Teardrops n Tiny Travel Trailers

I saw this inexpensive 4' x 8' CNC machine on Kickstarter yesterday. Looks very interesting. If you have a router and two bricks...you can get the rest for about $350 they say. Worth a look. maslowcnc.com.

Here is the actual link.

http://www.maslowcnc.com/

Thanks guys, this looks awesome.

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Cool! Will the stepper motor bearings take the weight of the bricks? How does it work when in a upper corner?

The Kickstarter started today. I know it has limitations but I am seriously considering this thing.

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The Kickstarter was fully funded in 2.5 hours! They have around 80 of the 400 left to claim for $350. They have 300+ left of the beta tester kits (you get it first) for $550.

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I think they claim +- 1/64" accuracy. That's close enough for my trailer.

Honestly, most anything I build with plywood I would be satisfied with 1/16" tolerance. Anything better than that would just be a bonus to me

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I'm highly interested in this too... just sent them $5 so I can get their news letters.

Tony

Very interested -
BUT
My knowledge of physics makes me very worried about how much real control there is over that router right at the outer bottom corners of a 4x8 sheet?
The chains will apply force up and inward, while the bricks will supply down force. What about outward? And anyone who has ever used a router freehand will testify that a router hitting changes in grain direction can and will exhibit sudden large forces in unexpected directions that will jerk a heavy operator around.

And the sag in those chains must either affect accuracy or be hell to calibrate out.

So the accuracy claims I will take with a pinch of salt.

Breytie wrote:Very interested -
BUT
My knowledge of physics makes me very worried about how much real control there is over that router right at the outer bottom corners of a 4x8 sheet?
The chains will apply force up and inward, while the bricks will supply down force. What about outward? And anyone who has ever used a router freehand will testify that a router hitting changes in grain direction can and will exhibit sudden large forces in unexpected directions that will jerk a heavy operator around.

And the sag in those chains must either affect accuracy or be hell to calibrate out.

So the accuracy claims I will take with a pinch of salt.

Digging around on that issue:

From the comment section:
"Out of curiousity have you done tests for the accuracy at all 4 corners as well as mid-points? Just curious if the design has an inherent out of true factor as it gets near the edges..."

Answer from Bar Smith:
"That's a great and pretty complicated question. There's really two limiting factors on the precision. The first is the repeatability so if you move the cutter to the location (10.0mm, 10.0mm) and then away and then back how close to the original position are you. Most of our error repeatably and comes from wobble in the carrage holding the router. The second source of error is the accuracy of the machine so if you move it to the location (10.0mm, 10.0mm), the question is how close to exactly 10mm away from 0 is it. This is really what you are asking about because the the accuracy changes with where you are on the sheet. The two limiting factors on how good the accuracy is are the resolution of our encoders and the precision which can be stored by a floating point number, both of which are much much much better than the .4mm repeatability so it ends up not being a significant factor. It gets a little more complicated because the dynamics of the system change as you move up and down because the tension in the chains changes, so I need to make the PID controller adaptive based on the chain length to give optimal control everywhere. If you are interested in how the software works, there is a difference depending on where you are on the 4x8 sheet, if you just want to cut things out, there is no difference."

So in layman's terms, the software is supposed to compensate for it, right?

Talked it over with the CFO (wife), and apparently my initial proposal for the expenditure wasn't strong enough. I knew I should have went with a PowerPoint presentation.

They've already presold over 500 units with 20 days to go, and they reached 4x their goal already.

Hopefully by the time they are available for "retail" sale I'll have enough change in my piggy bank.

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Fop.

I believe the chains are under tension via bungee cable or spring along the sides.

In one of the videos he explains that he initially had a four chain setup, but it was just complicating the system without benefit.

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And now they've uped the ante with Z-Axis capabilities.

T