Old G-11 gets a Tune Up.

[netwolf]

Hi All,

With the help of Apoman (Peter) and Kal (Andrew), I finally gave my old CG-11 mount a tune up. Peter has a CG-11 mount that he has had for many years and has done the bearing replacement mod on his and pulled it appart to regrease it. So he offered to show me and Andrew how to tune up our mounts, after work today. Pete did a lot of the talking and the working, and I helped where possible. We only got through mine today as it was getting late. So we plan to do Andrews Monday evening.

All went well, we took apart everything and soked all the parts in Alcohol and cleaned them with a toothbrush to get the old grease out. Then regreased it then placed it all back together. Also took the opportunity to remove the stepper motors and replace with the lightly used Gemini Servo motors that i recently acquired, these will be used with the Sitech Controller to make the mount a computer controlled Goto. I will later add a ArgoNavis for independent goto control.

So i am all set just need to solder some Din connector cables for the Gemini motors to connect to the Sitech controller.

Hopefully Monday we will tackle Andrew's mount. I certainly learned quiet a bit from Peter and my thanks to him for helping me with this. Always a great guy to help you out and give advise. I am very confident now with opening up my mount and knowing how it all fits together an operates.

Here are just a couple of snaps of the work being done. This used to be my old desk when i worked in this facility 2 years back.
We will try and take more pics with Andrew's mount.

As Pete kept saying "brush it till its buttery smooth", now it is very smooth.

Regards
Fahim

[[1ponders] (Paul)]

Go for it guys

I just hope when your finished they track better than the one you had the camera mounted on.

[Omaroo (Chris Malikoff)]

Great stuff Fahim

A new mount is very smooth - so it must be good to have it back as good as new. How's the worm? Do you have a high precision bronze one fitted ot the old steel?

I've recently been looking at the Ovision (France) replacement worms, which are reputed to bring a G11 up to Astro Physics-quality PE precision of less than +/- 5 arc seconds. Not cheap at about US$500, but a good upgrade for the future. They also sell extensions to the RA housing which allows you to better clear the steppers or servos, and to delay meridian flip by a few hours.

This accessory allows the user to get a few additionnal hours of tracking before having to flip the mount at the meridian. It allows the user to continue to track and image well after the meridian, with the scope under the mount, with the stepper or Gemini models ( gemini system allows the user to delay the meridian flip). This perfectly machined piece nicely matches the finish of the G11 RA axis and does not change the orthogonality of the axis, and reduces interference of the scope with the mount (depending on the size and length of the OTA).

Anyway - we digress. Nice job! It's good to bring back a great unit to original performance again huh!

Pic 1) Original worm (new "high precision") from Losmandy

Pic 2) Modified worm - to AP-quality specs +/- 5 arc secs

Pic 3) RA spacer

[g__day (Matthew)]

Good work - though I am surprised how small the worm gear is, it looks 1/3 of the size I'd imagined it would be!

[Omaroo (Chris Malikoff)]

Originally Posted by g__day

Good work - though I am surprised how small the worm gear is, it looks 1/3 of the size I'd imagined it would be!

It's probably a bit deceiving, but there's some beefiness to it when you hold one.

I've added the comparative images of the two worms now.

[netwolf]

The person I bought the motors of Larry has done the Ovision upgrade on his Titan mount, as well as the Maxon motor upgrade. Larry reports a much better performance than what he got on paper from Ovision. But he needs to do further testing. I first contacted Ovision some months back and the price was a bit higher then and then i noticed the 499USD price on Losmandy users group. The knew price makes it look more ecconomical. Peter and I are eager to see the results for these and are considering the upgrade. I hope that the tune up will improve things a bit and I will test it before making any further changes. Having the Goto system now will make testing the current mount a little easier for me.

I currently have the older Steel worms, Peter has the bronze HP ones that he upgraded to on his mount. I considered them but would rather save my money and get the Ovision. I think the Ovision might make the G-11 more of a mid range mount than the "top of the bottom end". If early reports are true then we may have a mount as good as the AP or MI mounts. For the near future this is going to be my mount for some years to come. So my intention is to get the most out of it that i can.

One other thing I learned was that unlike Peters mount mine does not need the third bearing modification, this is sometimes required on older G-11 mounts. The bearings seem to be in the correct place from Factory. I belive this maybe due to the Mount being purchased via Company7 by the original owner.


Regards
Fahim

[netwolf]

Update did Andrews Mount after work today and we noted some differences. The Bearings were all seized up, could not get them to move at all with the fingers. Mine would move if with a bit of force but Andrew's would not budge.
There were signs on the RA and DEC shafts that the were just slipping on the bearings. Anyway a bit of elbow grease and some Alcohol got the bearings rotating more freely. Also cleaned all the other washers, gears, worms etc with Alcohol. Then greased everything one by one with Slick 50 and put the mount back together. Now its Buttery smooth.

Some photos here.
1. Dec Axis lower Bearing, not how this is all the way to edge. This is the way it should be. Some older mounts the bearing was further in. Some times this was fixed by adding a third bearing if there was enough room If not you have to get this bearing out and replaced it.
2. Dec Axis and RA shaft assembly.
3. Dec Shaft.
Both shafts are cleaned with Alcohol and greased with Slick 50.
4. RA Axis, RA gear and RA worm post cleaning and greasing with Slick 50.
5. Greasing the RA worm.
6. Peter finishing off the RA Axis.
7. Peter and Andrew replacing the Dec Gear and Worm.
8. Andrew Brushing Dec Axis top bearing.

Regards
Fahim

[Kal (Andrew)]

Buttery smooth hey Fahim

I'm suprised the mount worked at all with all 4 needle bearings on the shafts completely siezed up. I guess that explains why I was seeing a vibration in the mounts tracking that would cause faint stars under high magnification to appear like doubles! Instead of a nice smooth motion the shaft was skipping over the bearing pins!

My mount looks pretty good now that I have the NGC-Max DSC and the aluminium motor covers from your mount installed