Blue bearings

[Pitt]

I understand that and agree on the heating the case. I hardly ever heat a bearing and then only in oil if absolutely necessary .

I just wondered about the reasoning of thinking that the balls would be ruined but the races would be OK to accept a much harder (though much more precise) ball.

In this case the cages are metal (Husky 372) unless he sourced some after market or other supplier

If the cages were plastic I would junk them

I am with you except the part where everything got hot enough to tinge blue. This bugs me. Also, my point was that if you can obtain them for a no pain cost, why take any risk? Just get new ones.. I am floored at how expensive saw parts are.. If my Dirt bike as a kid would have cost this much for Pistons rings and cylinder, my bike would have been a planter for the lawn, because I couldn't afford it. So anyplace I can bring my own steak to the restaurant, is fine by me. This is one.

 

[Lakeside53]

Not sure about the Husky bearings in question, but many saw bearings are custom -not obtainable from a bearing house. Even those sporting common numbers - like 6302, may have an custom internal radius ground to allow for mating to the crank lobes and stress relief, ot even a custom external size (a couple of 10ths less for fit). Yes, often you can get away with a standard replacement for a custom bearing, but not always.

 

[ShoerFast]

I am with you except the part where everything got hot enough to tinge blue. This bugs me. Also, my point was that if you can obtain them for a no pain cost, why take any risk? Just get new ones.. I am floored at how expensive saw parts are.. If my Dirt bike as a kid would have cost this much for Pistons rings and cylinder, my bike would have been a planter for the lawn, because I couldn't afford it. So anyplace I can bring my own steak to the restaurant, is fine by me. This is one.

Posting more on entertainment value then certifying aircraft for service here. The real question should read something like having an oven that truly 'blued' bearings in just a few minutes, set at 450 . As his oven would have had to be at closer to , or better then 550 deg. and the bearings in there for better then an hour. (for a true 'blue' on any steel)

If that were the case, I WANT THAT OVEN! , as it sounds like it would be fun for a lot of stuff!

What really happened , IMO , was the rust preventive coating that the bearings were shipped with turned blue, or solidified 'blue' ,,,,, but for the matters of the thread, would not have effected the bearings integrity.

For a matter of having to reorder parts, wait till they get there, or spin the ones you have, those few minutes would not have me waiting for new ones,,,,,, if I needed the saw.

 

[Crofter]

We dont really know how long the few minutes really was, but if, and I say if, a blue tempering colour heat was reached by the bearing, won't the blue colour come just about instantaneously in air. You can sand it off to bright and it reappears at once if the temperature is still there I found. Sanding it off after it has dropped to room temp really wont give an indication of what temperature it had reached at its peak will it?

I guess whether a person want to risk it or not is an individual thing. Given a choice some people will feel empowered by taking the chance and others will feel good about having taken the safer route.

 

[RaisedByWolves]

I think it should be noted that any oven will overshoot its set temp when first coming up to temp. The thermostat only senses the temp of the bulb, not the internal temp of the oven, plus the elements are roughly 1500-1800* when the power to them is shut off.




If that bearing were in close proximity to the elements (3-4") it could have been heated way above whatever the little dial was set for via radiant heat. Then theres the factor that some ovens have a built in Pre heat mode........






.

 

[clintb]

I called applied industries tech, and asked about chainsaw bearing. They told me probably the same as the ones they sold, so i went to a fastenal store and got sealed bearings for about $1.75ea., pulled the seals, washed the grease out with brake cleaner. When i welded titanium at work it would turn blue if air ever got to it while it was still very hot. We would take a piece of tungsten electrode and scratch the pipe, when you hit the dark blue it would just slide over the blue spots meaning it was a lot harder. I tried scratching the blue bearings and seemed like it had different hardness in places. One more things on this 372, shows a o-ring between the bearing and the spacer that the seal rides on and the clutch holds tight. I tore apart 2 of these and don't remember a o-ring , ya'll know about this?

 

[Al Smith]

I called applied industries tech, and asked about chainsaw bearing. They told me probably the same as the ones they sold, so i went to a fastenal store and got sealed bearings for about $1.75ea.,

That could be true,in some cases,seals as well. How-some-ever,in the real world,as with dealing with Stihl in praticular you will find that this is not true.

Good old Stihl,as with many German manufactures has OEM bearings and seals.In other words they own the rights world wide for their distribution.

You might as well bite the bullet and pony up the money,because that's just the way it is.

Back to the blue bearings.I can't add much other than a little experiance of years ago.I worked a maintanence shut down at Timken bearing in Bucyrus Ohio .It was interesting watching the things be made.More steps involved than one would realize.

To get the balls in the race,they actually distort the inner race one direction and the outer race another.All this and not crack the races,amazed me.

 

[jensen 32000]

Re bearing assembly

I thought that most bearings were put together by stacking all the balls in one side, then put in the innner race to the other side (distort perhaps?), spread the balls, then install the separator. The separator on any radial ball bearing, keeps the bearing intact. Some maximum capacity bearings have a radius ground in to the races get the extra balls in. I've worked as a Milwright and on cars for many years, and if I want to get a bearing apart (to inspect for exact wear inner and outer race/balls), I remove/destroy the ball separator and they fall apart, and sometimes on there own if they are really worn. You sure someone wasn't puuling your leg about streching them? You put a bearing in a press, and it don't take mach to crack, about the same as glass. Oh yeah I was taught 250 degrees max. Use a 100 watt light bulb to heat the bearing, just stick it on top. Besides if you use these blue bearings, how long do you wait to start bragging that they havn't failed yet? I think ten years would be the minimum, unless you cut daily. Good Luck!

