Drive Cage Creation

posted Feb 1, 2014, 11:07 AM by Andrew Stock   [ updated Feb 1, 2014, 11:09 AM ]
Hello everyone!

I've made some nice progress on the drive cage over the past few weeks, and got far enough that I figure it's time to share some of that progress! As you will recall from last time, I had cut out the side walls of the drive cage and cut the air vents out of them (albeit roughly.) First, I spent some time cleaning up those vents using a rat tail file, some sandpaper, and in some places my dremel with a sanding drum on it. I also completed the vents on the "D" shaped side of the enclosure. This just made the vents look a little more professional... like they were cut with a nice CNC instead of an 'ape with a saw'.  

Next, I moved on to the wooden frame that I was building earlier. I'll be using this frame as a "mold" of sorts when I start bending the drive enclosure into the "D" shape I've been talking about. In order to accomplish the angle, I used my table router with a 3/4" rounding bit. 

SO much easier than my original plan of shaping it by hand with a file/sandpaper. :P Nice, uniform, and a perfect fit to the original design:


Next, ever the cautious builder, I did a dry run of my planned process with some scrap acrylic first. My two big concerns were that A) The bend wouldn't happen uniformly, leaving me with a crease or corner and B) that the vent holes would deform as they are close to the area I am going to bend and they are the weakest part of the piece of acrylic. Fortunately, my heat gun came with a special head that seems to have been custom crafted for this purpose:


The little shield attached to the end of the gun in that picture directed hot air down while letting me protect the part of the acrylic that already had the holes in it... nice! I started by heating the area closest to the vents and applied no pressure downward... I just heated it until the edge sticking out started to sag on it's own a bit. I then moved the heat gun slightly downward, applied a little more pressure, down a little more, little more pressure, etc. The result:

Perfect! The bend seemed to take to the mold flawlessly, without too much deforming or anything. I think the real key here was excessive heat, allowing gravity to do some of the work, along with distributing the heat so that a large area was malleable rather than a small area that would tend to just bend. Either way, worked well.  I double checked it against the detailed diagram, just to make sure I had my measurements right:

Looks good! It's a little off, but that's due to this piece being a scrap, and relatively smaller than the actual piece will be. Now, for the larger piece, I made one small tweak. Since the surface I was heating was much wider, I wanted to make sure that I made a uniform 'bending point' so that the curve happened evenly. To do this, I figured I could clam a block on top of the acrylic piece I was about to bend, so that it was sandwiched between the mold and this block. This would also help ward off some of the heat from the delicate vent area, as I would be heating this piece much longer due to it's increased size:

I followed the same general process, heating an area, moving down, heating, moving, etc... but made one small tweak at the end. Once the piece was completely bent 90 degrees and more or less flush with the mold, I noticed that it was tending to try and bend back to it's original shape a little bit... more like an 85 degree bend.  To fix this, I clamped another board on to the side of the now-bent acrylic, then re-heated the whole bend for a bit... just to soften it up and let it reset into it's final form. I left the wood braces on for a good 15 minutes so that the piece was completely cool before moving it. 

With the heat gun part out of the way, time to move on to assembly! I cut some quick clear acrylic blocks that would serve as the 'mounting' point in my case, then set everything in place, just to verify.

Coming together! Next, I cut some acrylic strips that would be used as the mounting braces along the inside of the drive housing.

I glued those to the inside of both of the faces of the drive cage using some of my IPS Weld-On #3... which was just as much of a hassle as I remembered from putting together my reservoir. This stuff is thinner than water, so it has some weird properties like refusing to stay in a syringe, then with the slightest pressure shooting all over the place. Needless to say, I screwed up during applying one of the eight pieces, and marred a bunch of the face of the drive vents. Doh!  Oh well, more of an excuse to use some of the Novus polish stuff I bought. I sanded down the marred area with 1000 grit sandpaper to get rid of the bigger ridges, then 2500, then #3 Novus, then #2, then #1... and done. Back to it's original shine, like nothing ever happened. It only took me an extra hour or two. 

With that out of the way, I reassembled things just to check progress:

Still lining up well! On to the next piece, the actual drive 'plates':

I cut out a bunch of clear acrylic squares, then used some spare drive plates and dead hard drives to sketch out where all the mounting holes would need to go. 

After finding all the locations, it was back to the drill press to drill all these holes. I started out with using the "right" drill bit that was tight fitting to the M3 and 6/32 screw sizes that would be mounting the drives... but found that the slight variances in placing my holes due to cutting this all manually with a drill press instead of a CNC or anything lead to stuff not quite lining up right... so I backed off and drilled the holes a tiny bit larger, to give myself some wiggle room when mounting the drives. 

There we are, drive plates all cut and ready for polish!

Next on the agenda, gluing the drive cage together, and then cutting and placing the 'backplane' area, where all the little SATA adapters will be seated. I have no doubt that will prove to be a lengthy exercise with a lot of measurement, screw ups, re-measurement, and eventual success.  Looking forward to it... until next time!