DIY parallelogram mount - azimuth bearing help…?

[Big Ian 65]

Hi everyone, following up on an idea I saw on binocularsky.com, I purchased a Neewer camera crane from Amazon, which I have mounted via a homemade azimuth bearing to a surveyors tripod. Once balanced with my 20x80 Celestron Bins, the system is quite stable with a reasonably quick settling time. However, my azimuth bearing, which is based on a lazy Susan bearing (well over rated) is far too free moving, and literally continues rotating for ages, making the assembly pretty useless… As a temporary solution, I have used wood working clamps to secure the upper and lower square plates, with some success, however this is a poor long term solution, and is not great. 
Do any of you have any ideas on how I can either a. Increase the bearing friction to slug the azimuth movement, or b. Fit some kind of mechanical locking system, or slo mo apparatus?

please see attached photos showing my current setup…

I have considered the following so far, but have not finalised on a solution. 

1. Find a sticky grease of some kind to slug the bearing.

2. Drill and tap the top bearing plate, and fit a knurled hand screw to introduce a mechanical friction source (may need two screws to balance the twisting moment)

I would appreciate any input, especially simple and cheap options… 😉

Thanks in advance for your advice!

[skybadger]

My first idea is to put a thrust washer bearing on the central bolt to increase the pressure between plates while still allowing rotation. Those lazy Susan bearings are quite loose. There's another type I used for my son base which are more massively constructed. I got mine from eBay, they run smooth not not free. 

Really like the idea though. 

Where do I get a tripod like that ?

[Peter Drew]

I had a similar problem with a Dob base that had a LS bearing.  I put a sponge in the centre of the bearing which was then crushed on reassembling the base and created enough friction to control the movement.     🙂

[Big Ian 65]

Thanks for the replies guys, fyi the tripod is a Leica surveyors tripod - it was an eBay special… I think it was about £30.

Unfortunately the central thrust washer idea won’t work, as the tripod bowl adapter fastens centrally to the bottom plate. The squashed sponge may work though.

[RobinH]

The sponge is a easy and cheap fix to try .  My diy P-mount uses a  typical Dob AZ pivot with 3 teflon pads riding on a plastic surface.  It did move too easily but  tightening the central bolt fixed it. I suppose with a lazy susan there is not an equivalent bolt to tighten. 

I found that the azimuth pivot can benefit from quite a lot of friction as the arm gives lots of leverage to move to position.

I have used a very similar surveyors tripod for my P-mount and added 2mm stainless wire ropes between the legs. This stops the legs splaying out when on flat concrete, but also folds up when the tripod is folded up for storage. 

Robin

[AstroKeith]

In the corners of your base plate you have space to add an adjustable brake. The 'shoe' should be curved, the height of the LS but with flat or leather etc only on the top half (so it contacts the upper LS bearing half)

Then a simple adjustable screw to push the shoe on to the bearing edge.

[Big Ian 65]

Robin, thanks for the reply, I will definitely add some wire ropes to the surveyors tripod.

AstroKeith, I think your idea is the solution I was looking for, I have some old bicycle brake pads which may do the job with a little profiling… thanks for your input 👍

[fwm891]

Brushes fitted inside the L S would act similarly to foam (toothbrush’s come to mind) 

[Merkhet]

A bit late in the day, but I have only just found this topic.

I use small amounts of Damping Grease on microscope sliding parts and camera helicoid focussing threads.

It may possibly work on the Lazy Susan ball bearing plate. Definitely works where two flat surfaces or two mating curved surfaces are in contact with each other.

I got mine from a company famous for oils and greases.  Nye  Oil.

Sold in various grades.  So you need to do some research.

Made to slow down movement between surfaces.