Cleverness and Mistakes
[3 May 2015]
One of the clever things about OpenROV is their use of everyday items to do the job in the machine. Case and point: the use of syringes in today’s step. Small tubes are needed in the end-caps, so they are cut from common, everyday 1 ml syringes.
In this step they have you put the syringes in a vice, hacksaw off the bits you need, and then clean up the saw cuts. I don’t have a small vice on my bench, and hacksawing didn’t really seem like the optimal way to do this, so I decided to so this slightly different. Instead of sawing off my syringe, I decide to use a pipe cutter — it will make a more precise and more square and clean cut.
Of course you can’t just willy-nilly try something and assume it will work, so I did a test first. The ends of the syringes are discarded, so I made a test cut on the end that was to be thrown away. It works great! After sanding and filing the edge flat (it was already pretty square), I deburr by twisting Phillips head screwdriver in the end, but there is almost nothing there to remove.
When I make the cuts on the piece of the syringe to keep, one cut is just past the plunger stop. There are two bits to the syringe here — an outer shell that the pipe cutter goes through just fine. But inside that is a nozzle, that is supposed to slip into the needle attachment. The pipe-cutter can’t reach this bit, so I simply roll the syringe while pressing on this bit with my Exacto knife, it and it shears it off nicely.
[9 May 2015]
Tonight I go through Steps 13-18 of my instructions, to assemble the endcaps. This is a messy messy step, as it involves doing large surface-cementing between flat round disks, and filling the gap with copious amounts of cement that bleeds out. The instructional video posted by OpenROV was quite helpful to watch before I started!
I do okay with the first one, but it’s a bit messy. Quite a bit of end-cap marring by cement running everywhere, but I think I do okay — there are no big crazy bubble areas between the panes of acrylic — the bonds look good.
On the second one I made a BIG MISTAKE. Despite being warned in the video, depsite being warned in the instructions, and despite attempting to be careful and lay the parts out and see how they are going to fit before I even touched the cement, I glued the last endcap flange disk on BACKWARDS!
The two endcaps are supposed to be mirror images of each other. Somehow I just flipped it all in my head when I was putting it together (maybe it was the paper peeling where I flipped it? or juggling the cement and disks together? or maybe just my L-R dyslexia?) In any event BIG MISTAKE.
So there are three possible courses of action:
(1) Acquire new parts and build a new, correctly oriented assembly. This is probably my first choice.
(2) Perhaps an edge could be cut down to give the right symmetry to the end piece; this would leave a flat edge on one side of the flange, and I don’t know the ramifications of that.
(3) I could have someone cut me new parts, and I could reassemble this stage one more time, correctly.
I emailed support at OpenROV and asked about purchasing replacement parts. We’ll see what they say.
The next stage involves soldering, but I’m still fuming so maybe I’ll wait to do that until tomrrow! 😛