Vibration Isolation / Support for Glass

Good point about the gaffa tape.

I meant it only for the nitride balls long term, not for the impact zone of creating the dent.

But thinking about it it would also probably turn into a nasty gluey mess after a few years.

The manufacturing process sounds a bit more tricky than I thought.

How about drilling a hole in a circle of wood of suitable thickness and diameter to fit into the brass cup - then giving it a good whack with a hammer?

Would that tend to deform the flat base so as to render it wobbly/unstable?

Or worth a try?

I agree with @IDAK thank you for sharing and if only I was handy I’d be on to it like a rat up drain pipe.

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Written like a true Aussie!

(OK, that’s not so surprising is it! :grin:)

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That should work, but to ensure centring you need to make sure the hammer strikes completely perpendicular and with the face of the hammer parallel to the surface on which the brass rests.

Yes it will deform the base enough to make it rattle; but grinding it flat again is easy (320 or 600 grade wet or dry paper used wet, supported on a flat glass plate).

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I can’t envisage how to grind the base of the brass cup flat by sanding it wet ‘supported on a flat glass plate’?

Easy, get a sheet of 'Wet or Dry" paper - i.e. a silicon carbide abrasive paper ( ‘grey sandpaper’ ) designed to be used either wet or dry. Cut a piece about 75mm wide by about 100mm length, wet it and hold it on top of the glass plate. Take the brass cup in the other hand and, pressing in the middle of the brass cup, using circular movements, rub its bottom on the wet or dry paper until it’s flat again. Rinse the abrasive paper in water and repeat for the next brass cup.

Make sure it’s its bottom you rub on the abrasive paper, not your own!

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Thank you so much for all this advice, Xanthe.

I really like the idea of trying this, but will have to fit it in with everything else.

All the best
Jim

I also agree with @IDAK. Thank you!

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I do also agree with @IDAK.

@Xanthe Thank’s sharing your time and expertise :smiley:

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Hi Xanthe

10 x 14.288mm (9/16") G5 Silicon Nitride (Si3N4) Ceramic Bearing Balls from Empire.rc (HK) are £62.

10 x 15mm Brass Cup Core Plug are £19.20 from Core Plugs International.

But the internal diameter of these plugs is only 12.6mm up to a height of 6.09mm.

Would this size ball touch the wall of the brass plug, or miss it?

And do you think the wall of the plug would keep the ball in place under normal use (along with the dent in the centre of the base of the plug)?

There’s a problem with those. The base thickness is just 1.15mm, that doesn’t allow much room for forming an indent on the bottom. The type of brass stop end for water fittings that I used are probably better.than core plugs as they are about 3mm thick at the base.

For a 14.3mm silicon nitride ball, I’d suggest using a 20mm to 25mm ball bearing (steel) to form the indent.

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To decide where to position the 3 balls under each glass, did you hold the Naim box underneath and tilt it to test where the weight is distributed within it, then put the points in a configuration that is likley to stabilize that?

And perhaps look at a photo of what’s in the box too, to see where the heavy components are?

e.g. if a transformer is in one corner, put a ball close by or directly under it?

I took indication from the position of the supports for the Fraim glass!

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If anyone has any experience of vendors of any of the following items, please let us know.
(e.g. specific sellers within t’bay, as one can get lost trying to work out which one is best):

  • brass stop end for water fittings

  • 10mm toughened glass sheets cut to size

  • silicon nitride balls

  • steel ball bearing

This is common practice on the forum on some other threads, so it seems to be within the rules.

thanks
Jim

Brass stop ends
Fleabay: plumbpartsglasgow or wwltd7779

Silicon nitride balls
Fleabay: mcr-spares-online

Steel ball bearings
Fleabay: ramparama or bearingwarehouseltd

Toughened glass: It’s usually best to source this locally as transport costs are often very high.

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Thanks Xanthe
You have a been brilliant and very generous with your time and ideas on this thread.
Cheers
Jim

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But how can one know what the toughening process was unless there’s a factory that does it nearby?

It’s covered by a British Standard.

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Would that normally be stamped into the glass?
Or just guaranteed by a good seller?

Yes.

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