Project ShapeOko: a $300 complete CNC machine | Hacker News Reader

Project ShapeOko: a $300 complete CNC machine

kickstarter.com

46 pointschaostheory7 comments

This is a TERRIBLE cnc machine. The only constraint on the gantry in the direction of the long slide are two sheets of 1/4" mdf. It's going to wobble terribly. Seriously, there are much better machines available at even lower prices, most notably http://makeyourbot.org/mantis9-1 which doesn't even need lasercut parts, only a saw and a drill.

@kliment: I'd love to see a better machine at a lower price than $300. Seriously.

I've spend the last 6 years trying to create one and if it ends up there is already one out there, I'm going to feel like a real fool.

You'd be surprised, it doesn't wobble terrible. In fact, it doesn't really wobble at all. There are 2 cross pieces in the back of the Y-axis at the top (one vertical, one horizontal) and then a full box under the work area which is tied in to each of the x-axis uprights in both the front and the back.

You can see some assembly pictures here: http://www.flickr.com/photos/edwardford/sets/721576228624053...

You can see some more pictures here (these include the full box under the work surface): http://keen101.wordpress.com/2011/03/03/progress-on-shapeoko...

If you have a suggestion to make that particular section even more ridged, I'm all ears. Not having an engineering background, I'm always interested in other peoples ideas! After all, I just made this up :-)

Sure it won't flex if you're only milling foam. The Mantis I linked to costs about $150 in hardware and motors and $100 in electronics (using, for, example, Sanguinololu from the reprap project and pololu stepper drivers) . It can mill PCBs and harder woods.

The problem with your setup is that your gantry is held on by two pieces of plywood. The gantry itself is decently rigid, as is the base, but the linkage between them is subject to flexing. The two wood plates are not rigid, they will bend like a springboard. What you need to do to stabilize them is to add a vertical support to each side that is at a 90 degree angle to the existing one. Wood can handle compression better that deflection, so adding a support like that (which of course must be rigidly attached to the sliding part below) would prevent it from flexing and give you a much more rigid machine. The gantry axis itself is stabilized by the slides, though it will deflect somewhat around the middle. The vertical axis seems okay.

Great idea with a wicked execution; another why-didn't-I-think-of-that moments. 'Over' funded is a good thing too.

I wonder if it can cut high carbon steels. It looks like it uses a Dremel-style tool. I guess it might work on annealed steel if you can slow the movements way, way down and maybe applied some cutting fluid.

Not a chance. It can only cut things less hard than the wood panels that keep it together. Anything harder and vibration is going to destroy your workpiece.

thats gonna be big

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