Hexapod Robot CNC router

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Hexapod Robot CNC router

Postby Matt Denton » Wed May 21, 2008 10:54 am

Ok,

So this is just a bit of fun, but has been in the back of my mind for some time now, and seeing one of Zenta's videos prompted me to give it a go.

Image

Using B.F.Hexapod with an additional floating pen attachment, and a utility I wrote to convert DXF files into translation commands for my p.Brain controller, I have got the start of a walking CNC router! Why... I don't know.. it just seemed like a good idea at the time!

Watch the video here.

I still have to add a small routing head and test the cutting capabilities, but you get the idea. Resolution of the work area is pretty low, somewhere between 7 & 8 bit, with about 0.5mm repeatability, so it's never going to make precision parts! Also I have only implemented straight lines within the p.Brain, so the utility converts arcs and circles into segments.

One obvious improvement to resolution & repeatability is to have a work surface (in this case paper) that doesn't move around, in this video the only thing holding the paper in place.. is the hexapod's feet. In order to keep the router out of the way while walking, I plan on attaching a servo to the router head to swing the head from a horizontal to vertical position. Or maybe I will have come to my senses by then!! If I'm really mad I could try some 3D milling.. as technically the hexapod Is a 6 axis CNC machine.
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Re: Hexapod Robot CNC router

Postby Matt Denton » Wed May 21, 2008 12:59 pm

Update on the router progress.

I have just about finished the router head, it took a bit of fiddling to get rid of the vibrations, but managed to find a small thrust bearing used on RC helicopters that did the trick. I have yet to mount it to the hexapod, plus there are a few tweaks to the spindle height, but it's more or less there.

Image

The collet I have made currently takes 1/8" bits, but I need to finish the 3mm version as most of my small router bits are 3mm shank. The motor is a 14 turn 380 brush-less motor, which gives about 3600 rpm/volt, so plenty fast enough! It will run from 6 to 10 cells, I think I will add a heat sink, as it tends to get a little warm even under no load. The MUX servo moves the spindle 40/50mm up and down the guide rails to the work surface.

Looking forward to getting on the hexapod and running some g-code through it, but work is slowing me down.[/img]
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Re: Hexapod Robot CNC router

Postby Matt Denton » Thu Jun 05, 2008 11:02 am

CNC hexapod cuts its first material!

Ok, so its only polystyrene, but its a start :)

Image

A couple of improvements were made to the router since my last post, most significantly I had a colleague make me up an dremel collet adaptor to fit directly onto the motor shaft, much better than my brass grub screw style colet.

For these two videos I'm using a 1/16" two flute slot cutter, the router is running at approx 35,000 Rpm, the additional battery on the to of the hex is a 12V NiMh 4500mah pack just to run the router. DXF files are loaded in to artcam where G-code tool paths are created. Due to the 10mm thickness of the poly and the cutter only being 6mm long, I chose to do two passes on the workpiece, this also shows that although the resolution is low, repeatability is good enough for multiple passes. Material is held down by the weight of the hexapod, which is current;y 4.3Kg with the router and additional battery pack.

[youtube=9LQrzuG5nFA]CNC Cut Poly Square[/youtube]

[youtube=EhM2bAqwPmY]CNC Cut Poly Femure - 2 pass cut[/youtube]

You may notice in the picture of the poly femur with the hole left in the poly, the hole has a cleaner cut edge than the cut piece. This is due to the fcat that foam and poly cuts better in a reverse direction, however, I forgot and generated the tool paths for a normal cut direction.

I also tried to cut 2mm ABS, however, this caused too much vibration in the tool, which in turn loosened the colet allowing the tool to slip out and cut too deep into the ABS. A square was cut, but not terribly accurate, some work needed yet!

Image
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Re: Hexapod Robot CNC router

Postby paulp » Thu Jun 05, 2008 3:54 pm

You do realise how dangerous this topic is dont you.

Pretty soon they'll be designing and milling their own upgrades and spares.

You'll open the door one day and be overwhelmed by 200 hexabots that built themselves overnight....

Seriously though, very cool, just shows the precision that p.Brain and V5 work to..

I have used the Dremel cutting tools extensively for projects over the years and cutting plastics such as Poly or Lexan is always a problem. The cutters dont seem to clear properly and eventually the friction causes so much heat that the plastic melts.

When cutting I always make multiple, very shallow passes that allow the cutter to clear and the plastic to cool down.

An air-blower also helps to keep the temperature down
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Re: Hexapod Robot CNC router

Postby Matt Denton » Thu Jun 05, 2008 4:21 pm

Just had a second go at the femur shape, I increased the size by 20% and reverse cut the piece.. much better!

Original and larger New part
Image

Close up of the cut edge.
Image
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Re: Hexapod Robot CNC router

Postby ucaboys » Thu Jun 05, 2008 6:23 pm

The precision is actually great compared to a CNC printer I made last year.
My version used plastic pellets and a Jet Nozzle form an old Cannon printer that hacked together
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Re: Hexapod Robot CNC router

Postby Matt Denton » Fri Jun 06, 2008 11:44 am

I had a go at 3D profiling today in high density foam. I have a few issues to sort out, mainly with my control software not having a puase or for that matter a stop button :o .. any who, I fed a 3D stl file into artcam and ran a couple of passes through the hexapod to get this:

Image

I admit its not great, but you can kind of make out the eyes, nose and mouth.. kind of. The large 1/8" scar on the face was caused by operator error!

I will post a video of this process some time after the weekend, and try another test next week.
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Re: Hexapod Robot CNC router

Postby MetalSkullRobotics » Fri Jun 06, 2008 5:34 pm

You have some outside publicity about this robot!

http://hackedgadgets.com/2008/06/06/hexapod-robot-cnc-router/
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Re: Hexapod Robot CNC router

Postby Matt Denton » Mon Jun 09, 2008 7:06 pm

Ok, attempt two at 3D cutting was much better.

I made a few improvements to the software that streams the data to the hexapod.. including a stop button! The cutter was the same, 1/8 ball nose. After a roughing cut, I did a raster pass with 1mm step, and a second raster pass in the opposite direction with 0.8mm step.

Image

I could use a smaller ball nose cutter to get a finer finish, but I think I'm approaching the limitations of the robots resolution.

Image

I will edit the video and upload when I have time.
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Re: Hexapod Robot CNC router

Postby Matt Denton » Wed Jun 11, 2008 11:19 am

I have just uploaded the 3D face video.

[youtube=quN37YskoaM]Cutting 3D face[/youtube]

To cut the face I did three passes:
1) roughing cut
2) X raster finish
3) Y raster finish.

The face took just under 30 minutes to produce.
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