Nmo mounts

cbrrider06 · #1 (**permalink**) 05-11-2009, 06:11 PM

Hey I was wondering if a standard 3/4 inch hole saw will work for my nmo mount, or will the diameter of the bit make the hole to big. Any suggestions will be apreciated.

DDan · #2 (**permalink**) 05-11-2009, 06:20 PM

Quote:

Originally Posted by cbrrider06

Hey I was wondering if a standard 3/4 inch hole saw will work for my nmo mount, or will the diameter of the bit make the hole to big. Any suggestions will be apreciated.

Do you or anyone you know have a unibit aka step-drill. That would be a better choice.

FFPM571 · #3 (**permalink**) 05-11-2009, 07:39 PM

Dont use a 3/4 hole saw.. Its too large. The mount will not fit securely. I dont use a step drill bit I use the antenna hole saw . If you have to use a step bit drill only til the mount fits securely and install the cable from the hole into the car not from the mount up through the hole.

tekshogun · #4 (**permalink**) 05-12-2009, 12:39 AM

agreed, antenna hole saw for 3/4" is the way to go

DieselFF918 · #5 (**permalink**) 05-16-2009, 06:24 AM

When I installed my NMO dual band my truck antenna on my truck, I used a standard 3/4 hole saw. Been over a year havent had a single problem with it.

n4yek · #6 (**permalink**) 05-16-2009, 07:33 PM

Quote:

Originally Posted by DieselFF918

When I installed my NMO dual band my truck antenna on my truck, I used a standard 3/4 hole saw. Been over a year havent had a single problem with it.

Thats what I used also, never a single problem or leak in 5 vehicles.

Taloniilm · #7 (**permalink**) 05-16-2009, 10:45 PM

I used a step drill on Wise 87's Tahoe ... no prob's.

wise871 · #8 (**permalink**) 05-16-2009, 10:57 PM

As a TalonIILM said, we used a step drill and the holes were perfect. The NMO fit nice and snug.

kb0nly · #9 (**permalink**) 05-16-2009, 11:09 PM

I like using a Unibit, or step drill as its also commonly called. The nice thing about using one is you can debur both sides of the hole with it also. I usually pull down the dome light in the center of the roof and use a shop vac in one hand and the drill in the other and just drill up through the roof and vacuum up all the shavings at the same time.

If you do it from the top use compressed air to blow away all the filings to keep from scratching the surrounding paint.

Taloniilm · #10 (**permalink**) 05-17-2009, 12:45 AM

I used blue masking tape to avoid scratches and drilled a pilot hole prior to deploying the step drill ...de-burring and final hole sizing was acomplished with the Dremel

tekshogun · #11 (**permalink**) 05-17-2009, 04:55 AM

Quote:

Originally Posted by Taloniilm

I used blue masking tape to avoid scratches and drilled a pilot hole prior to deploying the step drill ...de-burring and final hole sizing was acomplished with the Dremel

Good idea. That's a lot of tape though, but when you want to be careful not to mess up the finish and body, you should do it right. Of course we are talking about drilling a hole into your car. . . .

jim202 · #12 (**permalink**) 05-17-2009, 06:39 AM

Let me ask a simple question here.

If the NMO mount requires a 3/4 hole in the sheet metal, how can a 3/4 inch hole saw be too large?
Maybe my school math taught me some strange back woods way of measuring, but a 3/4 hole saw
makes a 3/4 inch hole. If the NMO mount requires a 3/4 inch hole, the normal person would think
that these 2 would be a match.

After drilling holes in vehicle roofs for well over 40 years now, I must be missing something here.
In some cases, it is hard to get the NMO mounts in if your limited in height or depth below the
surface. A second source of an install issue is when the sheet metal is thicker than the normal
roof.

I still would like you to elaborate on just how a 3/4 inch hole saw is the wrong size. I am loosing
sleep over this. I am wondering just how many NMO mounts that I have installed over the years
that are not installed correctly.

My real choice is to use a hole saw that has been modified to have a ridge welded to it to prevent
you from slipping and going too deep and getting the head liner. Larson even use sell a special
hole saw with a replaceable blade to make the 3/4 inch hole.

Please let the group know just what the problem is when using a 3/4 hole saw.

Jim

Quote:

Originally Posted by FFPM571

Dont use a 3/4 hole saw.. Its too large. The mount will not fit securely. I dont use a step drill bit I use the antenna hole saw . If you have to use a step bit drill only til the mount fits securely and install the cable from the hole into the car not from the mount up through the hole.

W9RXR · #13 (**permalink**) 05-17-2009, 06:56 AM

Jim, it depends on the skill and carefulness of the operator. If a 3/4" hole saw works for you, that's great!

My experience with hardware-store hole saws in sheet metal is that they tend to wobble around and you end up with a hole that's larger in diameter than the saw. On the other hand, I've had great success with a Unibit step drill. I put 10 NMO mounts on the roof of a Ford Expedition with an Irwin Unibit and was very pleased with the result.

The hole saws that the antenna manufacturers (Larsen, Antenex, Maxrad, Comtelco) sell for installing NMO mounts have thinner blades and finer teeth than hardware-store hole saws. Also, these NMO mount hole saws have shorter blades which I think gives the blade more stability and, therefore, result in more precise holes.

FFPM571 · #14 (**permalink**) 05-17-2009, 09:43 AM

W9RXR answered it exactly as I would have..

kb0nly · #15 (**permalink**) 05-17-2009, 10:49 AM

Also the antenna hole saws sold as such are made to go through the thickness of the roof and not much more so it doesn't hit the headliner, but yes, good explanation as i was just about to post the same response.

That's why i like using the unibit instead of a hole saw, less chance of wandering and wallowing out the hole size.

tekshogun · #16 (**permalink**) 05-17-2009, 02:03 PM

very interesting, please keep it coming!

code3cowboy · #17 (**permalink**) 05-25-2009, 12:34 PM

I guess Im lazy but I have the antenex hole saw toy and it works just fine.

dcpaq2 · #18 (**permalink**) 06-14-2009, 12:09 PM

Guys,

I use an antenna hole saw from a company called Ripley out of Cromwell, CT. A very nice saw and even comes with replacement blades.

Doug

vehiclesolutions · #19 (**permalink**) 07-03-2009, 12:32 PM

I use the same hole saw listed above, has worked out well and the repalcable blade is a great idea.

Rob_K · #20 (**permalink**) 07-22-2009, 10:48 PM

I have probably read 50 different posts on many sites about drilling holes for an NMO mount. The best idea seems to be to purchase a drill specifically for the job. So, I bought one.

Here is my question; how come a 3/4" hole is too small for an NMO? I have 2 different NMO cables, one is Antennex and the other is one I got from HRO (Hustler?) and both of them are 1/16" larger than 3/4".

I used my brand new Antennex HS34 to drill a hole through an old cookie sheet. I measured with my tape measure and it is 3/4". The NMO is 13/16" (That is 3/4" + 1/16") and does not fit.

The Antennex cable came with the "fender" bracket and I measured it, 13/16".

I really don't want to have to Dremmel that extra 1/16" on the roof of my vehicle.....

What the heck did I miss?