Getting started with case design


#1

Hey team. I have a few more questions as I’m (painfully slowly) trying to design my own case. The stock case is great, but I’m looking for 50% more space for some switches, pots, and 1/8" in/outs.

So I’ve got the “standar_case.svg”, and I’ve got Inkscape. And Inkscape opens up the .svg. But then when I go to do anything, it’s a mess. Does anyone have any great advice for getting started with Inkscape? Link to a tutorial? (I should probably search on google…). I’m hoping this case design turns out well enough I can share it with the community.

Thanks!


#2

Thanks Schrab!


#3

Yo guys, I’m glad that this tut is useful for more than one!


#4

Awesome, schrab!
thanks!


#5

Totally awesome Schrab! Thanks for taking the time to do this!


#6

Great Tutorial schrab!

One point i want to emphasize: DONT TRUST THE DATASHEETS/EAGLE FOR MEASUREMENTS. All these tiny 1/10 mm offs will add up so your 3D Modelled case most likely won’t fit. Prepare to print a Cardboard Model and adjust everything to exact fit before cutting it in the real Material.

My first Case took 4 Iterations to get it right…


#7

Now set fill to solid color and stroke to none to check everything is correct

And don’t trust Eagle, cheap rulers etc. Use Messschieber and measure real PCBs, jacks and knobs. Actual size may vary from datasheets and eagle part dimensions. Very important to check sizes after exporting from eagle. Mistake at this step can make a lot of extra work.
Modifying original case files is also good and easy way =)


#8

Now unlock red elements and combine them same way for every part. After that substract them from blue parts using these commands in Illustrator/Inkscape


Red elements should be over the blue ones (we are substracting red top from blue bottom)
Ant here is final result


#9

Now continuosly select all elements belonging to the same part and combine them to new compound shape

In illustrator

in Inkscape
The result should be like this


If you get something like this (look at middle-top element)

See the top line of element is higher than gridline.

Undo, zoom, turn on snapping and grid and move it to its correct place, or just resize it from one side to overlap needed element (if there’s no overlap elements will not make new shape)
Switching to outline mode (Ctrl+Y in Illustrator, View->Display mode->Outlines in Inkscape) will help finding such mistakes.

It’s very handy to lock all red elements while combining blue.
Finally we got this

It’s VERY important to have closed shapes for every case part. CNC Laser is cutting every line and every point.


#10

Now let’s make face panel holes.
10 mm for pots, 18mm for encoder, 12mm for button caps (i’m using round caps from ebay, like in this case)
Just resize existing circles to new diameters. Check that reference point is in the center. Resize LCD window to 74x28 mm.
For 4-pole Mission board we can make additional holes to access trimmers. Distance from pcb to trimer avis for Vishay T93XA is 8mm. Draw 2x4mm circles with centers in 12 mm from inner bottom line of case (2.5mm + 1.5 mm + 8 mm)

Now it’s time for some cleanup. Delete all ancillary elements. Leave only needed for substraction. Color all hole elements to one color and case to another, or use layers.
We should get something like this


side elements can be duplicated after substraction to minimize efforts.


#11

ok, move on further.
distance from pcb to the central axis of midi jack is 10.3 mm, audio jack - 8 mm, DC power - 6mm
Height of nut - 2.5 mm, thickness of the PCB - 1.5 mm
Diameter of holes for MIDI jacks is 19.5, audio jack - 13.5, DC jack - 9 mm
Draw vertical guides according to exported from eagle dimensions (good idea is to export tOrigins layer. It will help finding components axis) Than add horisontal guides. Draw circles.


#12

You’re the Man, Schrab!


#13

resize-delete-resize-delete… you should get this


(you can look at attached illustrator file)


#14

Clone rectangles from side elements to top. We’ll delete it later, after using as guides.

At this step we need to clone out top element to make bottom side.


Resize top/bottom ledges to 26 mm and clone to the bottom of front/back element


#15

awesome tutorial!


#16

Add elements for bolts and nuts
Hole diameter is 3,1 mm.

closed path at the right side will be used for extrusion.
the grid is 1 mm.

Allign elements to the grid and axis of case elements. They should be symmetrical to X and Y axis.


#17

Turn on grid, set it to 1mm. Also turn on "snap to grid"
Than draw rectangle around PCB. Top line close to midi jacks, 3 mm space for left and right and 2 mm for botom

This is our inner dimensions.
Then add 3x6mm and 3x3mm rectangles to the corners.


#18

Sh*t! I have some scaling problem. Need to check all things.
UPD: Scale factor at Eagle printing dialog should be 1.009


#19

Ok. First you need to know inner dimensions of your case. Best way to make precise case is using eagle pcb dimensions.
Open PCB in eagle.


Turn off all layers except Dimension, tPlace, bPlace (Press “none” than check necessary layers, we need components from both sides)

And press OK.
Note that PCB is mirrored.

Now print this to PDF file (or PS, depends from supported formats of your vector editor) Scale factor should be 1.009

Do the same for filterboard PCB. (now you need only top layer elements)

Now open PDF in your Vector editor and check dimensions, they they must be near 120,4 x 88,4 for pcb dimension rectangle.


#20

Open PDF’s in editor, ungroup all and (optional) delete all except elements marked with red. Holes in case will be based on it’s position and dimensions.


Don’t forget to flip digital board horizontally.

Than combine them into one (copy, paste in place or position manually by pcb holes with good zoom)

Now we have all needed to draw our case except vertical positions of holes.