Anyone use a lubricant when drilling metal doors?

A bar of Ivory soap works well, and doesn't make a mess like a liquid.

Anytime you use a metal tool to cut another material it is a machining process. Every machining process is a compromise between tool life, finish and cutting speed. Coolant is a variable in this process. It allows for a higher cutting speed, an improved finish and a longer tool life.

There is however a practical matter of making a big mess to consider also.

Ask yourself if you are smoking a lot of hole saws. If you are getting good life out of what you are doing, then you are probably OK. If you are making a bunch of blue metal chips and smoke is coming off of the door as the paint is burned from the friction then I would consider that something is wrong.

If this is the case, slow down the speed of the hole saw, and push a little slower. Some times this is difficult as all drills are not variable speed.

When you are drilling the holes remember the larger the diameter the faster the cutting edge is seeing the job. Faster is not always better as it creates heat faster than it can be carried away in the chip that is being created. Coolant carries away more of the heat allowing the job to be done faster.

This is real important in a production environment where time is money. it is less important in deadbolt installations as the first priority is a good job, and taking one minute longer to punch a hole is no big deal.

My recommendation is to let the results of your efforts guide your choices. A carbide tipped saw will handle a lot more heat before dulling, but carbide is pricey and will fail if it is smacked around to much. A good high speed steel hole saw is an excellent choice in my opinion as if you treat it gently it will give you a good long life, and quality results. I do not use coolant. (Other than the ambient air.)

I hope this helps.

another point is how thick is the door and whats the metal? drilling 1/8" aluminum, I would really like to see a lub, cause aluminum is a PAIN to dig out of the teeth.. 1/8" steel? again, needs something, BUT slow speed is the thing as well. --Shiva--

I agree with everything Roger Shoaf stated.

Now if only you could convince my wife that this is an appropriate attitude. :>)