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CNC Plasma - Group Build?


simonr

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This evening, I started building something almost 'arty'! Or at least something with the kind of aesthetic embellishments you would never bother with if you were cutting out the bits with a band saw.

It's a Theo-Jansen inspired walking robot.

post-74-0-34838400-1426282957_thumb.jpg post-74-0-90732300-1426282986_thumb.jpg

Where is the Land Rover content?

post-74-0-37183500-1426283001_thumb.jpg

I'm using 2 x P38 window winder motors to drive it!

I'm going to use an Arduino MicroView (which is very cool) to control it, using two PIR sensors to detect people (or maybe four legged creatures who come and defecate in my garden!) and scuttle towards them.

I've slowed down the cut speed to 1000mm/min and reduced the current to 25A and the cut quality is much better than before with less 'ripples' on the sides of the cut. The bits for one leg pair took about 4 mins to cut then 10 mins to clean up with a disc sander.

Only another 5 sets to make!

Si

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Solidworks does stuff like this really well! Inventor and the rest do a pretty good job but IMHO, SW wins on complex linkages and analysis. If you turn the axle shaft on either side, all the linkages animate properly too.

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Potentially. It's not brilliant for high accuracy holes - but you could cut the components then drill the holes separately. As an experiment, I cut some slots in a piece of 6mm plate and used these to guide a fold. I just bent it in a vice then welded the Vee's created as the slots were bent. It produced a good, tight radius bend.

Si

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  • 1 month later...

I'm amazed how well that walk simon, dead smooth and straight. Love it :)

What Walk?

I credited LR4x4 & in particular Robert in the Instructable as without both, it would never have happened! We have one new LR4x4'er, Bobby-gg as a result!

Robert - What's wrong with your Z? Maybe we could Improve it?

Mine took several iterations on the CAD and two goes in metal to get it right - but I'm very happy with it now!

Si

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Si thanks v much for the credit for inspiration comment it was very much appreciated and unexpected

Did not want to taint your build thread with my unrelated thought process hence posted in my original thread

Cynical is it suppose to be "work" /"worked" as the word "walk" confused me in your post (damn autocorrect isn't that clever!)

Has anyone who bought Si's kit got it up and running? If so why not post pics or a video?

Rob

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I opened the box to admire it and that was as far as I got. Having had a good read thru I kinda feel like I've bitten off more than I can chew, having no electronics or IT skills. I started to build a shopping list on eBay but the pulleys are out of stock and I ground to a halt really

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I opened the box to admire it and that was as far as I got. Having had a good read thru I kinda feel like I've bitten off more than I can chew, having no electronics or IT skills. I started to build a shopping list on eBay but the pulleys are out of stock and I ground to a halt really

All the Electrickery and a good proportion of the IT is covered in the Instructable linked above. Anything else - post the question here & I'll answer best I can! (then include it in the instructions!).

All the wiring is via screw-terminals so it's easy to change if you get it wrong. The only critical bit is power to the right terminals with the right polarity - nothing else you can do will damage the components (so worth tripple checking!).

Si

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Sounds like you've started something Si! :i-m_so_happy:

Soon as I get nearer having a running 110 (don't laugh at the back there!), I will look seriously at building one myself. Got some ideas for custom metalwork that will be awkward to make by other means.

I've been wondering though: Would it be possible to equip it with a higher-power laser too? Such that one could engrave text (p/ns, 'slot A', 'Tab B' etc) or mark the location of holes too small to make with the plasma torch.

Matt

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I've been wondering though: Would it be possible to equip it with a higher-power laser too? Such that one could engrave text (p/ns, 'slot A', 'Tab B' etc) or mark the location of holes too small to make with the plasma torch.

It would. The problem is the size, cooling & power requirements even for a low power (say 40W) laser. It's the reason the laser is stationary and they use a system of lasers / optic fibre to carry the beam to the cutting head.

Even to etch metal, you need quite a high power laser - as most of the energy reflects off the shiny surface. Whitewashing the surface can help.

I think the best option so far (Thanks to RobertSpark) is to mount an automatic centre punch on the Z axis - so you just centre punch the hole centres.

In a similar vein, you could mount one of the vibrating hand engravers to the head. You should be able to use it to both centre punch and engrave text. I might even give that a go!

Si

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turn the sound down

plasma + scribe

https://www.youtube.com/watch?v=92MiZrY44tI

plasma + scribe

https://www.youtube.com/watch?v=Mi5CS5tKPGA

plasma + scribe

https://www.youtube.com/watch?v=EPgbngKA0qQ

drill + scribe + plasma

https://www.youtube.com/watch?v=111-BTfApXs

pneumatic scribe (the common choice for CNC work): chicago cp9361 (there are similar alternatives / copies).

http://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&_sop=16&_nkw=chicago+cp9361&rt=nc&LH_PrefLoc=2

Instead of a big heavyweight carriage and sacrificing axis travel length I'm trying to think of a way that I could use a quick toolchange method of swapping between the three tools (plus camera scan and touchprobe) so they are always aligned and it saves me time recalibrating everything. There is the possibility to edit the sheetcam postprocessor to take account of toolchanges, and you can use "brains" within Mach3 to control auxiliary relays to open and close pneumatic valves.

Rob

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All the ones shown were vibratory engravers (like a needle gun) hence noisy! Another option is a rotary engraver which will not upset your wife / neighbors!

I guess with a pneumatic engraver - you could feed the air into a single acting, spring return pencil cylinder to provide the movement and return. That's actually a lot simpler!

As you say, you can set up the two as different tools with tool offsets (so it knows your engraver is say 100mm away from your plasma tip).

In Sheetcam you can use different Layers in the drawing to select different tools - so you put the lettering & hole centres on one layer and cutting on the other. You can easily change the order in which it cuts each job - not good if you cut the part before you engrave it!

http://www.ebay.co.uk/itm/PRECISION-AIR-MICRO-GRINDER-KIT-ROTARY-TOOL-Kit-15pc-CRAFT-ENGRAVE-MODEL-/181721170987?pt=LH_DefaultDomain_3&hash=item2a4f6d042b

plus

http://www.ebay.co.uk/itm/10-x-Carbide-PCB-Engraving-Bit-CNC-Router-Tool-30-Degree-0-3mm-Tip-J3-3003-/331130232897?pt=LH_DefaultDomain_3&hash=item4d18e66041

plus

http://www.ebay.co.uk/itm/Aluminum-Alloy-Mini-Pneumatic-Air-Cylinder-CDJ2B-12mm-Bore-50mm-Stroke-/121496373179?pt=LH_DefaultDomain_3&hash=item1c49bf87bb

with a bore just bigger than the OD of the engraving tool. Saw off the non rod end of the ram and attach the engraver directly to the piston so the air can flow through the piston into the tool. Attach a tension spring to the rod to retract when the air is switched off plus an adjustable end-stop to set how far / hard it pushes down on the surface of the steel.

Si

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