What size/type bit needed for NMO mount and hideaway strobe?

rwo978 · Post by **rwo978** » Tue Jun 01, 2004 6:58 am

Going to be getting a new vehicle soon and looking at doing the antenna mounts myself, instead of paying almost $100 for them. Probably going to have 3 or 4 NMO roof mounts. What size/type of bit do I need? Where are these available and what is the cost average? Also, can the same bit be used for hide-away installs, or does that take a different type and/or size.

joe1234 · Post by **joe1234** » Tue Jun 01, 2004 7:13 am

The NMO takes a 3/4 hole I use a varybit you can get theses at any lowes or home depot or somthing like that... cost for a varbit ranges from $30 to $50 make sur it can do at least 3/4 as for the hideaway strobes it takes 1 inch... I use a 1 inch hole saw but a vary bit that does 1 inch will work and is much easier to clean up... but to find a vary bit that does 1 inch is not cheap............nmo 3/4 strobe 1 inch

JohnWayne · Post by **JohnWayne** » Tue Jun 01, 2004 7:34 am

Most strobes take a 1" bit. Get a good hole saw to do the job, like a Lenox. As for the NMO mounts in the roof, don't bother with a Varibit or anything that you get from Lowes/Home Depot. Use only the correct tool, which is an NMO hole saw. Using a regular bit on a roof is a good way to ruin a headliner.

I have the NMO hole saws on sale this month for $17.60; normally $22.00. Plus you can use the BATLABS coupon code to save another 10%. You can get them at:

http://shop.waltel.com/cgi-bin/store/co ... temid=HS34

Thanks,
Jeff

c17loadsmasher · Post by **c17loadsmasher** » Tue Jun 01, 2004 7:24 pm

And when you do drill the holes for the strobe, have a shop vac handy....I've seen people drill the holes and they can't get all the little plastic shavings out. If you have a shop vac right there you can catch the majority of the shavings before they make it into the light assembly. Someone else out there may have some other tricks. Either way, the shavings look like crap if they're all up in the light assembly.

ccomm911 · Post by **ccomm911** » Tue Jun 01, 2004 7:32 pm

Beat me to the punch on the shop vac - a must have when drilling hide-a-ways - Especially on the newer style headlights that are made of a composite material rather than traditional plastic. Another idea for the NMO hole, you can also use the shop vac for this as well - just be VERY CAREFUL not to let the nozzle of the vac drag or rub across the roof if any shavings exist. Or, wrap a shop towel in a circle around your mark befor you drill, then vacuum out around the towel. One more thing - yes, the Antennex 3/4" hole saw is also a must have - no more punctures head liners with this awesome tool! You'll only do it once then go out and by one! Stay safe all. Just my .02 worth.

thebigphish · Post by **thebigphish** » Tue Jun 01, 2004 9:41 pm

a little compressed air and one of those bendy-straws for the can does an excellent job getting drill-leavins from out of the fluted lenses that some new cars have, that and the shopvac are definately necessary...

eboe · Post by **eboe** » Wed Jun 02, 2004 3:13 am

maybe it's just me, but who drills through the roof with the headliner in place? how do you plan on running the wire if you never take the headliner down? my headliner comes down first, then i look at the underside of the roof skin to plan the location, then i drill. sure, those nmo saws are nifty and they clean the area around the hole in a nice neat circle, but for me a regular hole saw works fine. ...and they're easy to find.

wa2zdy · Post by **wa2zdy** » Wed Jun 02, 2004 4:33 am

Or if you have access to both sides of the sheet metal, a 3/4 inch Greenlee chassis punch works very well. Again, you need access to both sides of the metal, like a trunk lid or with the headliner down.

That deal from John Wayne looks good. If I were still doing much in the way of installs, I'd buy that hole saw from him.

Good luck.

jhooten · Post by **jhooten** » Wed Jun 02, 2004 4:53 am

Take out the dome light and drill the hole from the inside out. You can snake the cable from the dome light cut out in the head liner to the b-piller with no problems.

If you do drill from the outside in, cover the area around the soon to be hole with masking tape before you drill. Keeps metal shavings from imbedding themselves in the paint around the hole and helps to keep the edges from chipping.

jim · Post by **jim** » Wed Jun 02, 2004 4:45 pm

Pulling a headliner is a waste of time. I never had any passenger car/SUV that required doing this. Pull the liner on a new Suburban with rear AC controls and overhead console and you'll be there for 2 hours. In that time, I can install antennas in 10 of these vehicles.

