Fiberglass Panels for DIY Modular Systems

The thing that amuses me most in the realization of modules for my (in the making) synthesizer is the research and study of the "right" circuits, the layout of the PCBs, the assembly and testing of populated boards.

The most boring part (for me!) is the work on panels...

The use of aluminum panels is common practice, but for some years now we have begun to see practical and economic alternatives.

The one that charmed me the most is the use of fiberglass panels in place of metal: it's easy to drill, tough enought for the application and cheap.

In this instructable I will show you a set of 3U (eurorack units) tall panels I layed out for my use, and share with you gerber files to have them manufactured by professionals at a low price.

To lay out these panels I made use of Doepfer construction details for the A-100 modular system.

The International standard adopted (DIN 41494 / IEC 297-3 / IEEE 1101.1) calls for two main units of measure:

HP - Horizontal Pitch of 5.08 mm (1/5 in)

U - Units of 44.45 mm (1.75 in) (See ANSI/EIA-310D-1992 and IEC 297-1, 1986)

Panels Height

Modules for eurorack systems are generally 1 to 6 units high (1U - 6U), which makes 3U high panels a good compromise for us. 3U means 3 x 44.45 mm = 133,35 mm. As per Doepfer notes, "The final height of the front panels is a bit less than 133.4 mm as the rim of the mounting rails has to taken into consideration."

Makes sense :)

This is why panels are 128.5 mm tall.

Panels Width

As we have seen, the unit of measure is HP (multiple of 5.08 mm). This means that, in example, a 4HP panel is 4 x 5.08 mm = 20,32 mm large. A certain margin must be taken into consideration so that the modules can be placed side by side, so we can round up to 20 mm.

Mounting Holes and Screws

The most important thing here is the slot center to slot center vertical distance, which should be 122.5 mm for a 3U panel.

3M screws are the standard used, so the hole diameter must be at least 3.2 mm.

An important thing to notice is that the left and right mounting holes are not at the same distance from the closest, vertical edge. The first hole center (leftmost) is always placed at 7.5 mm from the left of the panel. The rightmost is placed at a multiple integer of 5.08 mm from the leftmost hole center.

Fiberglass panels I have layed out for my own use are very simple. They are almost plain, 3U panels with elongated mounting holes and exposed copper on the backside to guarantee an electrical connection with racks metallic rails.

I layed out four panles for now: 4HP, 6HP, 8HP and 12HP, but PCB layout dedicated softwares make the realization of any other dimension fast and painless once you get used to it (EDIT: 16HP panels files are now available!).

In the attached picture, the measures for the 6HP PCB (for your reference). Holes (vias actually) are 3.6 mm in diameter. I used a trick to ovalize vias: I placed more than one "regular", circular vias, side by side with a spacing of 0.5 mm. There are cleaner methods to obtain the same reasult (i.e. by toying with pads), but this is simple and worked like a charm.

Gerber files for all the panels measures I have worked on can be found HERE (github). You can have them manufactured at THIS link (JLCPCB): press the "quote now" button, upload the gerber file, select a nice color and save to your chart. Repeat the process for all the panels measure you want to have manufactured, then have them shipped to you.

Simple as that :)

Notice that blank panels files I shared include the board file (.brd). This means that you can add holes and silkscreens where you want and have then your custom faceplate manufactured. Nice uh!? :)

I had 10 PCBs for each of the three measures I was in the need for: 6HP, 8HP, 12HP. The PCBs calculated price (at today) is less than 26 euros for them all. With a slow shipping method and considering VAT, they will cost you no more than 50 euros. I think it's a very good deal for 30, excellent quality panels!

My projects are free and for everybody. You are anyway welcome if you want to donate some change to help me cover components costs and push the development of new projects.

>>HERE<< is my paypal donation page, just in case you would like to contribute ;)

The feasibility of using these blank panels to close racks empty spaces or to increase the clearance between modules is out of question.

What one could debate is the actual possibility to use them as structural supports for modules.

I have candidate these panels for both these pourposes, so I have had the opportunity to drill some hole in them and place my custom made modules.

From a workability point of view, I think that attached images speak for themself: you can drill precisely dimensioned holes to accomodate your modules, without running the risk to crack or break the PCB in the process.

Consider that I only have a cheap hand-drill (not a columnar drill or other specific gear) and a wood panel with some log to keep everithing securely in place, so my equipment is barebone. I also have very limited manuality (I prefer to spend time on writing codes and layout PCBs), so if I can do it, you can do it :)

So, are these suitable for the use in our synthesizers?

Well, provided you don't go too low in panel width, my impression is that (up to 3U in height) 1.6 mm thick fiberglass panels actually are, and all my modules will be accomodate in fiberglass panels. Reinforced fiberglass is not aluminum, obviously, but for my experience it is a very good candidate for the application.

