When you need to make a Hole Saw in sheet metal, you need the right drill bit. Get a drill bit designed for metal and sharp enough to cut through the thin sheet without it ripping or tearing it. For this, a pointed and sharp-edged twist drill bit is recommended.

The answer can be found in three simple words: 

Don't slip, drill! You should bear down and drill slowly to prevent the metal from getting hot enough to warp. Also, using a lubricant, such as oil or water, which will help reduce friction and keep the drill bit cool as you drill.

How do you secure the metal while drilling a hole for a clean hole? 

Clamp it as securely as you can to a work surface, with a vise or clamps. This will keep the metal from jolting or vibrating during drilling, which would result in a more precise hole. I also like to butt a chunk of scrapwood under the metal so that you don't punch a hole through your table with the punch.

What we do here is keeping the control and precision throughout the drilling, as you need: 

We are drilling into thin sheet metal, if you loose that or go to fast or slow you will create a junk looking drill bit and a hole saw. It is crucial to keep the drill stable and vertical to keep the hole neither deformed nor removed from center. You should pause the drilling to inspect the hole and make any necessary adjustments to maintain an easy experience.

Hole smooth and professional

Once the hole is cut through the sheet metal, a deburring tool or sandpaper can be used to make the hole smooth and professional. That would not only make the hole look better, but would eliminate any sharp edges to scrape an arm on. Wiping away any metal debris and applying a layer of paint or paint protective coating to the metal also aide in shielding it and creating a smooth surface.

So in summary: 

Drilling a smooth hole in thin sheet metal involves having the right drill bit, good technique, secure metal, control and accuracy as well as a little bit to go to clean it up. With these pointers and the opportunity to practice to perfect your drilling, you can have clean and accurate holes Circular Saw Blade in sheet metal for your projects. What is most important is that you air on the side of safety and do not rush to make this the best you possibly can be. Enjoy drilling.