best way to make holes in hull?

[JRK]

The thread below about filling holes suggested to me that I ask about making holes. I need to make 2 holes through the hole, about 5/8", for a ham radio antenna cable. I have a bulkhead mount to affix in the holes where the exterior antenna attaches to one side and the radio attaches to the interior side. I have a hole saw, and before I get to cutting into the hull, was wondering if others have done so and have recommendations on best practice. I plan to go through one surface at a time, because I am not sure what I will find between the hulls. I plan to make the holes at the smaller dinette on the Oliver I, single axle model. 

[Geronimo John]

I like using a fine tooth circular hole saw.  Cut softly into the fiberglass to slowly penetrate.

GJ.   

[Steve Morris]

40 minutes ago, Geronimo John said:

I like using a fine tooth circular hole saw.  Cut softly into the fiberglass to slowly penetrate.

GJ.   

Long ago when I had boats, I'd run the hole saw backwards to cut through the gelcoat, then forward though the fiberglass. This almost always eliminating chipping.

Edited May 23 by Steve Morris

[John Dorrer]

5 minutes ago, Steve Morris said:

Long ago when I had boats, I'd run the hole saw backwards to cut through the gelcoat, then forward though the fiberglass. This almost always eliminating chipping.

Tape the surface to be cut or drilled

Edited May 23 by John Dorrer

[SeaDawg]

1 hour ago, John Dorrer said:

Tape the surface to be cut or drilled

And, start with small, sharp bit at low speed. Expand.

[CRM]

10 minutes ago, SeaDawg said:

And, start with small, sharp bit at low speed. Expand.

I always start with a very small bit, then a counter sink bit until the gel coat removed is slightly larger than the final hole, then finish with the final size drill bit. This has worked every time for me- so far...

[DavePhelps]

Another option, and one that I prefer to traditional saw toothed hole saws, are diamond grit hole saws.
The hole is much cleaner and smoother, there is no chipping of the gelcoat, you have much more control with the cut, and no drama of worrying about the holesaw catching an edge and torquing your hand off or marring your work piece...especially on the larger holes. 5/8" will not be a worry with that here.

5/8" is pretty small, these probably won't have a pilot drill, but you can still use them effectively with the proper technique, or using a template as a guide. If you are set up to use Lenox hole saws and have the mandrel for it (and 7/8" isn't too big) I'd consider this:

https://www.amazon.com/DG-HOLESAW-14DG-22-2MM-PK/dp/B002QMK8VQ/?_encoding=UTF8&pd_rd_w=Ou7U8&content-id=amzn1.sym.a725c7b8-b047-4210-9584-5391d2d91b93%3Aamzn1.symc.d10b1e54-47e4-4b2a-b42d-92fe6ebbe579&pf_rd_p=a725c7b8-b047-4210-9584-5391d2d91b93&pf_rd_r=EGJYD83A35XQGWK1X3ST&pd_rd_wg=HMKiX&pd_rd_r=ea23425b-78dc-49b7-9ce2-921c2afd6922&ref_=pd_hp_d_atf_ci_mcx_mr_hp_atf_m&th=1

Otherwise, I'd still get a 5/8" diamond grit (Bosch makes great smaller bits) without the pilot bit. Use water from a spritzer when drilling!

Dave

 

 

[MAX Burner]

Here's a clean install for your SO-239 and ground connection for your rig on the interior wall...

FYI, we always use a spring punch on the gelcoat prior to any drill bit action:

[Ollie-Haus]

A Forstner bit is a very clean way to cut holes in fiberglass. Make a very small pilot hole, 1/8", and then use the size you want the hole to be. Light pressure and run the drill at a medium speed. 

Forstner Bit Set

[Boudicca908]

Thanks to the original poster for this question. I'm not there yet, but hope to eventually follow suit for my ham radio. I haven't done anything to alter my Ollie, yet. Slow and steady, slow and steady. 

[Jim and Chris Neuman]

Agree completely with the hole saw recommendation.  Will add that it must be extremely sharp and of high quality ... recommend bi-metal hole saws of professional grade construction.  Cheap is never worth the cost as you can get hundreds of dollars worth of pissed off when a poor quality tool fails causing you to make a major screw up.  Never more true than with cutting tools.

It may not be possible, depending on the job, but if possible stop just short of complete penetration of the hull and then make a cut from the backside through the existing pilot hole.  This will ensure a clean cut on both sides of the hull as it eliminates exit slivers.

[ScubaRx]

These are what I use for any holes larger than 1/2”. 
 

[topgun2]

1 hour ago, ScubaRx said:

These are what I use for any holes larger than 1/2”. 

WOW!

[JRK]

I said the same thing. WOW. 
thanks for the suggestions. Parks On The Air (POTA) is fun ham radio activity. Hole in the wall will keep the bugs out, maybe. 
I used Forster bits for woodworking. Diamond blade also seems sensible. 
I actually took the trailer to a mechanic for an electrical issue. He has been in the trailer business for more than 30 years, and said that this was the first Ollie has had seen, and that it is the best made plastic trailer he has ever seen. I want to keep it that way. 
john NS6X

[Ronbrink]

On 5/24/2024 at 3:20 PM, ScubaRx said:

These are what I use for any holes larger than 1/2”. 
 

HOLE-E COW BATMAN!

[SNY SD UP]

On 5/24/2024 at 3:20 PM, ScubaRx said:

These are what I use for any holes larger than 1/2”. 
 

Steve,

Are these next to the Lathe & Drill Press when you are under tow???

[SNY SD UP]

Seriously, there are number of 'Hamies' on the forum. 

Bugeyedriver (OL I) MaxBurner (OL II) that have probably done this before.

And ScubaRx could probably alert you as to where best to drill so as to NOT snag anything.

B~Out