Trick to trimming shingles?

I need to trim shingles on an outbuilding. Previous answers on the issue say to use one of those little hawkbill linoleum knives. Is there a trick to making a clean cut with that knife? I'm using new knife but it sure wants to gum up in the asphalt and is very hard to cut even with the shingle being very warm.
Jim
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The best way to trim asphalt shnigles is with a circular saw with a carbide blade. First snap a chauk line from the peak to the fascia. Then starting at the peak slowly make a nice straight cut following the line. Make sure you allow for any imperfections in the rakers by allowing a little over hang like 1/4 to 1/2 inch. Make sure you wear long sleeves and googles as the stuff flies everywhere. Good luck
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A good hook blade in your utility knife will do fine. A hot shingle is not as easy to cut as a cool one, IMO. You should wear "googles"! And use a chalk line.Tom Work at your leisure!
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True. Buy a couple packs. They don't cost that much and they do a great job.....
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Thanks for all the tips everyone. Sounds like I was going at from the wrong side with the wrong knife.
Jim
Red Neckerson wrote:

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I score them with a regular utility knife blade on the back side and then bend them until they break. I don't cut them all the way through because the granuals on the face dull the blades too quick. I get a clean cut this way with no gummed up blades.
AZCRAIG

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scribbled this interesting note:

In a utility knife use a hook blade. You can get them most anywhere you can buy the utility knife. The blades are super sharp and are designed for relatively long usage.
-- John Willis (Remove the Primes before e-mailing me)
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