Saturday, April 28, 2012

Cargo Rack, Part 4

In this series: Part 1, Part 2, Part 3Part 4.


I wanted a bit of a retro look for my bike-rack, since I think it'll compliment the lugged frame well.  That being said, I don't think that anything TOO retro will work.  After all, it's a lugged frame with an 1 1/8" headset and compact geometry.

You can already see that the rack has a bit more "shaped" look than a lot of older racks.  To offset that, I'm adding a wooden deck to the top.

Frickin' Lasers

I'm no carpenter, and I've yet to take the woodshop safety course that would get me access to the tools I'd need here.  I have taken the laser cutter course though, and can do pretty much everything I need with that.

Plus, you know... LASERS.

The laser cutter basically functions like a printer.  The darker a color is, the more power the laser pumps out.  You set it up for your materials, do some trial and error, and then burn the hell out of whatever you're etching.  Specific line widths trigger a vector cut, which is usually set to cut all of the way through.

Since the cutter I was using could only go through thinner pieces of wood, I cut it out as two pieces: a top and a bottom.  I also divided the file up into a bunch of layers, so that I could do all of the surface etching before cutting the piece away from the plywood sheet, which can shift things around a bit. 

If you look carefully, you can see that I've cut my face into it next to the "if found, return to" bit in case I ever have to prove that I own the damned thing.  The miracle of the laser cutter is that it's incredibly easy to do that kind of thing.  

Woodworking: An Inevitable Learning Experience

I had considered using the laser cutter to bore the screw holes in the deck for me, but decided to use the rack itself to line things up, since there were going to be some inevitable imperfections.

Once the holes were drilled in the bottom piece, I countersunk them a bit and then ground out a dimple on the top to make room for the head of the bolt.  The idea is that the heads of the bolts are sandwiched between the two pieces, with the threaded ends sticking out.  That way there are no holes in the top, but I can still secure the deck.  I also cleaned the bolts with acetone in a glass bottle, to make sure that the glue would really stick to them.  Don't be tempted to do this in the paper or plastic cup that you have sitting around your shop.  It will melt and it'll smell horrible. 

I assembled the whole thing with a nice layer of heavy duty wood glue in the middle and tacked down the corners.  Then, I clamped it in a vice with some scrap wood over it to prevent dents.  If I were to do it again, I'd use much thicker wood scraps and drill it out so that the bolts wouldn't get in the way.  As it was, I had to slip extra glue into a few areas using a business card and then re-clamp a couple of times.


After a heroic sanding to round the edges and remove excess glue, I stained the deck (and some scraps) a bunch of times to find the right look.  Lots of sanding and re-staining, and re-staining again with different stain on top...  

Eventually, I ended up coloring in the letters with a black pen for contrast, then staining with a light red and a dark brown stain.  On top of that, I added three coats of a marine sealant designed for use on the railings of boats.  It smells a lot like peppermint and probably kills you if you taste it out of curiosity.

I think it turned out pretty well.  There are a few spots where I sanded too much near the edges.  I think others will see them and think that they're intentional "weathering".  They'll annoy me, but I'm going to wait until the bike is done to even think about re-doing anything on this.

Next time: hopefully I'll have some brazing (mostly practice) done for the next post.  I planned on doing that today, but the tinted glasses that I'd been using for eye protection wandered off.  I tried briefly to use darker shades designed for gas welding, and found that I couldn't tell the difference between a bit of red glow and bright screaming orange.  

In this series: Part 1Part 2Part 3Part 4.

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