Aluminum Body F150 NMO Mount in Roof

[CopperWhopper67]

What is everyone's thoughts on using a step bit instead of a hole saw?

Also a tad off topic but just because it was brought up:

I have a brother in the Shingle Springs area.

Shingle Springs is my hometown! I never thought I would see it named on the forums. Small world I guess.

 

[mmckenna]

What is everyone's thoughts on using a step bit instead of a hole saw?

I know people have done it. I think my brother in law did one of his trucks with a step bit. It can absolutely work if you are super careful. You need to be 100% sure you stop at the 3/4" point and go no further. You also need to be 100% sure the point of the bit doesn't go through the headliner or anything else. The aluminum used on these trucks is a very hard alloy, so images of it tearing like a beer can aren't likely to come true, unless you go way too fast and with too much pressure.

The reason I'd never use one is that if you screw up, the cost of fixing it is going to be way more than the cost of just getting the right tool for the job. It is way too easy to screw up with a step bit, and kind of hard to screw up with the purpose built hole saws.

Your truck, your choice. As Clint Eastwood said "Do you feel lucky?"

 

[AK9R]

You need to be 100% sure you stop at the 3/4" point and go no further.

When I have used step bits, I put some paint on the step just above the size that I want. As the drill is spinning, you can see how close you are getting to the desired size.

You are correct that you need to be careful. Keep the bit perpendicular to the surface you are drilling to minimize tear-out. Pause after each step so you can assess your progress.

Good point about the cost of fixing the roof of a 50 to 90 thousand dollar truck vs. the cost of the proper hole saw.

 

[6079smithw]

Good point about the cost of fixing the roof of a 50 to 90 thousand dollar truck vs. the cost of the proper hole saw.

I had a friend that did installs for a town in CT; radios, light bars, etc. who swore by this Ripley hole saw.
I bought one on his advice and have had excellent results. It ain't cheap ($44.00 IIRC) but works as advertised
especially when you can't drop a headliner.

As my late Dad would say: "If you don't have time to do it right, where will you find the time to do it over?"

 

[AK9R]

"If you don't have time to do it right, where will you find the time to do it over?"

I used to work for a company that never had time to do it right. But, they always found time, usually by stressing the employees, to do it over.

 

[mmckenna]

I had a friend that did installs for a town in CT; radios, light bars, etc. who swore by this Ripley hole saw.
I bought one on his advice and have had excellent results. It ain't cheap ($44.00 IIRC) but works as advertised
especially when you can't drop a headliner.

The Ripley hole saws are the gold standard. I've done fine with my Laird hole saw, but I'd love to find one of those at a decent price. Last one I found came with the 1-1/4 for the low band whips, and it was priced pretty high.

 

[wwhitby]

What is everyone's thoughts on using a step bit instead of a hole saw?

I learned a very long time ago to always use the right tool for the job. A 3/4 hole saw made for NMO mounts is more expensive, but IMHO, its worth it.

As my late Dad would say: "If you don't have time to do it right, where will you find the time to do it over?"

My late Dad always used to tell me that if you do it right the first time, you don't have to do it again. And even as a smart-mouth teenager, I knew he was right. I still give that advice out to people.

BTW, I found the Ripley HSK-19 hole saw available online for $38.99. That's not too bad. I'm planning on a new truck next year, and, yes, I'm going to drill holes in the roof!

 

[AK9R]

Looks like the Ripley HSK-1 includes cutters for both 3/4" and 1-5/16" holes. The HSK-19 just has the 3/4" cutter.

Some of the ads online for the HSK-19 are confusing because they show the HSK-1 with both cutters. But, the catalog on Ripley's website provides some clarification: https://ripley-tools.com/wp-content/uploads/2022/03/Broadband_Catalog_2019_Web_Rev_C.pdf

 

[mmckenna]

BTW, I found the Ripley HSK-19 hole saw available online for $38.99. That's not too bad. I'm planning on a new truck next year, and, yes, I'm going to drill holes in the roof!

Got a link?

 

[AK9R]

Google it, man.

Ripley Antenna Hole Saw Kit - 3/4

Ripley's HSK-19 is designed for use with 3/8″ (9.5 mm) or larger electric drills during the installation of permanently mounted mobile antennas. It's special drill bit prevents the saw from walking & the hole depth is limited to 0.125″ (3.18 mm) to prevent damage caused to the underlying...

www.techtoolsupply.com

BTW, Tech Tool Supply has all sorts of cool stuff for low-voltage installers.

