:44 AM

Wow!! At 240 secs and 1625mm unguided, that's just fantastic!

Congratulations!


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Hilmi
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Re: Ovision upgrade new [Re: dawziecat]
      #5890261 - 05/29/13 06:53 AM

Terry, I still bet it's not good enough to make you regret buying the AP1100

But yes, I was amazed. Today I found somewhere hidden on the www.gemini-2.com site how to actually make the PEC curve you create in PEMPro stick to the Gemini II. I will try that process today and see how round the stars turn out after that. There is still some elongation. It's not much, I know that with stacking most of it will go away but I still want to see how round I can get the stars to be natively without processing. That might even be a collimation defect and not a tracking issue.


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dawziecat
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Re: Ovision upgrade new [Re: Hilmi]
      #5890533 - 05/29/13 11:13 AM

Quote:

Terry, I still bet it's not good enough to make you regret buying the AP1100




Well, I'm still waiting of course and likely will be for quite some time yet. My cheque book is ready . . . but A-P is not.

If I thought I could ever come close to your results at 4 min and 1625mm, I likely would have never considered a more costly mount.

In the meantime, I play with my RAPAS!


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gdd
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Re: Ovision upgrade new [Re: dawziecat]
      #5890696 - 05/29/13 01:01 PM

Hi Hilmi,

Great results! PEC may take you the rest of the way.

I have been getting good results with my OPW on M51 with 3 minute exposures at 1000mm with my Canon 350D when I remember to tighten everything down, get a good PA, and maintain consistant east side bias with my string/weight contraption. I did one 6min exposure by mistake that had slight trailing due partly to drift.

Gale


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Hilmi
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Re: Ovision upgrade new [Re: gdd]
      #5890776 - 05/29/13 02:04 PM

Gale I'm not done yet. I still have the gearbox replacement then the ballance tuning. I also have a sticky main dec bearing to work on.

Only then will I be happy.


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pfile
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Re: Ovision upgrade new [Re: Hilmi]
      #5891207 - 05/29/13 07:38 PM

Quote:

I no longer have any regrets buying the G11 other than the time wasted troubleshooting.




that's the thing though, how many months have you been at this? i think new users need to be aware of this.

regardless, congratulations are in order for what you've achieved. nice work.


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Raginar
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Re: Ovision upgrade new [Re: pfile]
      #5891282 - 05/29/13 08:28 PM

Rob, he's been at this now for about 9 months. And, it's taken significant tinkering to get it to this level (ovision, new worm block..).

I guess the biggest take away is that you can do it if you're willing to spend the cash. That's something you can't say about a CGEM or an iEQ45 since they lack the upgrade path.

Hilmi, that's an awesome picture.

Edited by Raginar (05/29/13 08:36 PM)


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gdd
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Re: Ovision upgrade new [Re: Raginar]
      #5891322 - 05/29/13 08:52 PM

Hi Hilmi,

Did you start out with the standard wormblocks or the OPWB?

Gale


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zytrahus
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Re: Ovision upgrade new [Re: Hilmi]
      #5891606 - 05/30/13 12:03 AM

Quote:

Terry, I still bet it's not good enough to make you regret buying the AP1100

But yes, I was amazed. Today I found somewhere hidden on the www.gemini-2.com site how to actually make the PEC curve you create in PEMPro stick to the Gemini II. I will try that process today and see how round the stars turn out after that. There is still some elongation. It's not much, I know that with stacking most of it will go away but I still want to see how round I can get the stars to be natively without processing. That might even be a collimation defect and not a tracking issue.




if you got a link for that PEC trick ^_^ I am interested


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Hilmi
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Re: Ovision upgrade new [Re: zytrahus]
      #5891666 - 05/30/13 01:10 AM

Gale,

I started out with the OPWB, which theoretically should be able to give good results but is just too picky about adjustment.

Stephen,

I did not get a chance to validate if this works, but basically, after you train PEC in PEMPro, you go to the Gemini ASCOM driver at the bottom right of your windows screen. You right click on the Gemini icon and choose advanced settings. Under advanced settings, you go to the bottom of the screen and you will find a little tick box that says "include PEC data" then click apply. This will download all your settings from the driver to the mount including the PEC curve. Yesterday I forgot to do a test by powering off the mount and restarting it, but I did confirm that the PEC buttons where visible in the hand controller after I selected this option.

