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Building the SimonR x-eng plasma cutting CNC table


Ruuman

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Hi All,

I haven't posted in here for a long time (work, life, etc, etc), but thought it would be good to run through my experiences with building up the CNC table and also try and keep me motivated to finishing it this time!

As some of you may know Simonr did a forum group build/buy for plasma cutter kits he did to his own design, original forum post is here: 

Now originally I was planning on making a 4'x4' table with the plan it would either winch into the roof of my garage or perhaps fold down from the wall and run it from my r-tech 30c plasma cutter http://www.r-techwelding.co.uk/plasma-cutter-r-tech-p30c/

So after a nice box of shiny bits turned up from simon and a mass of ordering all the various bits and bobs (motors, controllers and belts) the kit was built up fairly painlessly. At the time my steel supplier couldn't get the exact box section Simon specified so I had to jump up on the wall thickness, not a major issue but the radius on the corners was larger and maybe not quite as fit for purpose, but it doesn't seem to be too compromised. 

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I then built up all the electronics onto a single board to keep things manageable for the second, later on it will all go into a nice box. While it may appear slightly scary for those who hate electronics but it really isn't too bad. The only major issue I ran into was the instructions on the control board port mapping being completely wrong which caused some head scratching, but all in all was straightforward to overcome. Then there was a bit of tweaking with the stepper motors to find the best compromise on speed and acceleration, it's pretty dam impressive how fast you can make it move

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So with everything built up and working the first thing to do was put a maker pen in and try and draw some lines.

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So with the table all built up and working it was time to rig up the plasma, this is where things started going wrong and why the project was shelved until funds and time allowed for it to be completed.

So I rigged the plasma torch up with cable ties so I could get things ready to test, later on I planned to make a more substantial torch holder.

2015-06-21 13.59.06.jpg

I then added two wires from the torch switch to wire into the controller board, all pretty straight forward.

The major issue is the plasma I was using only had HF arc start, not a pilot arc. Every time the arch struck and it wasn't a perfect strike the electromagnetic interference drove the controller nuts and would either lock the axis or introduce a vibration in the motors and would only respond if it was powered off and on again.

It was so bad the board actually died on the z axis and I had to buy a replacement (luckily very cheap)

Now the wiring I was using was quite poor and I could have done some better grounding and isolation to try and improve things, but on further reading up on the net it turned out this was a very common issue. After a bit of messing around I realised I really need a better plasma and while I'm not knocking the r-tech (for what it is, it's pretty good and well made).

So after looking at the piggy bank fund there was no chance I could afford something like a hypertherm or even the r-tech 50. So after tripping over the table god knows how many times I decided to shelve it and come back. On the plus side breaking the table down into sections was very quick and it packed away nicely.

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So that brings us to today, finally a bit of time off over Christmas, a little older, probably not much wiser I decided to dig the table out again but with some changes. Now I've decide I don't want to have the table stored away, it wants a permanent home to live as it will motivate me to use it more.

So the plan was now to reduce the size down to a 2x4 table, the reality of the situation being I could probably get away with a 2x2 table for almost every project I do, but I had the space available so why not.

After clearing and moving the mountain of junk out of the shed I manage to get to the desk and decided this will be the perfect base.

Shortening the table was very simple and just required cutting down the box section down, shortening the threaded bar clamping rods and cutting the belts down.

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I added some risers to lift up the table up off the desk as I plan on having a water bed slid under. I will also be adding some metal to the floor and walls of the shed to keep the fire risk down.

I also wired in the floating head limit switch but still getting my head round the code to make this work properly.

 

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So now onto the question, I have the funds for a new plasma and want to get something good. so the short list is:

Oxford Cutmaster 550 http://www.migtigarc.co.uk/oxford-cutmaker-550-plasma-cutter-403-p.asp

Tec-Arc Opticut 65 http://www.migtigarc.co.uk/tecarc-opticut-65-plasma-cutter-397-p.asp

Hypertherm 45XP http://www.rapidwelding.com/dynamic/Category.aspx?c=APMX45XPHS&o=0&zl=0

Now I'm leaning toward the oxford and tec arcs, British made (same company) and I've been very pleased with my oxford mig, lower cost and the cutting performance is massive, not that I'll ever need to cut 30mm

I'm going to stick to a hand torch for the second though a proper machine torch will be on the cards if all goes well.

The tec arc they will customise with CNC port and possibly add a torch connection that would be handy if I want to do some hand cutting and don't have to remove the torch off the machine.

