Cutting soundhole in carbon?

Bax Burgess · #1 09-23-2018, 07:05 PM

Resale value is not a concern. How well/easily does carbon cut? I could use a Forstner bit, if that's a good way to go. It's a Rainsong.

Earl49 · #2 09-23-2018, 07:11 PM

Your best bet is to call Dave at Rainsong, or alternately Joe at Blackbird and ask about it. (My Blackbird Lucky 13 has a 2½" diameter side sound port which was obviously cut into the upper bout after the body was laid up in the mold). And my Rainsong has a square barn-door for the Fishman electronics.

Other places to enquire would be a local auto body shop that works on Corvettes or maybe a boat shop.

mirwa · #3 09-23-2018, 07:38 PM

You want a hole cutter with fine teeth.

Steve

Bax Burgess · #4 09-23-2018, 08:19 PM

The Forstner bit has a keen edge, which I'll figure approximates fine teeth. And Earl, what is the quality of finish around the soundhole edge?

Otterhound · #5 09-23-2018, 08:57 PM

Carbon fiber shards will lodge themselves in your lungs if you do not use proper protection . They are very sharp , and once lodged , will remain so .
If you do attempt this , please use proper protection .

Bax Burgess · #6 09-23-2018, 09:10 PM

Thanks much.

BT55 · #7 09-23-2018, 10:06 PM

Nevemind - wrong answer to your question.

mirwa · #8 09-23-2018, 10:28 PM

I wouldn’t use a Forster bit personally.

Steve

Bax Burgess · #9 09-24-2018, 01:18 AM

The dust sounds nasty. I might be doing this with a hole saw and brace drill.

jonfields45 · #10 09-24-2018, 11:03 AM

RainSong sides are a single layer of CF with extra CF or glass reinforcement at the neck and end pin. The top and back are a sandwich with a significant spacer. RainSong glues the inside and outside CF (glass for inside of the back for some models) layers directly together at the edge of the spacer leaving no spacer exposed (take a look at the sound hole or the internal edges of the top and back). I don't think you want to cut into that sandwich material.

Bax Burgess · #11 09-24-2018, 12:20 PM

I've just now felt along the inner edges. The sides have an inner layer, not as thick as top & back, not a sandwich as you said, but definitely layered. I'm going to take Earl's recommendation and contact Dave at Rainsong. Glad that I didn't blindly jump into this.

Bax Burgess · #12 09-24-2018, 12:39 PM

Chatted with Dave. Cutting into the side, at Rainsong they use cutters, ones with diamond coated teeth. Since this is a one time job, he said I could use a new, non-diamond hole saw. I'll use a drill bit to open a starter hole, then use a hole saw with the drill bit center to open a 3/4" hole.

Seagull S6 · #13 09-24-2018, 01:12 PM

Remember to drill at a slow RPM with moderate pressure. CFRP is some tough stuff and can dull cutting tools quickly if you use high RPM's and light pressure.

Bax Burgess · #14 09-24-2018, 03:31 PM

High rpms with light pressure dulls the teeth faster than using moderate to heavy pressure? I won't be kicking up the dust with high rpms, but wouldn't have figured that.

BT55 · #15 09-25-2018, 10:01 PM

Quote:

Originally Posted by Seagull S6

Remember to drill at a slow RPM with moderate pressure. CFRP is some tough stuff and can dull cutting tools quickly if you use high RPM's and light pressure.

I just Googled drill speed for CF and 3000-5000 RPM is recommended.

I own a Rainsong H-OM and it’s a great guitar and I understand your desire to add a sound port. But if you were to sell the updated guitar would the sound port reduce the guitars value?

I would recommend selling the Rainsong and buying an Emerald. I think that the OEM soundhole would provide what you are looking for and you’ll have an unmodified guitar.