Tips for PCB/panel design?

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snowtires
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Tips for PCB/panel design?

Post by snowtires » Tue Jul 20, 2021 10:48 am

I found a circuit that I'd like to make into a PCB and I have everything entered into EasyEDA, but I am trying to think things through and can't figure out how to set it up to make sure the parts on the PCB and the holes on the panel line up perfectly. How do you do that? Are there any good tutorials out there?

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Re: Tips for PCB/panel design?

Post by pjbulls » Tue Jul 20, 2021 12:59 pm

I put my holes/cutouts directly on the actual PCB, and then copy those into a separate file. You only need the outline and any holes for panel controls, everything else comes after. Doing this messes up your original design so make sure to safely store that somewhere first (or do it in a clone), and you also have to be careful that the 'snap' feature doesn't cause anything to jump out of alignment, but on the whole it doesn't take more than a few minutes.

The biggest challenge is figuring out how big your cutouts should be for the various parts, and where they have to go exactly...

e:
as to how you figure that out exactly, often the footprint has some silkscreen that gives clues, however, don't blindly trust that. The datasheet should contain the relevant dimensions that tell you exactly how far from the mounting pads the actual hole(s) will have to go, though in some cases it takes a bit of calculation and in the worst case a little bit of guesswork. Depending on the part (LEDs) a little bit of misalignment won't be the end of the world.

Here's some very standard holes that I put in pretty much every design:

Thonkiconn jack = 240 mils (6.1 mm) diameter
Thin pots, like tall trimmers = 255 mils (6.5 mm)
Metal 9mm pots, encoders = 276 mils (7 mm)
6 mm pushbuttons with these caps = 205 mils (5.2 mm), or 140 mils (3.6 mm) for those capless ones.
sub-mini switches = 200 mils (5.1 mm)
LEDs obviously take the diameter plus some small margin, e.g. for 3mm LEDs I put 122 mils.

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Re: Tips for PCB/panel design?

Post by guest » Tue Jul 20, 2021 2:33 pm

i use various layers in my PCB layout for all the mechanical and dimension stuff, and then be sure to turn those layers off when making the gerbers.
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Re: Tips for PCB/panel design?

Post by abschall » Tue Jul 20, 2021 4:04 pm

On Eagle I duplicate the .brd and .sch files. On the schematic file I delete resistors, IC's, capacitors and components which won’t look through the panel. I only keep the jacks, pots, switches and LED's. By keeping those components, I know exactly where the centers for the various holes are so using the "hole" tool I cut out the holes on the board file. Once I have all my holes and cutouts at the right positions, I remove the components. I then have a board that has the size of the component pcb (106 mm tall and N HP wide) with holes and cutouts at the right positions.
The standard panel size is 128.5 mm, I then have to extend the bottom and top edges by (128.5-106)/2 = 11.25 mm. The sides have to be extended to the closest HP width (the component PCB has to be a few tenths of a mm smaller than the panel). For actual dimensions and mounting holes placements I always refer to the Doepfer "A-100 Construction Details" document. http://www.doepfer.de/a100_man/a100m_e.htm
I believe that the procedure is somewhat similar on Easy EDA.

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Re: Tips for PCB/panel design?

Post by MikeDB » Tue Jul 20, 2021 7:04 pm

In EasyEDA there's a documentation layer where you can place many shapes. This never becomes part of the Gerber so cannot mess up the PCB, but can be exported to various tools for making metalwork.
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Re: Tips for PCB/panel design?

Post by Flounderguts » Tue Jul 20, 2021 9:17 pm

I use Easy EDA a lot.

For the holes, the best way to do things is to make sure the pad of the component is centered so that the 0,0 point is in the middle of the hole you want. Footprint editor is your friend...companies and 3rd party footprint makers rarely stick to conventions, so it's a good habit to go into the editor and check that it is aligned and built the way you expect.

