fixing fan to wall - inch thick rubber pad ?

[sm_jamieson]

I want to make a rubber / plywood sandwich to mount a fan on. 25mm each. Anyone know where I can get 25mm thick rubber, size about 150mm square ? Cheers, Simon.

[Frank Erskine]

This firm:-

A E Taylor

rubber sheet up to 1/2" thick you could sandwich two bits together. They may even have up to 1" thick if you contact them. They seem to have a vast range of stuff.

I've no connection with them except as a customer.

[newshound]

Do you know anyone with horses? Stables are often lined with heavy duty rubber matting about half an inch thick, sometimes dimpled or ribbed one side but that wouldn't matter. You might find someone has trimmed off a six inch strip to fit their box. (I have a couple of such strips myself, but they are used elsewhere). You'd need two thicknesses, of course.

[Frank Erskine]

No. I'm not after rubber sheet though... :-)

[sm_jamieson]

TBH I could get a rubber doormat from tesco and chop it up. They tend to be slightly cellular which could only help. Simon.

[Ronald Raygun]

to reduce the risk of electrocution, no doubt.

[Nightjar]

I used to buy large, thick, dense foam rubber in kits for lining instrument carrying cases from RS Components which contained two sheets about that thick, as well as one thinner one. I don't have the part number any more though.

Colin Bignell

[Dave Liquorice]

Prsumably to isloate any vibration? That is not quite as simple as it might first appear to be. Best isolation is achived only when the compliance of the softer material is "matched" with the applied static and dynamic loads.

"Matched" is difficult to explain but at the extremes something that is too "soft" will deform towards its elastic limit and become "solid". Something that is too hard won't deform enough and transfer the vibration like a solid.

You also need to ensure that any fixings don't "short circuit" the compliant layer.

[Tabby]

exactly. I tend to use tap washers for this sort of thing, and find them very effective, so I suspect an inch of rubber mat is both OTT and much too stiff, unless its a big industrial fan.

Yes. In practice I've found that just 2 tap washers and 2 metal washers on a PB screw do the job fine for extractor & ceiling fans, despite the apparent potential for this.

[Dave Liquorice]

I'd have thought tap washers too hard, at least the cheap plastic jobbies that the sheds seem to sell these days rather than good ole fashioned rubber ones. Even an old rubber one I'd have thought to hard.

But with the arrangement you suggest you aren't short circuiting the compliant layer, if you omitted one of the washers you would.

[Tabby]

The potential for short circuiting comes from the side of the screw, which is rigidly coupled to the wall, touching the fan casing. But even on wall fans it hasnt been a problem in practice.

Re the tap washers, bear in mind the amount of movement required is tiny. Assuming you dont have a blade broken off or something.

NT

[sm_jamieson]

I got some cheap rubber mats from halfords to cut up, but I've had a change of heart after reading the latests posts. I will mount a piece of OSB to the wall using the washer system, then so it again with fan against the board. 2 layers of isolation. Should be good. I'll take back the mats, or cut one and use a DIY rubber washer, although I suspect they are too hard. I'll find some soft rubber washers somewhere. Simon.

[sm_jamieson]

the screw and transfer vibrations though. Simon.

[sm_jamieson]

Well I've got some rubber fuel hose (8mm internal, 15mm external) to use around some 8mm frame fixings and the rubber / metal washer arrangement, to fix a piece of timber to the wall. Fan will be fixed to that. Sorted ! Cheers, Simon.

[Tabby]

Good, if its a very big heavy fan. I posted a reply, but it seems to have not shown up, ie that while the screw touching the case can in principle short circuit the damping, in practice its not happened.

NT