As for a Greenlee punch....another waste of time. Sure, it makes a beautiful hole, but takes 400% more time and besides, the hole gets covered with the antenna regardless of what produced it. If you were making a hole whose diameter or looks were very critical, there's no substitute for the Greenlee. A holesaw may leave a slightly jagged ID to the hole, but you're done in 20 seconds and the NMO fits it!

apco25 · Post by **apco25** » Fri Jun 04, 2004 11:50 am

But Jim,

quality and time can be balanced.

I'd rather install a perfect NMO than a jagged, ragged hole that will end up rusting quickly.

I've seen so many cars "ripped" into with dull hole saws, rough cuts and the like its sick.

I would argue a greenlee doesn't take 400% long to do. Maybe a mintues worth of work if that?

drill hole, insert punch, turn punch done

And if you want really fast then the UNIBIT works perfectly.

Bob W · Post by **Bob W** » Sat Jun 05, 2004 7:43 am

wa2zdy wrote:Or if you have access to both sides of the sheet metal, a 3/4 inch Greenlee chassis punch works very well. Again, you need access to both sides of the metal, like a trunk lid or with the headliner down.

That deal from John Wayne looks good. If I were still doing much in the way of installs, I'd buy that hole saw from him.

Good luck.

I agree - The Greenlee chassis punch cuts beautiful holes, but you have to make sure that the one you get REALLY cuts a 3/4" hole. If you walk into HD or LOEWS and get the one marked 3/4", you will cut a 1 1/8" hole. If you get the 1/2" one that they sell, you get a 7/8" hole. The one you want is 730BB-3/4. The Antennex or Moto saws claim they clean the paint around the hole. I'm not convinced this is a positive thing. I've seen several instances where enough moisture has gotten under the mount to let the rusting begin. I always seem to get good electrical contact (yes, I check) with A/S NMO mounts using the Greenlee punch. This is on Electric line trucks where everything gets rattled to death.

wa2zdy · Post by **wa2zdy** » Sat Jun 05, 2004 1:01 pm

Bob W wrote: . . .I agree - The Greenlee chassis punch cuts beautiful holes, but you have to make sure that the one you get REALLY cuts a 3/4" hole. If you walk into HD or LOEWS and get the one marked 3/4", you will cut a 1 1/8" hole. If you get the 1/2" one that they sell, you get a 7/8" hole. . .

Huh?

I've never heard of this phenomenon. I have a 3/4" chassis punch that just happens to make 3/4" holes. Then again maybe there are rip-offs out there that aren't actually made by Greenlee. Mine is.

Post by **HumHead** » Sat Jun 05, 2004 3:12 pm

Greenlee manufactures primarily for the electrical contracting trade.

They use two different sizing conventions, depending on the product: hole size, and conduit accessory size.

A .750 Greenlee puch will make a 3/4" hole. A 3/4" Greenlee punch will make an appropriately sized hole for a fitting for 3/4" ID conduit, which will be comfortably larger than .750"!

Just have to know which tool you are buying.

Since I only make a couple of antenna holes in (my own) vehicles every year or two, I take the time to use the Greenlee punch. I then stick a Dremel tool with a grinder bit through the hole and grind the underside of the roof clean in the two spots where the mount touches, and I'm off. No rust, no leakage, no exterior paint damage.

It's probably way too slow for volume work in a shop, but for your own personal ride, why not put in a little extra time for the best possible job?

wa2zdy · Post by **wa2zdy** » Sat Jun 05, 2004 8:25 pm

Thanks Humhead. Now ya know, I didn't know that. I know little about the electrical business. As many here know, electrical and electronics are two VERY different animals!

Now you've got me thinking. . . unfortunately, my punch is in my toolbox and that's not here. So I can't look. But I will look at it just for jollies. I actually will confess, I'm thinking it may well say .750 on it, rather than 3/4. I of course mix the terminology, but now knowing what you just said, I realise there's a difference.

Hmmmmmmmmm . . .

Yes, as I said, the chassis punch requires access to both sides, and that hole say John Wayne pictures on his site does look like a great tool. But for me the chassis punch has always worked.

Thanks for the info, I'll be looking at my punch when I get to it.

rwo978 · Post by **rwo978** » Sun Jun 06, 2004 9:23 am

Thanks for all the responses. Guess I'll have some shopping around to do to find the right tool for the job. Don't want a hack job either, so we'll see what happens.

Wes · Post by **Wes** » Sun Jun 06, 2004 10:52 am

My question is why would anyone want to drill a 3/4" hole in their roof when you can go with the 3/8" mounts and have lots more stabilization in thin roof metal.......

The only way I put a 3/4" mount in a roof anymore is if I am out of 3/8" mounts......

My $0.02

Wes

What size/type bit needed for NMO mount and hideaway strobe?

What size/type bit needed for NMO mount and hideaway strobe?

Mount Sizes

NMO/Hide-A-Way Holes