Drilling The Holes...Which Direction?

[ohiohonda]

I have used and own the dewalt hole saw that you used as well as the version above. Even the agressive hole saws from the big box stores. All can drill the same holes. It's just more forgiving with the one above.

 

[jim202]

here is a stepbit

Neiko 10194A Titanium Step Drill Bit, High Speed Steel | 1/4” to 1-3/8” | Total 10 Step Sizes https://www.amazon.com/dp/B000FZ2UOY/ref=cm_sw_r_cp_apa_hEn.ybP58PC6C

best way to drill through sheet metal.

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Big problem with a step drill is that they extend way beyond the material your trying to drill. The 3/4 inch size is generally near the drill end and not the sheet metal end. This presents a much greater chance to make contact with the head liner.

You should also wrap some tape on the step drill to indicate which level is the one you need to use. If your not careful, you could go beyond the correct size hole and now your really in trouble.

Another draw back to using a step drill is that it lets all the cutting chips to fall down onto the head liner. Depending on how fast you have the bit spinning, these chips could be rather hot. Need I say any more?

But do as you choose. It's your vehicle and your wife you have to answer to when the head liner gets damaged.

 

[KC4RAF]

Agree with you Jim on the step drill. They can be a bugger when drilling for an nmo mount. Long time ago, what I did to make sure I didn't go pass the 3/4 cutter, I use a magic marker to mark the next larger hole. But as you suggested tape works just as well.
My self, I like using 3/4" hole saw.

edit:
That one that The Antenna Farm has that ohiohonda linked to; For the price it seems high, BUT
if you'll be doing several or more hole cuts, it's worth the extra money.
The big advantage is that your bit will go through what looks like about a 3/4 depth or there about. I like that feature.

 

[enine]

Something that I've done in the past with a typical hardware store hole saw is to put it in my drill press first then drill through some scrap wood. Then you clamp or sit all your weight on the scrap wood to hold it in place and use it as a guide when drilling with the hand drill. It helps keep the bit from walking around or tilting sideways.