 

[PES+]

I called applied industries tech, and asked about chainsaw bearing. They told me probably the same as the ones they sold, so i went to a fastenal store and got sealed bearings for about $1.75ea., pulled the seals, washed the grease out with brake cleaner. When i welded titanium at work it would turn blue if air ever got to it while it was still very hot. We would take a piece of tungsten electrode and scratch the pipe, when you hit the dark blue it would just slide over the blue spots meaning it was a lot harder. I tried scratching the blue bearings and seemed like it had different hardness in places. One more things on this 372, shows a o-ring between the bearing and the spacer that the seal rides on and the clutch holds tight. I tore apart 2 of these and don't remember a o-ring , ya'll know about this?

503 26 30-19 is supposed to go in the groove of 503 77 91-01

I hardly ever find any trace left of the o-rings either after high hours

I asked about them years ago and never did get a straight answer from Husky

 

[Al Smith]

I thought that most bearings were put together by stacking all the balls in one side, then put in the innner race to the other side (distort perhaps?), spread the balls, then install the separator.

The seperator or cage goes in last of course.The proceedure as I described it was told to me by a production foreman at Timken but I really couldn't tell what was happening.Parts go in one end and assembled bearings come out the other end of the assembley machine,magic maybe.

 

[PES+]

http://www.youtube.com/watch?v=eGyoMuE4gDQ

 

[Dan Forsh]

Blue balls will fade with time. As the colour fades you should also find that they fit as the swelling will also go down.

:blush: .....sorry, this isn't the vasectomy thread is it.....

 

[ShoerFast]

Frank , WolveMan

The way I understand it, no , a few minutes, - half hour even, given any reasonable distance from the heating element. No, the oven temp could not have been off by that much, nor could the oven have over-heated by that much to have a true 'blue' on the bearings.

The way I am seeing this, steel heats at a bout the same rate that it loses heat, it takes a good amount of time for steel to come down from a temp, and steel conducts heat into itself well enough that a surface blue would not be possible. As for myself, I do a lot of house-oven tempering, recently with 52100, and do like to stack the steel, and wrap with aluminum foil and set on a middle to 3/4 the way up oven-rack, and hold for better then 2 hours seems more consistant results. Along with what your saying, those card-board frozen pizzas do like the bottom rack, as there crust will finish better.

I think you both have very good dogs in the hunt, if the hunt involved steel that were a lot thinner, picture a old-school razor blade, but bearings and there race's conducting heat from each other would not blue so quicker, nor the oven be off by that much. just my $0.02 .

Edit: Here is a question to the bearings integrety, is the oven rack 'blued' ? (like one used over charcoal, that gets into the mid to higher 500's deg.)

 

[Crofter]

Shoer, I wonder how well you read my post #44. I am only quibbling here with the point about how long the related colours take to develop once the item has reached a certain temperature Not how long it it might take to reach that temperature.
In using the term "true blueing" I think you are referring to the thick and durable colour and case hardening treatment like what is done on some revolver frames etc. That does take time to create, but not in my experience, the appearance of the temper indicating colours. The racks in my oven are chrome plated and the temper colours associated with carbon steel would not apply.

 

[ShoerFast]

We dont really know how long the few minutes really was, but if, and I say if, a blue tempering colour heat was reached by the bearing, won't the blue colour come just about instantaneously in air. You can sand it off to bright and it reappears at once if the temperature is still there I found. Sanding it off after it has dropped to room temp really wont give an indication of what temperature it had reached at its peak will it?

I guess whether a person want to risk it or not is an individual thing. Given a choice some people will feel empowered by taking the chance and others will feel good about having taken the safer route.

Shoer, I wonder how well you read my post #44. I am only quibbling here with the point about how long the related colours take to develop once the item has reached a certain temperature Not how long it it might take to reach that temperature.
In using the term "true blueing" I think you are referring to the thick and durable colour and case hardening treatment like what is done on some revolver frames etc. That does take time to create, but not in my experience, the appearance of the temper indicating colours. The racks in my oven are chrome plated and the temper colours associated with carbon steel would not apply.

Good point! As 52100* is a 'Chrome Alloy Steel' the temp/colors would be off via the % of chrome, but still makes a point that the color base is a place to start.

*52100 has more Chrome then Carbon.

 

[rshaffer3]

opinion of a materials engineer

I spoke with a materials engineer at my work. He's been with Westinghouse dealing with specialty metals, weld procedures and heat treatment for 40 years.

Anyway his opinion was that if you want to be conservative or if you're worried about the bearing ruining the saw over time that they should be pitched. If the oven got that hot and they soaked for a while he thinks the hardness could have dropped below 60 Rockwell C and could wear quicker over time.

The bluing, however, was of no concern and is not a true indication of the time or temp. that the bearing was heated to. The blue is nothing more than light oxidation. The steel could actually go from yelllow to blue and back to yellow a number of times during the heating cycle. Something about reflection in the prism spectrum or crazy stuff I forgot in my college physics course from being hung over.

Anyway, there you have it. If you want to be safe get new ones and if you don't think they were in the oven that long or got all the hot you could roll the dice. But the bluing really tells nothing.