Rods "Spaceship" Scratch built Plasma Cutter build

Don't you hate it when you loose a post just before you hit save?

Anyway, I wanted to show 2 more pics.

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The drive pulley on the stepper has slipped so I need to shorten the brass standoff legs which won't take long.

And this one of th ealuminium channel that takes over from the drag chain to protect the wiring.

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I still have to mount this part and undercut the drag chai end so the cables are not as exposed as they are in this pic.

It is worth mentioning that I've made extensive use of 60mm wide Aluminium flat bar. This easily fits in most small milling machine vices.Most material is 6mm thick but also some 12mm thick. This means this design is ideal for entry level milling machines so anybody can build this in their home workshop.

I have a Seig SX3 milling machine which has done most of the work here but there has been a little bit of lathe work machining the drive shafts. Anybody with a decent home workshop can build something like this.

So next post will cover off on the enclosure and wiring.and then we can talk about software configuration which is what tis forum is all about.

I only got an hour or so to play today but I added an adjustment screw to control the float switch movement. All I did was remove the part the sensor is mounted to and drill and tap an M4 hole for a countersunk screw and lock nut.

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I did think of turning up a knurled knob but the M4 screw will do the job just as well. If I get too much wear in the aluminium, I'll add a countersink screw in the bottom part to act as a metal seat.

I have not measured the movement precisely but I would say movement of well under 0.5 mm will trigger the float sensor.. I'll revisit this when I get the float switch input actually doing something useful in the software.

Well I solved a problem today that had been bugging me for 18 months or more and was the impetus that made me upgrade to a Mesa ethernet card.

You see, back then I built a plasma CNC controller back then and shoehorned it into an old Plasma case
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I could never get it going and put it down to experience and tore it apart at the beginning of this build.

Anyway, becasue I am still waiting for my motion control hardware to arrive, I decided to reinstall LinuxCNC on the MiniBox PC I have. Once again I had no luck but realised that the real problem was that the ribbon cable I made had the connectors round the wrong way.

I tried to correct the problem but I never have much luck modifying ribbon cable connectors and yesterday was no exception. I ended up ordering a new on of eBay but emailed my mate Chris to see if he had a spare. Turns out he didn't but my query motivated him into finally making a longer cable for his Smoothstepper on his mill so he gave me the old one.

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He knows a lot more about electronics than I do and we bench tested my cheap Chinese breakout board and confirmed it was working perfectly and the signals and LCNC is seeing both inputs and outputs. Anyway, once I got it home, his old ribbon cable worked a treat. Everything is running perfect on the breakout board now.

The old VIA motherboard has latency of about 18000 so I think it will be fine for when I'm ready to make another CNC machine. Actually, I have my eye on a converted Seig X3 mill but really think I'll struggle to house it and a plasma table in the garage.

I did do a bit more work on wiring the controller up including the torch on relay and THC input. I added a LED light for the torch and a switch to simulate the ArcOK signal but still have to tackle the wiring.

From the UPS tracking, it looks like my linear rails and carriages are now in the country and the gear racks and stepper gear boxes are somewhere between Singapore and Australia. I spent a bit of time last night designing the gantry end plates. The plan is to have it all designed in the next week or so so I can send the parts out for laser cutting when my suppliers get back in the new year.

Well, reality won. I didn't buy that mill so its back onto the plasma table. I just did not have room for it.

This morning was quite a momentous occasion as after 6 months, I was finally able to join the gantry to the table in my 3D model.

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As it stands, the model has a water tray but I really would like to build a downdraft table and have some ideas on that.

There is still a bit of work to do including mounting the X axis stepper motors but It will come together pretty quick from here. Most of the parts will be CNC laser cut using steel for the table and aluminium for the gantry ends. The gantry ends will have a folded return on the edges for stiffness. I will probably also add some stiffening braces on the outer sides of the gantry.

Both shipments of linear rails and racks are set for delivery tomorrow, so I should be able to finish off designing the main parts once I can check some dimensions.

I also managed to wire up and test the ArcOk signal and the torch on switch today and an M3 command made a very satisfying click of a relay which turned on a light I'd rigged up that will be replaced with the torch switch. My manual ArcOk test switch is also being read and switches on a light on the control panel.

I'm sure I'll have a lot of questions on the software side of things once I start configuring LinuxCNC so please keep following along.

One thing I don't really get is how to use a signal more than once. eg. how to use the ArcOk input to turn on an indicator light AND trigger a light attached to an output.

Nice build! The only thing I did over on my plasma was to add a water table, I didn't quite do that right as I can't bring the water level up to the bottom of the sheet. The splashing water keeps the metal cool so it doesn't warp. If you need the recipe for the plasma quench holler.
I took a water heater tanks and placed it horizontal under my table and connected low pressure air to it and a dip tube to the table drain. Pressure forces the water up and I close the water valve then open the vent. After cutting is done I open the water valve and it all drains back.

JT

BIgJohnT 28 Dec 2016 21:17
Nice build! The only thing I did over on my plasma was to add a water table,

John, thanks for the encouragement. Its been a long time since I bought my Mesa hardware from you. Hopefully, it won't be long before this is built now! My downdraft design is still a work in progress, but I was planning on doing something like this a a drop in replacement for the water tray. There is a pull out drawer on the opposite side to clean out dross and scraps.

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All of my motion parts arrived over the last few days and I finished modifying the gantry ends to mount them last night.

I bought these timing belt gearing mechanisms to save me having to make my own.
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These run about 4:1 reduction for a NEMA 34 motor using a 1.5 module rack and pinion so they'll give about 27mm per rev.

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You trust can't always trust Chinese listings. The listing said the supplied pinion drive was for 14mm shafts and a pinion with a 12.7mm bore was provided. This makes sourcing the right stepper motor harder as most in Australia are 14mm.

I did find one on Steppers on lIne with a 12mm shaft which at 3 amps would be a perfect match for the 2.8 amp NEMA23's I was going to use.Of course the other problem is that it had a machined flat on the shaft, not a keyway. If I go any higher on the amps, I'll run out of power and a larger power supply will be hard to shoehorn into my enclosure.