Help with bearings

"mlcorson" wrote: (clip) Also, found items seldom match up perfectly, all complicated by the fact exact measurements are seldom known. How would I go about this? (clip) ^^^^^^^^^^^^^^^ If you want to minimize your cost by using "found" components, I suggest you look for pld motors, fans and the like--and incorporate them in the design of your sculpture. Bearings have to fit, which usually will involve some machining, which it seems you can't do.

I dunno, he said he has a minilathe and a minimill.

Don't overlook inline skate bearings. Good low-friction, small, sealed and cheap.

I agree with "adapt" but until you get into large sizes motor end-housings tend to be die cast alloy: impossible or at best tricky to weld. However automotive structures are more commonly steel and therefore weldable. You might think about wheel hubs, prop shafts, the ball joints on steering links. Also there are two basic sorts of "bearing": plain, and anti-friction or rolling element (i.e. ball or roller bearings). For plain bearings, bronzes were the traditional material, or greased cast iron if the sliding distance isn't too great. But all sorts of common plastics are good, e.g. polythene or nylon; they don't necessarily need lubrication, but they won't take high load or high speed (especially at the same time). You might find the sort of thing you are describing in a car steering column. Ball bearing assemblies will give lower friction and take higher load, but may need some lubrication and may jam up from getting rusty. It all depends on the application. It is possible to weld to ball bearings, but the weld may not be strong and the bearing will distort and lose its original hardness, at least locally. Another thought, the bottom bracket of a bicyle frame contains (removable) ball bearing assemblies. You could hack off the tubing as you see fit and weld to that.

Leo, Yes, cost can be a concern, but what I wanted to say is that virgin materials make more sense in this situation. Otherwise, I'd end up with sculptures made of fan blades, and motor bearings and drive shafts....not exactly what I wanted to do all the time. Not a bad suggestion as a possible solution though. Also, yes, I am a novice on the lathe and mini mill, but I can use them and I am willing to learn whatever it takes to mount bearings and have them work in my projects. All part of the learning curve. Fun too!

-Mike

look for pld motors, fans and the like--and incorporate them in the design of your sculpture. Bearings have to fit, which usually will involve some machining, which it seems you can't do.

Indeed. and they will hold a surprisingly large amount of side load. And very cheap on ebay and in surplus places.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

"mlcorson" wrote: (clip) I am a novice on the lathe and mini mill, but I can use them and I am willing to learn whatever it takes to mount bearings and have them work in my projects. All part of the learning curve. Fun too! ^^^^^^^^^^^^^^^^^ Sorry, Mike, I overlooked the last part of your original post, where you mention machine tools. And, I think you SHOULD use your lathe and mill just because they are there. To mount a ball bearing, the outer race should be a light press fit into a machined recess, and the inner race should be a light press fit onto the shaft. If you make it too loose, it will slip--you can correct that with Loc-tite. If you make it too tight, you'll have trouble with assembly, and you may disturb the beasring clearances enough to make them roll rough.

As some others have mentioned, roller blade wheels have excellent bearings. I have several of them in use, which came from junky shoes from flea markets.

Another possible bearing source: remember when every workbench had a belt-driven grinder/wire brush? Those arbor-shaft assemblies are still knocking around.

Not knowing the sizes or weights of your projects it is hard to advise you on the type of bearings you may need. Go to

then click on "Products" in the upper right hand side of the page. Toward the bottom of the page click on "General Bearing Knowledge Base". There you will find information on all types of bearings including mounted units (which don't require machining to mount). If your loads and speeds are moderate (60 RPM for example) you might try UHMW or Nylon - both of which can be machined and which are available in pillow block style. Once you have a better idea of available styles and capabilities come back with any questions you might have. Good luck.

You can probably cheat to a degree on your bearing "fit" by using a pillow block style bearing that uses set screws to hold the shaft. You will get run out anywhere from a little to a lot depending on how loose the shaft fits but for a moving sculpture you can cheat a lot by just wrapping some sort of shim around the shaft.

JohnF

Try alternator bearings from the local auto junk yard