LinnStrument Dark Mod

[Roger_Linn]

I understand, Frank. The problem is that the stock playing surface has the correct thickness and softness to correctly spread the force of the screws evenly to all positions between them, thereby insuring that all of the touch sensor's electrical contacts are correctly pressed against the mating contacts on the circuit board beneath it. It would be difficult to find a similar solution.

One option would be to cut the center playing area out of a stock LinnStrument sheet, then place it on top of your sheet of thin film, then attach the stock top panel and screws. This would insure that all of the touch sensor's contacts make correct electrical contact, while allowing the playing surface to have only your desired thin film above the touch sensor and nothing more. And the stock sheet is only $60 + shipping, which is cheaper and easier than buying and cutting a custom sheet and custom top panel.

[FranklyFlawless]

I did contemplate about that idea for quite a while. It would work, but I have other modifications in mind other than just the alternative playing surface. Like Lars earlier in this thread, I do not want labels on the top panel, but instead of removing them or reversing the panel, I can fabricate a custom top panel instead. This also raises questions about what I actually want to do about the isolated column, which I have not answered quite yet, but I have plenty of unrefined ideas.

[Roger_Linn]

That’s fine, Frank. I’m happy to help if you have any questions.

[LarsDaniel]

Hi Roger,
If one found a suitable sheet of silicone for a no-grid playing surface, I am wondering about the coating that is on the stock surface: What type of product and process is that? Is it a readily available product, and how is it applied?

The other reason for asking is, that on my linnstrument I can feel a difference between the not-so-used corners (they have the nice new-surface-feel) and the more used center part, where it is clear that the surface is a bit more sticky. It is not a problem yet, but I can imagine that it will get to a point where I need to do something. And that something *could* be to re-apply coating, *if* that was possible.

[Roger_Linn]

Hi Lars,

The problem may be due to accumulated finger oils in the more heavily played areas. You could cleaning the surface with soapy water, which may help.

The replacement playing surface that you purchased in January of 2022 has the current matte-finish polyurethane non-stick coating, which is very durable and shouldn't wear off as did the earlier playing surfaces. That said, I've only been shipping these newer surfaces since August of 2020, so it's possible that this newer non-stick coating is merely more resistant to wear after many pitch slides. If that's the case, I'll honor the two-year warranty and send you a new one for free.

The companies that make such coatings intend them for coating things like buttons on TV remote controls and have no interest in tiny markets like musical instruments. I tried many different suppliers of molded silicone sheets, which they call keypads, and most simply don't respond when I say I want to make only hundreds at a time for musical instrument purposes. The company that makes the current playing surfaces for me is in Taiwan and offers me very few options for the non-stick coating. I chose the option that feels the best and is supposed to last the longest. They apply the non-stick coating in a clean room with a professional fine atomizer spray, applied by a skilled worker. Oddly, their matte-finish polyurethane coating feels much better than matte-finish polyurethane coatings from other companies I tried, and I don't know why. Presumably the Taiwan company happens to use a specific vendor's coating that works better for my purposes. So I feel lucky that I've found them.

In summary, I think it would be impossible to both find a good matte-finish polyurethane coating and to apply it yourself with good results. In the early development of LinnStrument, I once tried experimenting with spraying a can of matte-finish polyurethane onto a stock silicone sheet, and the results were disastrous. That said, if a local paint shop has a fine sprayer and has a matte PU coating option that might work, you could try asking them to do some experiments.

[FranklyFlawless]

Ultimately, such an expensive tooling process from General Silicones for achieving the necessary coating was why I took interest in Lar's DIY hardware modifications in the first place.

One unexplored experimental idea I had for the playing surface/touch sensors was using a lubricant. My initial thought was PTFE, also known as the brand name Teflon, which is used on cookware as a non-stick coating. I decided to go for the FEP and PFA films instead because they are less committal, but still provides the material qualities I want. It is coincidental that the ones I ordered from CS Hyde use Teflon fluoropolymers.

[LarsDaniel]

Thanks for the elaborate info, Roger. I feared it was something that is not very DIY-able.
I recently washed the surface, because there was a visible dirty look to the most used area, but afterwards the surface was actually a bit more grippy, which I guess can make sense, as some grippy surfaces (e.g. ping-pong bat) are most grippy when clean.
Have you ever experimented with wood? (Disregarding the non-translucent nature). I am just curious.

[Roger_Linn]

I didn’t consider wood because of the need for translucency, plus it didn’t transfer enough force to the sensor below. But the SoundPlane from Randy Jones’ Madrona Labs has a wood surface that I think works very well.

[FranklyFlawless]

Wood was one of the many materials I considered for an alternative playing surface. The Soundplane uses walnut as its playing surface. I also considered cherry wood, to match the LinnStrument's wood sides. The main issue that stopped me from pursuing it further was thermal instability, as wood naturally expands and contracts, in a similar vein to the parchment paper mentioned earlier in this thread. Wood also requires maintenance/upkeep, as it is a biological material and is highly moisture absorbent. Lastly, the Janka hardness scale is quite different from the other hardness scales, although I am confident it does not matter much if you are using approximately 1,000 lbf or higher, as common walnut and cherry wood species are within that range.

Other than wood, I have considered neoprene (Continuum), brushed aluminum (Morph), acrylic, glass, and many more from McMaster thanks to Roger. My focus is sliding across the playing surface as easily as possible, so my criteria are materials with a low coefficient of friction. I took all of your experimentations, hardware modifications, and various issues into account when selecting a suitable material to minimize regression.

[Roger_Linn]

Regarding friction, some friction is needed. For example, if there’s no friction then vibratos will slide back and forth and it will be difficult to hold pitch after a pitch slide.

[FranklyFlawless]

ETA for the FEP and PFA films from CS Hyde has been rescheduled earlier to this Tuesday, which is tomorrow.

[FranklyFlawless]

The package arrived very late, but I made the time to test both the FEP and PFA film materials out.

They do not seem to be slippery compared to the polyurethane coating on the silicone, so I put them back into their paper rolls. I will need to contact the plastic fabrication company in my local area and see if they can provide a solution for an alternative playing surface material. Once I have done that I will provide another update.

[John the Savage]

It's almost as though Roger put a ton of thought into the design and formulation of the current playing surface... I'm starting to get that impression anyway.

Cheers!

[FranklyFlawless]

I agree, but it does not work for everyone. That is why there are threads about plastic strips, speed bumps, Lee ND filter sheets, removing Braille regulation dots, and so on.

I sent an email to the plastic fabrication company in my local area about a slippery plastic playing surface, so if they respond I will post again in this thread.

[Roger_Linn]

I agree, Frank. One size doesn’t fit all. I feel very honored and lucky that you and others find LinnStrument close enough to your ideal that you choose it as the basis for your enhancement experiments.