Smoke when using hole saw and drill press

[kahlid74]

Tested using a hole saw and my shiny new drill press last night.  All arcade machines I've built before I've used hand held corded drills and done it manually.  Bought a drill press just because they rock and I want to do lots of stuff.

Got about 1/5 of the way through and saw dust turned to smoke.  My guess is I'm pushing down to hard/fast and it's not cutting but melting the MDF.  I read about forstner bits so I'll try some of those but I'm looking for confirmation of what I'm doing wrong.

Also, should my drill press be on maximum speed as per the drill press's instructions?  They recommend 3000 RPM for cutting wood.  It's what I currently have it at but I just wanted to be sure.

[HaRuMaN]

Hole saws will do that to MDF, it's normal.  You could go slower (slower lowering the hole saw, not drill rpm) and that might help.

Forstner bits won't burn MDF.

[yaksplat]

You have to base the speed off of the diameter of the bit.  3k rpm should be for smaller drill bits.  When cutting a 6" hole i'll drop the speed as low as i can on my drill press.

You also have to remember to back the blade out to release the trapped dust.

Any chance that your hole saw is dull?

[TopJimmyCooks]

What yaksplat said, slow way down for such a large bit.  Also, in a lot of materials such as mdf or metal, it helps to rock or angle the hole saw a little, so its not cutting the entire circumference at one time.  you can't do this with a drillpress, which is why I prefer to use a 1/2" corded drill for large HS's.  At the slower speed, your Drill press may be stopped by the bit's friction depending on your belt tension and motor size.  if so speed back up some.

Also, mdf will gum up the blade teeth with dark brown glazed mdf dust - you may need to stop periodically and clean some of that off with an eraser or paint thinner or brass brush. 

[BobA]

Sometimes the hole saw will get so gummed up that you have to use a screwdriver to break the burned MDF off the teeth of the saw.  The heat seems to make the MDF dust into a glue like substance that has to be removed before the hole saw can be used again.

Going slow and backing off the hole saw to realease the MDF dust often seems to help.   If you have a vaccum then use it to remove the dust each time you raise the hole saw.

[EightBySix]

Also backing off periodically will allow the bit to cool. Often best to take lots of little bites.

[kahlid74]

Got a forstner bit and the difference is night and day.  I left the RPM at 3000 and after trial and error have found that if I push relatively hard it cuts right through with little to no burn.  If I push softly/slowly the bit starts to burn the MDF.

Insane.  How I built all these cabs using a hole saw and the forstner bit was always right in front of me.  I'm an idiot.

[BobA]

+1 on the Forstner bit.  I didn't realize your hole was button sized or I would have recommended one earlier.

[dextercf]

Sorry for hi-jacking, but what if the panel is metal and you don't have a drill press.
What bit/tool to buy?

[TopJimmyCooks]

A good sharp (new) carbide hole saw with pilot bit is the easiest and cheapest way to drill holes in sheet metal in button/joystick sizes.  The best way is an electrician's knockout punch but its a bigger investment than most people want to make for a few holes in a CP, $50-70 per size v/s maybe $10-15 for a hole saw and arbor.