UNIBIT and NMO hole mount drilling - Interesting Findings!

apco25 · Post by **apco25** » Fri Jul 04, 2003 10:43 am

Per the previous threads I've picked up one of those fancy titanium nitride coated UNIBITS.

I've used the various NMO hole saws before and greenlee hole punches.

Any special technique or tips in using a UNIBIT? I'm confident in my tool handling abilities - I just want to be sure ahead of time. I don't want to goof up the roof of a 40k dollar truck.

fire-medic8104 · Post by **fire-medic8104** » Fri Jul 04, 2003 4:13 pm

I have found that if you drill a pilot hole the same size as the tip of the unibit it will start and go much easier (when in metal). In plastic it normally will cut through very easily.

FMROB · Post by **FMROB** » Sat Jul 05, 2003 9:44 am

One word of advice, DON'T USE IT......That is for mounting antennas. Yes, It will work, But like you said, you don't want to goof up a 40k roof...The special antenna bits made by antennex, maxrad, cableco, etc. work awesome, and they are much cheaper than those nice uni-bits. Tessco sells a antennex model for about 14.00 with replaceable saw blades....Cuts a perfect hole, cleans a nice ground/o-ring surface, and cuts to the correct depth as to prevent reverse antenna holes through the head liner (also known as the shower nozzle). Unibits can't be beat for fire walls, and espicially I wouldn't even think abot using anything else to cut into a headlight assembly for a strobe tube....Just be careful....But remember, there is a proper tool for every job...

Chato · Post by **Chato** » Sat Jul 05, 2003 10:14 am

Apco, I'm not sure whats Bambinos talking about, those UNIBITS work just fine. I have personally used one many times on sheetmetal (roofs, etc...) without any problems. You can use them with or without a pilot hole. (But a pilot hole sounds like a good idea to me. I have used a #21 drill bit for my pilot holes-slightly smaller then the tip of the UNIBIT.) The headliner is a concern though. The bit that I have is over an inch long. What I have to do is pull the headliner down just a little bit, right where the hole is going to be drilled.

Yes its true that they make tools just for this type of thing, but I like the UNIBIT because I can drill holes in other places that arnt always 3/4", and the UNIBIT makes a perfect hole every-time.

~Chad

TomSlick · Post by **TomSlick** » Sat Jul 05, 2003 12:50 pm

I spoke to a Havis-Shields installer a while back. They use regular hole saw bits (and maybe also UniBits). They avoid problems with the headliner by holding a "paddle" made of plywood behind the spot being drilled.

FFParamedic571 · Post by **FFParamedic571** » Sat Jul 05, 2003 3:09 pm

Ive never seen or hear of using a "Unibit"' for an antenna hole. The commercial hole saws made for that puropse work fine and the chances of going too deep and getting too big of a hole is too risky. I also use a " roof board" Its a 16" x 4" 3/4" plywood with a 1" hole on one end to hang on to it . The wood stops any chance of going too deep.

When I drill strobe tubes I use a regular 1" hole saw. The unibit gets too much debris in the hole. It looks really tacky when you leave the shaving in the corner lights and headlights.

Firewall holes are most often 1 1/4 " for the power side holes and 1" for the strobe cables.

FMROB · Post by **FMROB** » Sat Jul 05, 2003 3:38 pm

CHATO, I always try to drop the headliner when doing an install of multiple antennas,,,,If I am just sneaking a quick one up on the roof and don't want to drop the headliner down is when I get concerned about the headliner getting punctured....Your gonna make me say it, but using a uni-bit is just a million steps closer to causing a semi-abortion of the roof,,,,Installers shouldn't be cheesy, Use the correct tool for the job, it assures a perfect cut every time.

FFP---I agree with you on the uni-bit making alot of shavings, But my experience with the the hole saws is that it will tear the refelctive metal shielding away from the composite lamp assemb....I just turn the HL assembly upside down and blow with low pressure shop air out all of the leftovers....It works well.

FFParamedic571 · Post by **FFParamedic571** » Sat Jul 05, 2003 5:16 pm

Rob, I usually end up using a shop vac to suck out any shavings. Its really a matter of prefrence, I guess. On the other end we get plenty of cars that had been in accidents. The body shop or city garage tries to repair the front hideaway strobes with an 1 1/2" hole and a ton of blue RTV.

apco25 · Post by **apco25** » Sat Jul 05, 2003 7:38 pm

I have several NMO hole saws of the appropriate design. There was a thread a while back talking about the UNIBIT and the clean holes it leaves.

Interesting how the subject gets a totally different response this time around.

I'll be ordering a new NMO hole saw anyway -

I will be dropping the headlinder probably completely down. its in 2 pieces on the 03 suburban so it won't be hard to manage.

