Author Topic: 15x30x7  (Read 1246 times)

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Offline aclarke

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Re: 15x30x7
« Reply #10 on: April 20, 2014, 11:51:29 pm »
There's a 3120 racesaw running sealed bearings, way less use than most work saws, but it works in that application. There are some interesting formulas for evaluating sealed bearing life that is based on rpm, shaft size, etc. Bearings in the 3600 and lower range have an impressive calculated life expectancy. Seems like the shaft to bearing i.d fit could be made vacuum/Pressure rite with the proper sealant?

Offline 3000 FPS

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Re: 15x30x7
« Reply #11 on: April 21, 2014, 12:24:07 am »
To be honest Adam I really don't know about the life expectancy of sealed bearings in a chainsaw application.

Sound interesting and sounds like you have some valid info.
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Offline aclarke

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Re: 15x30x7
« Reply #12 on: April 21, 2014, 09:35:47 am »
Just tossing around ideas, I'll look for a junker saw to try this out in real world conditions...

Offline Al Smith

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Re: 15x30x7
« Reply #13 on: April 21, 2014, 09:49:59 am »
The problem being with those PTO side bearings is that they are radiused on the inner race  to fit the crankshaft which has a radioused shoulder where the bearing meets the crank .A standard metric bearing won't work .

To make matters worse the outer race on the outward side of the bearing is where the seal fits,not in the bearing pocket. They really went to extremes to assure propritory rights on those things .Thus instead of paying 10 bucks for a seal you pay 20 .

Offline aclarke

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Re: 15x30x7
« Reply #14 on: April 21, 2014, 09:10:51 pm »
Good point Al.  those Stihl engineers and marketing guys are real rascals!!  Lol

Offline Al Smith

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Re: 15x30x7
« Reply #15 on: April 22, 2014, 05:17:25 am »
That type OEM mentality is typical of most things originated from Germany .It's all good stuff they just like to control the after market of which they do .


Now of course it's possible to reengineer those items but the average guy on the streets has neither the money nor the means .We've done it at work but it's a chore and expensive .

Given enough time though and if there is a market somebody will eventually make after market parts .Case in point 200T cylinders and pistons .