[Yehuda]

I'm an industrial design student at DAAP, and as part of my capstone project I'm designing and building an open-source, self-replicating CNC gantry router. This will be the third wooden CNC machine I will have made; the other two were the free or "book" machine, and the BlackFoot 4.1 from BuildYourCNC.com. While I appreciated the BlackFoot for what it was, I wanted to see if I could design a much more ridged machine while still using plywood as the main material, therefor retaining the self-replicating aspect of the design.

My basic approach was to build an x axis gantry that would support the y axis gantry between two arms, as opposed to hanging off the side one. The challenge, however, was building in adjustments that could compensate for variations in material and washer thickness that would change the size of the y axis gantry. My solution was to leave one arm "floating", held in place by adjustable clamps.
Other features:

• The x and y axis will be driven by #25 roller chain, with a 3/8" lead screw on the z.
• The y axis rails are mounted to a solid 2x6 to provide extra stability
• All v-groove bearings are adjustable from one side, allowing for the pressure on the rails to be adjusted.
• The rods that connect the x axis drive sprockets to the x axis drive motor are supported on either side of the sprocket, preventing bowing of the rod.

I've just finished the first version of the design, and I would really appreciate some feedback on it. In these screenshots, grey lines represent the path of the rollerchain. Please let me know if anything is unclear, or if you'd like to see more views. Thanks!

The X axis gantry:



The Y axis gantry:

[louieatienza]

Pretty cool... like a wooden mechmate...

[morganbarke]

Good work on the design. I am looking for an self replicating open source design, exactly as your are designing. Are you keeping a blog, so we can track your progress and know once publish your g-codes and parts list?

In terms of feedback, mechanically it looks sound and is something I find quite difficult to assess from your 3D images, without actually getting my hands on it. But aesthetically, I would suggest you involve more curved contours, so it looks more organic and less mechanically, in line with self replicating ethos.

Nice one!

[Yehuda]

Thanks for the feedback!
I am indeed keeping a blog of my progress; it can be found at SindrianArts.com. I'm about to start construction, and I'll be posting updates there as well as here.
As far as a more organic look, this is something I'd like to explore with future revisions, but for this first one I wanted to keep it simple.

[morganbarke]

Thanks for the feedback!
I am indeed keeping a blog of my progress; it can be found at SindrianArts.com. I'm about to start construction, and I'll be posting updates there as well as here.
As far as a more organic look, this is something I'd like to explore with future revisions, but for this first one I wanted to keep it simple.

Cool, thanks.

Yes, wise idea about keeping it simple. Perhaps the organic look is something that the community can provide once it is tried and tested.

[morganbarke]

Will you be using the same or similar components to the Black foot 4'x8'. Am I to expect a similar cost for Build?
"blackFoot 4x8 Kit with electronics: $1326.90" (not including wood components).

Would be great to know, so I can start putting some money to one side...

[emerz]

I noticed that your table design is similar to the links you provided regarding torsion boxes. Would it be fairly easy if I substituted an 80/20 type table and then just faced the top board on the stack? I don't see the point of a torsion box here. My understanding is that it's only necessary to have adequate support for the work piece and that the surface can be trued after assembly.

Other question:
Would I have much trouble shortening it from 4x8 to say a 4x4 or 4x3? What about the gantry? would 3 feet be an easy reduction? I know that as you add more area you suffer less effective losses from gantry movement, but unsure exactly how much.

Thanks!

[Yehuda]

Sorry I didn't get back to both you sooner! Something might be up with my notification settings...

So far, the costs are pretty similar, but they might end up a little higher once I enter everything. Also, don't forget to account for the cost of the gantry parts as well; while the design is free you still have to get them milled out my someone. I'll be selling kits of the kikori (it's new name) once I get my business up and running (probably early July), and you'll be able to pre-order them at a good price through my kickstarter project once that's up in the next couple weeks or so. Won't know the actual price until I see how fast my machine can mill them accurately.

As far as using an 80/20 type table, the thing is is that since the rails the gantry rides on are attached to the table top, using the machine to face the top board will only result in a work surface with the same imperfections as the original table top. That being said, as long as your rails are straight and your gantry square, you could theoretically use the kikori mounted on a non-flat surface to mill out the parts of the torsion box, since your variation should only be in the Z direction. Not sure if I would try it though.

Finally, the length of the table can be whatever you want; you just need long enough rails and chain. However, keep in mind that because of the width of the gantry (in the x direction) it's cutting area is going to be 28" shorter than it's travel distance. It wouldn't be too hard to shorten the Y axis of the gantry either; I forget the spacing of the holes, but you could probably just use a saw to cut down a few parts as long as you did it in increments of the hole spacing on the Y arms.

[Yehuda]

Apologies for not keeping this thread more up to date, but building the kikori (my machine) has kept me pretty busy.

I'm proud to announce that it is now successfully up and running! I've already used it to make some parts, and I'm surprised by the level of accuracy I'm getting! I ran one set of parts that consisted of a small piece made to fit in a rounded slot; there was supposed to be a 0.01" gap between the two pieces, and when I measured the finished parts the gap turned out to be 0.011"!
(You can see pictures of the parts here.)

For those who'd like some technical details, this was done by a simple 1/8" plunge cut router bit in an ER 20 on a 3 1/4 HP Porter Cable router spinning at 21K RPM and moving at 20 IPM.

If you'd like to follow my progress, I post pretty regularly to my blog Sindrian Arts.

[prcdslnc13]

anymore updates as to when youll be releasing plans? Also how much wear have you seen in your rails with the increased weight of your massive gantry, compared to the blackfoot?

[eloid]

a photo of the finish router would be great