Ok so I drilled a hole in the roof of my new truck for my nmo coax base. Use a 3/4 still they said, now the hole is to big for the nmo mount. It ended being an 1" size hole. Don't ask me how because the bit was 3/4". My question is how do I fill the gap and make this nmo coax base work?
Thank,
John
Yeah, this happens.
There's a thing called "Trade Size" hole saws. These are designed often for electricians and are designed for drilling holes for conduit fittings.
1/2" trade size is actually 7/8" diameter
3/4" trade size is actually 1 1/8" diameter.
It's critical to understand this when choosing hole saws or chassis punches. It's important, as you've discovered, to know if you are getting a "trade size" or a normal hole saw.
A true 3/4" hole saw will work just fine, same with a true 3/4" chassis punch. The "official" NMO hole saws do work well, and are a good choice.
So, what do you do?
There's a number of options:
Plug the hole with a plastic plug. Done right these work well.
Go to a body shop and have them weld in a plug, as MCore25 suggested. It'll cost, but it'll be done right.
You can get a "thick" NMO mount and a big fender washer and see if you can make it fit.
You can try some of the various ways of patching it, bondo, a JB Weld patch, etc.
If you can get to the underside, you may be able to get a proper 3/4 punch or hole saw and drill a sheet of steel to go on the underside. A similar patch/fender washer, or similar, might work on the outside
It all depends on how good you want it to look.
As they say, lesson learned. Not impossible to fix, but not easy.
Since the top of the NMO mount is standardized, there isn't a different type of NMO mount that's going to make this work.
Good luck, and let us know how it turns out.