So, first off I started filming chemistry videos again on a semi-regular basis. First video is on solvent distillation, and the next about bioplastics.

Next up is a video about the Toronto Mini Maker Faire which happened not so long ago.

Anyway, real life is busy, so perhaps I’ll get around to making more videos!

You can view my video entry on my channel on youtube below, but once you do, please do vote for my entry daily at http://www.mytektronixscope.com – help me win a primo DSO so that I can further my capabilities for research.

Video: Inductive Current Sensing – The 10kA Challenge (Tektronix Scope Contest Submission, HD version)

If you are interested as to where you can find a hackerspace near you, just visit hackerspaces.org for a listing of cool places like this near you!

Image: before (left) and after (right)

Read on for a detailed, image heavy post about the entire process.

The reasoning behind embarking on such an intensive overhaul was because the old bench was too ugly to photograph or film video for anything due to stains, burns, and scratches. Additionally any video overlays and titles were always problematic since both white and black text tend to blend in far too well with wood grain, decreasing legibility of the overlays, a solid background of either white or black would prove to be more useful than just plain wood. The old bench had no water or chemical resistance, and was hard to clean as well.

The old bench was so bad, this is what I had to start with – burns, scrapes, stains (mostly activated carbon), etc:

Image: a well used workbench

So the tl,dr; version of my workbench resurfacing saga is as follows:

• Sanded plywood bench
• Filled and smoothed with 2 coats of drywall compound, sanding after each coat (note: dust hazard!)
• Coat of primer paint
• 3 Coats of flat black latex paint
• 5 Coats of Minwax polycrylic finish

The longer version starts from here:

The first step was to prepare the surface, mostly by removing everything on the bench, cleaning it up, and sanding it down with coarse sandpaper. This is mostly to reduce the surface variation, and remove any built up crap on the surface to prepare it for refinishing.

The next step was to fill in the surface with drywall compound, CGC drywall compound is essentially a mix of silica, calcium sulfate, and other viscosity modifiers like ethylene glycol, etc. Filling in the plywood texture helped the overall finish be as smooth as possible as well. I chose drywall compound over other products like polyfilla for several reasons: cost, and inertness. Drywall compound is about $6-8 for a big tub large enough to finish several rooms of a house, while polyfilla is significantly more expensive. Additionally, drywall compound is mostly mineral based with some organic binders for good measure, while polyfilla contains more organics that could be heat sensitive or chemical sensitive. Polyfilla does have 2 main adavantages – strength (less brittle and crumbly), and shrinkage (lower amount of shrinkage upon drying. Regardless, 2 coats of drywall compound were used, with sanding after each coat. It should be noted that drywall compound is a significant inhalation hazard: it contains silica and other fine mineral particulate that can cause silicosis  and the dust released has the consistency of icing sugar, a respirator must be used.

Image: wonderful stuff, drywall mud (left), post sanding of first coat (right).

After 2 coats of drywall compound with sanding, the surface was fairly smooth and ready for painting. A single coat of primer was applied so that any additional paint applied ontop of the first layer would not soak into the highly porous drywall compound.

Image: primed and ready for paint!

At this point I also prepared the fiber-board backing for the workbench by measuring and cutting it to size. I purchased 2, 2′x4′ panels from Home Depot with a white coating already on them. I wanted to do the measuring and cutting before I had any finishing coats on the surface.

Image: measuring lab bench back-board.

Now, I used a roller to apply some flat black latex paint onto the primed surface, it took 3 coats to get satisfactory results.

Image: (left) ready for paint, (centre) wet paint, (right) dried paint.

After the paint layers had been applied, the top-coat was applied. I used Minwax Polycrylic as an alternative to polyurethane (or even water based polyurethane varinsh) since the weather outside does not allow me to use polyurethane or other coatings which have higher volatile organics or toxic chemicals.

