MAC Tiber Bear

[n3kf]

Ok. I'm stuck. I had this timber bear sitting around for a while and decided to get it running again. Yeah I know it's heavy and many don't like it. For me it gets the job done. It chews up the huge oaks and poplars that fall on my property. Anyway, I pull the pull starter and the rope breaks. Put a new knot in the starter pulley, wind it up, and it breaks again. Starter working as expected, but the rope is too short. I can yank it all the way out. Ok, get a new rope. Put it on, pull it, and the rope doesn't return. With some help it does. Anyway, take the starter apart. Where the pulley goes into the plastic housing, it's very tight and does not rotate freely. Clean it up and it's still tight. Bearing surface on aluminum pulley is OK as is the plastic sleeve it slides into. Tried grease and oil. Gets smoother but still sticks. The more you pull the starter, the more it gets stuck. Spring looks OK. Spring grabs onto pulley fine, but does not push it back to the unwind position freely. It's as if the plastic shaft has swelled up. But it worked for 20 years, and after a couple pulls that broke the starter rope off, the pulley binds on the shaft.

Any ideas? I figured. I could sand the plastic shaft down, but that makes no sense. Thoughts? Thanks

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[rwoods]

Post your question over in the MAC stickie thread may get you an answer. Ron

 

[Wood Doctor]

I found that if the starter rope is too long on the Mc 610, that causes more return problems than if it's a bit short. Or the cord is wound up one or two extra turns and that tightens the spring up too much when the rope is all the way out. BTDT

 

[Jasonrkba]

Sounds like rope diameter is to big.

 

[n3kf]

Sounds like rope diameter is to big.

Same size, but the pulley is sticky with and without rope.

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[n3kf]

I found that if the starter rope is too long on the Mc 610, that causes more return problems than if it's a bit short. Or the cord is wound up one or two extra turns and that tightens the spring up too much when the rope is all the way out. BTDT

Pulley is sticky with or without the rope. If I wind the pulley up by hand, and let it go, it binds up.

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[Jasonrkba]

Have you cleaned the spring and area that it sits in?

 

[Jasonrkba]

Im trying to remember but if you over tighten the pulley it will also stick. And the shaft that it spins on has to be clean and greased.

 

[Mnmacguy]

Does the pulley bind when the nut on the pulley bolt is removed? There is suppose to be a small washer that acts as a spacer so when you tighten the nut it isn't clamping the pulley tight to the recoil cover. The order is a small washer, then a larger thin washer, then the nut. And make sure that small washer is flat on the recoil cover post and sitting inside the pulley's inner lip.

Also check the back side of the pulley for corrosion, cracks, or buildup. It should be clean and smooth otherwise the spring might bind.

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[n3kf]

Does the pulley bind when the nut on the pulley bolt is removed? There is suppose to be a small washer that acts as a spacer so when you tighten the nut it isn't clamping the pulley tight to the recoil cover. The order is a small washer, then a larger thin washer, then the nut. And make sure that small washer is flat on the recoil cover post and sitting inside the pulley's inner lip.

Also check the back side of the pulley for corrosion, cracks, or buildup. It should be clean and smooth otherwise the spring might bind.

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Yes that washer is there. But it binds on the post by itself without the spring and without the bolt. I just don't get it. It worked fine. Then I broke the rope trying to start it. Now it binds. I gave up and started removing a bit from the plastic shaft by sanding it down with very fine sand paper. Spins much nicer and not binding quite as much. A little more work and it will be moving fine. Just don't get how it went from spinning fine to being tight. Oh well.....

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[Mnmacguy]

Yes that washer is there. But it binds on the post by itself without the spring and without the bolt. I just don't get it. It worked fine. Then I broke the rope trying to start it. Now it binds. I gave up and started removing a bit from the plastic shaft by sanding it down with very fine sand paper. Spins much nicer and not binding quite as much. A little more work and it will be moving fine. Just don't get how it went from spinning fine to being tight. Oh well.....

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The only other thought I have is something I found by accident. I was messing with a broke aluminum pulley and found out that there is a steel insert/liner in the mounting hole. The inner lip is part of it. Could have corrosion between the steel and aluminum narrowed the inner hole size? Doubtful but thought I'd mention it.
Do what you need to get your saw running again. It's a great saw. Definitely worth fixing.

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[n3kf]

The only other thought I have is something I found by accident. I was messing with a broke aluminum pulley and found out that there is a steel insert/liner in the mounting hole. The inner lip is part of it. Could have corrosion between the steel and aluminum narrowed the inner hole size? Doubtful but thought I'd mention it.
Do what you need to get your saw running again. It's a great saw. Definitely worth fixing.

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Yep. Thanks. Some mysteries aren't meant to be solved. My son is a materials engineer and i used PB Blaster to clean up the old grease. He is wondering if that may have swelled the plastic very slightly. Who knows. Thanks for the help.

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