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Discussion Starter #1
Earlier today, I rounded over the edges on a piece of walnut using a Bosch 1/4" roundover bit. Even though I kept the router moving, there were some burned spots. I guess I don't understand how a bit burns. The bit was brand new, so it was presumably sharp. When the bit comes into contact with the wood, why does it burn instead of just removing the wood, if that question makes any sense? Inquiring minds want to know.
 

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John
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from the sound of your description uneven feed rate( you may have slowed down intermittently while cutting it) walnut, cherry are a few that burn easily.
I usually make two cuts after the first cut lower the blade slightly and make the final cut illuminating burns.
 

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From the sound of your description uneven feed rate (you may have slowed down intermittently while cutting it.) Walnut, cherry are a few that burn easily. I usually make two cuts after the first cut lower the blade slightly and make the final cut illuminating burns.
Dumb question, I know. Is the burning related to the amount of wood being removed?
 

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see if this helps...

what species are you routing....
 

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Discussion Starter #5
see if this helps...

what species are you routing....
I'm not sure. The wood was given to me, and I don't know how to tell it apart. It looks like walnut, but it's not quite as dark. Cherry? It's not exotic. He kept all of the exotic cutoffs.
 

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Mike
think of it this way like rubbing 2 sticks together to start a fire. some wood makes better kindling.
when you slow down the feed rate, the router bit continues to move at the same speed which causes friction against the wood, there is where the burns show up.
it is a problem that is really hard to eliminate the trick is to keep it down to a manageable situation
 

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Discussion Starter #7
Mike
think of it this way like rubbing 2 sticks together to start a fire. some wood makes better kindling.
when you slow down the feed rate, the router bit continues to move at the same speed which causes friction against the wood, there is where the burns show up.
it is a problem that is really hard to eliminate the trick is to keep it down to a manageable situation
John, I understand what you're saying and will heed that advice. What I don't understand is why there is friction between the bit and the wood. Once the bit turns 180 degrees, the wood that it comes into contact with is removed. What two surfaces are rubbing together to cause the heat? I guess it has to be the outside edge of the bit and the wood.
 

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John, I understand what you're saying and will heed that advice. What I don't understand is why there is friction between the bit and the wood. Once the bit turns 180 degrees, the wood that it comes into contact with is removed. What two surfaces are rubbing together to cause the heat? I guess it has to be the outside edge of the bit and the wood.
from elsewhere in the world of forums..

Some of the guys from the woodworking club took a tour of a production cabinet shop last week. Lots of commercial furniture for hotels, schools, etc.
One of the things the owner said was that when you are using router bits, you want "chips" to fly off, not "sawdust." Chips will carry off the heat, sawdust will not and causes the bits to overheat. I heard the same thing a few years ago from the Bosch engineers.
So, the old advice to run a profile with your router, then lower the bit 1/32 for the clean up pass is not the right way to do it.


http://www.routerforums.com/tools-woodworking/72642-rethinking-router-folklore.html
 

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I bought a Bosch bit awhile back and wasn't too thrilled with it, and switched to Freud and been very happy with them they just seem sharper, I can tell by the resistance against the wood when I feed the material thru.

Just my unscientific observation.

Herb
 

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I bought a Bosch bit awhile back and wasn't too thrilled with it, and switched to Freud and been very happy with them they just seem sharper, I can tell by the resistance against the wood when I feed the material thru.

Just my unscientific observation.

Herb
agreed...
Bosch bits are so-so...
 

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I bought a Bosch bit awhile back and wasn't too thrilled with it, and switched to Freud and been very happy with them they just seem sharper, I can tell by the resistance against the wood when I feed the material thru.

Just my unscientific observation.

Herb
Actually Herb, I think you're on to something there.

The sharper bit should give less resistance all other things being equal. Similar to a saw blade I would think. Dull blade...lots of resistance and burning. Sharp blade...easy cuts and no smoke! :smile:
 

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Discussion Starter #12
Actually Herb, I think you're on to something there.

The sharper bit should give less resistance all other things being equal. Similar to a saw blade I would think. Dull blade...lots of resistance and burning. Sharp blade...easy cuts and no smoke!
That's what I'm thinking, but what do I know?
 

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Mike; re the wood ident. thing. Walnut has a very distinctive musty smell. Something like your Great Grandparents antiques or something. I can't really describe it but once you've smelled it you won't forget it.
I don't mean that it's really nasty, just distinctive (full disclosure; I don't like the smell).
 
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