Protolab

a Shared workshop for creation and innovation

4x8 CNC Build Part 1

This weekend marked the official beginning of our CNC build. Before we can get to the machine itself, it needs a sturdy base to rest on. I did a little research, and after reviewing some build logs online, and the plans for the CNC, we settled on 49x120 inches by 32 inches tall. 

Even without knowing the precise final dimensions, I've been designing the general construction of this table frame in my head for a few days. Mentally building something before actually building it is a critical making technique. Mostly because it's free. You can iterate, and plan, and try different things all in your head or with a napkin and pen. Going through this process will save you TONS of time come build day. It'll also help you create a more mature finished product than you would have if you'd just hacked something together without any planning at all. And like anything else, it gets easier the more you do it.

Armed with a solid mental plan, and the final dimensions of the project; I headed off to pick up the lumber. I probably should have brought a bigger vehicle, but I made it work.

A bunch of 10 foot lumber hanging out the back of our Civic. 

A bunch of 10 foot lumber hanging out the back of our Civic. 

Back at Protolab, we started by cutting the 8 foot 6x6" posts down into 6 32" legs. Each cut took 3 passes on our 12" mitre saw, rotating 90 degrees after each pass; I could have done it in 2, but it was easier to keep the cuts aligned with three. 

Then we assembled the first 10 foot long side. Pro Tip: When you buy a 10 foot length of lumber, don't assume it's exactly 10 feet (120 inches) long, it's probably a bit longer. I forgot to measure the 2x8's (because I had no plans to cut them) before we built the first side. Luckily we hadn't gotten too far along before realizing, so it was relatively painless to take the legs off and trim the 2 2x8's down to 10 feet.

After getting the 2 sides together, we quickly confirmed 49" wide would work with the plans, and made some measurements. Once we'd cut some 2x4's and a couple of 2x8's down to size, it was easy enough attaching the two sides. Clamps are your friend :)

The two sides attached. Starting to look like a table.

The two sides attached. Starting to look like a table.

Now this next part turned out to be my favourite moment of this build. Before we braced the middle of the table, we wanted to make sure it was square. When I measured it, it was already perfectly square! I couldn't believe it. 

I attribute that little success to 2 simple things: Careful measurements and cuts (measure twice, cut once); and the use of clamps to make sure everything is tight before screwing it down. Because of this, the table couldn't help but be a rectangle once it was put together. It was about 1/2 an inch wider in the middle, but perfectly square. 

Time to move on to bracing the middle, and closing that 1/2 inch gap.

The finished table is very very sturdy. There are still a couple of small things to do before I can really call it complete though. It could use a lower perimiter of 2x4's close to the floor, to help keep the legs plumb over time, as well as to serve as the foundation for a storage shelf under the machine. We also need to add some kind of adjustable foot to the bottom of each leg, as our floors have drains and are graded just about everywhere. 

 

More updates soon.