Lube suggestion

[Richard N]

Sky-Watcher Classic 200p Dob. Az bearing seems pretty sticky. Tried some GT85 but that’s not helping. Suggestions?

[Mandy D]

@Richard N The az bearing on a Skywatcher dob should not need lubricating, ever. It runs on PTFE ("Teflon" ®) pads. Have you checked how tight the central bolt is in the Dob base? If that is too tight, the azimuth motion will stick. Slacken it off until it works OK and remove the lubricant you have applied.

[Richard N]

27 minutes ago, Mandy D said:

@Richard N The az bearing on a Skywatcher dob should not need lubricating, ever. It runs on PTFE ("Teflon" ®) pads. Have you checked how tight the central bolt is in the Dob base? If that is too tight, the azimuth motion will stick. Slacken it off until it works OK and remove the lubricant you have applied.

Thanks. The bolt is not tight. I’m not convinced that the supplied pads are ptfe. Are you certain that they are?

[bosun21]

Buy a lazy Susan bearing. A good quality one is really smooth.

[Mandy D]

2 hours ago, Richard N said:

Thanks. The bolt is not tight. I’m not convinced that the supplied pads are ptfe. Are you certain that they are?

No, actually I am not. I haven't actually examined any since I first took delivery of my 250PX several years ago. PTFE is really quite soft and flakes easily, but I now think I recall the pads being hard. I'm sure others have said they are PTFE, though. If I can find the right spanners, I'll check mine.

[Mandy D]

@Richard N Almost certainly PTFE on mine. It is white with a very low coefficient of friction and feels soft enough. It certainly slides well on my AZ baseboard. Have you owned yours from new? Have a look at the photo which shows one of the pads stapled in place and the centre washer.

[Richard N]

2 hours ago, Mandy D said:

@Richard N Almost certainly PTFE on mine. It is white with a very low coefficient of friction and feels soft enough. It certainly slides well on my AZ baseboard. Have you owned yours from new? Have a look at the photo which shows one of the pads stapled in place and the centre washer.

Thanks. Mine is second hand but unused. The pads look similar. Maybe I’m expecting too much from a simple system. 

[Louis D]

You want some stiction to allow it to hold its position when you stop moving it.  Perhaps you're expecting no stiction?  Just make sure the ground board and pads are clean.

[Spile]

I’ve read about folk lubricating the pads but then needing to reapply lubricant a few months later. I have not applied anything to my pads or bearings in two years and I am not aware of any increased friction. If I do, I’ll simply clean them.

[LDW1]

I just use some very small amounts of petroleum jelly on any equipment that needs a bit of refreshening lube touch up.  Have used it since the 60's on anything that will not be exposed to water, its a water based lube.   PS:  I apply it with a tooth pic.

Edited August 17, 2023 by LDW1

[Mandy D]

@LDW1 petroleum jelly is oil-based, unless you are using an alternative that I am not aware of. It also well known that it attacks latex rubber. For PTFE it will be fine, as will most chemicals, as PTFE is pretty much chemically inert and resistant to chemical attack.

[Richard N]

Thanks for all the replies and suggestions. Over the weekend I will strip it down and perform the following steps:

 

1) Tighten the bolt heads that protrude though to the bearing area in case they are dragging

2) Make sure that the staples holding the "ptfe" pads are below the pad surfaces

3) Pack out the centre friction disk slightly to reduce the weight carried by the PTFE pads.

4) Wipe the surfaces clean.

 

These are all suggestions that I have seen here and on other fora. I appreciate the need for some stiction but at the moment it's virtually unuseable on anything but the lowest magnification.

[LDW1]

4 hours ago, Mandy D said:

@LDW1 petroleum jelly is oil-based, unless you are using an alternative that I am not aware of. It also well known that it attacks latex rubber. For PTFE it will be fine, as will most chemicals, as PTFE is pretty much chemically inert and resistant to chemical attack.

Mine is called Vaseline, never had a problem in over 60 yrs. !  The OP asked a lube question, I answered with my preference, I haven't visually seen their situation, its their decision !

