Rods "Spaceship" Scratch built Plasma Cutter build

I did a fair bit of 1.6mm cutting the other day and had a bit of trouble with the probing,



This is a small portion of the stockpile I have of 1.6mm sheet. We had a few big jobs over the last couple of years that we could not use the full amount of the full sheet so I have two large pallets of offcuts,

thefabricator03 wrote:

Phil, If you add those changes that Rod suggested, I am more than happy to test it out. I have a ton of 1.6mm sheet offcuts I can use to test.

And here was I thinking I might get around to painting my plasma table while the water tray was empty....
There is plenty of 2mm material lying around here to...

When you think about, there is no valid reason to trigger a probing error when probing is under way... Just back up until contact breaks and resume at normal probing speed.

rodw wrote:

And here was I thinking I might get around to painting my plasma table while the water tray was empty....
There is plenty of 2mm material lying around here to...

Its always the way when you put something in to use before its finished, its never a good time to pull it apart to do more work on it. Always one more job to go before you can do it. I know that feeling very well.

thefabricator03 wrote:

Its always the way when you put something in to use before its finished, its never a good time to pull it apart to do more work on it. Always one more job to go before you can do it. I know that feeling very well.

I think the best way to to avoid painting it would be make something else for it. In my original design, I made allowance for a pull out material support


I think this would be a useful feature for when I index a full sheet. I just need to get a length of pipe. I have some casters I can put on the legs so it can slide in and out.

Its also a job that needs the water tray to be emptied so I can roll the machine way from the wall to insert the said pipes into the holes in the laser cut endplates on the side rails.

I've been working with Sheetcam trying to do stuff I've not tried before. I've been playing with using tabs along fold lines becasue I don't have a press brake. I'll probably only do this for prototypes and get production parts folded outside. But here is what I have so far.on a simple folded channel.

So if anybody can offer guidance on how to fold the perforated part and how long the cuts vs the tabs should be on 2mm steel, please let me know..



And what I am planning to make. A 1200mm long channel. I'm hoping its good enough to handle a 100 kg load with the brace in the middle.



To do this, you need to make your DXF files with the fold lines in it and then move the fold lines to a new layer in Sheetcam.

Create a separate operation for this layer with no offset and then on the Cut Path tab for that operation, there is a holding tabs button.
The trick in there is to click on the "place tabs" button to actually create the perforated line or nothing happens.

I've also had a play with the remnant offcut option to and that looks handy as well.

So it looks like before I do this, I need to get some material, make my slide out material rest, refill my water tray, test Phill's new probing routine and maybe even have a play with the void crossing stuff I did ages ago as with remmant cutting and sheet severing, that would be useful so I can cut right off the sheet.

Its probably worth mentioning that with remnant cutting to sever a sheet, Sheetcam starts in the centre of the sheet and makes two cuts, one to each edge from that point. Maybe its something Phill could consider changing his sever routine to do. (really neads void sensing to work well!)

Well I think you can blame Tommy for this. My new CNC best friend (and latest supplier) is Ron Nollet, the Aussie Lam Technologies dealer.

So tonight I am AUD $1.1k poorer and Ron is sending me 3 x Lam Technologies DS1076AS22 stepper drives and the Lam programmer. He assures me the S22 means they are the latest in super high speed drives so we'll see if my Mesa cards can feed them pulses at a pace they can devour!

These are AC drives that accept up to 65 volts AC and their advantage is that you can connect them direct to a bare toroid transformer without the need to add a rectification stage to convert to DC power. So give them 65 volts AC and they will send around 90 volts DC to the motor. at 6 amps or 8.5 amps peak.

I've also been in touch with Tortech an Aussie manufacturer of Toroids.and they have a product that can be set up to deliver 32 volts at 20 amps and they'll wire them up for me so if I get two of them, I can connect them in series so they output 64 volts at 20 amps which is enough to run a whole forest of stepper motors!

So the spaceship has always been a bit of a test bed and I've been working with my other new CNC engineering mate Marshall in Texas who has come up with this crazy spreadsheet model designed for stepper motor selection. Eventually I got sick of navel gazing at spreadsheets and decided I wanted to see if I could launch the spaceship into orbit up there with Elon's spaceX rocket!

You can't just bolt up drives of this calibre up to crappy $50 motors the Spaceship currently runs on its thrusters so we've picked out some commercial quality drives that are 5 amps and can easily handle 90 volts (to a maximum of 144 volts). According to the manufacturer's data, they can handle up to 10 amps so they are a good candidate to try out the Lam's boost function Tommy has blazed the way with. So all in all, the thrusters will be replaced with afterburners!

So then I'll need some encoders and I suspect good ones won't be cheap. So I also need a Mesa 7i85s to read the encoders!

When I've played around with torque curves. it seems these motors will give another 20 % or so of torque up to about 300 RPM if they are boosted. After that velocity, the performance reverts to the 5 amp curve. I figure the need for additional torque is going to be down low from a standing start rather than when doing rapids so that should be a good match to the Lams. In fact our model, says we only need 3.3 amps (4 amps peak) at 71 volts so we have an enormous range to boost the Lam drivers to.

So its going to take while to get everything delivered to the spaceship/s hanger so its probably going to be an incremental retrofit.

I guess the overall objective is to improve acceleration which in turn should improve cut quality and be able to present the spaceship as a commercial prototype table rather than a DIY table so it should command a higher price if I ever choose to sell it and build another to Marshall's engineered design. Maybe 30+ metre rapids might also help production speeds too.

So stay tuned for the next developments

Looking forward to seeing the results Rod!

My Leadshine drives can take AC input voltage. I did not think to use a torodial without a rectifier to get the 70VAC. Pretty clever stuff.

thefabricator03 wrote:

Looking forward to seeing the results Rod!

My Leadshine drives can take AC input voltage. I did not think to use a torodial without a rectifier to get the 70VAC. Pretty clever stuff.

Yeh, that was Ron's idea! You may need to check out how good their internal rectification is if you went that way.

Now I think I need another Lam drive. I can't really leave a crappy $40 ebay drive in there for the Z axis beside them can I?

Would compromise the build quality for sure. We need to see that z axis humming along as well!

thefabricator03 wrote:

Would compromise the build quality for sure. We need to see that z axis humming along as well!

No need to hum, its got plasmac helping it out so it only needs a leisurely stroll. The model says it needs a NEMA 34 which is actually 1 kg lighter than the closest NEMA23! But that was to cut corrugated iron at 6100 mm/sec. 20 m/min on a 5mm pitch ball screw.

I know Ron has a LS1073A in stock which is an open frame one which would actually be perfect but a DS1073 would look sexier!