What should I do?

[cahullian]

Was in Sydney last week and had a chat with Lee at Andrews and told him about my very stiff focuser. He told me to send it to him and he would sent it to his guy in Brisbane. IT MAY TAKE 2-3 WEEKS TO GET IT BACK. I don't want to go without viewing for that long. Any ideas how to loosen it up a bit? I have unscrewed (a little)the four screws holding the focuser arm, but that hasn't helped at all. I'm on holidays for 2 weeks starting Friday and dont want to go the entire holidays without looking up. Any help in this area would be very much appreciated. If push comes to shove I could always use the time to heavily modify my scope (Frankie, If you have seen my due shield you would understand why I called it Frankie) and add an eyepeice or 2 to my collection.

Gazz/Irish

[iceman]

There's a plastic screw on the back of the focuser (not the 4 in front) that determines how tight or loose it can be..

Tighter, you get less slop in the barrel but harder to focus up and down. Looser, it's easier to focus up and down, but you get slop in the barrel.

Try that one.

If it's still bad, you can do what John Bambury does occassionally with his R&P (same as yours), and that's pull it apart and re-grease it with better lubricant. Apparently that can make a reasonable difference.

The other option, is to spend $100 and get a crayford from Andrews. It will bolt straight into your existing focuser holes in the OTA, and it is a 300% improvement on the R&P. Anthony (frogman) has the crayford on his 12" dob - did you get the chance to try it up at Kulnura?

The last option, is to spend $300 and get a moonlite CR2 (http://www.iceinspace.com.au/?moonlite). It's the top of the range, obviously. You'll need to drill 4 new holes into your OTA to mount it though.

[rmcpb]

Irish,

Before you go spending too much of the hard earned or even worse, breaking something, have a look at this page on tuning a GS rack and pinion focuser. It made a world of difference to my scope:

http://www.tomhole.com/Focuser.htm

Cheers

[cahullian]

Thanks Mike and Rob I will look at all your suggestions:eyepop:
Gazz/Irish

[Thiink]

Great page Rob, it looks like I might be pulling apart my focuser this weekend if it is cloudy. What did you use to relubricate everything? I have a can of silicon spray sitting at home I might give a try (the stuff is great!).

[ving]

I pulled mine apart and degreased it (just the gear part). I have silicon spray too, I think its a bit too light... but the stuff they have in there is more like glue :/

[rmcpb]

The silicone spray is OK with the usual care.....KEEP IT AWAY FROM THE OPTICS :)

I used some light lithium grease I found in the back of the shed and that worked OK. After saying that I think I may be upgrading to the Crayford soon or, should I buy the new 6mm eyepiece I want? Always too may things to do and buy and not enough time or money.

Keep looking up.

[cahullian]

Your not wrong Rob
I loosened the screw at the back a little and that freed it up a lot. I will have a go at taking it apart and hitting it with some silicon or whatever I have hidden in the shed.
My wish list
Argo Navis or skycommander
Frankenstein stickers and iceinspace sticker
crayford focuser
and an Indian curry for dinner

Gazz/ Irish

[Thiink]

I'd be applying the silicon by spraying it onto a cloth and then onto what ever parts needed lubricating, wouldn't spray it directly onto the parts. That should be enough to keep it away from my optics.

[Sausageman]

I second that Simon, don't spray any stuff near your optics, it could cost you a lot of work, or money getting it off.
Fingers are best.
I'm not sure about the Lithium grease either, You need to know if it is acidic or alkaline, alkaline stuff eats aluminium.

Mike

[Starkler]

The glue grease that comes as standard is horrible sticky stuff that gets thicker in the cold weather. I couldnt disolve it with metho or turps and ended up using paint thinner as a solvent.
I used a standard automotive grease to regrease . After regreasing with a lighter grease it becomes apparent that they used such thick sticky grease to hide the machining imperfections in the rack and pinion. Even with the rough spots in the movement, I found the exercise well worth the effort.

The GS crayford focuser is certainly a worthwhile upgrade, especially if they still sell for $100 ! I paid $170 to get one from the states before they were available here and still see it as good value for money.

[asimov]

Good old petrol dissolves the stuff too.

[[1ponders]]

Hi guys. I did the same thing for my R&P on my refractor (same glue grease). I rang Bintel and asked what they used for regreasing. Super Lube synthetic grease from Wagners Electronic Services, in Ashfield Sydney. Great stuff. While it didn't turn my R&P into a crayford, the improvement was substantial. Also used it for regreasing the entire mount head. Unfortunately I found I had the same problem Starkeler getting the old glue out. I'm not sure I did a good enough job on the mount head, but the focuser was great.