Image: (left) wet polycrylic coating, (right) dry polycrylic coating

After the first polycrylic coating, the surface was gently sanded to enhance inter-layer adhesion, however this only revealed that the initial drywall compound layer wasn’t smooth enough as initially expected leaving holes in the black paint all over the place. A thorough sanding to roughen the polycrylic layer and one coat of black paint later, the surface was smooth and ready for more coats.

Image: (left) bench with imperfections in black paint layer, (right) new layer of black paint

Once I had the bench surface smoothed and painted black, the rest was just the repetitive task of painting more coats of the polycrylic coating onto the surface for 5 coats total (excluding the early failed coat).

Image: more polycrylic! More!

Once all the layers of polycrylic had been applied and given a solid day and a half to cure, the bench was pulled back from the wall, and the backboard attached. The back board was just thin fiberboard purchased from Home Depot, attached to some 1×4 lumber. In retrospect I may have wanted to attach the back board to a total of 4′ high, not just 2′ high, though any clean background is better than none.

Image: The resultant bench surface with back-board

All in all this took about $80 in materials (with enough leftover paint to do at least another 2-3 benches this size) and about 5 days involving odd hours of sleep to get the number of coats quickly.

Image: After so much work, the end result was worth it.

The real test will be over the next few weeks. I took a chance using this polycrylic coating not knowing how good its going to be. It will continue to harden over the next few weeks, increasing resistance to scratches, chips, etc, showing whether or not it is a suitable surface for a workbench. Worst case scenario every month or two I can sand and strip off a thin layer of the top 1-2 coats of polycrylic and apply an extra 5 coats in a weekend if it sustains significant damage with heavy use.

Oh, and mission complete.

Most of my personal project time over the past few months has been spent working on a academic project which will (hopefully) be published in J. Chem Ed. in near future. My major contribution to the project is now complete, so now I have some more time to focus on my own projects. And even while I was in my dry spell, I was still working to design in CAD several electronics projects which need to be fabricated ASAP to meet some deadlines.

Now that I’m ramping back up for high gear on my own personal projects, I’m going to resume my normal blogging habits and attempt at least a weekly update to keep everyone interested in cool happenings. Its not my usual style to blog on topical stuff vs showcasing a project (or progress thereof), but I’ll give it my best shot.

Next on the chopping block: sprucing up my workbench so that it looks cleaner on video, and that leads me to my next point, hopefully weekly videos. I have a nice long list of chemistry technique videos as well as experiments that I’ve wanted to showcase on video for some time now, but been primarily discouraged by the unprofessional look of the bench. Soon enough that will change! I’m refinishing my benchtop surface and adding a back to the bench to clean up the look.

On top of the upgrades to the workspace, I’ve got a new computer to edit videos faster, more lighting in the basement for clearer videos, and a more streamlined workflow. Stay tuned…

Results

These are some strange results that I need to reconcile before carrying forward, particularly the odd thrust value of the 500gph motor in forward.

Future plans involve testing nozzle shapes such as straight nozzles, nozzles with collimating fins (to reduce turbulent flow or increase laminar flow), and Kort rings. Anyone with expertise in this area feel free to chime in with comments.

Stay tuned for more details, as the goal is to complete construction in time for summer 2011.

Key specs:

Rated depth: 100m
Rated pressure: 1.081 MPa or 156psi

Construction:
sch80 PVC pipe for electronics pods, 1″ CPVC pipe for frame, and aluminum for cross-bars

Power source:
Internal sealed lead acid batteries

Propulsion:
Modified bilge pumps

Instrumentation:
Pressure, temperature, compass, internal monitors (temperature, voltage, current consumption, [humidity/water sensor]). Video over IP camera

Control system:
Surface control computer
Onboard microcontroller with ethernet connectivity, control via tether.

This coming year I decided to send them some laser cut acrylic, some of which is just because they are awesome, and one item for their DBFH craft along (where people make crafts, send them in, and they get auctioned off for charity). Below are some photos of 2 items I sent the group as gifts, and not shown is a similar DBFH acrylic plaque that will hopefully auction well.

Just a few hours ago the countdown officially started to the Desert Bus for Hope charity marathon, so gear up for some fun!