::: EDIT 9/29/15 NEW CONSTRUCTION ! ::: EDIT 9/29/15 NEW CONSTRUCTION ! :::
Back to this build
Thanks for checking out the progress as slow as it is...
More little steps towards completion... I've made a few changes to the design... I decided to incorporate a piece of the Dell monitor to cover the back and to provide a mounting/enclosure for the VGA controller board.
I laser-cut and milling-machined all the pieces for the back half of the case. It's coming together nicely using solvent (methylene chloride) to bond the separate pieces of acrylic together.
A computer model to illustrate the concept:
The rear-half of the case :
case back n.JPG
(116.37 KB. 1288x926 - viewed 212 times.)
case back i.jpg
(366.89 KB. 1134x739 - viewed 190 times.)
Glued along the back are gently curved
walls 17mm high that are cut from an acrylic tube 2" (~5cm) diameter, .125"(~3mm) thick.
Diagram Round Edge.jpg
(334.5 KB. 1400x880 - viewed 206 times.)
Inside the front-half of the case :
Copper Screen Locks.JPG
(372.65 KB. 1558x874 - viewed 213 times.)
Glued to the front are 4mm thick x 17mm tall flat
walls, almost rectangle, except the ends match the curve of the curved tube edge.
The LCD will be attached to the front face by gluing the tabs of the LCD panel to a thin (.025" 22 gauge) constructed frame of copper sheet with holes that are punched out. This copper hopefully acts as an RF attenuator not an RF antennae
Onwards to progress!
In my test piece you can see what the rounded edge will look like - this is pictured as the LCD side is face-down, rear face-up...
(144.15 KB. 2044x1920 - viewed 209 times.)
Accurately cutting the locations of the holes/edges relative to the front/back faces is very important for this particular design , but it can be said for all these DIY-Cintiq enclosures... you risk destroying your delicate electronics if you squeeze or flex the various layers because of wrong measurements/cuts where your surfaces of contact are made. It's also nice to pick the tablet up
so account for forces that could cause issues with alignment of your components during handling.
Here's my process for fabricating the various pieces so far...
Take a 2" tube of acrylic, put a wooden dowel inside to hold it, mount it in a lathe, cut ends off, round sharp outside edge using corner rounding router bit.
(437.79 KB. 1200x900 - viewed 178 times.)
a tube corner round .jpg
(370.72 KB. 1200x900 - viewed 184 times.)
a tube rounded.jpg
(351.39 KB. 1200x900 - viewed 181 times.)
Setup tube over wooden dowel in laser cutter. Take two long cuts to make strips from tube.
Laser tube setup.jpg
(393.28 KB. 1920x1440 - viewed 185 times.)
Setup wood dowel as a fixture in milling machine and tape acrylic piece to wood dowel using double-sided carpet tape to hold it down (this stuff holds VERY STRONG, but just to be sure I also put some clamps on it too)
curve edge mill setup.jpg
(399.58 KB. 1920x1440 - viewed 187 times.)
Mill long edges straight and plunge a 10mm end mill bit to make cross-holes for carbon fiber tube
curve cross hole mill setup.jpg
(359.9 KB. 1920x1440 - viewed 189 times.)
Whoo! that was a lot of work just to make two edges
damn they look sweet though!
Ok, so then I lasered the flat pieces which get attached to the curved pieces and will be the frame around the Dell monitor back piece. I didn't get any pictures of that process, but here's one of the pieces in the mill setup to cut the 50° angle so that it will mate to the curved edge.
Chamfer Edge .jpg
(418.96 KB. 2560x1920 - viewed 189 times.)
I used this fly-cutter with a custom made cutting bit which I made myself to get the exact angle I needed on the edge:
(160.79 KB. 1200x900 - viewed 192 times.)
I also put some work into making a special jig to hold the curved edge while it gets bonded to the flat pieces:
(258.89 KB. 1200x1600 - viewed 189 times.)
Then it was time to bond the separate pieces together. I wish I had gotten more pictures of this, it was pretty hilarious how many clamps I used to hold everything together while the bond cured along the curved edge
Here's the progress so far:
bonding back case.jpg
(332.09 KB. 1812x1788 - viewed 229 times.)
Kinda hard to tell what your looking at because it's all clear acrylic except for the black ABS Dell monitor piece and it's all sitting on top of a glass table on top of a another table
. But I've got all the acrylic pieces bonded together.
Next step is strengthening the frame. I designed and milled these little blocks to go along the edges. I just have to saw these apart and glue them in and the back frame will be complete!
anchor block nest.jpg
(360.71 KB. 900x1200 - viewed 199 times.)
P.S. @Aerendraca : Yes, the 'Plastic Bonder' Epoxy did everything I needed, and it's yellow color won't be a problem, those parts won't be visible, AND I won't be gluing any of the laser-cut edges
Ultra High Molecular Weight Polyethylene (UHMW); I've came across UHMW at work while I was machining parts for conveyor assemblies. It's a very low friction, durable and machinable plastic. I planned to cut the stiffener blocks that I could not make from acrylic sheets, but it turns out UHMW will not work for this. It's mostly used to protect sliding surfaces, it doesn't glue well (read up on it, and it did the worst in my tests), and thermally expands as bad as wood.EDIT:
Polyphenylsulfone is the much better alternative I found, and we happened to have some throw-away chunks of it at the company I work for! This stuff actually bonds beautifully to the acrylic using the methylene chloride solvent glue
I already have! This is what the grey stiffener blocks are made from now.