Well, I have now glued a second, and a third attempt at this. And I'm still not satisfied! Aarghhh!!!!!
What's the problem? Simply put, the problem is making the glued edges look good. This acrylic reveals every little defect when gluing. Each attempt has gotten a little bit better, but they are still not good enough.
Attempt #3. Better, but the edge is still not pretty enough when viewed from above...
My problems seem to boil down to two issues. First, I was using the wrong glue. I bought some slightly thickened glue (called "syrup") from US Plastics, because I thought it might be easier to deal with than the very thin liquid solvents. I was afraid of the glue going where I didn't want it to go. The trouble with the thick stuff is that it is much more likely to trap some bubbles, and, when it does go where you don't want it, it stays.
My second, and far more severe problem, is that you have to finish the edges ABSOLUTELY FLAT before the glue joint will be pretty. If they don't sit perfectly flat, you can see the gaps when you are done. This latter has been a real problem, because as I try to polish the saw marks off the edges, I seem to be rounding the edges. I think a lot of these issues are coming about because I get in too much of a hurry. The plexi I'm using is 1/4", so it has to be flat across a very large distance. Here are some of the things I've learned from this process:
- If the plastic supplier is willing to finish the edges, LET THEM DO IT! It's really pretty hard to make perfectly flat nice edges.
- If not, and you're building a box, you have to get those edges completely flat, or you will see the problems when you glue. Acrylic is very unforgiving, especially the thick stuff, like the 1/4" I'm using.
- Use a sanding block with a hard backing (like a block of wood) to sand the edges. Failing that, place the paper on a hard flat surface and make like you're lapping a heat sink. TRY HARD NOT TO ROLL THE EDGES!
- A scraper also works very well. Run a utility knife blade backwards over the edge. The scraper cuts faster than most sandpaper. I like it as an initial step to take out any nasty marks left by sawing.
- An electric palm sander is generally a bad idea--it'll sand quickly, but it rounds the edges. OTOH, if you really screw up, the palm sander, some 220, some 400 grit, and the Novus polish will fix almost anything.
- I used a 200 tooth plywood blade to cut the acrylic on a table saw and went very slowly. I had no chipping or melting problems.
- I have also used a router in a router table to clean up the edges. Again, feed slowly and you'll have no melting or chipping. This worked well for me.
- The glue is a solvent, and will turn edges clear that are not polished clear. Hence, don't bother polishing where you will glue. Even a 220 grit finish seems to come out pretty clear. Go to 400 grit if you want a real clear joint.
- It's Hell getting bubbles out of a joint. Again, this is much more obvious with thick 1/4" plexi than thin stuff. The edges have to be totally flat, with no high or low spots. Wick the glue in with capillary action. Clamp for about an hour then set aside over night to finish drying.
- If you need to seal for water, here's a nifty trick a friend taught me (he builds aquariums). Mask the area right up to the joint with scotch tape. Run a filet of silicone with your finger. Peel off the scotch before the silicone dries (else you'll pull up the silicone). You get a nice clean filet with minimal contamination of the clear plexi.
- Another tip, suggested by my brother, is to build the bottom four sides first. I had started by gluing sides to the top. However, building the base first allows you to lap the whole base flat. Since its fairly big, you are much less likely to round those edges, and will get a better result for the all-important top edge.
I am beginning to see why the original creator of the block design, Petzl, simply had his acrylic machined by professionals. It's hard to get this right and looking good!
And the Fourth Try is the Charm!!!
Finally I'm ready to move on to the next step. In this case, that next step would be fabricating the mounting system for the waterblock. I went with a variation on the original Swiftech mounting scheme, which uses bolts through the mobo and springs to even out the tension on all four corners. In addition, I added some nifty nurled wheels to make it look cool instead of just using the ugly Philips-head screws the Swiftie comes with. All of this meant two trips to the hardware store and another $25 spent. Did I mention that making your own waterblock is not a way to save money?
Here are some pictures of the latest progress:
Drilling holes. Make a pilot, and then gradually increase size. Lube and cool with water or you'll be sorry!
OK, now this is what I'm talking about now!
Still a lot left to do. I've got to decide how to attach the plexi cover to the copper base. There are several possibilities:
Once I get that sorted, I need to drill and mount the barbs. There are a couple of possible approaches to that:
Now do we want the barbs side by side at bottom?
Which one looks better? From this angle, I guess I like diagonal. But when viewed from the top window, the bottom position will look nicer. Also, with diagonals, I have to try to channel the water down three races with two dividers. With the bottom barbs, I can get away with a single divider and u-shaped flow path.
Once the barbs are mounted, I need to investigate mounting some LEDs in the four corners underneath to light this sucka up. Lastly, it'd be a good idea to pressure test this thing to make sure there are no leaks!
A Mini Investigation into the LED Situation...
Since I have multiple acrylic covers kicking around, I decided it would be a good idea to take one of the messed up ones, drill it, and stick four blue LEDs in to see how I liked the effect. Check it out:
Oh, oh. He's been to Radio Schlock. What's this? Blue LEDs? WOOT WOOT!
Yes, the brilliant electronics wizard can manage to connect four diodes in series, albeit not very elegantly. But this is a test!
And there you have it, ladies and gentlemen of the jury...
What do you think?
I haven't decided yet. I wish things would diffuse a bit more, but don't see how to "make it so". Must ponder...
Another sick thought, embed 2 CCFL tubes in this thing, drilled into the sides...
The Great Glue Stick off...
I need to figure out what kind of adhesive to use to attach the acrylic block cover to the copper base. Folks on the forums basically suggested two possibilities: Plumber's Goop and Permatex Blue Gasket Sealant. Both are essentially RTV/Silicone products. I used one of my scrap block covers and some scrap sheet copper to see which one works better:
The glues are applied...
Then I flip the block over and stick it down onto the copper sheet...
The result? They both stick about the same. I'm going with the Goop, because its clear and I like the cosmetics better.
All material © 2001-2006, Robert W. Warfield.