As of the previous post on the project, I had loosely test assembled the router base. Since then, I got more fasteners and did the final assembly of the base frame. I initially was fine with the idea of having the router live on the floor in the basement, but after considering the size and weight of the unit, it seemed that some measure of mobility was in order. Plus, having the router up a bit higher would be nice for accessibility. So with another order of 80/20 extrusion, and the scrap left over from my initial cutting, I had just enough material to make a very nice mobile cart. I’m becoming addicted to 80/20 – it’s expensive, but makes building such assemblies a breeze.
I grabbed some cheap locking casters at Harbor Freight, and they were perfect for the project, as the mounting holes were just right for the 5/16″ carriage bolts used to assemble the rest of the frame. A piece of MDF makes for a nice lower shelf where the controlling computer may live once I get that far. I can even add in another shelf easily thanks to the T-slots.
One thing that I wanted to address with adding the cart base was to increase the (already substantial) rigidity of the table and allow any twist to be adjusted out. I tapped the bottoms of the original stubby 8″ legs for 5/16″ screws, and then turned points onto some hex head screws to center them into the holes of the adjoining extrusion. A piece of angle extrusion on the inside corner of each leg then clamps the two pieces together once the screws have been adjusted to level out the table. I haven’t gotten the leveling to be perfect, but it is most definitely ‘good enough’, especially for the expected accuracy of such a machine.
Finally, I completed the two carriages for the main axis. Fine Line Automation and CNC Router Parts carry these for $33.50 each, which I thought to be a bit high. After machining a pair of them myself, I’ve rethought that assessment, and now they seem like a pretty good deal. I used bearings from VXB for the rollers, and everything went together quite nicely (though I did have to machine down the heads on the machine screws for clearance). I’ll have to readjust the torque on the fasteners, though – the nylon washers I used between the bearings and the blocks crush and deform enough to let the washer wear against the red seal on the bearings, causing drag. With a bit of red Loc-Tite to keep things in place, I should be able to back off the pressure to allow the carriages to slide more freely.
As much of a pain as they were, I’ll still machine the remaining 4 carriages myself, seeing as how I have the bar stock already rough sawed (and all the bearings purchased). But before that, I’ll start work on the main leadscrew and associated hardware so that I can have an axis of motion to be proud of.
PS – James Jones directed me to an intriguing project he’s heading called CubeSpawn. It’s a flexible manufacturing system based on T-slot extrusion – once I realized that it’s not just another T-slot machine, but a modular system, I began to ponder the sorts of automated assembly line things it could make possible on a small scale.