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- posted October 18, 2017 in Husqvarna: Ask & Answer > Chainsaws
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Karla,
Sorry, it was late last night. I meant to say, divide the circumference by the number of teeth on the sprocket, not the other way around. Anyway, it's the circumference, not the diameter.
I think I have found both the replaceable sprocket nose tip kit and the eight tooth 3/8" drive sprocket on the Bailey's web site. I will call them to discuss this issue before ordering. I think the 7 tooth sprocket needs the longer (replaceable tip) bar. The one piece bar that the dealer sold me is at the limit of chain tension adjustment with a new 72 driver chain. Once the chain is broken in it won't stay on the bar.
Tracy
- posted October 18, 2017 in Husqvarna: Ask & Answer > Chainsaws
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Karla,
Thanks for your input but I think you are a little off base. An 8 tooth drive sprocket will result in faster chain speed and less torque than one with 7 teeth, (both 3/8" pitch). For a given RPM, the chain will move 8 teeth (3 inches) per revolution as opposed to 7 (2-5/8 inches). Measuring pitch is not complicated, no special gauges needed. On a gear/sprocket, it is the number of teeth divided by the circumference, not the diameter. On the chain, it's simply the distance between drivers. To get a more accurate measurement, measure across several drivers with the chain laid out straight and divide by the number of spaces between drivers If the pitch of the sprocket is not the same as that of the chain, they will not mesh.
Back to the original problem, as I noted, the bar with the replaceable sprocket nose is a little longer than the one piece sprocket tip bar, though both are marked 72 drivers, 3/8" pitch, 0.050" gauge. I think going from a 7 tooth sprocket to an 8 would compensate for that difference.
You have aroused my curiosity. Just what is an experimental chainsaw person? Do you design or customize them?
Tracy
- posted October 16, 2017 in Husqvarna: Ask & Answer > Chainsaws
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I have had the same problem with my Rancher 460. The original bar had a replaceable sprocket tip and is slightly longer. Replacing the whole bar cost less than replacing just the tip on the old one when it went bad but that's when the trouble began. Both bars are marked for 72 drivers, 3/8" pitch, 0.050" gauge. I have been using 70 driver chains with a 20" bar from my old McCullough 3.7 CID saws. They were great saws in their day but they have been retired in favor of the Rancher 460. I think my drive sprocket has seven teeth and there may be one with eight, both 3/8" pitch. I came across this forum while trying to research that.