Batboard

If you are debating to drill a hole in your car or not, check out this website: http://www.gmrsweb.com/gmrsjeep.html .

Jonathan you gave a good link. For those interested in GMRS that website also hosts pretty much the biggest board for it (along with FRS). It also has some basic repeater building information.

With such great access to the underside of the metal roof, I would have used a 3/4 inch Greenlee punch and avoided the problem with the metal shavings. I would also have gotten a cleaner cut than you get with a hole saw, which is what was used even though it's not specifically mentioned.

But then again, this kind of access is probably one in five hundred.

Tom, W2NJS
...in D.C.
(...veteran of many roof and trunk antenna installations...)

While we are on the discussion of drilling holes in vehicles, what experience do you all have with respect to vehicle leasing companies and permanent antenna installation on the roof.

Assuming, the antenna is removed before return and a plug is placed in the hole.

Every one is scared to put a hole in their roof, but if done correctly, it will never rust out and is way better than mag or glass mount.
I use a magnet to carefully collect the shavings...
I have seen others installs where the shavings were just left there and they RUSTED INTO THE PAINT!
I also added antennas to others install only to discover they didn't put theirs in the MIDDLE!

I agree with Tom, anywhere two sided access is possible, the Greenlee punch is the way to go. I use it for my work. Trunk lids and roof jobs through the interior light are perfect for the chassis punch. As Tom siad, a perfect hole.

Good luck,

what about the Antenex and other 3/4 hold saws

Hole saw cuts are nice but nothing compared to a punched hole. A punched hole is MUCH cleaner with no shavings left over to mess up the paint.

That webpage was great. I never thought to look for the screw hole for the overhead console for removal. I was able to run my first roof antenna on the burb today and it went well. Thanks for the link!

(They hid the screw pretty well, but took 20 sec's to get the console out!)

Are you guys talking about the Greenlee "SlugBuster" Manual knockout punch kits, or something else?

Those Greenlee thingamabobbers work good, huh?

Greenlee makes chassis punches. Ever look in an old radio and wonder how they got those odd-shaped holes in the chassis? That's how. Drill a pilot hole, then assemble the chassis punch on opposite sides with the bolt through the pilot hole, then use a wrench to tighten the punch until it goes through. This is why you must have two sided access to use the punch, but if you have that, the punch is the way to go.


Good luck,

Where do you get these? Sears? Or do you have to custom order them?



-RC-

Sears doesn't have them - Any vendor that specializes in industrial tools will have them. They are the only way to go in thin metal. I generally drop the majority of the headliner when I install on the roof. With todays snap together construction it takes little time to do it. I don't like to mount anything on top of a domelight myself.

Brett

well here in st they can be purchased from Electrical Whole salers

Also i think it is Lowes or Homdepot sells them too


just you have to makew shure you have 3/4 in no 3/4 Conduit punch 3/4 conduit whole is bigger than the 3/4 inch one

Last year I installed an FT90, less the control panel which was up in the front of the car, in my Outback. I used a Greenlee punch to put holes in the cardboard/wood/fabric panels in the back where the radio's bracket was mounted. Really made a clean job out of something which would have been a mess if I'd tried to cut freehand holes for the wires to "come out" and connect to the radio. There was room in the side compartment to put the radio but the FT90 gets too hot for any confined space when it runs 35 or 50 watts. So the radio sits vertically in the "trunk" and does its thing and I have no cooling problems. But the point of all this is the very neat holes the punch made for the several wires (power, speaker, serial control & mic audio, and the antenna cable, to get to the radio.

I believe that the Greenlee pilot hole is usually 3/8 of an inch, BTW.

Tom, W2NJS
...in D.C.

Here's a link where you can by online if you can't find any local to you.
http://www.irvansmith.com/catalog2/part ... ches.shtml

An antennex or similar 3/4" hole saw is so much easier than a Greenlee
punch. Also, a Vermont American step drill works great and doesn't leave
burrs and you can use it to drill other things around the shop ( the blunt
step drill, not the pointed one... it won't catch on the headliner while drilling). What I would do when installing antennas on the roof of vehicles
is I would stick a empty plastic pop bottle up in the headliner while drilling
to keep the headliner away from the drill.

Curt, K8AI

I have probably 100+ Greenlee punches so I am very familiar with them. Some are better than others.
AS to using hole saws, try using the carbide tipped type,
they cut a perfectly clean hole (as good as, if not better than
a punch) and there is a shoulder so you can not over penetrate.
FYI a 1/2"C. hole punch is 7/8" dia. a 3/4"C. hole punch
is 1-1/8". The Greenlees that I have found to be the best
are the "Slugbusters" they split the slug in half. They produce
a very clean hole.
J.B. AD6WX

Greenlee's are only great when they are sharp/new. When they have been used alot, especially when cutting thicker metal, they get dull very fast. We have 18 sets of them where I work, and they are great for some things and suck for others. One problem I see is that in order to use one on a vehicle, you almost always have to remove the headliner, except on applications like that identified in the link.

There is something I really didn't like in the link.....

"When this mount tightens down it makes excellent electrical contact. The bottom of the mount has sharp edges that scratch the inside metal to make good contact."

If you really want to make a good connection/ground for your antenna, take a couple of minutes and sand off the paint on the inside where the NMO mount seats.