Pfile, my advice with future G11 buyers with dreams of imaging is not to waste time and budget for the Ovision worm upgrade right from the start. It is my personal opinion that unless you are imaging at short focal lengths, this is a mandatory upgrade. I am not sure, but I even feel the slewing is quieter after installing the new worm.


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orlyandico
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Re: Ovision upgrade new [Re: Hilmi]
      #5891771 - 05/30/13 03:35 AM

i'm not so sure about that. i know someone who has a stock G11 and his measured PE is way less than 10" p-p.

he's imaging quite happily with it, no tweaks or anything.


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Hilmi
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Re: Ovision upgrade new [Re: orlyandico]
      #5891774 - 05/30/13 03:39 AM

At what focal length is he imaging and what pixel size?

At the pixel scale I had, with a smooth PE curve of 16 arcseconds peak to peak I still had elongated stars because the original worm gear seemed to be more sensitive to bad balance and wind due to the excessive backlash I had to leave to get that smooth PE curve.

On the other hand, with this upgrade, I had yesterday imaged one of my best images in terms of star roundness unguided. Once I get my guide came back, I bet I can get even tighter stars.

At 360 mm, I was able to image with the original worm gear unguided. I suspect that it would also work very well up to around 1000 mm, but honestly, at the 1600mm - 2000mm, the original worm gear and OPWB were no fun to use and almost made me quit the hobby. There have also been variable reports of recent worm gears being sub par. Maybe I had been unfortunate to have those worm gears (including the replacement one that i had ordered to replace the one I damaged while trouble shooting the mount).


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orlyandico
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Re: Ovision upgrade new [Re: Hilmi]
      #5891797 - 05/30/13 04:38 AM

you're right Hilmi, he was at about 950mm (ES127).

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Hilmi
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Re: Ovision upgrade new [Re: orlyandico]
      #5891849 - 05/30/13 06:37 AM

You see, I consider that a short focal length (relatively speaking). So I still stand by my recommendation that the cost of the Ovision worm gear be budgeted for if somebody plans to buy a G11 for imaging.

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orlyandico
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Re: Ovision upgrade new [Re: Hilmi]
      #5891851 - 05/30/13 06:40 AM

.. at long FL.

from what i see a significant fraction of people doing AP, do so with refractors.


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Hilmi
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Re: Ovision upgrade new [Re: orlyandico]
      #5891871 - 05/30/13 07:09 AM

I'd say most people actually use 8" Meade or Celestron SCTs

Edit: That's besides the point. If for a $500 + shiping increase in the price of the price you can improve the PE of the mount 1/4 the original PE with minimal effort from the user, why not. We spend $500 on far less useful imaging accessories.

Edited by Hilmi (05/30/13 07:26 AM)


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Raginar
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Re: Ovision upgrade new [Re: Hilmi]
      #5891947 - 05/30/13 08:24 AM

Hilmi,

I agree. 500 bucks to most of us is alot of money but we do spend as much as that on things like AO or an OAG.

Your results are awesome .


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pfile
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Re: Ovision upgrade new [Re: Raginar]
      #5892189 - 05/30/13 11:16 AM

the thing is, i believe there is something wrong with the recent batch of G11s. 30" pk-pk is way out of spec historically speaking.

to be honest the absolute value of the PE is not really a problem. what's a problem are spots in the worm that have a slope too great to be corrected by autoguiding, which is what got me.


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Raginar
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Re: Ovision upgrade new [Re: pfile]
      #5892201 - 05/30/13 11:26 AM

Rob,

There does seem to be a rash of 'bad' stories lately. I wonder what changed.


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saadabbasi
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Re: Ovision upgrade new [Re: Raginar]
      #5892271 - 05/30/13 12:07 PM

My G11, bought in 2009, had 8" peak to peak (stock worm). Never upgraded to Ovision or the new worm Losmandy offered either.

Edited by saadabbasi (05/30/13 12:08 PM)


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Hilmi
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Re: Ovision upgrade new [Re: saadabbasi]
      #5897376 - 06/02/13 07:12 AM

Gearboxes are in. I've got to fly to Abu Dhabi for work tonight, so I doubt I will get the modification done before the Thursday. How unfortunate. I was looking forward to getting this done tonight.

RS components delivered the gearbox, and the motor pinion gear has a smaller hole than what was mentioned in the specs. I don't have the correct tools to ream it to size since the hand 1/8" hand reamer I purchased wont go through the hole, it's too tight of a fit.

Edited by Hilmi (06/02/13 08:55 AM)


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