Telescope Reviews: "Hyper-tuning" your GSO crayford

Okay, a few CNers told me they are having trouble with their GSO-made crayford. They worked at the beginning but then all of the sudden getting stuck, stiff, slipping, or whatever. Adding more tension by the thumbscrew makes matter worse, etc etc.

I think, instead of just telling them. I am posting my trick here so that everyone can benefit.

"Hyper-tuning" your GSO crayford

Before you start, you need a few things. The focuser of course. A few pieces of tissue. And.....drum roll.......grease. Yeap, you heard it right.....GREASE! Repeat after me! G-R-E-A-S-E.

GREASE!

You may think "Are you crazy? Grease for crayford? Reason I get the crayford is because I HATE grease!"

Well, I am one of the odd balls (I think those who call themselves "artist" do qualify for that) so don't argue with me

In fact, ALL my GSO focusers (I have FOUR, three refractor type and one reflector type) have gone through the treatment (which I am going to tell you) with grease (again G-R-E-A-S-E......GREASE!) and they all have been working great. If you don't believe me, turn off your computer and head to bed or do something else

Okay, lets start.

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Picture below. A product photo of the GSO crayford

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Next, a photo of the grease (repeat after me, GREASE. Sorry I can't resist

). The type of grease should be light/thin one *NOT* the thick type otherwise it will make the end result really bad. I pick a light white lithium grease (GREASE!

)

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Now, time to break the focuser apart, YAY!

If you have a dual speed type. Take off the simpler knob (not the dual speed one) from the shaft.

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You see there's a little plastic tube like thingy (the one sitting on the shaft). Take it out too but keep it in a safe place as you will need it later.

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Pull the shaft out so that the drawtube can be taken out from the focuser's body

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Before I move on, let me explain why I am using grease (GREASE!!!!!!

)

I have been looking at moonlite, WO focuser for a long time and I always wonder why these focusers are pretty smooth. WO and GSO focuser share the similar type of mechanic and why WO is smooth than GSO's all the time. I first thought it was the focus shaft and knobs. Then I realize this is not the answer. The real answer is the DRAWTUBE.

WO and Moonlite have smoothly anodized draw tube and the suface is so smooth and reflective while GSOs has rough texture. That really causes friction and resistance. For smooth focus action the drawtube has to be smooth.

The grease I am using here is not just for lubrication but also for "polishing" the surface of the drawtube.

Let's move on....

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Now, apply a small amount of grease (GREASE!

) on the drawtube's flat area. Spread it out.....think of applying wax on your car. Wait for a few minutes. Then wipe the grease out COMPLETELY.

This is pretty much a work of polishing the surface.

You may have to do a few times. The flat surface should few a lot smoother after that.

I first thought about using car wax instead for the polish but then realize grease (GREASE!) and car wax may not play well to each other. So I decide to use grease (hurray! GREASE. Long live the grease!

) all the way.

Do the same on the "bearing mark" area (the black line, all crayford tube have these due to the contact of the ball bearing/wheel in the focuser). But leave a bit of grease there.

......and the shaft (remember to WIPE OFF the grease completely!)

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Now, look at the focuser body. Now apply a bit more grease on the four wheels (circled in the photo). Leave the grease there

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Here's the tricky part - to put the focus shaft back to the focuser. You will have to loosen up ALL the bolts or screws at the bottom of the focuser so that the draw tube has more wiggle room to let the shaft back in.

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Remember the little black plastic tube thing? Put some grease on both end and put it back to the shaft

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Put everything back in and start to rack in and out the focuser a few times. And pull and push the focuser drawtube back and forth (by hand) at least 10-20 times (have to wear out the shaft and the drawtube's contact surface to improve the contact a bit)

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After that, the grease is all over the draw tube (as seen on photo)

You may do the clean up but leave some of them on the area where the four wheels' contact (the lines, remeber?)

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Now, since the focuser has smooth drawtube that means it will slip easier. But don't worry, this is what the tension knob is for. Yes, a bit more tension is needed (The focuser is able to handle a 2" focuser, with a 2" EP, and no slip). Crayford focuser need to have a balance between smooth (or slip if you prefer) and gripe (or friction) in order to operate well.

In terms of smoothness, base on my experience, is really very close to moonlite after the modification. But that's depending on what kind of lubricant you use. If you use very thick grease you will get a very sticky focuser.

Any questions? Feel free to ask

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