Computer Case Hack

If you read this post title and think I’m going to discuss corrupting your friends hard drive or tell you how to steal their photos from that beach trip, your going to be disappointed.  In true Wood Shop Mike fashion, this post is about utilizing a commonly found item to serve a need in the shop.

I’m using a CPU case here to house the electronics for Big Blue.  VFDs (variable frequency drives) don’t like dust.  Bad things happen when lots of dust, debris, or metal chips get into electronics.  So, instead of buying an enclosure specifically intended for these items, I used an old computer case.  
Why did I use a computer case?  Well, a new enclosure for a VFD is going to cost you a couple hundred dollars.  A regular size computer case has plenty of room for a VFD and brake module.  Used cases are easy to come by and normally will still have fans or power supplies in them.  Check your local surplus warehouse if you’re have trouble finding a candidate for surgery.  

I started out this project by removing all the existing components, minus the fans.  I took the fan off the CPU and kept the power supply around to use later.  Then, I started laying out the electronics and decided on an arrangement that made me happy.  I marked where I want a hole in the top of the case so I can still use the VFD on-board controller.  

Cutoff From Power Supply

This is the fan off of the VFD.  It conveniently runs on 24V DC, as do the other fans from the computer case.  Here I’m splicing a “supply cable” into the leads for this fan.  I’ll then use wire nuts to tie the three fans together.

Stealing Power!

Before I cut the “window” for the on board controls, I verified that everything will line up once cut.  Everything looks good so lets get to it!  I used a cut off wheel on an angle grinder to make the opening.  I should pause here and reiterate that hand tools can bite you!  You technically aren’t suppose to use an angle grinder without a guard…  Decide for yourself.  I will say, the time it takes to put the guard on (if it’s off) sure beats the time it would take to stitch your hand back up!

Cut Here!

Back to cutting.  I make a series of plunge cuts and connect the four corners. Oops, I went a little far on one…  Lets say it’s got character now.

After checking the fit, everything seems to line up just fine.  Victory is mine!

Now I drilled and tapped holes for the brake module.  After that, just fasten the brake in place (bottom of case) with the appropriately sized screws and that’s done.  

I’d like to point out what seems to be a peg leg.  My “shelf” was just a bit flimsy and needed some extra support.  I just happened to have a scrap piece of wood lying around…
  

Almost there

I used cable glands for the comings in and goings out of the power and control cables.  These are awesome little guys that protect your cables from wearing around a sheet metal edge.  They also grab the cable and keep it from pulling out of the terminals on your electronics.  Ain’t no body got time for a fire!

At this point I realized I don’t have a 3/4″ hole saw. I had to stop and go get one…  Drat…

Well with all that said, I spent a few hours on this.  That even includes going to the store!  The VFD and brake module are both surplus Allen Bradley units, together they cost in the neighborhood of $300. The pendant, cables, and plug were close to $50.  My Dad wasn’t using this case any longer so that was FREE!!