Panel Meter and Switch Box for China Blue & White

Overview

This has been an ongoing project and I finally got to finishing it and making it look presentable.  I will hit on a few points of the construction to help you make yours.  This is not going to be an exact step by step.  Can't really do that as you may need to alter the design based on switches you have or can get and the meter you have or can get.  But this outline should get you most of the way there.

To complete the install you will need the file to cut the acrylic sheet.  You can download it here:

PanelMeter

 That zip contains a Corel Draw file that has all the parts and pieces as well as a couple tools you will(may) need.  All the important stuff is at the top on the layer list.  The first layer "Box Done (Export These)" is the finished pieces.  Keep in mind all clearances are based on the acrylic sheet I got from Menards which says its .220 thick but I measured it in several places and it varied between .200 and .210.  You might want to tweak it for the thickness of your material.

All slots are 0.1mm short to compensate for my laser's kerf.  All tabs are 100% normal size so you only need to adjust the slots.  So, if a tab is 25mm, its slot will be 24.9mm.

When you go to cut the pieces, you will need to decide how many switches you want.  I am only going to use 4 right now but I added 2 extras for later.  Easy to add them now.  Not so easy later.

Material List & Tools

Here is the material list:

  • 4x M4 x 4.6mm heat inserts (McMaster-Carr)
  • 4x M4 x 10mm Cap Head screws (McMaster-Carr or local True Value/Ace)
  • (2) 18x24 sheets of Acrylic 0.220 Menards® SKU: 4334464
  • (2 to 6) Mini SPST or SPDT toggle switches Ebay: 302241862850
  • Various wire and connectors as suits your installation
  • Heat Shrink Tubing to insulate wires
  • Short section of silicone tubing
  • 3" Panel meter, 0-50ma (or 0-100 but the dial resolution will be less)
  • Sandpaper
  • Paint (gray primer, hammered white, and shell white plastic paint, see below)
  • Stiff white felt (or whatever color that floats your boat) Hobby Lobby: 0831101806 (optional)
  • A few wire ties

Here is the tool list:

  • Drill with Stepped drill bit and set of bits for pilot hole.
  • Soldering Iron and solder
  • Allen wrench to fit the cap screws above
  • Crescent Wrench
  • Wire clippers
  • Wire Strippers
  • Bath Towel
  • Duct Tape

 

Cut

Export the 7 pieces from the "Box Done (Export These)" layer and ship them to your laser to cut.  Arrange them to make best use of your sheets.  Make sure you decide how many switch holes to cut.  As I said, far easier to add the extra switches now and just not have them do anything than have to take the box off and drill holes for more later.  But, thats your choice.

Remember to cut 2 of the bottom braces.

Export the Tray Liner, its for cutting the felt to line the tray with.

And export the two pieces in the "Tools" layer.  One is a socket for the meter nut and the other is a holder for the switches while you wire them.

And lastly the Bottom Template.  This is to be cut out of card stock or copy paper.  Its a drilling template for the top of the machine.

I will presume you are able to cut the acrylic pieces so I won't go into all that

NOTE: Save the slot cutout from the back piece (shortest of the 3 slots).  This will be used to make a wrench for the meter nuts.  The meter wrench piece can easily be cut from the round meter cutout to conserve sheet space.

 

Glue

Time to glue!  Almost!  Test fit the entire box as a whole.  Also verify meter fits, and switches fit.  Now is the time to fix anything that isn't right.

Ok, now glue!  But DO NOT GLUE THE BOTTOM BRACES!  YET!    Put them in place (tape) to hold the box square.  But only glue the body of the box, not the bottom braces.  They will be added later after wiring and installation of the meter and switches.  You can do that with them in place but its a lot easier without them.  If the ends bother you not being panted, you can do your electronics install, glue them, and then hit them with a spot of paint.  I didn't bother.

The box should cure overnight.

Set the wrench piece flat on the table.  Take the slot cutout from the back piece (remember I said save it), and stand it upright on the area to the back of the wrench piece.  It should form a giant L.  Glue that up and set it aside to cure. It will be used when you mount the meter.

 

Solder & Wire

While the box and wrench are curing, you can get on with the wiring pieces.  Attach wires to the back of your meter.  Make sure they are sufficiently long to reach down to the ground wire coming out of your HV PSU.

Technically this is a ground line you are measuring the current of.  Still, I stuck some silicone tubing over the rear of the meter terminals after I had tightened them down.  Better to be cautious than sorry.

Attach 3 switches to the soldering holder.  They only need to be snug as they are only there long enough for you to solder them.  Here is how I wired mine:

I used 18/4wg security wire (Home Depot).  This gives me a common power and 3 signals out and its shielded.  One wire for each bank of switches.  Easy stuff.  Make sure you verify which pair of contacts is the ON pair if you use SPDT.  Most of the time its the pair opposite the handle direction, but best make sure with a meter now :)  As you can see I kept the shield ground and simply wraped around the wire jacket.  If I ever want to put LEDs in the box, I will need a ground.  There it is.

