Hello,
I'm looking for a bearing with approx 8-10" i.d., like a slewing ring with mounting holes, except for light loads. There's no more than a dozen or so pounds of load in any direction and never above ~200 rpm. It must be low and uniform friction, and positional accuracy can be ~
0.002" Googling for slewing rings or turntable bearings turns up bearings too massive for the app. Hope there are existing bearings that approximate this.Ben
There's plenty available in light cross section, but I'm not aware of any with mounting holes as a standard.
Kaydon Reali-Slim:
Ned Simmons
google for "lazy susan"
Ned Simmons wrote in news: snipped-for-privacy@news.suscom-maine.net:
I can't mount such a bearing. Who can make it into a slewing ring? In the Kaydon catalog a 10" bore X-type bearing with 1/4 x 1/4 cross section seems like it would suffice, provided it was unsealed and had the proper spacers for low friction, but it needs to be mounted. Another consideration is what would one of these beasts cost mounted? They also describe a slewing ring of plastic balls and aluminum races but couldn't find specs.
Ben
Kaydon will do specials -- for a (likely hefty) price. If all you need is a bolted flange mount for the bearing an aluminum housing could be machined to do the job. Depending on size and complexity, $300-400 is my SWAG for the cost of such a piece.
Ned Simmons
Ned Simmons wrote in news: snipped-for-privacy@news.suscom-maine.net:
Out of curiosity I bought a lazy susan bearing.
I have to stop thinking "slewing ring". I asked a Kaydon engineer (he probably thought I was some guy with more money than brains) to suggest a slewing ring for no more than a dozen pounds in any direction and 10" i.d. So he goes on to recommend an MTO-265 10.4 i.d. (great - the i.d. is right) and is over 16" o.d. for $1946.00. Weighs 54lbs, couldn't make it to 200 rpm, and has a moment load rating of 62000 ft.lbs. Why they even bother. And their aluminum ones are military only. Now I get the idea; slewing very heavy things slowly.
An in stock 12" reali-slim has 55 in-oz starting torque. That's too much. I think it'll have to be something custom, but will have to wait for that. Perhaps something with far less balls; the 12" has
196 and tighter clearances than I need. I just need a bearing that's a step up from a lazy susan.Ben
Is it entirely unfeasible to have one made? I work in a machine shop, and all you'd need is a mill with a rotary table. Cut a groove in a couple of pieces, throw in some plastic balls, and voila!
Good Luck! Rich
"Rich Grise" wrote in news:cUYGc.27203$ snipped-for-privacy@nwrddc03.gnilink.net:
That's precisely what I was thinking of. The bearing won't have much of a load, so, if you put in say, ball separators for 40 balls, I think it would reduce friction, or at least keep torque constant. What would be used for separators?
I'm not familiar with mill capabilities. Wouldn't a lathe produce a better, more accurate finish (in 6061 for example) for the ball grooves?
The odd thing about the lazy susan bearing is that since it's a two piece bearing, they put the balls in by removing a screw plug on the side. The grooves were machined with the plug in place, which requires the plug to be in exactly the correct position, or it interferes with the balls. I was going to replace the steel balls with Delrin, but that plug there would eventually tear them up.
Ben
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