I used a drill with a 3/4 inch wood boring bit to drill into the trunk lid of my car.

I used a plasma cutter for the 8 holes in my roof..... too bad that nothing will fit in them.
SG

I hope some of these ideas are not serious,
hard to tell sometimes. Sometimes the
smartest guys/ gals do the funkiest things.
If you shoot your vehicle with a 50 cal. the
hole should be just about right.
J.B. AD6WX

I really did use a wood boring bit to drill the hole...it worked perfect, whats wrong with that?

J.B. if you use a 50 cal and shoot straight up, when it comes down it is a perfect 3/4" hole. Takes alittle practice to get it right.

The other thing you can do, this works very well, is flip your vehicle upside down and lower on the drill, very stable. Requires a very good mount for the drill though.

Measure with a micrometer,
Mark with chalk,
Cut with an axe...

I tried using a torch on the first 3 cars, that ended in disaster, tried the first one from the inside, the headliner went up in flames really fast, did the other 2 from the outside, forgot to check the inside of the cars after cutting the holes..... more flames. The plasma cutter is the hot ticket, just can't get really round holes, I will probably rent a car to get practice on, I saw the local rental lot had a Vette', I could try on that first if they will rent it to me.
SG

Speedbore or auger?
J.B. AD6WX

Sorry, not casting aspersions.
I just have a hard time sometimes telling the difference
between when someones pulling my crank, and when the person posting is using crank, or they are quite serious and just
have a novel method.

J.B. AD6WX

spectragod wrote:I tried using a torch on the first 3 cars, that ended in disaster

You may be joking but I know some people that would try that. In fact, one of them has already had one vehicle of his burn to the ground overnight.

I used what is known as a "Step drill bit" for installing the eight antenna's on my roof. It is a one peice, cone shaped, self-tapping, drill bit that drills in 1/8" increments, from 1/4" to 3/4". I measure/mark where I want the holes, and drill them out without a pilot hole. It works great. One neat thing about the bit is, if your turning it at the right RPM, you can accually see the numbers on it and know what size hole your currently drilling. The only problem(s) I can see, is the fact that it is 1 1/2" long, so you'll have to take down the headliner, and it cost between $30 and $40, depending on what brand and where you buy it. Stays sharp though, I have cut quite a few holes now and it still seems to work well.

~Chad

Chad,
I use exactly the same thing. I have a titanium nitride coated bit, not cheap though. I put electrical tape above the 3/4" mark, that way I can't overdrill. It does a perfect hole. Same thing as you, you of course have to drill a pilot hole. Here is the key, start with a very small drill bit if you are unsure you are in the exact location. This gives you alittle bit of play to move slightly. Then step up in drill size. If you are only putting in one hole, or any hole that you can pull your dome light, etc., then pull the light, etc. and stuff a towel inside the headliner and drill from the top, the towel will catch any chips, etc. and hold the headliner away.

dave

The step bits or uni-bits work well, but trust me
try a carbide tipped bit. They are the item.
Either way, if you want them to last for ever (almost )
try dipping any kind of bit in "CUT-EASE". Its a wax
based cutting aid. One more cool tip (no pun intended)
take a magnetic level and put it on its side as you are
drilling the hole, all the detrius sticks to the magnet.
J.B. AD6WX

I need to make a hole this week on my roof. I can not use one of those step bits due to the location and what is below. Can't I just use a 3/4" steel drill bit and a pilot hole? Why are we making this so complex?

Obviously, I have NEVER drilled into a vehicle roof before, so pardon my ignorance here. If I can't use the bit, I suppose I can try the 50caliber or maybe the torch idea.

I think folks are just offering alternative ways to put the hole in - including the .50 and acetylene torch. Intriguing ideas, the last two.

I've used a pilot hole and a 3/4" bimetal hole saw for the half dozen I've done. Just make sure to clean up the burrs and collect the mess, and you're good to go.

I want to do mine, but when I can, Mother Nature seems to have other ideas!

Good luck.

Gordon

Guys...

It's a hole. You're not making a masterpiece here.


I just use a hole-saw with a pilot hole, I've never had a problem yet, and I've done a few dozen holes.


M

Well 3/4 suck you guys sould try using 3/8 hole mount. better bite on the metal easier hole to fill.

I did it today. Worked out GREAT. I picked up a 3/4" steel hole saw at the hardware store and went to town. I'll have pictures up here once I get the remote head kit and everything installed for the CDM.

Has anyone ever used a wood boring drill bit to drill a 3-4 inch hole? I drilled three of them in the trunk lid of my car and it worked wonderful.

Our chief tried that once on the roof of his Bronco. It totally mauled the sheet metal. It was bent and mangled all around the hole. It took hours to make it all flat and level enough to seal the water out.

I didnt have a problem like that with mine.

That's because you used a Indiana wood bit, not a Conneticut wood bit, they are different, because to the different types of wood that is available in the mid-east and the east coast, hope that answers your question.
SG

I always put a hole in my brand new cars, doesn't matter whether it was a Porsch 914 or my latest, a new Expedition. It's the only way to go, to make sure you are, with hi-power radios that you are transmitting the power out of the antenna and not inside the car, which can play hell with the on board electronics nowadays. A trick I use for those hard to access area above the fiberglass headlines, I use a paper or styrofoam coffe cup to lower the headliner in the area of where I am drilling, it also serves to collect all the drill remants.