I've been lucky enough to have a Saturday at a friend-of-a-friend's big fabrication studio over the weekend passed, to tinker with an idea of making a detachable platform to increase the surface area on top of my rear Tubus Fly Evo rack. I chose the world's most narrow rack, to keep things light (on the world's heaviest bike) okay for lashing a cylindrical dry bag to, but relatively impractical for carrying anything else.
I had an idea of combining this post with a little bike-build overview of how my bike is shaping up in preparation for cycling to Denmark in July. However, I think it will have it's own post at some point, where I can go into more detail about it all. Maybe before the trip, maybe afterwards. This one will be just about the rack.
Now first things first, I would not have been able to make this without the brains of Jake, (whom you know) and Odin (Studio owner and fabrication mastermind). Jake has the DIY-or-Die attitude and Odin has the tools, the machinery, and the know-how to facilitate my idea on the first attempt. I did not really 'make' anything; I conjured up the concept, of which fundamental features were contributed by Jake and Odin and the 'making' process seemed to be shared between the three of us.
It started with a piece of aluminum perforated mesh sheeting that I picked up on eBay for £9.90 delivered. 3mm in thickness to stop that flexy-wexy and with perforations of 5mm in diameter (initially to fit 4.8mm zip-ties!). I thought I'd cut this down to extend around 1" from the edges of my rack, to essentially increase the surface area by 2" in width and length without making the platform look obtusely large. The first problem was, I of course had no idea how to cut metal; but Jake said he'd show me and he was up to London in a few days to do some tinkering at Odin's studio. This was my opportunity, to shoot free throws with Malone and Stockton! You can't turn up to the court emptyhanded, so I had my towel, my own ball, and some rubber edging. This was £4.60 delivered on eBay, (running total £14.50). I brought my zip-ties too, which cost me a few quid a while ago, but these we didn't end up using, thanks to Odin.
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| One man's offcut is another mans racktop. |
I explained my idea; cut the sheet down to the same shape as the rack-top, plus an inch on all sides, put on the rubber edging and then zip tie that puppy down to the Tubus rack. One thing immediately stood out to Odin - to try making the platform removable without the use of single-use zip-ties. He said he'd fasten me some brackets to mount the racktop onto. It all sounded good but I imagined some basic kind of metal tube clamp scenario and left Odin to his word.
To get me started, Odin helped me draw up the shape onto the aluminum sheet, matching the shape of the rack Then spoke me through the steps of cutting on a band saw, and sanding down the edges on a belt sander. Sending me off to start cutting out my racktop, he brought digital caliper to the rack and started measuring out the spacing and tube diameters for the brackets.
After cutting down the sheet to shape, I checked in with Odin who had put his mastermind bracket sketch into the computer and generated a 3D model to send to the CNC machine. Using a scrap block of aluminum he was able to cut out two bracket pieces (first try) that clipped into place on the underside of the rack. To these he drilled mounting holes, threaded these and then gave me bolts and washers that were just under 5mm in diameter (ie, perfect to fit through the perforated holes of the rack). Somehow he worked out how to position the mesh sheet on top of the rack so that the supplied holes in the sheet would align with the fabricated brackets. The foresight of a true master.
I watched some CNC'ing happen, and then was shown how to sand off the remaining material that I missed on the ban saw and smooth the edges of the sheet with a belt sander. Very Cool. The rubber edging that I had bought off eBay was designed to mount onto something 3mm thick, originally designed for car components, and clipped onto the edge of the sanded racktop with just a little pushing.
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| The big CNC machine. |
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| Two mounts CNC'd out of aluminum block. |
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| The author, post ban saw and pre belt sander. |
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| Rubber edging. |
We lay the racktop on the rack and noticed that there was a bulge that stopped the platform from sitting flat on top of the rack. The tubing from the Tubus rack comes up from the rear axle, meets the horizontal top tube of the rack, arching over to the adjacent side before dropping back down to the other side of the rear axle. The arch between the two horizontal tubes (the mounting surface of the rack) actually comes up higher than the mounting surface, leaving a bulge in the flat surface. I could have noticed this earlier, but placing the racktop on top it was only apparent when it wouldn't sit flat against the tubes of the rack.
With in a few seconds, Odin traced a line on the racktop around the bulging area below. Transferring the racktop to a piece of equipment called a hydraulic press. With a larger sized metal circle beneath the rack, he was able to press the rack to create a raised section, when flipped upside down would compensate for the raised area on the mounting surface of the Tubus rack.
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| Readying the hydraulic press. |
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| Pressing. Peep the bulge. |
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| Sitting flat on the tubes of the rack. |
Then it was just assembly. From the workshop, to the falafel shop, and the corner shop for some beers and we caught the remaining afternoon sun in the park. All up it was £14.50 for racktop materials, the rest donated by Odin. That's around half the price of three wraps (two falafel and halloumi, and one just halloumi) and some beers.
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| Finished racktop. |
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| Perforated pleasure. |
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| Underside of the genius brackets. Cool light-play comes free with mesh racktop! |
Although I did very little, I learnt quite a lot. That seems to be the way that making goes in the early days. On top of the learning was the pure satisfaction of making something with some friends, in the sun, with Hank Williams playing on the speakers. Massively thankful to Jake for the encouragement to try and fabricate the racktop. At some point, this 'you can do it yourself, if you try' attitude is infectious. Jake has learnt these things the hard way, so it's a luxury for me to have someone pushing and guiding me to develop some making skills. More fundamentally to the days work was Odin, so thank you, for letting us use your workshop, for so willingly taking on board my little project and for showing me the ropes on how to use some of the machines. It was inspiring to watch you work for the speed in which you can apply the processes of fabrication. Hope you get your motorbike sorted so you can come and meet us at some point on our ride to Denmark (and beyond?!).
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