Guiding woes

[gary1968]

As some of you folks on here might be aware, I am having a nightmare guiding my CG5GT........

At Kielder last weekend I was fortuate enough to have both Starflyer and Blinky there to pick their brains as to the cause of my troubles......

My 1st big problem I think was that I had set backlash compensation in the HC. The result of this is when PHD was sending guide pulses to the mount most if not all of the 'pulse' was taken up trying to overcome the settings in the hand control. I switched off the backlash compensation in the HC and behold it started guiding, and guiding fairly well.

We left it running for a while but every now and again the dec guide graph would go 'suddenly' haywire (from near perfect to right off the scale). After some discussion we decided that the most probable reason for this is either a high spot on one of the gears or a bit of crud inside the mount causing it to jam.

So, the decision has been made, I am to take the mount apart for one of the Astronomyboy tune up's, at the very least the dec axis will be done.

Just one question for now though, does anyone know where to get stuff called 'Super Lub'? or at least I think thats what Ian (starflyer) called it. Any advice as to a supplier for this grease or indeed an alternative would be great.

A little write up will follow the mounts strip down.............

Gary

[blinky]

I got some good lube from Halfords, it's some form of silicone grease stuff. I have actually seen an HEQ5 regrease guide that used the same thing so it must be OK. I will bring it through on Wed and you can hold on to it till you have done yours.

Cannot believe we are talking about lube!

[gary1968]

Cheers Craig, much appriciated. Still 'very' wary about taking the mount to bits but it needs done so I'll just have to get on with it.

Gaz

[AndyKeogh]

I am sorry to hear that you are having so much trouble getting guiding to work. I also have a C5 ASGT mount and have been considering an " astronomy boy" tune up so will be very interested in how you get on.

I find that most of my errors are in RA rather than declination especially now that I have aligned my polar scope . Will you be taking photographs as you dismantle the mount?

It would be interesting to know how the different lube affects the limiting friction of the mount. Based on experiments with some kitchen scale weights and a metre rule shows that my mount will; not start to move until I attach a 1lb weight 50cm from the axis.

I would be interested to know what weight moves your mount before and after you change the lubrication.

Andy

[roundycat]

I think you will be better off with molybdenum disulphide grease rather than anything silicon based. Silicon tends to migrate to places where you don't want it.

Dennis

[gary1968]

Andy,

I may well take some pics as I go, but have you seen this page...... Deep Sky Eye Observatory There is a great detailed 'how too' on there.

I'm not sure I can check the limiting friction, I dont have kitchen scale weights. I will try other things that I find lying in the garage and weigh them to try and answer your question.

I dont polar align through the polar scope. I now use the All Star Allign routine in the latest version (4.16) of the HC firmware, have you upgraded to that yet?

Anyway, watch this space.........

Gary

[gary1968]

I think you will be better off with molybdenum disulphide grease rather than anything silicon based. Silicon tends to migrate to places where you don't want it.

Dennis

mmmmmm, thanks Dennis. I will have a look see where I can get that. I used to work in Mitsubishis' VCR factory in Livingston, we used stuff called Molykote in there for the VCR deck, that just might have been the stuff for the job, might still be able to find some lying around. If I remeber rightly its horrible black stuff that gets everywhere when you use it.... lol

I'll bear your comments in mind mate, thanks.

Gary

[blinky]

Horrible black grease....... Maybe thats the stuff Synta use that everybody complains about, maybe they were right after all!

[gary1968]

Nah Craig, the stuff Synta uses in more akin to treacle, Molybdenum grease is very, very good. Not sure how it will perform in sub zero temps though, a bit of research required on that one.

Gaz

[alfi]

hi

superlube is one brand of PTFE based grease, any ok PTFE grease will do, you can find it in car accesories shops, and also in bike shops.

alfi

[blinky]

Ah no it's PTFE Grease that I have, I think.....

[gary1968]

PTFE Craig, thats even better. if you bring it through anyway that would be great.

I am planning to try this at the weekend, if Debz doesn't have any other plans that is.

Or, maybe I should leave it to after the Abernethy outreach thing we are going to.

Gary

[alfi]

hi

PTFE is one of the most "slick" lubricants / greases available on the commercial market.

it forms a strong binding to the metal surfaces, and are very resistant to wear and tear.

i worked with cars 20 years ago, and saw a demonstration of it, where they used it as a oiltreatment, just ca. 0,5 liters in the oil, then ran the engine for a couple of hours, removed all the oil in the engine, and the coolant, and then we took the car for a 30 minute drive, and it was still running when ww came back.

i would not advice such a use, but it shows that it is a very good product.

with our use, 1 treatment should hold a lifetime.

it also is aging resistent, it does not dry up like many others do.

alfi

[david o]

Gary,

One word of warning if you're going to do an AstronomyBoy on your CG-5.

It is very easy to strip the threads out of the holes in the castings that the worm assemblies mount onto when you're adjusting the mesh of the worm gears. I know from experience.

The repeated tightening and slackening needed whilst adjusting the set screw is what did it to mine. That and the monkey metal the casings are made from.

Good luck with the strip/rebuild.

[gary1968]

Thanks for the warning David. I dont suppose you can remeber the size of the screws that stripped? I only ask I would bring home some Helicoils just in case the worst happens.

But I will heed your advice, thanks.

Gary

[MartinB]

This is where I got mine from Loctite Super Lube Grease 85G : Tooled-Up.com

[david o]

Gary,

Here's some info on those screws for you.

The Dec. worm assembly retaining screws are, at least on my CG-5, "M-Five" (Metric 5) standard screws.

Replacement of the two horizontal hex screws:-

A shaft length of 3~4cm seems about right, passing through the whole length of the threaded hole and out the other side, spreading the torque across all the available thread.

It allows placement of a washer under the head - a good idea seeing as how soft the casting is (mine was marked after only a few slackenings and retightenings during adjustment).

It also permits the use of a washer and nut on the inside of the housing - there's lots of space and nothing to foul in there - if you have already managed to strip the threads to any degree.

And the two vertical hex screws:-

A shaft of 2cm is all that there is room for without fouling the worm mounting shaft.

Sufficient length to place a washer at either end and a nut at the bottom to hold things together.

[AndyKeogh]

Andy,

I may well take some pics as I go, but have you seen this page...... Deep Sky Eye Observatory There is a great detailed 'how too' on there.

I dont polar align through the polar scope. I now use the All Star Allign routine in the latest version (4.16) of the HC firmware, have you upgraded to that yet?

Anyway, watch this space.........

Gary

Thankyou for the link. I will not rush into modding my mount yet but will digest how it can be done.

Not too sure which version of the controller I am using as I do all my controlling with NexRemote V1.6.25 and use 2 star align with 4 alignment stars and then polar align on the last alignment star.

Andy

[gary1968]

Thanks for the info David..... :-)

I 'was' intending to do this at the weekend but SWMBO has just told me I am decorating the livingroom. At least I should recover some of the brownie points I used to go to Kielder.

Thanks again mate,

Gary