 

Prep and Paint

Yea, I know this is crazy.  But SAND the surface of the acrylic.  Thats right, scratch the hell out of it.  On purpose!  It helps the paint to stick better.  Round off any corners you want except the bottom edge.  Do the top.  4 main vertical corners.  Inside edge of tray.

Wipe it down good to remove any dust and hit it with flat gray primer paint and let that cure (whatever it says on the can you got).

This is optional.  If you just want a smooth box, forget this whole step.  But if you want the texture to sorta match the laser cabinet, then you will need Rustolium Hammered paint.  I chose white.  Don't be fussy with the color.  This is gonna get covered up with the right color.  Give it a couple good coats to make the texture prominent.

You will need Rustoliun Plastic in Almond.

The plastic part is totally pointless with 1 or 2 layers of non-plastic paint.  But I found this paint in "Shell White" to be an almost exact match to the "white" on my laser cabinet.  Give the box a couple good coats and let it cure well.

 

Assemble

Time to put this bad boy together!  Gather all your parts and pre-assembled parts.  Make sure you have that meter tool.

Despite having the meter tool, its still not a walk in the park to get the meter nuts on.  So I mounted my meter first (switches second).  Get the nuts started by hand and spin them down.  Make sure to do any final tweak on the meter position and use one finger to push the nuts down to hold it in place.  Now reach in with the meter tool like a 90 degree open end wrench and tighten the nuts.  You aren't torquing the heads on a F1 racer.  Its a meter.  Snug is good.

My switches will not fit through with BOTH nuts and the washers.  So I spun off the bottom nut.  I placed the anti-rotate ring on the inside with the lock washer and nut on the outside and it was a perfect fit.  Snug down all the switches.

When you are done, NOW you can glue in the bottom cross braces.  Add a couple weights to hold them while they cure.

While you got it upside down, might as well install the heat sets too.

When done, should look something like this.

Drill

 Ok, while the bottom braces are curing you can get on with drilling the cabinet.  But you need to protect the electronics first.  This is where the towel and duct tape come in.  Bet you were wondering why a bath towel huh?

Use the duct tape on the edge of the towel and tape it up against the corner inside the controller compartment.  Tape it all the way around on 3 sides.  Let the towel drape out of the compartment into a trash bin or whatever.  This will catch all the metal shavings from drilling and keep it all out of your electronics.

Tape the bottom template in place where you want the box.  I mounted mine about 1/4" forward of where the sheetmetal is bent to slope down.  And I centered it horizontally betwen the access lid and right edge.  Make sure you clear any internal brackets.

Drill 4 pilot holes in the center of each of the 4 screw holes.  Enlarge with a stepped bit until a M4 screw fits through with a bit of play.  Don't want the holes too tight.  Makes assembly a PITA later.

Also drill out two holes to fit your silicone tubing.  I made mine in the center so I could tie them together top and bottom so they could never come out of the holes unless I snipped the ties.

And inside.

Notice the interior bracket I referred to earlier!  Thats why I said make sure to check them when laying out the template.

 

Attach the Box

Time to actually attach the box.  Slip the wires through the silicone tubing.

Invert the box over the screw holes.  Insert M4 screws through the back left corner and get its threads started in the heatset.  Don't tighten.  Now do the same for the front right corner.  And finally pick up the other two corners.

Finger tighten the screws.  If you waited overnight after gluing the bottom braces on, then go ahead and tighten them with your allen wrench.  If you didn't wait, leave it finger tight until the glue has had overnight to cure.

I used Male/Female wire connectors.  That way I can remove the meter and plug the two ends together from PSU to Tube in the event the meter fails, it doesn't shut down the machine.  It also guarantees the meter is hooked up the right direction (+ to tube, - to PSU).  I havent wired up the switches yet.  Those wires are tied off for now.

 

In Action

So, here is what it looks like in place:

And yea, my box is perfectly flat on the bottom.  The sheetmetal is not :)  Oh well.

 

And a pulse test says its all good!

Yes.  That is a Burlington meter from before I was born.  I tested it with two DVMs.  It says 14.1ma.  So do both digital meters.  I would say its still working after over half a century.

 

Paint and Texture Match

 Here is natural room light:

And here it is with flash.

I would say you ain't getting a better match out of a can of spray paint.  The texture is really close too!  That is if you used the hammered paint step.  If not, your box is smooth.

 

As for the tray liner, here is the product:

 

And with the piece cut (25% at 100mm/s works perfectly for my machine).

Here is the liner in place with my lead weights and the odds and ends I always need handy.



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