Ultra Simple Dob Azimuth Bearing Upgrade No Machining No Drilling

[Polar Bear]

This is the first mod to my newly acquired 250px.

The teflon pad bearings on the mount are quite simply atrocious for a scope that costs over £400.00 new. 

Simple solutions are on hand though. Enter the B-Tech BT540 Television Turntable.

These were available on Astroboot for a while and Amazon UK but they are currently out of stock.

I am sure other brands of a very similar nature are available.

This is a 16" bearing with a 75KG load bearing capacity.

1. Remove the dob mount pivot bolt and remove the teflon pads.

2. Remove the sticker centre from the turntable and push out the 2 part fixing so it comes apart. On checking the innards it is quite well made with steel bearings running in 3 channels.

    The centre hole is the same diameter as the pivot bolt so no machining is necessary.

    Put the unit back together, you can apply a little contact adhesive to the outer edge, this will aid assembly later.

3. Cut in half the dob mount centre bush. For ease of assembly I glued each half back into the woodwork with some contact adhesive.

4. Obtain a replacement centre pivot bolt that is 30mm longer than the original.

    Should anyone need one to try this mod let me have your address and I will pop one in the post to you. I only have 3 so it is on a first come basis.

5. Line everything up and reassemble with the new pivot bolt.

Total build time about 20 minutes including waiting for the glue to dry and a 10 minute trip to my local nut and bolt shop.

Mount is totally transformed, smooth and stable.

No machining required whatsoever ..... simples

[knobby]

Nicely done ! ... Is it too smooth now though

[Polar Bear]

Nicely done ! ... Is it too smooth now though

Lets just say it is very smooth.... needs to be tested in the outdoors yet.

I have a quick fix in mind if some resistance is required

[Kropster]

Is this smoother than the usual 'lazy suzan' ball-race style bearing mod?

Being plastic, I think it may prove less robust than steel in the long run.

[Polar Bear]

Is this smoother than the usual 'lazy suzan' ball-race style bearing mod?

Being plastic, I think it may prove less robust than steel in the long run.

The plastic is quite hard and one advantage is no corrosion. It is very smooth and I think it will last some time, especially considering our average weather. 

I have however upgraded to a Skytee 2. Although the base was improved I was still unhappy with it in the Altitude.  http://stargazerslounge.com/topic/232141-de-dobbing-a-250px-and-upgrading/