Eurorack Dimension Questions and Help

As the title implies - this thread is for Panel Dimensions, Rail Sizes, DIY Case Information, etc.

I will start off with a Diagram that seems to have helped MANY beginning DIY’ers.


This is from Doepfer’s website that contains all of the details of the A-100 Case Construction.

This diagram however, confuses me.

Here is why, and maybe, hopefully, someone can shed some light on this aspect.

1hp = 5.08mm
2hp = 10.16mm
and so on.

hp is multiples of 5.08mm

and here is my confusion -
1hp Actual Module Width = 5.00mm
2hp Actual Module Width = 9.80mm
and so on…

^ what in the actual #$%@ (lol)

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Nothing constructive to add but that’s the reason why I went Kosmo format.
Bought the cheapest eurorack pair of rails that use sliding nuts I could find and I’m using those as default size of my case.

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If I understand your confusion correctly, the answer is on the page:

The actual width of a front panel is a few tenth of a mm less than the calculated value (i.e. multiple of 5.08 mm resp. multiple of 1/5") to have a little bit tolerance to assemble the panels.

Though it does seem like a 2hp module should be 10mm.

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The ones that really get me are when you get into the larger sizes and the differences are vast… like
14hp = 71.12
14hp Actual Module Width = 70.80

^ thats like… not a small difference… lol

The reason this is bugging me is because I am trying to make a custom case but I have no clue how wide to make the rails so that when modules are in it, there isnt a shit ton of gaps… lol

But going by that guide is confusing as hell.

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Yeah, this one cropped up for me too a while back. In the end I went with ‘Buy rails and end cheeks, assemble and measure’, which is a valid option if your buying premade rails. However if you want to make your rails too, Synthracks have a handy dandy guide to how long they should actually be (based on the ones they sell) so you can build custom cases - https://synthracks.com/eurorack-rails

It also lists common panel widths and the actual height they are expected to be (cos they are slightly smaller than 3U to boot). Again, these are not actually a ‘standard’ but they have matched up with all my purchased modules dimensions so I am guessing they are correct.

[EDIT] Just realised the original Doepfer article also lists the correct panel height. I must have been hasty back in the day and missed it… doh!

I think it basically comes down to how companies want to round their measurements as the Rack Unit is measured in Imperial and everything else about Eurorack is measured in Metric.

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I’d say 0.3 mm is pretty small :slight_smile: (12 mils, 1/80th of an inch, four human hairs…)

Looks like they’ve chopped off about that much on most panels, “to have a little bit tolerance to assemble the panels.” The module width is the grid size, after all. You want to make the panels a tiny bit smaller so they fit.

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Basically it’s “1HP = 0.2 inches = 5.08 mm but shave a bit off that to make sure things fit” and Doepfer tells you how much they shave off, but other makers might shave off a little more or less. A few tenths of a mm one way or another isn’t likely to cause trouble. If you really want to make sure your modules fit tightly with no gaps and no overlaps, use slide nuts, but I use threaded inserts and don’t worry about the tiny tiny gaps.

The thing that really causes trouble is a few makers use a different system for the distance between the edges and the mounting holes. Not sure who but I know GMSN was one. The difference is several mm, even at the extremes of slotted mounting holes. I ended up enlarging the slot to get my GMSN module to play nice with the rest.

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THE WORLD NEEDS TO BE SEAMLESS GOD DAMMIT… :stuck_out_tongue: :stuck_out_tongue: :stuck_out_tongue: lol.

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But no seriously, thank you everyone for the help.

I am friggin AWFUL with measurements… didnt have a ruler or a caliper on hand lolol. was just reading numbers on a laptop screen without thinking of any conversions haha.

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If you want to make your own panels with your own hands, you definitely need a good ruler and caliper. This photo says all :stuck_out_tongue_winking_eye:https://www.instagram.com/p/B8oNhi7h4wC/?igshid=prr0kner9ree

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As it’s all on sliding nuts, you only have one gap and that’s at one end or the other of the run.

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Check these out :smiley:
A 4hp 3u hp Ruler -


and a 60hp 1u hp Ruler -


:smiley:

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Hey man, I get the confusion. Had the same worries,

I finally settled on lasercutting a wooden rail that has 3mm holes spaced 5.08mm apart, and that should work out fine I hope, but I won’t have any “official” modules to test it.

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