So hopefully on the 3rd/4th I will be putting an order down for something and the project can continue.

I'm also very tempted to mount a laser on it for messing about, you seem to be able to get a 2.5w laser for about 80 quid on ebay and it looks to cut thin wood ok and quite good at engraving things. http://www.ebay.co.uk/itm/445nm-450nm-2500mW-2-5W-Blue-Laser-Module-for-DIY-CNC-Cutter-Engraving-Engraver-/172420215653?hash=item28250bb365:g:YgAAAOSwWTRWz~1I could be fun

 

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Right decision made and money put down. I've ordered an Oxford Cutmaster 550, they are customising it with a torch connection and CNC control port. I've stuck with a hand torch for the second but can have a machine torch later.

Hopefully should arrive next week sometime, I've also purchased a 2.5w laser. Annoyingly the next 3 weekends are already fully booked :(

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  • 2 weeks later...

Right, well I haven't got the plasma yet as I've been off sick, but the little laser turned up and it's pretty cool. The controller board relay can switch up to 20amps @ 14v and the laser only needs 2.5amp @ 12v so it was easy to wire straight in. A couple of table ties to secure.

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After a bit of messing about I found you could get significantly different kerfs with the focusing ring.

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Just a word of warning if you get one of these, get some laser safety glasses. The light is ridiculous and a stray reflection will do serious sight damage, the glasses are very cheap. I found on the ply I was marking the 650mm per minute travel speed was the quickest it would go and still maintain a good result.

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Video demo is here:

 

Plasma should be here next week! :)

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Oooh...I like the laser!

Have you determined what it will cut?  The favorite seems to be Black Acrylic.  I'd be interested to know what thickness it will manage. 

Something else to try once you get the plasma up & running (and get bored of cutting Steel) is to try cutting wood, polycarbonate & glass.  You are probably thinking "Simon must have been on the Beer this evening!  That's impossible!"

If you coat said material with photo mount spray, then stick a sheet of Aluminium foil to the surface - it becomes conductive.  Connect your earth to the foil and cut away!

It's tricky to get the feed rate just right - but you can get a nice cut.  Cutting wood / plastic makes an unbelievable amount of smoke.  I was most impressed with glass - you can get a nice melted, finger safe edge.  I've only tried it on window glass - but it ought to work on laminated or toughened. 

Si

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Hi Simon,

The laser is pretty smart, it doesn't have much cutting power, from my experiments so far

10mm foam rubber take approx 6sec to punch a hole
3mm abs plastic (black) took 3-4second to punch a hole (my god it stinks) I think thin stuff it probably would cut, but very slowly.
thin cereal box card cuts at about 200mm/min maybe a bit less

I'm going to see if it will burn off engineering blue or sharpie from metal, could be really handy for laying out projects before milling.

I just purchased the full version of sheetcam and paid the extra 25 quid for the laser raster module. It's running a wood etch at the moment, looking forward to the result, though it needs some more tweaking.

Thats a great idea with the foil, but I'm going to rig up some fume extraction before I even get close to attempting that!

just for reference this is a demo of the oxford cutmaster I'm getting, I'm wondering if the thermal heating mode might have some interesting possibilities too.

 

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Well a bit more messing around and learning. I've just been experimenting with the raster mode, which basically turns the CNC table into an old dot matrix style printer. The process to create the data file is a bit more complex than straight CNC dxf's, but not to bad.

Basically you need to find an image you think might work, simplify it and convert it to a vector graphic (i used inkscape for this whole process) you need to use the SVG file format to import into sheetcam and then handle it like a normal file, but under tools there is a raster option.

raster test.jpg

Now the issue I have found is there is a 100ms delay from the torch control turning on until the next line of G-code being executed and this seems to be hardcoded into mach 3. This causes hotspots at the start of each line and each break of the line, this is fine when trying to cut something, but really causes issues on marking. There is apparently a work around mentioned here: http://hobbycncart.com/publ/cikkek/mach3_temaju_cikkek/switching_a_laser_under_mach_control/8-1-0-29 but I haven't got my head round it yet as I'm pretty new to g-code.

In this case it has had the unfortunate effect of burning through the back of the nice notepad my girlfriend bought me for Christmas, but I kind of still like the result.

2017-01-15 16.16.25.jpg2017-01-15 16.16.12.jpg

Another useful finding is that using the height adjustment the kerf width can be accurately controlled. So you can setup different tools in sheetcam with different heights and feed rates to achieve the same burn level but with a different kerf. If the 100ms delay issue wasn't there it would work perfectly!