 

[6079smithw]

BTW, Tech Tool Supply has all sorts of cool stuff for low-voltage installers.

Good price. Got mine with only the 3/4" for $45-50 or so in AZ a few years back
as part of a promo sale. May just get another from Tech Tool if its only 39 bucks.

 

[mmckenna]

Google it, man.

Ripley Antenna Hole Saw Kit - 3/4

Ripley's HSK-19 is designed for use with 3/8″ (9.5 mm) or larger electric drills during the installation of permanently mounted mobile antennas. It's special drill bit prevents the saw from walking & the hole depth is limited to 0.125″ (3.18 mm) to prevent damage caused to the underlying...

www.techtoolsupply.com

BTW, Tech Tool Supply has all sorts of cool stuff for low-voltage installers.

I ordered one earlier today. Had trouble finding it via google. Kept finding higher prices.

 

[wwhitby]

Google it, man.

Ripley Antenna Hole Saw Kit - 3/4

Ripley's HSK-19 is designed for use with 3/8″ (9.5 mm) or larger electric drills during the installation of permanently mounted mobile antennas. It's special drill bit prevents the saw from walking & the hole depth is limited to 0.125″ (3.18 mm) to prevent damage caused to the underlying...

www.techtoolsupply.com

BTW, Tech Tool Supply has all sorts of cool stuff for low-voltage installers.

Sorry, I should have posted a link in my original post.

The company that AK9R shared was the same on that I found.

Knowing how I am, I'll probably order it just as soon as the price goes up!

 

[krokus]

I noticed the description of the HSK-19 says the shoulder will score the paint, for better grounding. My thought was that I want to not leave bare metal on the weather side of the mount, to avoid future corrosion. Am I missing an advantage to the scoring?

 

[6079smithw]

I noticed the description of the HSK-19 says the shoulder will score the paint, for better grounding. My thought was that I want to not leave bare metal on the weather side of the mount, to avoid future corrosion. Am I missing an advantage to the scoring?

The shoulder is designed to remove a small amount of paint around the hole. The mounting flange nut has a groove on
one side with a O-ring. The ring is a bit larger diameter than the unpainted surface and is installed facing downward.
This acts as a moisture seal for the hole and the unpainted surface. This feature is one reason why the saw is kinda costly.

I've done a bunch of installs with this tool over the years and have yet to lose a ground from leaks or corrosion. $$ well spent.

 

[KC8ONR]

I noticed the description of the HSK-19 says the shoulder will score the paint, for better grounding. My thought was that I want to not leave bare metal on the weather side of the mount, to avoid future corrosion. Am I missing an advantage to the scoring?

From my experience of using this saw i have never noticed any scoring of the paint on the outside, then again I don't use any pressure at all , I let the saw do the work. I do use a small piece of emery cloth to clean the hole a bit , I also sand the underside where the ground will be. Most of the ground is on the underside anyway

 

[AK9R]

I also sand the underside where the ground will be.

With the Larsen NMOs that I've installed on my personal vehicles, making a good ground on the underside seems more important than grounding on the top side. Of course, you have to have access to the underside. If working from the top side, I suppose a small strip of sand paper wrapped around an index finder would do the trick.

 

[6079smithw]

I also sand the underside where the ground will be.

Good practice, not just for the ground but also to remove any burr or high spots on the edges.
Be careful though, that edge can bite your finger which hurts like hell. (I speak from experience.)

 

[krokus]

The underside was what I understood to be the important part, with the topside mainly being weather seal. I have used primer, or touch-up, along the rim of the new hole. Also preferred to use some type coating on the underside connection, the prevent oxidation. (Such as small amount of anti-seize, or battery terminal treatment.) That might be the Navy conditioning coming through, as salt eats everything it can.

From my experience of using this saw i have never noticed any scoring of the paint on the outside, then again I don't use any pressure at all , I let the saw do the work. I do use a small piece of emery cloth to clean the hole a bit , I also sand the underside where the ground will be. Most of the ground is on the underside anyway

With the Larsen NMOs that I've installed on my personal vehicles, making a good ground on the underside seems more important than grounding on the top side. Of course, you have to have access to the underside. If working from the top side, I suppose a small strip of sand paper wrapped around an index finder would do the trick.

 

[ra7850]

I never even though to mention (I forgot I even had it) I have the panorama moon roof so I can only get it installed about 4 inches into the roof behind the rear brake light. Knowing this, is roof mount still advised?

I had that problem, the installer said its a non issue. I had him drill 2.