Wednesday, March 27, 2013

The Block

As I wrote earlier, there was a Home Depot run on Sunday. We picked up quite a few things but the critical item, at least in go-kart terms, was a 2' by 4' sheet of half inch birch plywood. Our kart needs a back bone and this is it.

The above image is from when we still planned to make it out of 1/8" aluminum, when we decided to make the change to wood we (Carolyn, master of splines) beefed up the cross supports and changed the profile to include the rear upward bend. Switching materials also meant switching machines. Waterjets will cut wood but wood gets soggy and it doesn't give the nicest edge quality. The clear choice was to put my newly found MasterCam skills to use and use the CNC router that lives in the MIT Hobby Shop. We encountered a small issue with lead in / lead out paths and an unnecessary finish cut but Ken helped us sort that out quickly and we got some very nice looking parts after a bit of trimming and light sanding.

The router drilled holes for us, but didn't add the recess we needed. We hadn't planned to recess the bolts but the extra thickness that came with using wood meant that recessing the screws was the only way our batteries would still fit between the panels. The CNC could have made the cuts but the tool change and getting the depth right was trouble enough that it was less work to just drill out the chamfers on the drill press afterwards. They still need stain but excitement got the better of us and we bolted them to the kart anyways.

It's not too comfy at this point so it was hard to tell if the rider position is okay. I think the plan for tomorrow is to disassemble and stain the wood pieces. We wanted to laser cut the cover for the block today but the 1/4" plywood is all used up. Technically this material was supposed to be used to test the fit of the 1/4" aluminum plates before cutting them on the water jet, but what good project doesn't have some abuse of provided materials.

This kart just gets prettier and prettier as the days go on. Eventually it would be nice to get the wheels on the darn thing to see if it's actually going to do what we need it to. Here's to hoping.

Until next time.