Turtle Wax On The Base Of The Rocker Box Makes The Dob Stick

[adarshajoisa]

I'm not sure if I'm posting this in the right section, but here goes.

My skywatcher 8 inch dob had a very stiff azimuth motion. After reading up quite a bit on how to make it smoother, I found general consensus around the idea of coating the base of the rocker box with turtle wax. So, I bought myself a jar of turtle wax, and proceeded to apply it. First, I cleaned both surfaces - the laminate at the bottom of the rocker box, and the teflon pads on the ground board thoroughly. Next, I applied a coat of turtle wax on the laminate, let it dry for a few minutes, and buffed it with a dry, clean cloth. I then reassembled the whole thing, and found that the azimuth motion was extremely smooth. The difference was astonishing.

That night, I set up my scope, let it cool as usual, and started observing, and I immediately noticed that it sticks when I try to move the scope in the azimuth axis. Once it gets moving, it moves a lot, so the motion now is very jerky. It's so bad that I now regret applying the wax. The motion earlier was very stiff, but not jerky. 

Is there something I did wrong? Is there a different way of applying the wax? It looks like after applying the wax, the kinetic friction has greatly reduced, but the static friction is the same or higher than earlier. What are your thoughts on this? Any advice is greatly appreciated!

[ChrisLX200]

I don't know where you got the information that you did, but the classic combination of Teflon (PTFE) and Ebony Star (a sort of rough Laminate) gives the best combination of static and dynamic frictions. By using wax you messed that up and I would suggest removing all traces of it.

ChrisH

[Paladin]

Chris:  You mention that the classic Dob uses Teflon and Ebony Star for bearings, a system set out by Kriege & Berry in The Dobsonian Telescope, which I assume is the source of your statement.  However, you are wrong to suggest that no polish should be used, as after experimenting, they concluded that it could help in achieving the optimum ‘stiction’.  Chapter 13 of the book describes building a simple 8 inch Dob, and was a huge influence on the design of my own scope:

http://stargazerslounge.com/topic/255887-8-inch-dob-finished-at-last/

The following is a direct quote from that chapter:

"Cut three pieces of Teflon 1 ½-inches square; attach them to the ground board directly over the feet using tiny finishing nails. Recess the heads so they cannot scratch the bottom bearing. Wax the bearings with car wax."

I tried various polishes on the Paladin Dob, and found that a beeswax polish has proved to be best, although whether it would work as well on a propriety scope, I do not know.

Best Wishes: Paul

[Starlight 1]

Will it work or not I past on that? Try candel wax !!!!

[Peter Drew]

I'm in the no polish camp. Provided the PTFE is clean and its mating surface is textured as with "ebony star" then the movement is good and reliable. The tightness of the central fixing bolt can be a big factor in getting things right.

[adarshajoisa]

I'm in the no polish camp. Provided the PTFE is clean and its mating surface is textured as with "ebony star" then the movement is good and reliable. The tightness of the central fixing bolt can be a big factor in getting things right.

Peter, 

The mating surface, on first glance, doesn't look textured, but if I look closely, it seems to have some small texture. It overall appears smooth. The central bolt that came with the scope can't be loosened beyond a certain point because the rocker starts wobbling sideways on the ground board if I do that. I've taken several attempts to get the right amount of tightening so that the base doesn't wobble, but even this makes the azimuth movement too stiff. That was the primary reason I decided to read up a little on the topic and tried the car wax. I would've tried buying some ebony star laminate and attaching it to the base of the rocker box, but I can't seem to find it anywhere here in India, and importing would prove too expensive.

[adarshajoisa]

Oh, and yes, I've thoroughly cleaned the teflon pads and the bearing surfaces before applying the wax on the bearing surface.

[Astrobits]

Ebony Star is simply an American brand name for a textured worktop laminate. Therefore try any worktop laminate that you can get that is textured.

I have never needed to wax my Dob bearing surfaces.