OK, what about a true dimensional 3/4 green lee hole punch? Those leave perfect holes and are meant for steel and sheet metal.

nmfire10 · Post by **nmfire10** » Sat Jul 05, 2003 8:28 pm

The times I have drilled holes in the roof, I put a tin can or styofoam cup between the headliner and where the hole is going. Usually the headliner presses the open top of the cup right up to the roof. The bit is drilling through the roof with the cup right under it. It collects the shavings and protects the headliner from damage.

jim · Post by **jim** » Sun Jul 06, 2003 6:53 am

Holesaw w/ pilot $12.00
Antenex antenna saw: $18.00
Unibit $31.00

Having your competitor find out that you ruined a $480.00 headliner in a new Impala because you used a 2" long Unibit and poked through: $PRICELESS !!!!

Use the correct tool!
http://www.antenex.com

FFParamedic571 · Post by **FFParamedic571** » Sun Jul 06, 2003 9:47 am

And you know the price of a new headliner for an Impala why????

Just kidding Jim...

The owner of my shop knows the price for a condenser for a 2003 tahoe really well.. Needless to say the driller no longer works for us..

ab · Post by ab » Sun Jul 06, 2003 11:27 am

I better not see a hole saw near a roof in my shop.

Use the right tool for the job,"Antenex antenna saw" is a very good one.
Unibits are ok for lots of things, like enlarging to make hole and bolt line up on used eq. reinstalls. Some times a holesaw has to be used but only on thick roofs (fire trucks, backhoes, farming), not on pass.veh.
We use a 1x2 board with the ends rounded to put between the headliner and the roof then twist to give more room for cable work if needed. WE always check to see where the roof braces are ,they can change from the last lot you done.We use the antenna saw for all holes on roof for antennas,lightbar,and other. Then we use a air hose to blow off the roof,DO NOT use a brush, it will scratch the clear coat. If you do not remove the metal shaving they will rust ,look bad unpro like. The cup trick will work real nice on vans with no headliners too,just add few inches of 33

I have seen the cheaper (hack) shops work when the their cust. come to us for repair ,sometimes on installs picked up that day and radio has no range.

FFParamedic571 · Post by **FFParamedic571** » Sun Jul 06, 2003 12:06 pm

AB, What do you do for a lightbar cable that is over 3/4" ? Some of the Whelen bar cable is at least 1"? What if the bar has an arrow, do you drill 2 holes?

jim · Post by **jim** » Sun Jul 06, 2003 12:35 pm

A pair of 3/4" holes works fine.

If the cable from a Whelen lightbar is too large, hit it bluntly several times with a 16 pound sledgehammer and tell them they need a better lightbar- like a Twin sonic or Visibeam.

FFParamedic571 · Post by **FFParamedic571** » Sun Jul 06, 2003 12:39 pm

Twin sonic and visibeams were the best 2 12g wires and 2 14g zip for the speaker, maybe 1 more wire for a set of flashers...

Ahh the good old days

ab · Post by ab » Sun Jul 06, 2003 12:59 pm

Sorry,we don' put on junk here. If it is a public safety we do only top self work or they can take their liability down the road.

but Jim is right.yup use 2 holes. and never drill into a b pillar

Post by **Code3Response** » Sun Jul 06, 2003 1:05 pm

Firemedic? Did I used to work for your shop? Ahhh, I was a true dumbass that day. Lemme guess - drilling holes for a speaker bracket on the horizontal brace in front of the condenser, correct? The price is $530 including parts, labor, evac and recharge

FFParamedic571 · Post by **FFParamedic571** » Sun Jul 06, 2003 1:22 pm

AB, Who said anything about drilling a B pillar? The last cars that had a B pillar you could drill were the 90 Caprices or 91 CV's. When I have to drill for a lightbar hole its a minimum 1" hole with a rubber grommet. In the roof. When we pull the B pannel trim which we do anyway for most cars because of the cage. Insert the roof board and drill the hole. No chance of going through the headliner. Since you have the headliner down to insert the board is when you check for roof ribs and wires. If the bar has an arrow on or in it its a 1 1/4" Ive fit a whelen cable and 2 strobe cables with a grommet through a 1 1/4"

Are you using a grommet or just alot of electrical tape and silicone?

Code3... Yep that was the one.. Cost was $600+

ab · Post by ab » Sun Jul 06, 2003 1:52 pm

B pillar in a ford crewcab for 2 14g for an old twinSonic put on by a truck after market parts shop.
Came here for radio install not to long ago. Have you seen the cable ran down the windshield with duct tape on a new dodge yet. Fire briers

"Are you using a grommet or just alot of electrical tape and silicone?" snapins and black GE silicone.

