Wobbly dob

[beamer3.6m]

I have built a dob base which works very well in alt. Finger smooth and enough stiction.

The azimuth is however not playing ball.

I have glued a 12" vinyl record to the bottom of the rocker box and then added furniture pads to the base board which run against the vinyl.

The problem I have is that the record and the felt pads have created a wobbly.

My base board is square so maybe this is the reason as I have a good 6" beyond the edge of the vinyl record all round.

How do I cure the wobble.

I added more felt pads further out but this reduced it but not fully.

Confused.

[knobby]

Define wobbly ... Start stop movement, side to side movement, rocking ... ?

[beamer3.6m]

I would define it as rocking but in all directions.

[Scott]

I would have thought there is too much give in felt. teflon pads in my opinion would be a better option. can we see some pick please for a better idea?

[knobby]

http://www.amazon.co.uk/Medipaq%C2%AE-Slide-Glides-Pack-Ultra-Low-Friction/dp/B002NQ7FJI

Something like this

[beamer3.6m]

Thanks knobby will gives a try. Saw some in local wilco

[Paladin]

"I added more felt pads further out but this reduced it but not fully".

Beamer, I suggest that you use only 3 pads placed as far apart as possible to get a rigid mount.  The classic dob design always uses 3 as any more will always cause rocking.

Paul

[Moonshane]

what Paul said.

[beamer3.6m]

"I added more felt pads further out but this reduced it but not fully".

Beamer, I suggest that you use only 3 pads placed as far apart as possible to get a rigid mount. The classic dob design always uses 3 as any more will always cause rocking.

Paul

Can I ask why 3 will reduce wobble when more will increase it. This seems counter intuitive?

[beamer3.6m]

Also are they best placed near the centre of the vinyl record or the outside.

I assume outside but again this could be counter intuitive.

[knobby]

Can I ask why 3 will reduce wobble when more will increase it. This seems counter intuitive?

3 will always balance ( picture a tripod) more than 3 will possibly not balance (imagine a wobbly table or chair )

[beamer3.6m]

Thanks guys.

3 it is. Time to remove some... Or 5!

[beamer3.6m]

Well I fixed it.

It was not the pads but the thin particle board I had used for the base.

Proper wood now used and still 6 pads

Vibration damping is about 2seconds but I am pleased with the result for less than £25.