Classic 200p dob

[CHRlS]

Hi,

I know this has been debated quite a lot over the years, but the reading I've done seems to be inconclusive with some saying something works whilst other saying something else works and none of them work and so on and so forth.

What I'm talking about is how stiff the azimuth direction is on the dobsonian base. Whilst observing at high magnification, it is all but to easy to nudge the target out of the field of view.

If you have one, what has worked for you?

Thanks.

[Spile]

It’s not been a problem for me. The degree of friction is just right on both bearings and I’ve not needed to lubricate either.

[John]

I have owned 2 of these but at least 10 years apart !

I picked up the latest one a couple of months ago. It is the 200P Classic model pretty much unused.

I was expecting some stickyness (for want of a better term) on the azimuth axis and when I first lighted the scope, it was there. The scope was useable but frustrating at high power because it was all to easy to apply too much push in azimuth to get it moving, overshoot the target, then do the same coming back the other way !

I tried different tensions on the central nut and bolt but that didn't really help. I then reminded myself of the old "milk carton washer" modification that I had used all those years back with my other 200P dob. 

For this new scope I found that adding a single large washer (about 100mm in diameter and with a 12mm hole in the centre for the bolt) made a noticeable difference in reducing the "sticktion" to a low and acceptable (for me) level while retaining stability in the mount base. I put my milk carton washer between the bottom board and the stock white teflon washer. I then bolted the mount base back together and applied enough torque to the central locking nut to hold things together in a stable manner. 

I think the way this works is that the additional thickness of the DIY washer takes a little of the weight off the 3 teflon pads that are used as the azimuth bearing. Some people find more than one DIY washer is needed but in my case one did the trick. 

I realise that other people use lazy susan type bearings and other approaches and those undoubtedly work for them. Different people have different preferences for ease of movement etc so this is why there is not 100% agreement on the best approach. People find what works for them 🙂

I have found the milk carton washer modification has worked for me 3 times now - I also owned a 10 inch Skywatcher dob a few years back and did the same thing on that - 2 washers needed with that one I recall.  

I have also owned dobs with lazy susan type bearings as standard and those needed some friction adding to the motion to get it to suit my tastes. 

 

 

 

Edited November 15, 2023 by John

[Carbon Brush]

I have used a few of the 'chipboard' type dob mounts. They always benefit from a bit of care.
These mounts are made in quantity to a loose spec. With any luck tension adjustment only gives a good enough result.
On a used scope, dismantle the base (a couple of spanners) and give it a clean up. Then reassemble with a very little bit of Mr Sheen type spray, or silicon grease, or petroleum jelly.
I have been amazed at how much muck can accumulate in there and been pleased with the improvement after cleaning.
The milk carton washer mentioned by @john is another good mod.
 

[niallk]

For my 250px, the stock base was fine in azimuth (I did adjust the tension in the central bolt).  For me alt axis was more troublesome!!

[CHRlS]

18 hours ago, John said:

I have owned 2 of these but at least 10 years apart !

I picked up the latest one a couple of months ago. It is the 200P Classic model pretty much unused.

I was expecting some stickyness (for want of a better term) on the azimuth axis and when I first lighted the scope, it was there. The scope was useable but frustrating at high power because it was all to easy to apply too much push in azimuth to get it moving, overshoot the target, then do the same coming back the other way !

I tried different tensions on the central nut and bolt but that didn't really help. I then reminded myself of the old "milk carton washer" modification that I had used all those years back with my other 200P dob. 

For this new scope I found that adding a single large washer (about 100mm in diameter and with a 12mm hole in the centre for the bolt) made a noticeable difference in reducing the "sticktion" to a low and acceptable (for me) level while retaining stability in the mount base. I put my milk carton washer between the bottom board and the stock white teflon washer. I then bolted the mount base back together and applied enough torque to the central locking nut to hold things together in a stable manner. 

I think the way this works is that the additional thickness of the DIY washer takes a little of the weight off the 3 teflon pads that are used as the azimuth bearing. Some people find more than one DIY washer is needed but in my case one did the trick. 

I realise that other people use lazy susan type bearings and other approaches and those undoubtedly work for them. Different people have different preferences for ease of movement etc so this is why there is not 100% agreement on the best approach. People find what works for them 🙂

I have found the milk carton washer modification has worked for me 3 times now - I also owned a 10 inch Skywatcher dob a few years back and did the same thing on that - 2 washers needed with that one I recall.  

I have also owned dobs with lazy susan type bearings as standard and those needed some friction adding to the motion to get it to suit my tastes. 

 

 

 

I was thinking more than likely going down the milk carton washer route, well start off with that anyway as it's the cheapest! Do you know the thickness of the washer you added?

[CHRlS]

18 hours ago, Carbon Brush said:

I have used a few of the 'chipboard' type dob mounts. They always benefit from a bit of care.
These mounts are made in quantity to a loose spec. With any luck tension adjustment only gives a good enough result.
On a used scope, dismantle the base (a couple of spanners) and give it a clean up. Then reassemble with a very little bit of Mr Sheen type spray, or silicon grease, or petroleum jelly.
I have been amazed at how much muck can accumulate in there and been pleased with the improvement after cleaning.
The milk carton washer mentioned by @john is another good mod.
 

I guess cleaning it and lubricating is the first thing to do and add a milk carton washer whilst it's unassembled.

[doublevodka]

How about https://www.firstlightoptics.com/misc/stellalyra-roller-bearing-for-dobsonian-telescopes-8-to-16-aperture.html

I've not used one myself, but the Stellalyra dob owners seem pretty happy so I'd imagine it's pretty good 🤷‍♂️

[John]

54 minutes ago, CHRlS said:

I was thinking more than likely going down the milk carton washer route, well start off with that anyway as it's the cheapest! Do you know the thickness of the washer you added?

The thickness of a Sainsbury's 4 pint plastic milk carton 🙂

 

[CHRlS]

2 hours ago, doublevodka said:

How about https://www.firstlightoptics.com/misc/stellalyra-roller-bearing-for-dobsonian-telescopes-8-to-16-aperture.html

I've not used one myself, but the Stellalyra dob owners seem pretty happy so I'd imagine it's pretty good 🤷‍♂️

It has good reviews on flo.

[CHRlS]

1 hour ago, John said:

The thickness of a Sainsbury's 4 pint plastic milk carton 🙂

 

For some reason I was thinking you meant a 100mm metal washer