Valve cap with carbon fiber inset

[muschem]

A few months ago, I worked with Matt Frost (https://www.frostcustombrass.net/) to have a couple sets of valve caps made for the Instrument Innovations rotors on my Butler C10 and C12. One set was light-weight, made out of delrin, and the other heavy-weight in solid brass. Matt was great to work with. Both sets look and fit wonderfully, and I had some fun trying various combinations to see what differences I could notice in response and sound compared with the original caps.

Not content to leave well enough alone, I had the crazy notion to see if a cap could be machined out of a thicker block of carbon - either layered carbon fiber sheets or forged carbon fiber block. I was looking for something that would complement the carbon fiber material used in the Butler horns. Matt was kind enough to humor me and give this a shot. Unfortunately, the experiments didn't work out well, which is not in any way a reflection of Matt's machinist skills - it turns out this sort of carbon material simply isn't a great material for holding fine threads, and it chips and becomes somewhat fragile as the wall thickness decreases. C'est la vie.

It then occurred to me that we could achieve the aesthetic impact of carbon fiber without needing to use a block of carbon as the base material. I asked Matt if he was game to try one more iteration - a solid brass cap, but with an inset on the facing side, which could hold a carbon fiber inlay. Matt knew exactly what I meant, and turned out another cap to test lightning fast. Here's how the three variations compare (top - delrin, middle - brass with flush surface, bottom - brass with inset):

ValveCapComparison_sm.jpg

The dimensions looked perfect for the material I had ordered to test. After I measured the inset diameter, my wife used her Cricut (https://cricut.com/en-us/) to cut out a circle in vinyl, which I could use as a template for cutting the inlay:

VinylInsetTemplate_sm.jpg

For the inset, I chose a twill weave veneer with adhesive backing from Dragon Plate - https://dragonplate.com/twill-weave-veneer. The veneer is thick enough to lay nicely flat, but thin enough to cut easily with hand shears. It is fully finished with epoxy resin, as opposed to prepreg fabric, which can be somewhat tacky and difficult to work with. I cut the inset just slightly larger than necessary, and then sanded the edges until the inlay fit nice and snug in the inset:

Cutout_sm.jpg

Here is the inlay inserted after sanding:

BeforeTopLayer_sm.jpg

This would probably be fine as-is, but I intentionally had Matt make the inset deeper than necessary, as I planned to pour a top layer of epoxy after placing the inlay. For the top coat, I had some Norland 61 laying around from a different project (it is great for setting tritium vials into flashlights and other gear), and I didn't need much to bring the inlay surface flush with the rim. This is a UV-cured adhesive, which is very nice, as it isn't as viscous as some other craft epoxies, and you don't have to worry so much about bubbles, heat, and long cure times. About 10 minutes exposure to UV (I use this UV light, but it is a bit overkill for small projects: https://www.amazon.com/gp/product/B0863HD955), the adhesive is set and ok to touch. It fully cures within about 7 days. Here's how it came out:

AfterResinCoat_sm.jpg

It is difficult to capture in a still image, but the inlay has a nice 3d effect as you move it and the woven fibers pick up light from different angles. I'm debating whether to give the brass body a quick spray of lacquer or just leave it to patina over time. Either way, it was a fun project, and pretty easy to DIY the inlay once Matt did the hard part of machining the body of the cap. I'll be ordering more now that the proof-of-concept worked well. Once I have a matching set, I'll take some pics of them on my C12.

[HawaiiTromboneGuy]

Wow, these caps look amazing. I’m a huge fan of carbon fiber and have a bunch of pieces on my car. It looks like this is a 2x2 weave that was used?

[WGWTR180]

I like!!!

[muschem]

It looks like this is a 2x2 weave that was used?

Yup, 3k 2x2 twill weave. Matches pretty well with the CF Butler uses on their horns.

I like!!!

Thanks!

I think the inlay idea could be pretty neat beyond just carbon fiber. You could have makers' marks, school logos, monograms, custom graphics, or just cool looking colored resin or other infills. Lots of options. The same notion probably works for finger buttons on valved instruments.

I have more on the way, but here's a couple shots of the one CF cap on my bass:

IMG_4749.jpg

IMG_4750.jpg

[WGWTR180]

As long as the weight can match up with my rotor cap I’d be interested.