[RAJAH235]

Hiya all, When I O/Hauled my r&p, I pulled all the old teflon tape out & started from scratch. Luckily a friend had a supply of various thicknesses, so I was able to get it juuuussstt right, no image shift & with NO grease/silicon spray of any kind. It only attracts dust & dirt imho.
:D L.

[ballaratdragons]

A Crayford is certainly a great investment.

Worth putting an EP purchase to the side temporarily. You can have an extra EP that won't focus easily like all the others, or a smooth easy focus for all the EP's you already have. Your choice!

[Thiink]

Would isopropyl alcohol be ok for cleaning the old grease out?

[cahullian]

Yes Ken I am seriously thinking about giving Lee a call and seeing if he will take back my bodgy focuser and give me a discount on a crayford one...because of the hassle I have had with this one...the worst that can happen is he'll laugh and hang up on me lol
Gazz/Irish

[cahullian]

BTW what is the difference between my bodgy focuser and a crayford anyway???

[ballaratdragons]

Slop!

Crayford doesn't have any. It is also adjustable and lockable.

R&P also has a slight backlash (some have lots). Crayfords have none and the focusing is smmmooooooooth!

[iceman]

C'mon guys, keep the banter out of threads like this please.

[Thiink]

This afternoon I just finished pulling my whole focuser apart (I took the focuser off the OTA to make it easier) and putting it back together again, as per the instructions above. All I can say it wow! It has made a huge difference. Its not silky smooth, but it is a big improvement over what it was like before. Before the end of the weekend I hope to have the secondary checked (thanks for the howto!) and centered, and the focuser put back square again.

Some notes:
- when people say the factory "grease" is sticky, they arent lying. The stuff is literally like glue, I had to wash my hands 50 times to get it off my fingers before trying to clean another part. The isopropyl alcohol I used worked well, the earbuds I used to clean the focuser with were a pain though, they kept leaving little bits behind stuck to the glue. It all up took over an hour to get the glue off, but even then I dont think its 100% out. I ended up using the silicon spray, I sprayed it onto an ear bud before applying it, and then wiped off any excess.
- either my focuser is missing parts, or the design has changed a little bit from the pics on the website. My focuser did not have the metal retaining clip, and also had teflon sliders instead of the plastic strip, and there was no allen key screws on the side of it. It has the holes, but they are filled in.

It was definitely worth the time, and if I dont end up with a craford focuser soon I'm going to have another go at getting the glue out.

[Starkler]

It took me a while to get the glue out, even with thinners as a solvent and using a stiff toothbrush. You really want to get rid of all traces of the horrible stuff.

[[1ponders]]

One thing you might want to consider Simon is Xylene (careful its an S6 poison so DEFINATELY wear glove and maybe even a respirator if doing it in a confined space like a garage), but one thing I didn't try and I haven't seen mentioned is the old fashion degreasing fluid for removing grease of machine parts. could it be that simple????

[Thiink]

Did yours have the retaining clip in it when you took it apart Geoff? Just wondering if mines either missing it, or isnt supposed to have one anyway.

I cleaned it fairly well, I am not really that keen to pull the thing apart again. That glue really was horrible, it took some scrubbing to get it off my hands (and even then they still felt sticky). I didnt think to try an old tooth bruth, I think it would have come off easy enough with the isopropyl and a toothbrush!

Paul: ouch! That sounds like nasty stuff! I think the upgrade to a crayford is a better idea, I dont know how much better the movement of the R&P is going to be even if I pull it apart again. Im fairly happy with how it is now. Im sure I could motorize it now I wouldnt have too many problems with how fluent the movement is. Degreaser wouldnt be a bad idea though, if I upgrade to a crayford I might play around with it to see what works best at getting the glue off 100%.

Thanks guys!

[ballaratdragons]

Acetone is very good at getting anything off anything. Problem is Acetone will also eat paint off too, so if the focuser has any paint on it, forget it!

I once wanted to paint a motorcycle tank in a hurry and I was told that acetone was the best to degrease and strip the paint off. Luckily I was working in a Fibreglass place at the time and I filled a drum with acetone, stuck the tank in for about 20 seconds, swooshed it around and pulled it out to see if it had degreased it yet. It had stripped everything off down to the bare metal! IN 20 SECONDS!!!!

Good stuff!!!!!

[cahullian]

Thanks for the tips guys I'll take them on board now that I'm on holidays he he he

[Thiink]

Hm, after putting my focuser back in and trying to square it up, it appears as though I'm going to need to shim it slightly. At the moment the focuser is about 3-5mm off being the right height. Anyone have any ideas? Taking it apart, clearning, putting it back together and squaring it as good I could has certainly made a difference!