How hot should LM chips get?

[phantomcow2]

The LM317 chip of my 4 axis board is getting pretty hot. My motors are running at 2Amps, I have 3. One of them is at 1.5.
It gets hot quickly after startup, not sure if this is normal or not. It has not yet shut down, i believe this is the one with a thermal shutdown so if it has not gotten that hot, i suppose thats good.
Should i try to make some type of an elaborate heatsink or what?

[HobbyCNC]

Does the fan blow air on it as I instructed several posts ago? It can get to 150C. Heat sink it if you want

Dave Rigotti
HobbyCNC.com

[phantomcow2]

Fan is blowing down at it. So hot to the touch is normal then
I dont think they are at 150c

[GrahamIT]

Originally Posted by phantomcow2 Fan is blowing down at it. So hot to the touch is normal then I dont think they are at 150c

Spit on your finger and touch the chip, it's too hot if it sizzles, so sink it.

[phantomcow2]

Well i have adjusted the fan so it aims more toward the LM chip, the chip is cooler. Still uncomfortable to touch but im hoping the heatsink I am making tommorow will solve, or at least help that

[GrahamIT]

Originally Posted by phantomcow2 Well i have adjusted the fan so it aims more toward the LM chip, the chip is cooler. Still uncomfortable to touch but im hoping the heatsink I am making tommorow will solve, or at least help that

How much higher is the unregulated supply voltage over the regulated, because the higher the excess voltage the more energy has to be dissipated by the regulator. A TO220 style case can sink about 25W when suitably cooled, so if you take the excess voltage being supplied to the regulator and multiply it by the current being drawn from it, you will get the wattage being dissipated by the regulator. Then you can work out the heatsink size required.