Sloppy Focuser

cjmarsh81 · #1 05-02-2006, 08:52 PM

Hello All.

I am starting to get annoyed with the crappy focuser in my Skywatcher Dob. It was great for the first few weeks, but now it is very sloppy. If I use the allen key adjuster to tighten it, this removes the sloppiness. Unfortunately, this causes the movement to be so tight that I end up moving the OTA instead of focusing.

Is there a replacement crayford style focuser that will simply bolt on? I have seen Iceman's article where he changed his and had to drill holes in the OTA. I am not game enough to drill holes in my scope just yet and am hoping for a bolt-off bolt-on solution.

iceman (Mike) · #2 05-02-2006, 08:55 PM

ahh the old R&P, that's the exact problem.. too tight or too sloppy. The GS crayfords (@ $99) are an excellent replacement. I *think* it will fit without having to drill new holes - Steve at MyAstroShop should be able to advise, or even matt who I think did the same (but if I remember, he had problems and got a moonlite instead).

So get some advice from him first.

cjmarsh81 · #3 05-02-2006, 09:00 PM

Thanks iceman

Matt are you there? Any suggestions? What problems did you have that made you change to a moonlite?

Thanks

matt · #4 05-02-2006, 09:26 PM

G'day cj

Mike's right. I had some problems with the GS crayford. The fit was OK on my Skywatcher (SW600) as far the base plate hole placement was concerned but there were problems with bringing objects to focus.

The focuser profile (maximum and minimum) racked in and out height was not the same as my original R&P focuser. I could have solved the problem by using an extender inserted in the focuser but I just couldn't be bothered introducing extra components into my focusing rig.

I also wasn't too impressed with the overall quality of the focuser, although I think it's OK for the money, if you know what I mean?

I ended up ordering a MoonLite CR2 dual gear unit from the US and am very happy with it although it costs quite a bit more than a GS crayford - try $500 versus $100 (or thereabouts).

I didn't mind the cost since as far as I'm concerned a smooth, precise and well machined focuser is worth its weight in gold compared to the agony of trying to work with something that drives you round the bend!

Each to their own. Figure out what you can live with and what you're willing/able to afford and go for it.

Let me know if you need any more help.

cjmarsh81 · #5 05-02-2006, 10:19 PM

If the $100 crayford is going to annoy me and it sounds like it probably will, I am willing to put up with my existing focuser until I save up for something better. The moonlite you went for did you have to drill holes to put it in? Are you happy with the moonlite?

I don't want to spend too much on it though, as I am going to start saving for an EQ6 tripod, and maybe another EP.

cjmarsh81 · #6 07-02-2006, 10:59 PM

I have read an article on the cloudy nights forum stating that synta(which my skywatcher is made by) use a lubricant on the focuser that resembles putty. They say to dismantle the focuser clean out the useless gunk they have put in there and use a real grease. When I get a chance I will put it apart and give it a go. The focuser was fine for the first few weeks, so perhaps if I re-grease I can get it back to that state. I don't need any fancy gear reduction at the moment so if I can remove the sloppiness to a reasonable level I will leave it at that.

janoskiss (Steve H) · #7 07-02-2006, 11:17 PM

Yes, you can pull apart, shim, and re-grease your existing focuser to get much better performance. If it is not teflon lined you can perhaps do that too. Roger at Bintel Melbourne seems to know all about how this can be best done, and I think it would be worth ringing him up and having a chat. Or send him a PM/email.

The GS Crayford should work though with a minimum of fuss. If it does not have enough out-travel for some of your EPs to reach focus, then you can get a barrel extension for it.

astronut (John) · #8 08-02-2006, 06:59 AM

CJ, Don at Bintel suggested Superlube, a synthetic grease. It repels dirt and grit. I used it on my two 30 year old Unitron refractors, they both have R&P focusers and what a difference it makes. Cheers, John

cjmarsh81 · #9 08-02-2006, 08:48 AM

Thanks guys, I will look into this superlube stuff.

rmcpb (Rob) · #10 08-02-2006, 09:07 AM

Cleaning, relubing and shimming your R&P will make a huge difference, give it a go.

As for the problems with the GS Crayford, they come on the Premium model GS scopes and the users all like them. I put one on my scope and love it so don't discard it out of hand. Also don't try to compare this $100 focuser with a $500 one, you get what you pay for but I have to say the installation of my GS Crayford was the best upgrade I have done to my scope yet.