Edited August 18, 2023 by LDW1

[AstroKeith]

4 hours ago, Richard N said:

Thanks for all the replies and suggestions. Over the weekend I will strip it down and perform the following steps:

 

1) Tighten the bolt heads that protrude though to the bearing area in case they are dragging

2) Make sure that the staples holding the "ptfe" pads are below the pad surfaces

3) Pack out the centre friction disk slightly to reduce the weight carried by the PTFE pads.

4) Wipe the surfaces clean.

 

These are all suggestions that I have seen here and on other fora. I appreciate the need for some stiction but at the moment it's virtually unuseable on anything but the lowest magnification.

If your pads are stapled on, the they are almost certainly ptfe. ptfe cannot be glued unless it is especially treated.

A 200 dob should move quite easily, so a good strip down and check is excellent.

Give the pads and the mating surface a really good clean. Then a wipe of a silicone based polish. Apply polish and then buff off.

Please dont use vaseline on the this type of bearing. Its sticky and will pick up dirt and grit.

[LDW1]

38 minutes ago, AstroKeith said:

If your pads are stapled on, the they are almost certainly ptfe. ptfe cannot be glued unless it is especially treated.

A 200 dob should move quite easily, so a good strip down and check is excellent.

Give the pads and the mating surface a really good clean. Then a wipe of a silicone based polish. Apply polish and then buff off.

Please dont use vaseline on the this type of bearing. Its sticky and will pick up dirt and grit.

Its not sticky if you apply it with a toothpick in minute amounts and let it work itself around, most unknowing applicants always tend to over do everything.  Now thats over 60 yrs. of lube jobs, lol ! I use it because it is so benign compared to most other lubes but it does a great lube job on lite applications. What the OP does or needs to do is not for me to say on that material.    PS:  Personally I wouldn't lube it at all, as someone said lightly clean the surface and see what happens. 

Edited August 18, 2023 by LDW1

[Richard N]

On 18/08/2023 at 09:02, Richard N said:

1) Tighten the bolt heads that protrude though to the bearing area in case they are dragging

2) Make sure that the staples holding the "ptfe" pads are below the pad surfaces

3) Pack out the centre friction disk slightly to reduce the weight carried by the PTFE pads.

4) Wipe the surfaces clean.

Update: Took the bearing plate off. Clear signs that the bolts were dragging slightly. Tightened them up (although they were already fairly tight). Cleaned up the surfaces. Added a thin shim over the centre bearing. I did try a CD as recommended elsewhere but it was too thick. Staples in ptfe pads were already recessed properly. Now reasonably smooth - can't expect miracles from such a simple system. If not much good, I will look to installing a lazy susan bearing.

[LDW1]

3 hours ago, Richard N said:

Update: Took the bearing plate off. Clear signs that the bolts were dragging slightly. Tightened them up (although they were already fairly tight). Cleaned up the surfaces. Added a thin shim over the centre bearing. I did try a CD as recommended elsewhere but it was too thick. Staples in ptfe pads were already recessed properly. Now reasonably smooth - can't expect miracles from such a simple system. If not much good, I will look to installing a lazy susan bearing.

Research lazy susan's they have their own issues. Do you really think your conern is that rare, it may be just the nature of the beast and with maybe a bit of perfectionism thrown in and with some inexperience expecting too much.

Edited August 19, 2023 by LDW1

[Richard N]

8 minutes ago, LDW1 said:

Research lazy susan's they have their own issues. Do you really think your conern is that rare, it may be just the nature of the beast and with maybe a bit of perfectionism thrown in and with some inexperience expecting too much.

All fair points. I want it to be working as the designers intended. It’s my first dob so inexperience and perfectionism certainly come into play. I think it’s as good as it can be now based on its very simple design. I suspect there is some learning to be done in pointing it accurately - a little like learning to play a musical instrument. Thanks for the warning on Lazy Susans. 

[LDW1]

3 hours ago, Richard N said:

All fair points. I want it to be working as the designers intended. It’s my first dob so inexperience and perfectionism certainly come into play. I think it’s as good as it can be now based on its very simple design. I suspect there is some learning to be done in pointing it accurately - a little like learning to play a musical instrument. Thanks for the warning on Lazy Susans. 

Many used to call that sticking ' sticktion ', my 3 SW Dobs were like that, I just lived with it, lol !

[Spile]

I’ve used a Dobsonian that didn’t have enough friction and I was glad to get back to my 200P.