Demi Rail - 34 and 42 HP Eurorack rails

This is a Eurorack rail. Each rail is 34 or 42 HP. “Demi rail” or half-rail because of the size limit of my 3D printer. Two are required to make a 1U or 3U Eurorack case. Four 42 HP rails can create an 84 HP Eurorack case. 

I built the 34 HP version to hold a Rene sequencer. (I also designed a laser cut box to hold the rails with a 4hp power supply in the back.)

This rail is also handy for fitting out “lunchbox” style Eurorack cases. 

The rail is designed for use with M3 rail bolts such as M3 Knurlies by Befaco*.

Mounting hardware is assumed to be M4 bolts.

The PETG is self tapping for the M3 and M4 bolts. But if you want you could run a tap into the holes. I have also had good results printing these rails in PLA.

*Note: If over time you may find that the rail “nut” threads have become stripped and are not holding the bolts well, it is easy to apply a small amount of “gel” or “thick” grade cyanoacrylate glue (“CA”  super glue) into the holes with a toothpick. Allow the glue to harden before re-inserting the bolts. Also do not overtighten the screws with a screwdriver. Hand tight is enough for rail bolts. 

A headless (two-sided) M4 bolt could be used to connect two rails together to extend their length. But the rail is designed such that it can be anchored from below or above and abut directly to the next rail. At the end of the rack a bolt can be threaded into the end of the rail. So one bolt in the end and one bolt from the underside of your case will hold a rail in place.

The hole at the end is positioned the same as a Tiptop Audio Z-Rail, and it is designed to accept an M4 bolt without the need for a nut.

These rails work with a power supply and flying bus like the 4ms Row Power or Tiptop uZeus. 

Important note: a power supply like the uZeus is expected to be mounted to metal rails which function as a heat sink. A PETG or PLA rail such as this is not much of a heat sink. If you are running the uZeus with a heavy power load you should probably attach it to a separate heat sink. I prefer the 4ms Row Power because it seems to run cooler than the uZeus. 

Print Settings

Printer Brand:

Prusa

Printer: 

I3 MK3S

Supports:

No

Resolution: 

0.15mm

Infill:

15%

Filament:

Hatchbox PETG (alternatively: PLA)

How I Designed This

Designed in Autodesk Fusion 360.

I designed this rail in conjunction with a design for a laser cut 9U 84 HP Eurorack case - 3 rows of 3U 84 HP. Currently, that design is not set up to use with this 3D printed rail for all the rows -- only the top "add-on" row. (It uses Tiptop Z-rails for the lower 2 rows.) But I may modify it and publish it if there is interest.

Category: Music