Burning blades / bits

[b_m_hart]

What's the significance of burning a blade (or bit)?  As in, why does it matter?  Aside from the obvious "you're working the machine a bit harder than you should"...

 

[Daviddubya]

In my experience, a burning blade or bit tells me the blade or bit is dull.

 

[pingvinlakrits]

When you see the bits/blades change in color the hardening is going and the bit/blade weakens and dulls fast.
This was very apparent to me yesterday, twice; when doing a rough cutout with jigsaw the blade changed color and then snapped... (was pressing it hard though) 
...and an hour later I was removing a window frame with the Fein Supercut and the blade got really hot (spit on it and it sizzles... ...tells you that you need to chill out some) so I cooled it down a bit but then it too snapped from the welding spots. The teeth weaken fast when hot. Too fast.

A guy I work with has no patience with his router (the OF1400) and he always tries to do it in one go, with chipping and bit burning and as a result his bits are dulling fast. My mileage on the bits (making two or three passes) are exponentially higher.

 

[mastercabman]

With blades,it could be that your are using a blade with  too many teeth.

 

[Daniel_n]

As Henrik already have said - high temperature destroys the hardening of the edge, not matter if it's a saw blade, drill bit or router bit.

To avoid overheating, a sharp and clean (no dust/hartz buildup on the edge) blade is a must. If it still overheats; lower the speed of the tool, increase the feeding rate, adjust so you don't remove all material in one go (use a couple of passes instead), and/or change to a blade with fewer teeth.

 

[robski]

hi b.m. for me its about finish, if my blade is burned/discoloured so is my workpiece. not such a big problem if the material is being painted white but if its being waxed or varnished like the solid oak doors i hung a couple of weeks ago it becomes an expensive issue. 4 checks i always make before i cut anything- the right blade, the right blade speed, the right feed rate and can i afford to replace it if i boz it!