A couple of weeks later, and I have something to show for my toil. First up is the main frame; it's as close to Tom's build as Bunnings would allow - that explains the brass piece at the top; it's the only fitting Bunnings had with screw holes. The rails are attached to the pipe with self-drilling, self-tapping screws; this saved me a lot of trouble with drilling the pipe as I only needed to get ~4mm pilot holes drilled with my hand drill; the screws and my stubby ratcheting screwdriver (which can generate prodigious amounts of torque) did the rest. The rails extend beyond the left edge to allow the full use of the X stage width.
The X and Y stages are cut from a large plastic offcut I got cheap from my local Reverse Garbage. The 60cm by 29cm by 1.5cm piece only cost me AUS$13, and whilst I don't know exactly what material it is, it's smooth, easy to work and hard wearing. I'm guessing it's actually nylon - it doesn't feel like acrylic, and a rough density measurement seems to match. In any case, I'm pretty lucky; the rails don't seem to damage it.
Below is the top of the X stage. I discovered that while most of this CNC design does not require rigorous attention to accuracy, there are one or two places where it's critical, and the primary rail (to the right) for the Y stage is one. It needs to be very square to the primary rail for the X stage below it, and this is a real pig to measure with the big block of nylon in the way. A piece of channel, a straight edge, a set square, a lot of faffing about and associated cursing and I think I have it close. If it needs trimming I made one of the mounting holes oversize to facilitate this later.
I was going to use more U channel under each stage as in Tom's build, but when I got to that point I changed my mind and used bearings. Here's the current underside of the X stage:
And here's the current underside of the Y stage (you can still see the price on it...):
When it's all together, you get:
(Ok, so I didn't quite align the top stage properly for the photo... :D )
Next time: Bearings and the elusive coupling nut.
2 comments:
Neat! I really should have used something besides wood for the tables of my mill -- I'm sure the wood's going to get festy.
Regards getting the X and Y axes square, I simply used the edges of the X table, which was cut from an MDF panel, as references for square. I simply made sure I used the "already cut when bought from the shop" edges for alignment references.
Messed around attaching coupling nuts this weekend, and simply made a big mess. :)
More updates soon, please.
Never fear, more updates are forthcoming; there's a good reason the bearings and coupling nut are going into the same post ;)
None of my table edges are square; heck, they aren't even particularly straight. There's only so much you can do with a jigsaw...
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