New 5 axis plasma build.

[AMEPro]

Hi all,

My name is Bram and I own a company called AMEPro. We decided it is time for us to build a plasma cutter, preferably a 5 axis machine. We did some research and decided on a 2,5 by 1,5 meter machine (98 by 59 inch).

As a 4th and 5th axis we plan on using a modified movinghead. since this can easily rotate a light we figured it would also be able to position the plasma torch. unfortunately this was not the case due to the pressure of the airflow against the work piece, so we upgraded the steppers in the movinghead.

I have attached some pictures from the movinghead we plan on using, we bought it for 75 euro, the 2 new steppers have cost us more. everything that we don't need is removed. 4th picture has the original motor next to the ones we fitted. The new stepers are nema17 0,44 Nm (62 oz-in)

So far so good, but in the next phase we run into a design issue: how do we touch off on the work piece if we want to start cutting under an angle? and how to get the THC to know in what direction to adjust? the possible solution we came up with is to add a sixth axis on the movinghead that can do this, any toughts? would this make it over complex?

The plasma cutter we plan on using is a hypertherm powermax 45 with machine torch.

Cheers,
Bram

[stekke_stim]

Going to follow this. I want to build my own cnc plasma cutter.

(Groeten uit Vlaams Brabant)

Regards

Stekke_stim

[Arthurmetal]

an original approach for sure.
I am just wondering why you would want to do 5 axis plasma cutting for.
The PM45 wouldn’t cut any thicker than 8 or 10 mm comfortably, so there is not much benefit in angled edges to accommodate your welding.
Or you plan on cutting precurved sheets like car bodyparts?
Very challenging project indeed,

regards, Arthur

[AMEPro]

Hi Arthur, Stekke_stim,

First of all nice to meet a fellow "vlaming", I will be posting updates as we go along.

We wouldn't exactly need the 5 axis, but is is a nice to have, we need to cut preformed parts, we could re-position the work piece every time one face is completed. But it would save us a lot of time if we could do it in one go + some faces have curves in them, which if we just cut in 3 axis would compromise the cut quality.

Occasionally it would be great to be able to cut angled edges, but we might need a bigger plasma cutter for that.

I have been playing in sketchup to be able to visualize what we are about to build, I have attached the result. It is a very basic drawing but it will give us and the ones interested an idea what it will look like.

The table can be removed if we need to cut something bigger than what fits on the table. Travel in Z axis will be 600 mm

Cheers
Bram

[stekke_stim]

how is the building going?

[Viesturs]

Hello, Bram!
Nice idea! I am in process of designing such a machine for a client.

Looking at pictures, I feel that the head will be too bulky for the task. I would recommend something more compact. I really like this solution:
http://www.youtube.com/watch?v=bZ2xyM2Gm9I]CNC Plasma 5axis - YouTube

The author has 2 more videos, take a look.

As for touching off and THC - what CNC controller do You intend to use?
I have a ready scheme, how THC can adjust the torch position along the central axis of the torch, while not moving the controlled point.
It would be done by dynamically adjusting the torch offset value (the distance from the point, around both rotary axes are pivoting to the tip of the torch). When touching off, You would touch the tip of nozzle to material and You would know, what the torch length offset is. From that point it can be dynamically adjusted (including few mm retraction for starting the torch) along the center axis of the torch itself.

The thing is that IMHO there is _no way_ to do it in Mach or any other closed source CNC controller. It is completely doable with LinuxCNC. Actually I already have done the basic principle on my own machine. Customized kinematics module takes all the calculations of compensating moves along x, y, z, that are required to keep the controlled point at the same spot as the torch length offset is adjusted.

[Teknition]

I like this solution

[Viesturs]

I like this solution

Ok, I also am a fanboy of different robots... I have built one:
http://www.youtube.com/watch?v=WSQO3IkQ0Lo] Welding robot with EMC2 (now - LinuxCNC)
I have several more videos with it.

I was just trying to suggest something that can be implemented, do You have any idea, how much would this plasma robot cost?

[Teknition]

Nice job on the welding robot! I watched your other videos and can see all kinds of different functions that it could do such as deburring parts. I have no idea how much the robot is worth, I found it on youtube when I was watching your first video.

[johndjmix]

Totally agree guys...once you have a cnc table built, you can mount so many tools to it, there is no limit!

--John

[AMEPro]

Hi Viesturs,

The idea for this machine is to be able to cut +/-90 degrees in all directions; the video on your post can't do that. I admit the head as it is now is rather bulky, I will look at it and see how I can improve that design.

My original plan was to use Mach3 together with the DTHC form CandCNC which I already bought. This setup can still change to linuxcnc and whatever hardware is needed.

the project was abandoned until recently, I have now built the base for the table which is much bigger than what it looked like on paper, it is 4.20 meters by 2.80 meters (I will post pictures in near future)

specs for travel in X and Y have increased a bit and are now at x: 3.35 meters and y: 1.85 meters.

My plan now is to get the table running with only 3 axis, and when that works, upgrade to the 5 axis system, once I am at that stage, I will certainly look at the linuxcnc route like you suggested.

I have considered using a robot arm for this project, but thought it would be too complex to go from G-codes to actual movement of the arm.

Bram

[Viesturs]

Hi!
Anything new on the plasma cutting machine build?

I have considered using a robot arm for this project, but thought it would be too complex to go from G-codes to actual movement of the arm.

Bram

LinuxCNC takes care of this issue.
It already comes equipped with kinematics modules for puma and scara type robot arms plus user is free to adjust and/or write new from scratch to suit it for particular machine (I wrote my own module for the welding robot). You simply specify in config file, which kinematics module should be used.
Kinematics module is the place, where these "cartesian space <--> machine space" calculations are done.
That means that user simply feeds in g-code, that describes tool's motion in cartesian space (just like any other machine) and then LinuxCNC internally calculates required motor positions to perform requested movements.