Nigel

[ollypenrice]

I'm surprised by this. When I first bought my big Dob I read in a normally reliable source, I don't remember which, that Turtle Wax was excellent for Teflon-Ebony Star. I found this to be so. The key thing is that the static and moving friction should be as close as possible so you don't get the jerk-overshoot syndrome. You can't buy Turtle Wax in France so when I ran out I bought a French silicone car polish instead. (The source recommended silicone generally and Turtle Wax in particular.) It was a disaster and made the scope impossible to use. I had to phone a friend in the UK to get some Turtle in the post immediately.

Since then I've gradually stopped using any polish at all, though, largely out of laziness, so maybe nothing is best. It probably depends on very specific factors like the precise formica and the precise weight of the scope, etc.

Olly

[ChrisLX200]

Yes, 'textured' as in lots of little rounded bumps - which reduces the contact surface area considerably compared to a smooth surface and this influences how it moves.

ChrisH

[mapstar]

I don't know where you got the information that you did, but the classic combination of Teflon (PTFE) and Ebony Star (a sort of rough Laminate) gives the best combination of static and dynamic frictions. By using wax you messed that up and I would suggest removing all traces of it.

ChrisH

The holy grail it may be in terms of the working properties but it's like the holy grail trying to find it, as in impossible!

I had to hunt around for a suitably textured laminate as not all are equal, I have tried quite a few and it took quite a while.

Peter Drew mentions the central bearing and I would agree. Try slackening it and then test.

I've used wax on my bearings as dew can cause a suction and the wax just prevents in staying on the surface. It's only slight but noticeable on 15" radius bearings.

[Moonshane]

I suspect as hinted at by Peter, if you loosen the central bolt just a very little you will see an improvement. the skywatcher bases do use a pretty smooth laminate. if you can find any with more orange peel texture, and glue on with contact adhesive to the underside of the rocker you will see a big improvement. I used turtle wax years ago and have not needed to ever reapply

[adarshajoisa]

After fiddling around for a while, I found that if I tighten the center bolt a bit, the jerk goes away. It's tighter to move, but there's no jerkiness. This kinda brings me to square one . I'll try finding a suitable laminate the next time I go shopping. Thanks a ton for all your help!

[Beulah]

I've been a SW dob owner for years and a stiff azimuth mount just needed taking apart and a bit of a clean. Just a cloth and a bowl of hot water with a squirt of washing up liquid.  

[adarshajoisa]

I've been a SW dob owner for years and a stiff azimuth mount just needed taking apart and a bit of a clean. Just a cloth and a bowl of hot water with a squirt of washing up liquid.  

I've tried cleaning the teflon pads with some lens cleaning liquid (I believe it's some kind of alcohol), and cleaning the bearing surface with a clean, damp cloth, but I'll give your method a try. Do you use the washing liquid-water mix only on the bearing surface, or on the teflon pads as well?

[Beulah]

Ah. I notice you are a 200p owner and the mount is different on the azimuth base...with the larger scopes, there is a sandwich of thin discs with cylinder bearings in between - that, and the mount facings, is what I cleaned:

http://2.bp.blogspot.com/-JbLqTBPqU1E/VQM2nzLFeiI/AAAAAAAAAjk/txDueIVnmJY/s1600/20150312_154301.jpg

Not sure if you can buy them for the 8" - I think the diameter is about 320mm...

With the 8"  you will have to follow the excellent advice on this thread.

[Demon Barber]

Just my opinion but the best i have found is Amour All http://www.armorall.com/products/protectants/original-protectant     built up in fine layers,defiantly is an advantage in wet ,dewy conditions,this is on my 15"Obsession. This is the advice of numerous Obsession users on the Obsession forum. Tried and tested..

Regards

Mike

[swamp thing]

Just my opinion but the best i have found is Amour All http://www.armorall.com/products/protectants/original-protectant     built up in fine layers,defiantly is an advantage in wet ,dewy conditions,this is on my 15"Obsession. This is the advice of numerous Obsession users on the Obsession forum. Tried and tested..

Regards

Mike

Thats good to know Mike, thanks