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Bearings

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hughie:


Its around if you really want it.
http://www.lignum-vitae.com/Products_Hydro-Bearings.html
http://www.exotichardwoods.co.uk/Woods_List/Lignum_Vitae-PaloSantowood.asp

BarryMobbs:
Hello,
 I have made the bearing bushes as you will see from the attached picture.
There are two bushes for each housing.
Each bush has a groove on the outside diameter for a location rib and a hole to locate on the grease nipple bush.
I used elm in the end because I have some and the machine will not be expected to do any real work so wear is not too much of an issue.
Presumably when the elm gets wet it will swell up and make for a tighter fit on the shaft. If the bushes were soaked in oil befor fitting would this help to keep water out or would it cause the elm to swell anyhow?
   Barry

Bryan Milham:
Interesting job you had there. Did you take any 'In Progress' pictures for us? I'd be interested in seeing how you made them.

Another use I remember for Elm was the making of coffins, as it resist rotting in 'damp' environments.

To throw my 2 pence worth in to answer your questions, All wood swells when it absorbs moisture so yes it will tighten on the shaft but by how much I don't know - I've seen an article on wood absorption etc if I can find it I'll post it.

By oil I presume you are talking about motor (mineral) type oils not our highly refined Danish Oils full of drying agents etc.

Again any moisture that enters the wood will cause swelling, but if it was oil I would assume that yes it would repel water/moisture to quite a high degree and also provide a lower friction, load bearing surface if the wood swells just that little too much. For Wagon Wheels I think Tallow (animal fat) was used.

BrianH:
Another bit of off thread but (perhaps) interesting trivia from that Dutch sawmill article was that the main shaft bearing was made of stone ...yes stone... and looked like the bottom half of the ones Barry has pictured above. This bearing had apparently worked fine for about 300 years until the mill went out of use about the 1980's.
At the planning stage of the restoration one of the major oil companies became involved and formulated a super duper special lubricant for the job.
When sawing work restarted at t'mill it was found that the bearings and shaft were running hot. After much head scratching by all all involved a local butcher mentioned that the original miller had had a standing order for a certain fatty part of a cow (perhaps sheep, perhaps pig). The oil company walked away in disgust when the stone bearings were smothered in this rancid fat and began to run as sweet as you like. Inside the mill cap it now smells like an abatoir but I know where there are two drums of very expensive, specially formulated stone-bearing oil if anyone is interested.............
Merry Christmas everyone
Brian

admalin:
Hi Barry

You still haven't told us what sort of machine the bearings are for. Having been involved in rotating machines from 1/4 hp motors to 300 MW generators, I'm curious.

Tony Malin

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