Align your board outline so that the upper left corner is at 0,0 on the PCB layout window. Now, place your components roughly where you want them. Select the component you want to place exactly, and look at the coordinates in the right hand boxes. You can make tiny adjustments here. Most importantly, you now know the EXACT coordinates of the component, and you can place an appropriately sized hole in the panel at exactly the same coordinates.

Also, if you set the grid increments to something like 0.01mm, a selected component (or hole, or whatever) will only move that amount each time you hit an arrow key. Be careful...if you move the bit, say, right a bit, EEDA will also align the up/down to the 0.01 grid of increments.

Another trick is to use the component align tools (right, left, up, down, center horiz, center vert) and array tools to place your components or holes.

I will often build custom panel footprints that work with the stock component footprints...they are made to line up with the components when I make the panels.

Another trick is to make 2 board outlines, and put the 2nd one something like 100 units to the right of the 1st...or with the right hand upper corner at 0,0. Now it's easy to build your panel with your pcb, and use the alignment tools to make sure everything lines up.

EEDA sucks for a lot of higher-level design tools...but in a certain lowbrow way it has fewer checks and balances, so you can find pretty powerful workarounds and hacks to get what you want. They recently updated the DXF import engine, and you can make some pretty complicated stuff using that. Unfortunately, they also disabled some layer options for certain types of shapes (probably because I was abusing them!) which made it far more laborious to do things like reverse color text or odd panel cutouts.

It's still possible, but you have to enter the shape coordinates in a text interface.
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snowtires
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Re: Tips for PCB/panel design?

Post by snowtires » Tue Jul 20, 2021 10:09 pm

Phew, lots to take in. Thanks everyone for the tips, I am starting to try to wrap my head around planning with the coordinates, that helps a lot!

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Re: Tips for PCB/panel design?

Post by MikeDB » Wed Jul 21, 2021 4:22 am

Agree with everything Flounderguts says apart from I find it best to put (0,0) in the centre of the top of the PCB. This makes placing pots or sockets symetrically about the centre line easier. One hassle with EasyEDA is switching from mm to inches and back again can cause some components to move fractionally, and this shows up better if things are placed at + and - a fixed interval about the centre line.
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Re: Tips for PCB/panel design?

Post by EATyourGUITAR » Wed Jul 21, 2021 5:37 pm

I add 0.15mm to the measurement I take with calipers. This gives me the drill size for tight fitment. I use plated through hole vias. I order from JLC PCB. Other PCB fabs will not give you the finished product with your exact dimensions so you will need to spec a larger drill to compensate.
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Re: Tips for PCB/panel design?

Post by Flounderguts » Wed Jul 21, 2021 6:53 pm

MikeDB wrote:
Wed Jul 21, 2021 4:22 am
One hassle with EasyEDA is switching from mm to inches and back again
you use INCHES??!?

Barbaric.

That said, I'm pretty good at 25.4 multiplication and division...
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Re: Tips for PCB/panel design?

Post by EATyourGUITAR » Wed Jul 21, 2021 8:56 pm

When a component manufacturer gives you dimensions in inches you use inches. I constantly switch between them. Sometimes I use the 25.4 conversion. Through hole components are 0.1 inch. Eurorack panels are in mm. Yeah I could do 2.54mm grid. But I also use 0.05in and 0.025 and 0.0125 grid for PCB traces between opamp pins because that is what it is.
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Re: Tips for PCB/panel design?

Post by Flounderguts » Wed Jul 21, 2021 9:50 pm

I do that in machine work. Because tolerances and the surface finish data is different.

But on pcb I'm all metric. I've seen too many dumb mistakes using both systems on one project.

I'm a firm believer in the idea that any system for any endeavour is equally as effective in the right hands. 2 finger bass? Great. 3 finger? Great.

But mixing two systems gets you into trouble. Don't mix Solidworks with Siemens. Frailing doesn't work great picking. Hell, some folks won't even have a drink of whisky if they've already had some vodka!

Ok, I don't really believe this, and generally I cheer for oddballs and hybrid techniques. And I admit I have at least $400 worth of junk pcbs because I placed a drilling wrong.

I blame the US imperial measurement system.
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