Where to start and what to avoid

I've done some laser cutter builds before but all using aluminum extrusions. A cnc plasma cutter has been on my list for a long time. I am trying to rid proprietary software from my life so the more open the better here.

I have considered doing the cncrouterparts kit for the plasma table without the electronics. Then just adding electronics well supported by linuxcnc. It's a popular kit. I've been unable to find info of anyone converting for linuxcnc. Documenting the process would probably have benefit. The kit seems to basically be aluminum extrusions with a couple custom milled pieces so easy to put together and mostly standard parts. I contacted them directly and asked about it working with linuxcnc but they just said they didn't know and pointed me to a forum for help. Possibly because the electronics they sell is an ethernet smoothstepper and they only support mach3. There is also question about whether aluminum extrusions are the right answer here..

There is also the option of getting a complete system and converting it. There are some that run CommandCNC which is "mostly" linuxcnc but I think with some minor proprietary parts? Seems like it'd be trivial to switch from those. The ones I've found are Star Labs and LDR Motion. They generally seem more rigid and better built.

Any thoughts?

Well, as you seem to have already realised the Ethernet Smoothstepper isn't an option with LinuxCNC.

Other than that, I would start with the mechanics and then the motors, then the drives and then ask us how to control them. There isn't a lot that LinuxCNC can't control.

See if you can get a complete kit without any electronics. Its a long journey to design and build a good table. Command CNC use their own external external THC. I think the future config will be the plasmac component which is described on this thread
forum.linuxcnc.org/plasma-laser/35449-an...ma-component?start=0

The right people are now testing it on real hardware and hopefully becasue the source is on github, it will find its way into the Linuxcnc core code one day. It has absorbed an enormous amount of work from a number of people into one plasma component.

Linuxcnc has the ability to beat the commercial external THC's on the Mach3 platform hands down becasue its all so tightly integrated into the motion planner.

rodw wrote: Linuxcnc has the ability to beat the commercial external THC's on the Mach3 platform hands down becasue its all so tightly integrated into the motion planner.

I think i mentioned this somewhere else, but, form my extensive experience with Linuxcnc and the "toma_thc" config that has less features than the one mentioned by RodW on hobby and professional industrial machines retrofitted with Linuxcnc, it beats most of the industrial controllers, period. Reliability is the main reason as it never fails, it is much faster to have the workflow from Inkscape to Linuxcnc directly than jump through hoops as most require. The main issue as it was mentioned several times is the lack of nesting, but one of my customers figured that out and made me aware of it several days back, the only procedure for nesting in inkscape is nearly the same as in sheetcam, select parts by the order you want them to be cut while holding the shift key and make the selection "Group". Tested it several times and it works as it should.

I have been watching the thread you mentioned rodw and it seems extremely promising. It is definitely what I have in mind.

One of the lasers I helped build and set up uses linuxcnc and the config found at github.com/bjj/2x_laser . I've borrowed and written quite a bit of code to make the process from Inkscape to laser as easy as I can for the local hackerspace. I look forward to doing the same for a plasma cutter. This is the area I feel most confident.

Where I don't feel confident is what mechanics to to start with. If I'm reading this right, the downside of going with the turnkey solution is that it will come with a thc with it's own motion control. I certainly would want to use linuxcnc for that. How difficult would it be to change that?

Has everyone here custom built their own? I was hoping someone would have experience with a kit or vendor.

Wher to start
A What Budget do you got
B What Part size is the Plan
C What envirerment do you got Plasma make Noce lots of dirt and ofcause EM
D Where are You for Parts to get USA Europa ....

jondale wrote: I have been watching the thread you mentioned rodw and it seems extremely promising. It is definitely what I have in mind.

One of the lasers I helped build and set up uses linuxcnc and the config found at github.com/bjj/2x_laser . I've borrowed and written quite a bit of code to make the process from Inkscape to laser as easy as I can for the local hackerspace. I look forward to doing the same for a plasma cutter. This is the area I feel most confident.

Where I don't feel confident is what mechanics to to start with. If I'm reading this right, the downside of going with the turnkey solution is that it will come with a thc with it's own motion control. I certainly would want to use linuxcnc for that. How difficult would it be to change that?

Has everyone here custom built their own? I was hoping someone would have experience with a kit or vendor.

I built my own forum.linuxcnc.org/show-your-stuff/32029...cutter-build?start=0
Well actually i'm still building it...

The way I understand smooth steppers work they also need a breakout board so maybe you could purchase the kit and throw the smooth stepper away and you might be able to take their Mach xml config and convert it to Linuxcnc parallel port with stepconf to get going and plug direct to the BOB.

But with your knowledge, you will have limited inputs and I guess fewer limit and homing sensors so you might need to add a few more sensors to the table before migrating to mesa hardware (or just use Tommy's config). Personally, I think plasma uses a lot of inputs so a Mesa 7i76e is a good choice. You might be able to get away with a 7i96 if you can sort out the encoder input. I'm not really certain if it has the encoder input or not. If you go to mesa, you really want to be using 24 volt power rather than what they use with the smooth stepper.

You can buy Z axis stages for plasma with breakoffs etc so you might be able to build your own table with X & Y and use one of them which is the hard part. I Would not build a Z axis again!

rodw wrote: The way I understand smooth steppers work they also need a breakout board so maybe you could purchase the kit and throw the smooth stepper away

They cost $180 (and that's $US, not your weak AUD$
So buying one and throwing it away seems suboptimal.

pl7i92 wrote: Wher to start
A What Budget do you got
B What Part size is the Plan
C What envirerment do you got Plasma make Noce lots of dirt and ofcause EM
D Where are You for Parts to get USA Europa ....

A <20k USD.
B At least 4x8
C It will be in my workshop and given it's own area. What should I be looking out for here?
D USA

This is an example of a star labs turnkey where they have config for CommandCNC.
starlabcnc.com/shop?olsPage=products%2Fs...rtherm-powermax-45xp
I've emailed them to ask more details on the electronics/thc.

Ok, you are looking at a good reliable piece of kit from people that have been around long enough they won't be gone next week. CommandCNC is a proprietary port of LinuxCNC ( 32bit Ubuntu, LinuxCNC 2.7.??) that uses proprietary CandCNC hardware, works fine but not a true open source build ( you will be dependent on them for support). You actually will not be able to build an EQUAL quality system unless you are good and cleaver at designing/building. Sourcing new materials for much less money is hard, volume purchasing has big discounts in the motion control world. If you have a year or two to watch for good deals on Ebay (which are getting quite rare these days) you can get quality low priced motion control parts. If you need an all in one software solution with commercial support go with a table run by the Flashcut software but you will pay for it.

You can build a quality table yourself and control it with LinuxCNC but it will require considerable mechanic, electrical and computer skills on your part to make it happen.

John