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pntrbl
01-04-2009, 10:04 PM
I've been digging on my own and think I know what's needed, but because I've never done this before I'd like to run it a flagpole and see if anybody shoots or salutes.

What I've got is a 16mm needle bearing from McMaster Carr, P/N 5905K58, that I need to fit to a shaft. The McMaster catalog has a bearing tolerance section that says for a 16mm shaft the clearance is +0.000, which surprised me. Shouldn't there be some allowance for expansion?

The minus is -0.011mm which I make out to be 4 tenths. :eek: I may be in trouble!

If I've got this wrong would someone please point out the error of my ways ....

Thanx.

SP

macona
01-04-2009, 10:27 PM
They make a slip on inner race for needle bearings. Can you modify to use one. You will have better life with a ground race.

pntrbl
01-04-2009, 10:37 PM
Yeah. I can cut it down for a sleeve. I was planning on polishing the last tenths but as always, I'm open for options ....

Let's see what I can find on Google.

Thanx Macona,

SP

beckley23
01-04-2009, 10:46 PM
You want a hardened surface for the needles to run on, you don't want to see what happens to a soft surface. Follow Macona's advice about the hardened inner race.
Harry

pntrbl
01-04-2009, 11:31 PM
The things I learn ....

I went ahead and did some polishing and was able to quickly verify that the section of shaft in question is in fact hardened. Well at least it's harder than the 1018 extension I welded on it. A couple of thou came off the 1018 just like I expected, but all the existing part did was get shiny!

A sleeve is the perfect solution. I think you guys saved me from another disaster.

SP

tiptop
01-04-2009, 11:43 PM
All the needle bearings I have installed had a hardened inner and outer race. I never measured clearances as they were new, but they run snug. If you are lying them up yourself, the general procedure I have used, was to stack them around the shaft w/sleeve in place and then take one out for clearance. Needle bearings if set up properly will handle quite a load. Jay

oldtiffie
01-05-2009, 03:23 AM
I've been digging on my own and think I know what's needed, but because I've never done this before I'd like to run it a flagpole and see if anybody shoots or salutes.

What I've got is a 16mm needle bearing from McMaster Carr, P/N 5905K58, that I need to fit to a shaft. The McMaster catalog has a bearing tolerance section that says for a 16mm shaft the clearance is +0.000, which surprised me. Shouldn't there be some allowance for expansion?

The minus is -0.011mm which I make out to be 4 tenths. :eek: I may be in trouble!

If I've got this wrong would someone please point out the error of my ways ....

Thanx.

SP

Well SP,

I checked the McMaster-Carr spec.

The shaft size is 16.000mm +0.000/-0.011. Your required shaft limits are 16.000/15.890mm. It does not say that there is zero clearance. My bet is that the bearing limits are about 16.003/16.005mm

The real tolerance you have - providing that you keep using the same shaft - which is a set/known size - is as follows:

Largest clearance = ((upper limit of bearing) - (lowest shaft limit)) - (1)

Least clearance = (( lower limit of bearing) - (largest limit of shaft)) - (2)

So, if you know the size of the bore (actual) of the bearing bore your limits for the shaft can be enlarged considerably over and above the limits in the Mc-M catalogue.

Anyway, even just using the catalogue figures you have 0.011mm (~0.00044" which is about 4 1/2 "tenths" which is just under "half a "thou"") which should fairly achievable.

As you say, your shaft is pretty hard, so I'd go with using it as the inner race. Using a sleeve will probably require either or both a larger OD bearing and machining a new bearing diameter on the shaft.

Mcgyver
01-05-2009, 09:05 AM
Yeah. I can cut it down for a sleeve. I was planning on polishing the last tenths but as always, I'm open for options ....


I'm not deeply experienced with them but remember when i have there something about the OD being over-sized so that when pressed into the hole it closed up a bit....in other words the final fit to the shaft or sleeve (i like that idea as i does need to be hardened) is in part determined by the bore holding the bearing

pntrbl
01-11-2009, 10:38 PM
I fished this thread back up to let you guys know I got my needle bearing fitted up. It was a definite stretch for my skill level but, after another happy day spent in the shop, :D , I got 'er done.

Since the section of shaft I was dealing with was already hardened I set up a pneumatic dremel for a toolpost grinder and then spent a stupid amount of time kissing off the silly millimeter I needed. There were some stone dressing lessons along the way and since I couldn't get a center in it with the dremel on the setup was extremely fragile. No room for clumsy on this one. Here's a Pic.

http://i115.photobucket.com/albums/n300/pntrbl/HardShaft.jpg

Still surprised I didn't eff that one up! Maybe there's hope for me yet ...

So Thanx again guys. It wasn't long ago that I didn't even know what a toolpost grinder was.

SP

darryl
01-12-2009, 12:23 AM
I see that rotor is mounted in a 4 jaw, so you must have centered the outboard end to get zero runout before grinding on it-

That would have been a good use for a steady rest.

Rich Carlstedt
01-12-2009, 01:10 AM
Macgyver is dead on.
For needle "CUP" bearings (like used in Alternators) the bearing OD (housing bore) determines interference, and unlike some bearings, you never want a loose fit as the needles will skid.

Rich

lazlo
01-12-2009, 10:44 AM
remember when i have there something about the OD being over-sized so that when pressed into the hole it closed up a bit....in other words the final fit to the shaft or sleeve (i like that idea as i does need to be hardened) is in part determined by the bore holding the bearing

There are different types of needle bearings. The one's I've used, which I think are the most common, are "drawn-cup" bearings, where the housing is not ground like a typical bearing, it's drawn through a die, the needle rollers are inserted, and the ends are rolled over, and then the whole assembly is hardened.

When I ordered a set of INA drawn cup bearings, I thought they had failed quality control -- they were out of tolerance on the OD and ID: they would just slide-off the shaft they were supposed to hold. I called INA, and the bearing engineer explained that the drawn cup bearings warp during the pressing and heat treat. The bearing shells are thin and designed to spring back into concentricity when you press them into the bore, which also closes down the bearing bore size.

There are also precision needle bearings, with ground housings, which are apparently a lot less common. From what the INA bearing engineer explained, these should be exactly on tolerance for ID and OD, and install just like a normal bearing.

By the way, I looked around for those needle rings -- the hardened races that you use when the needle bearing runs on a annealed shaft, and I couldn't find them anywhere -- MSC didn't carry them, and I couldn't find them in McMaster either.

Does anyone have source for these? Ordering them directly from INA is really, really expensive.

beckley23
01-12-2009, 07:12 PM
I think you're stuck with INA for the inner races. You may also try Torrington/Timken for needle bearings.
My bearing supplier has been supplying the Torrington/Timken needle bearings lately, that I use on a machine I manufacture.
Harry