1/2 inch pitch chain sharpening question for expert (Art Martin?)

[Johnc(ks)]

I have a couple of older chainsaws (David Bradley and Homelite) that still use 1/2 inch pitch (round filed) chain. I managed to find a couple of N.O.S. chain loops for primary cutting use, and I have a couple of well worn loops for backup. The cutters on the worn loops have been ground back to where they are only about 1/3 as long as the

cutters on the newer chains, but I have maintained the 35 deg. filing angle and the .030 depth gauge setting. The problem is that the worn chains don't cut worth a crap, even with sharp cutters. I read somewhere that you could make them cut better by filing at a steeper angle, and I read somewhere else that lowering the depth gauges would help. My question is....does anyone have experience at making these large pitch chains cut better when the cutters have been ground back considerably? I hate to scrap these no-longer-available chain loops when the drive links, rivets, and tie straps are still good. BTW my neighbor's McCulloch 1-42 with 7/16 pitch chain has the same problem with his one and only chain loop.

Thanks,

John C.

 

[Art Martin]

Johnc (ks),

You mentioned that the chains are round filed. Do you mean that the chain is a round tooth or do you mean that it is a chisel tooth that is round filed? On the chains that are filed way back toward the rear rivet, you should drop the depth gauges down to .040” to .045” to maintain the proper cutting efficiency of the new chain that starts out at .030”. The top plate angle of 35° is fine as long as you drop the handle end of the file down around 10°. Also, try to get the side plate at a 10° positive angle or slope. This will give a more hollowed appearance to the tooth and a thinner front top plate angle. The same would apply for the 7/16” pitch chain that you mentioned.
John Lambert has posted some fine close-up pictures of round teeth with the correct filing angles. Perhaps he could post them again for you to refer to.
Hope this helps.

Art Martin

 

[sedanman]

Off the topic but Oh, well! Art, It's good to see you.

 

[Johnc(ks)]

Art,

Thanks for the info. My worn 1/2 in. pitch chains have round cutters, like the "chipper" cutters shown in the Intertec manual. When I got the David Bradley saw, the chain on it had plenty of cutter left, but had been filed back to a top plate angle of about 70 deg, and I couldn't cut straight to save my life. By the time the saw shop finished grinding it back to 35 deg, the cutter was almost back to the back rivet. I'll try you recommendations as soon as I find some wood that's big enough to justify getting the big saws out. Thanks again.

John C.