FFParamedic571 · Post by **FFParamedic571** » Sun Jul 06, 2003 2:55 pm

I haven't seen a twinsonic on anything in a while... The closest I have seen is an areodynic last month. The local FD wanted it on a new pick up. It hadnt been inservice since the mid 90's It showed broken lenses, rusty hardware and 3 burnt out bulbs. We made them a deal to refurbish an all light street hawk for the cost of trying to fix the areodynic. The last guy they went to quoted them $700 install of the beat up bar, siren and radio install.. we did all that and got them a good refurbished bar and added a headlight flasher..

I have seen some serious Hack work, The big MSS here if they cant fit the speaker in the grille of a unmarked car ... Hey just attach it to the underside of the back bumper..

jim · Post by **jim** » Sun Jul 06, 2003 4:04 pm

I like that "speaker under the back bumper!"
I just found a CVic with it's Federal speaker mounted in front of the radiator with a wire tie through one hole and a bungee around the entire thing! It was put there by a dealer "installer."

jim · Post by **jim** » Sun Jul 06, 2003 4:06 pm

Um.....by the way, the Twin Sonic thing was a joke.

Post by Pj » Sun Jul 06, 2003 4:36 pm

FFParamedic571 wrote:AB, What do you do for a lightbar cable that is over 3/4" ? Some of the Whelen bar cable is at least 1"? What if the bar has an arrow, do you drill 2 holes?

I had a 9622M08 which had three cables...power, control, and traffic advisor. All fit without much of a problem in a 1 inch hole.

spectragod · Post by **spectragod** » Sun Jul 06, 2003 6:36 pm

Pj wrote:
FFParamedic571 wrote:AB, What do you do for a lightbar cable that is over 3/4" ? Some of the Whelen bar cable is at least 1"? What if the bar has an arrow, do you drill 2 holes?
I had a 9622M08 which had three cables...power, control, and traffic advisor. All fit without much of a problem in a 1 inch hole.

You can drill a 1" hole and use a 1" plastic push in grommet, been there, done that.

SG

Twisted_Pear · Post by **Twisted_Pear** » Tue Jul 08, 2003 10:29 pm

I highly recommend the Antenex hole saw ("X-Act Hole Saw"). It does the job right and fast. I wouldn't choose anything else for any type of NMO mount, unless it's really thick metal. Then I would use a step-bit if the clearance provided it.

Check it here.

-Wayne

gtl7001 · Post by **gtl7001** » Wed Jul 09, 2003 5:21 am

A 40K truck is a lot of money to be experimenting with. You didn't say if this was your personal vehicle or an agency vehicle. If it were an agency vehicle I think all the suggestions posted will work, it really depends on your familiarity with the equipment . I wouldn't feel comfortable trying out a piece of equipment for the first time on a 40K truck. Perhaps a practice run on a junk car. A second alternative if this is your personal vehicle is to purchase one of those no drill trunk lip mounts. It doesn't look as professional but at least it will not leave a hole in your personal vehicle and most of them have rubber feet to protect the vehicle paint. Good luck.

Post by **Code3Response** » Wed Jul 09, 2003 7:14 am

LOL. It is his personal vehicle, a 03 Suburban. I dont think you can fit 7 antennas on lip mounts on one of those!

apco25 · Post by **apco25** » Wed Jul 09, 2003 9:03 am

I have installed at least 100 NMO mounts on various vehicles, personal and government over the years.

I'm not shy about drilling holes, hell I already put a door mounted unity spotlight and drilling that hole was 4 hours of work to do it right.

The point is I want it done the right way and if that means I put extra work into it I will. I take the extra steps on any project to make sure its perfect.

I've decided to compromise with 4-6 NMO mounts on the roof and any secondary bands will be on glass mounts.

I may in fact use the maxrad dual band coupler or the austin triplexor to squeeze several radios on to one antenna.

The last truck I owned had 8 antennas.

spectragod · Post by **spectragod** » Wed Jul 09, 2003 11:23 am

Daggone, just 40K, you must have gotten a deal on yours, mine was 45K plus the extra's.

SG

apco25 · Post by **apco25** » Wed Jul 09, 2003 1:09 pm

yeah I did get a hell of a deal. knew the dealership owner - that helps a bunch.

I didn't order any of the doo dad type options, put all my money in all of the 3/4 ton mechanical options they had, like upgraded wheels, off road tires, plow prep, extreme towing package,lift gate, , running boards, locking differential.

Things i choose not to order

onstar ($800 dollar cell phone?)
XM radio
Quadra-steer (probably mucho expensive when it breaks and the issue of extra tirewear.)
luggage rack (gets in way of antennas)

ordered LS interior instead of LT which for 5k didn't appear to be worth it for power adustable pedals, heated leather seats and some other silly stuff.