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One simple option for the delay on spindle start (which you a currently using to switch on the laser / plasma) is to use the coolant output (turns the coolant pump on & off on a lathe / mill) which has no delay.

The Oxford Plasma heating mode looks useful enough to consider buying one just for that!

Si

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Ahh ok, I think thats a similar theory to the post I included, they were using M10 and M11 which is the vacuum control as best I can tell.

As I say I'm very new to g-code so still trying to get my head round the finer control aspects. I assume I either need to mod the post processor or adjust the port configs in Mach 3 or both to get this to work. Still will keep me busy in the evening and I've moved the fan heater to the shed now so can't complain!

I'll do a write up on it when it arrives they seem pretty new on the market, but from what I've read everyone is impressed and they were great to deal with. I need to also wire a 32amp circuit into the shed :( 

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2 hours ago, Tim_NZ said:

Really interesting project, thanks for writing it up :) Is the laser strong enough for cutting gaskets?

 

Cheers,

Now that is a bloody good idea! I think it would do gasket paper no problem. Ill see if we have any neoprene gasket material at work too. That would be really good! 

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I'd imagine cork gasket material would cut quite easily if it gets through neoprene? It might be necessary to use some sort of vacuum table to hold the material flat though, (which has it's inherent risks with fire etc!).

 

Cheers,

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cnc / plasma / laser delay....

With Mach3, you use the dedicated laser input and there is no delay, M10 Px M11 Px (m11 turns the output on, and M10 turns it off .... think of the "0" and "1" as digital logic for on and off)

The Px part is the output number, i.e. if you set Output 3 within Mach3 to control the laser (plasma) etc without delay, then use M11P3 (on), M10P1 (off)

 

Now there is a catch..... you need to command a motion move because M11 + M10 requires motion in order for it to be triggered, so the next line of your gcode must have some motion, what I useto do was use a phantom axis "B", so I would write:

M11P1

G0 B1  (rapid cnc motion of B axis to position "1")

and

M10P1

G1 B0    (rapid cnc motion of B axis to position "0")

 

There is another catch........ if you are using a cheap motion controller (very specifically far eastern) then M10 + M11 probably won't be hard coded into the motion controller as they are not functions actually dependant upon Mach3 but upon the motion controller, the only way that they work directly within Mach3 is when you use the parrallel port.   That being said, Simon use to use (long time since we chatted) the UC100, which is a very good motion controller (I use to use the smooth stepper with Mach3 + Mach4, but now have a UC300eth and a UC400eth which I use with UCCNC..... very much better!!! and designed for lasers and plasma cutters... I know I have been one of the people chasing the features to be added).

 

Sheetcam is very good and you can write your own / modify the post processor to enable the M10Px and M11Px to be hard coded to the "pendown" function within the post processor.

 

Few other things..... M10 and M11 are handed differently in UCCNC (they are the other way around, and P is the power intensity in % or bits 0-255), and if omitted just mean 100% as its a PWM signal that is output on the pin (ie M10  will mean 100% output, full on).

There are a lot of very good features in uccnc but it will only work with a UC100, UC300usb / UC300eth or UC400eth controller.

 

Rob

 

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That controller looks very smart. I like the idea of the CNC machine being a proper device on the network, rather than being some kind of glorified parallel-port driven plotter which requires an attached computer to run it.  (Yes, I know of course it still requires a PC running UNCNC/Mach3)

 

Might be worth starting your own thread RobertSpark, I’m sure many of us would be interested to see what you’ve done; Would prevent us dragging Ruuman’s thread too far off-topic.

Edited by UdderlyOffroad
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http://forums.lr4x4.com/topic/100205-diy-cnc-plasma-laser-gcode-etc/

started other thread in case anyone has any questions / requires any assistance.

 

Si, No not gone anywhere as I said in the other thread, I've had a few goes at it but not built anything.  Primary hobby is suppose to be rebuilding the 90, but I've ended up an expert (yes hasbeen drip under pressure) by necessity at mach3, sheetcam, uccnc, and plasma cutters, THC, C, C# etc .... but still not got a 90 rebuilt.....

Rob

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Cheers for the info Rob, hopefully have a chance to play this weekend. The plasma has arrived and it looks like a great piece of kit. I will do a bit of a review when I get a chance.

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just wish there were more hours in the day!

 

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