Roller case bearing

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What you folks think?
Using Nj204 instead of the usual 6204
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One thing to measure would be the inner part compared to the other bearing to make sure its the same and dont pinch the crank or be to loose. Know what i mean?
Everything matches in terms of dimension specs, but you're right i need check for interference carefully

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I use them on several saws, pto side on 076 for milling. nj204 . On a 288 with nj203 both sides need a shim for correct clearance. a dolmar 120si, with nj202 & others. Dolmar 143 & some Dolmar 111 came that way
 
I use them on several saws, pto side on 076 for milling. nj204 . On a 288 with nj203 both sides need a shim for correct clearance. a dolmar 120si, with nj202 & others. Dolmar 143 & some Dolmar 111 came that way
Nice, i bet they're the best for milling. Since the load is aways constant and high. I got a nj203 that im going to put on 288 too, only on the pto side. Which will let me not worry about shim and side to side play.

Yes the old dolmars always came with that setup, 143 and 166

Did you notice any lag in spool up? Acceleration and deceleration speed effected?

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That is good. there will probably be a little more heat in those big rollers due to the increased surface area so clearance is important.
Looks like an interesting mod and as it has been used before it should be good.
Keep us posted about the outcome.
 
I’m sure the bearing should be more than able, my concern would be the bearing pocket not being able to handle the added pressure if you really push the saw hard.
I am not sure whether the incidence of spun bearings is from bearing failure or the pocket getting stretched.
 
I’m sure the bearing should be more than able, my concern would be the bearing pocket not being able to handle the added pressure if you really push the saw hard.
I am not sure whether the incidence of spun bearings is from bearing failure or the pocket getting stretched.
Usually the bearing pocket gets wallowed because ball failed to spin catching the outer race when pushed in hard in the cut, in this case roller is better because it will still work in high load.

Basically ball bearing fails when load exceeds its capacity making it slip on the pocket

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Im not an engineer or anything but would heat be an issue? rollers must generate more heat at high rpm that ball bearing due to increased weight and friction area?
 
Im not an engineer or anything but would heat be an issue? rollers must generate more heat at high rpm that ball bearing due to increased weight and friction area?
They have c3 clearance, which is good for high heat applications. As long its being run under the specified rpms it will be fine

What you said will be applied on instances when they go above recommended rpm, in this case nj204 is good for up to 16k rpm

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Roller or needle bearings can handle a heavier load. You can install these in the husky 288 Xp. The ball bearings hold the end play but as long as you shim the roller bearing to take up the difference in end play it should be ok.
 
Roller or needle bearings can handle a heavier load. You can install these in the husky 288 Xp. The ball bearings hold the end play but as long as you shim the roller bearing to take up the difference in end play it should be ok.
Precisely
Interesting with 288 running rollers on both sides, the shim is added on the crank between the bearings right?

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Precisely
Interesting with 288 running rollers on both sides, the shim is added on the crank between the bearings right?

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I use small round arbor shim under the inner bearing race and crank . Install case with gasket, bearing,crank make sure bearing fully seated. I check end play.( I start with .005 shims under both races to start with). Then I add or subtract to get .004 to .006 clearance ( I get this number from what Dolmar 143 are ) I have checked several roll bearing saws & concrete saws
Some Dolmar saws came with shims under outer races but I like them under the small inner race ,,, much easier to set clearance ( use small clamshell 2 bolt bearing holder to get between crank & race tighten press off)
I think the saw spools quicker, but never tested them ,,,, butt feel.
Heat is not a factor. the crankshaft load is spread out over the crankshaft & case better.
The only drawback is $$$$.
 
I doubt the heat generated from added friction due to larger contact surface area is noticable.

The mass of the NJ204 is 0.11kg. I wonder how that compares to the ball bearing. Doubt you will notice and loss in engine acceleration. The outer race is stationary and the rolling elements only spin at a fraction of the overall rpm.

I think if you did a blind test and had two identical saws, one with a cylindrical roller bearing on the clutch side and another with double ball bearings, you wouldnt be able to tell the difference. Let us know how it works.
 
I doubt the heat generated from added friction due to larger contact surface area is noticable.

The mass of the NJ204 is 0.11kg. I wonder how that compares to the ball bearing. Doubt you will notice and loss in engine acceleration. The outer race is stationary and the rolling elements only spin at a fraction of the overall rpm.

I think if you did a blind test and had two identical saws, one with a cylindrical roller bearing on the clutch side and another with double ball bearings, you wouldnt be able to tell the difference. Let us know how it works.
I agree with you completely
Its surprisingly super smooth for a roller bearing, will report once i get it running

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