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Movable Positive


Chris Woollard

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My house organ has a positive division measuring approximately 2m wide by 1m deep by 1.4m high.

It comprises a heavy outer case containing display pipes which are connected by conveyances to the wind chest, upon which the remaining pipes stand internally. The wind chest is not directly connected to the outer case but simply sits within it. The positive is positioned against a wall which makes direct access for tuning from the rear impossible. The action is direct electric to a slider chest. It has its own small blower installed within the case.

 

Does anyone know of a roller system which could take the considerable weight of this assembly and make possible movement at least 18" or so forwards so that tuning from the rear becomes possible. Raising the height a few inches would not matter at all.

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Without knowing something more about the weight in numerical terms, I can't really help. However bear in mind that there is often a consequential problem about using rollers/castors, even if you can find items which will be man enough for the job. They usually result in a considerable reduction in the total area in contact with the floor, and thus a considerable increase in pressure under the rollers (because pressure equals total weight divided by total surface area in contact with the floor). Depending on their construction, this can therefore ruin floors. It can also cause potentially serious structural problems if the weight (redistributed by the rollers) becomes focused on just one or two joists, compared to the situation without rollers when it might have been more evenly spread across several of them.

 

Sorry to be a Jeremiah but I have come across these sorts of problems before.

 

CEP

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Yes, there shouldn't be any weight distribution problem with a concrete floor in a structural sense. If it's covered with parquet-type material the rollers could cause havoc with that though as the organ is dragged back and forth - just because of the pressure as I outlined above. As to the type of rollers to use, you might look at so-called 'piano rollers' or 'piano dollies' as used by specialist furniture removers. They can be obtained quite easily. I've seen the underside of a moveable plinth which bore the weight of a huge 4 manual detached console in a cathedral and it incorporated several of these. Rubber tyred ones are probably best to minimise floor damage.

 

CEP

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I have managed to source eight very heavy duty fixed castors (using roller bearings) easily capable of carrying the load so I am going to construct a thick plywood trolly base using these. Delignit is available readily at this size but that is probably going overboard. I also have to make two smaller and lighter trolleys to hold two concert grand actions the primary requirement being an absolutely level bed - but that is another story.

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  • 1 month later...

I have a player piano which is heavy (probably c1/4 tonne or so) & a new natural oak engineered floor floating on insulating underlay. This is not a good combination for metal rollers to stand or move on. I have fitted 6 compo. castors supplied by our tuner. 4 where the original castors were & 2 further ones along the back of the frame. This distribution prevents damage or floor 'creep' when the piano is moved.

 

Bear in mind they will raise the load by about 1/2 - 2/3 the height of the original metal rollers. Fit as many as you need to the load all at the same level but make sure there are strong handling point on the organ frame. You will also need two people to move the instrument as having multiple wheels does not make it easy to 'aim'!

 

There is at least one specialist piano castor supplier with a wide range on the web.

 

Jeff D

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Jeff,

I have completed the job now and everything has worked out fine.

Using very substantial castors plus the heavy plywood base has certainly worked. It was a two person job of course and I am pleased to get it over with just before I retire rather than waiting any longer. Fortunately my floor is concrete and poses no flexing problems at all. The organ was dismantled for the move onto the platform, there being no safe way to simply raise it. It moves very smoothly.

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