I am still working on the basic framework of my synth, but I will update this instructables with my findings and impressions in case there is any ;)

Let me give you some operative suggestions:

1. Start by tracing your layout on adhesive paper. Noting the diameter of the hole near where it will be drilled will help to avoid errors in case of multiple, different panels ;)

2. Drill a small hole with a very small drill bit (1.5 - 2 mm). Be careful because the position of this hole will determine the center position of your final hole. This drill acts as a guide for the following bits and help you enormously keeping the final hole well placed.

3. Widen the guide hole step-by-step by using drill bits larger ad larger. I suggest to start with 2 mm steps, but you probably should use 1 mm steps when widening holes with diameter higher than 7-8 mm and especially when approaching the final hole diameter.

4. When you have all your holes drilled, use a small, round file to remove copper chips on holes borders.Notice that this phase will increase a little the hole diameter.

5. Clean the PCB with soap and water.

Keep in mind that chips coming from the PCB can be conductive because of copper layers on both surfaces. To avoid shorts and damage to your modules it's important to get rid of those chips carefully.

I had to go up to 8 mm drill diameter for potentiometers, 9.5 mm for 6.3 mm female jacks and 6 mm for latching switches (see picture).

Keep your driller speed low: there's no need to go fast with fiberglass. This will also prevents fumes emission and avoids a localized temperature rise. It also reduces the whole risk of injury.

Always when working is necessary to wear the correct PPE (Personal Protective Equipment).

As a general rule when working with fiberglass:

- Safety glasses or goggles will prevent the fibers from entering the eyes

- Masks that cover the nose and mouth can prevent workers from inhaling or swallowing the fibers

- Wearing gloves reduces skin contact and may prevent irritation

Take into consideration that we are not dealing with plain fiberglass, but with a composite material. Dust and mist created by drilling, milling and other activities may release chemicals (by-products or manufacturing residue) and residue from the materials and tools that could cause adverse health effects.

To reduce risks from volatile chemicals work in a well ventilated area.

When working with powered hand drills:

- Wear safety glasses or a face shield (with safety glasses or goggles)

- Keep drill air vents clear to maintain adequate ventilation

- Keep drill bits sharp always

- Keep all cords clear of the cutting area during use

Remember: it is about your health and safety that we are talking about

Aluminum is the standard material when dealing with modules for synthesizers. If you have adeguate tools (or adeguate friends :D) you can machine them with no problems, but what if you have not?

Well, after reading this instructables the answer is obvious - "fiberglass blank panels": easy to drill, sturdy enought and cheap.

But what if you still want aluminum?

Aluminum PCBs are an option for some time now. Having aluminum blank panels machined by PCBs manufacturers is something we, synthesizers enthusiast, can take advantage from and likely a new sector of business for PCB manufacturers.

I asked JLCPCB to realize some 1.6 mm thick front panels to take a look at them and see if those are actually adeguate for our use... bet it, they are!

I had a 3340 VCO panel realized starting from gerber files I layed down, but also some 12HP panels. In the pictures attached to this step you can see them.

What about costs?

Single layer aluminum PCBs have more or less the same cost of two layers fiberglass PCBs.

I made some simulations and, in this very moment (august 2021), 10-20 pieces of aluminum panels shipped to my place (Italy) with the slowest method available (which depends on package weight) would cost me (customs dutyes and taxes included):

10 pieces, 3U 6HP - 9,13 euro (Standard special Air Mail, 13-22 business days delivery) -> 0.9 euro/piece
15 pieces, 3U 6HP - 11,80 euro (Standard special Air Mail, 13-22 business days delivery) -> 0.8 euro/piece
20 pieces, 3U 6HP - 16,52 euro (Standard special Air Mail, 13-22 business days delivery) -> 0.8 euro/piece

10 pieces, 3U 12HP - 16.62 euro (Standard special Air Mail, 13-22 business days delivery) -> 1.7 euro/piece
15 pieces, 3U 12HP - 21.05 euro (Standard special Air Mail, 13-22 business days delivery) -> 1.4 euro/piece
20 pieces, 3U 12 HP - 27.73 euro (Global Direct Line Saver, 12-15 business days delivery) -> 1.4 euro/piece

10 pieces, 3U 16HP - 19.53 euro (Standard special Air Mail, 13-22 business days delivery) -> 2.0 euro/piece
15 pieces, 3U 16HP - 27.73 euro (Global Direct Line Saver, 12-15 business days delivery) -> 1.9 euro/piece
20 pieces, 3U 16HP - 33.82 euro (Global Direct Line Saver, 12-15 business days delivery) -> 1.7 euro/piece

Definitely good for a custom, color-masked, pre-drilled and silk-screened (or blank if you prefer, cost is the same), 1.6 mm thick aluminum panel/face plate!

Panels PCBs pictured in this Instructables are sponsored by JLCPCB, a high-tech manufacturer specializing in the production of high-reliable and cost-effective PCBs. Their customer service is very good and PCBs a great value for the money.

Thanks!