Another Bearing ??

[uute]

Going back to the original senario, is there a plane bearing that would survive w/o pressurised oil? How hard would the shaft have to be?

1 5/8" at 2100 is under 900 fpm, fed with an oil cup, guess that doesn't leave much for cutting forces on 50-70kpv bronze.

just trying to think it through, maybe learn somthin

[uute]

Been reading the recent bearing posts, seen what Evan posted for Snowman about the superfinised shafts for high speed.

Had planed a mill spindle w/ 1 5/8" shaft of 303 stainless in sintered bronze bearings. Top speed is 2100 RPM. Am I looking at trouble?

Shaft would be just filed & polised w/ 400/600 grt sandpaper. Not heat treated. At those speeds, shouldn't be running anything but a small endmill or drill.

Space constraints lead me away from tapered rollers.

uute

[Millman]

4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

------------------
BFH

[Forrest Addy]

"...shaft of 303 stainless in sintered bronze bearings. Top speed is 2100 RPM. Am I looking at trouble?"

Yup.

Spindles should be pretty hard for wear resistance in the spindle taper (above Rc 50 in most commercial machines. 303 stainless is quite soft and malleable and has an unfortunate tendancy to "fret weld." You'd be much better off using a pre-heat treated medium carbon or alloy steel (Rc 35) for this application. It's more difficult to machine but it gives excellent finishes and better wear in a plain bearing.

Sintered bronze bearings in this size and RPM are not reccommented without pressure lube to transfer heat away from the bearing. If you're going to do that you might as well use bearing bronze. In mill spindles of the past they used bronze bearings scraped to fit with tapered journals and adjusted the diametral clearance by machining off the thrust face of the bearing to loosen it or the spindle thrust face to tighten.

[torker]

<font face="Verdana, Arial" size="2">Originally posted by Millman:
4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

</font>

Attaboy Millman! Nice answer to the guys question!
So who made you the "Grammar Nazi" around here? (You may want to check some of your own spelling in previous posts)
I see your giving others hell about using the search function also.
Is that because you don't know the answer...or you just want to see your name in print?
Russ

[mochinist]

<font face="Verdana, Arial" size="2">Originally posted by Millman:
4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

</font>

Seriously you have mental problems.




[This message has been edited by Neil (edited 03-03-2006).]

[Forrest Addy]

Please. Lets stick to shop problems not personalities.

[Evan]

Superfinished is the term South Bend used to describe the finish on the hardened and ground spindles they made for their lathes with plain bearings and the "high speed" option.

A highly polished spindle isn't a good idea. It needs a certain level of very fine roughness to hold an oil film on the surface. When you see specs for this kind of application they will usually specify a maximum and minimum surface finish roughness.

Millman,

I thought you were familiar with high precision machining. Superfinishing is a standard industry term, also called microfinishing. Try doing a Google on superfinishing.

Here, I'll save you the trouble:

Google superfinishing

[Wirecutter]

<font face="Verdana, Arial" size="2">Originally posted by Forrest Addy:
Please. Lets stick to shop problems not personalities.</font>

Second that - thanks, Forrest

[Carl]

<font face="Verdana, Arial" size="2">Originally posted by mochinist:

Originally posted by Millman:
4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

</font>

Seriously you have mental problems.

[This message has been edited by Neil (edited 03-03-2006).]