LS is just as nice and i still got the BOSE audio with in dash CD-changer.

Twisted_Pear · Post by **Twisted_Pear** » Wed Jul 09, 2003 8:52 pm

No lockers?! Oh well, I guess you won't off-road it too much.

-Wayne

k4wtf · Post by **k4wtf** » Thu Jul 10, 2003 2:32 am

apco25 wrote:yeah I did get a hell of a deal. knew the dealership owner - that helps a bunch.

$38K for my 2003 4wd w/lockers in LS trim. It does have the adjustable pedals. They're....neat. I have actually used them on long trips when to relieve arm fatigue, I moved closer or further from the steering wheel.

How easy is it to remove the headliner? I'm considering several maxrad low profile antennas. Any tips on the headliner, where to mount the antennas and an easy route for the coax is greatly appreciated!

deleted the luggage rack, running boards, locking differential.

With exception of the luggage rack (which I'll never use but, it will help hide the maxrad antennas), those are the options that I appreciate the most on the 2003 when compared to the 2000 I had. The locking diff makes a huge difference. The running boards are nice too.

What I miss from my 2000: The center console (the '03 has 60/40 bench), the lights under the mirrors, the cargo-doors vs liftgate.

Things i choose not to order

onstar ($800 dollar cell phone?)
XM radio
Quadra-steer (probably mucho expensive when it breaks and the issue of extra tirewear.)

I have no need for onstar or XM but, quadra-steer would be nice on a daily basis getting into or out of my garage/driveway.

--
John

Susan157 · Post by **Susan157** » Thu Jul 10, 2003 6:14 am

WE have used Knock Outs
We have used Uni-Bits
We love the 3/4 inch hole saw.

UNTIL the Uhf 3 db gain base loaded
antennas came back completely ripped
out of it's hole.4 different TRUCKS.
They went through the local CAR
wash.

We now use the uni-bit and make the hole
3/8 wide and 5/8 long (About)for these installs.
We turn the antenna kit 90 degrees to the
5/8 hole and now it is resting across the 3/8
hole. No more returns for installs.

apco25 · Post by **apco25** » Thu Jul 10, 2003 8:13 am

Um no, I have the locking dif and ALL the other mechanical options.

I deleted the luggage rack. sorry for the missleading post

apco25 · Post by **apco25** » Thu Jul 24, 2003 3:39 pm

Well, the UNIBIT - HOLE SAW debate continues.

I'm about a day away from mounting the antennas on the truck so I did a comparison of the unibit VS the antennex X-act hole saw.

I used almost identical thickness sheetmetal to the roof and found out the following.

The UNIBIT by far made a true circular hole, with no burs, tears or sharp inners edges - smooth clean hole that was perfect.

The Antennex saw produced a slightly more irregular hole, no where as clean either.

The NMO fit exactly inside the UNIBIT hole, while the antennex hole saw left some play with the ID of the hole.

I made several test holes with each bit, and clearly the UNIBIT came out on top.

FYI, I'm using a UNIBIT with a MAX depth of 3/4 so it is not as deep a bit as some of the larger dimensional models.

I tired the bits in both a drill press and free hand and the suggested RPM.

The UNIBIT was Titanium-Nitride Coated for hardness.

apco25 · Post by **apco25** » Fri Jul 25, 2003 9:16 pm

The antennas all 6 of them are done and installed as of today!

Finally getting somewhere with the install. I'll throw up another post with pics tomorrow.

and for the record the UNIBIT worked flawlessly with no problems at all on the suburban's roof.

Post by **Code3Response** » Fri Jul 25, 2003 10:16 pm

Cool. Look forward to seeing the pics! Im assuming you dropped the entire headliner? Do you have the rear air package? That was a pain to dropping the headliner due to the air channels running THROUGH the roof.

apco25 · Post by **apco25** » Fri Jul 25, 2003 11:31 pm

I have the luxury of dropping the rear portion of a 60/40 split headling on the suburban.

I didn't have to mess with the AC ducts or the front headliner at all.

That was part of the reason not to mount then all in a row to the front.

So all the antennas are mounted in the section and a lot less work.

6 fit with 24 inch spacing nicely.

Chato · Post by **Chato** » Thu Sep 30, 2004 3:41 pm

See.... I told you the UNIBIT works the best! (told ya so, told ya so.... j/k)

~Chad

Primesite · Post by **Primesite** » Thu Sep 30, 2004 5:36 pm

Jeez, Chato....
It's nice to collect your thoughts before replying, but 14 months to say 'told ya so'?
That's gotta be a record.

j/k

UNIBIT and NMO hole mount drilling - Interesting Findings!

UNIBIT and NMO hole mount drilling - Interesting Findings!

UNIBITs work fine...

Using the right ToolS for Mounting of Antennas.