diy bearing idea

[graeme uk]

hello all, new to this forum so first off hi!

secondly, ive been thinking of making a tt, and have been thinking about bearings.

Am i right in saying that the main problem with making a usual type bearing is the tight tollerence of machining needed between the center pole and the outer bush?

I was thinking about how to get it machined, and though about getting an engine shop to do it.

Then i realised, these parts already exist.
Has anyone tried using a valve from a cars head? These are very strong and very acurately made/machined with a very smooth finisg. If this was used, with the thin end machined to support the bearing and the wide end welded to a base to fix to the plinth, the bronze bush thats pressed into the head, the valve guide, can be used as the outer tube.
These two parts are already very free moving but very well fitting. After all a valve needs to freely move up and down with no sideways movement.

Does this make sense? im new to all this so im not sure how to describe things in ways you wil understand.
Has it been done before?
I probably wont be able to try this idea out for quite a while as im too busy, but thought i'd share the idea now.

[poobah]

A valve bushing is pressed into the cylinder head... becoming smaller in the process.

The bushing is then machined for a loose fit to the valve about 0.002-0.004" (0.05 - 0.1mm) this is to allow room for the valve to expand with temperature (more for exhaust valves).

A valve could make a good spindle provided the clearance to the bushing was greatly reduced... say 0.0006 - 0.0008 inches. Oil film will consume the gap and provide a tight yet smooth bearing.

You can purchase shaft, bushing and hubs though... not so expensive.

[graeme uk]

hmmm, thanx. More play in them than i though. I suppose all other parts will be the same. I was thinking of ways to use the center pin in the piston and the small end bearing, or cam shaft bearings, but they will all have larger clearences to allow for expansion.
Back to the drawing board for the easilt made, cheap DIY sollution.

[poobah]

Actually wrist pins & connecting rods have the right clearence (when new). Designed for high pressure (small clearance) and equal temperatures.

[Paul Dimaline]

Has anyone ever tried to make a Well Tempered bearing? Although by no means "easy" the more I look at it the more I think it could be done with a half decent pillar drill.

[graeme uk]

wrist pins hey, ill look into it. Ive got access to loads of engine/car parts.
The other thing i was thinking is car wiper spindles.
On 60's beetles you have the assembaly that bolts to the windscreen scuttle and a spindle that runs through it.
When there new there is no play at all, but they spin freely.
I just chucked two out so cant look into that, however theres loads of jags over my friends workshop, they may yield something.
There must be options in automotive parts. You can get different size bearing shells for when you re-grind cams/cranks so you could make up and clearence you like. And they have oil ways to keep em lubed up.
Just a matter of finding ones of a suitable diameter to reduce drag and a long enough length to support properly.
I was thinking of looking into flywheel platters, and crankshaft journals but this is getting seriously too heavy duty
would look nice and industrial though.

[poobah]

you know... an entire engine standing on its nose with an LP on the flywheel and a tone arm would look d4mn cool though...

[graeme uk]

sure would. Use a beetle engine and you could still carry it around.
Who needs a electric motor, just run the engine. Might spin it a bit fast though.
I am sure theres something in the automitive world that will work, just not sure what yet.
I have access to a metal lathe anyway, so ill sort something.

[poobah]

You know... you could even put a strobe on the ring gear teeth.

I would not use the real crank bearings... or crank. a smlle shaft would have less friction... but it would look cool.

[Pjotr]

Originally posted by graeme uk
sure would. Use a beetle engine and you could still carry it around.
Who needs a electric motor, just run the engine. Might spin it a bit fast though.
I am sure theres something in the automitive world that will work, just not sure what yet.
I have access to a metal lathe anyway, so ill sort something.

Does me think of the Lirpa’s steam turntable If you Google around on it you will find some interesting reviews.