Plasma Table Build - Plasma Bot 4.0

[Rambozo]

There isn't really any problem with swapping X and Y, but it will change how you do your programming. Standard convention is that as you are facing the machine, X moves left to right, Y moves towards you and away from you and Z moves up and down. But for most gantry type systems X is normally the long axis. (as it is on the diagram you showed) That does not seem to match your machine. It also depends on how you want to view parts on your machine and on your computer screen.

Yes, you can have problems if the acceleration is too high for what the motors can move your system. But with the motors removed, it won't really matter. So run the motors off the machine and check that they are all going in the proper directions and move by the proper amounts. Once that is confirmed then you can move on to acceleration tuning. If you jog at a slow speed or by a small amount, the acceleration won't matter, either.

[SeanMurphy265]

I'm in the process of uploading a video to youtube. I lowered the velocity and acceleration settings and that did the trick. I set the velocity to 100 and acceleration to 50. I have everything moving, but I have to set my soft limits, and check the steps per unit.

[SeanMurphy265]

[SeanMurphy265]

I'm getting closer to the end, I finished the machine torch mount, set the soft limits, and calibrated the steps per inch. I was hoping to cut something out today, but I ran out of time.

I picked up some shaft collars at my local Fastenal store to make the torch mount for the Z axis. I drilled and tapped two holes so I could have some adjustment from the torch. The torch is sitting level on all sides. The collars are way too heavy for what I am using them for, but they were local, cheap, and no shipping charges.








I'm going out of town tomorrow, but I am ready to see if it will cut! I've been doing some reading on sheet cam and MACH3. I'm getting better at MACH3, but there is a lot to learn!

[EmptyNester]

It looks like you've mounted the torch pretty high above the table surface. It seems to me that that is pretty common. Is there any particular reason for that?

I'm trying to figure out how high to make mine, but couldnt think of a reason that I'd need that much height. I've using the Z-axis from ShopDroids and I think that has about a 6" travel. So, it seems like I don't need a lot of height.

Am I missing something that I need to consider?

Thanks

[SeanMurphy265]

Where it is sitting in the picture above it's completely bottomed out on the table and all the way down. I'm still playing with sheet cam so I have not ran my own gcode yet (I have not had much time), but when I set the material thickness it should adjust the cut height. I also did not want the torch to go below the table surface. I'm not sure if I need the full 6" of travel, but if I need it I have it.

[SeanMurphy265]

I spent some time today trying to run some g-code. I used sheet cam to generate the g-code. running Mach 3
I get a line 0 error. How do you edit the line?

[Rambozo]

I spent some time today trying to run some g-code. I used sheet cam to generate the g-code. running Mach 3
I get a line 0 error. How do you edit the line?

Mach doesn't have an editor built in. You configure what text editor you want to use under General Config. You can use Notepad if you have nothing else. I like EditNC. They used to have a lite version, but I don't see it anymore. You might still find it on the net somewhere.

http://www.ebair.com/editnc.htm

I've never used Sheet CAM, but you probably have to set it up to use the right post for Mach and your machine.

[SeanMurphy265]

I solved my G-code problem by purchasing sheetcam! I ran my first g-code tonight with the plasma turned of. I taped a sharpie to the torch and let it go. I still have some motor tuning left. I will shoot some video tomorrow. I do have a couple of questions.

1. How do you remove the pinion gear from the shaft on the motor? I need to put a larger set screw in the Z axis, and I cant get the pinion gear off.

2. The table is cutting the part backward. Is that normal?

My new running total is
$3,257.99
+ 175.00
3,432.99 total

[EmptyNester]

Sean - or others....

Sorry this is a little off topic - but I'm looking for suggestions on how to attach the rack to the gantry rail.

I have 1/2" VHB tape and 1/4" racks.

Should I put the racks side by side, attach the tape and slice apart?

Is it better to put the tape on the rail, then the rack on the tape?

Any suggestions on how to make sure the rack goes on straight?

Thanks

[SeanMurphy265]

Sean - or others....

Sorry this is a little off topic - but I'm looking for suggestions on how to attach the rack to the gantry rail.

I have 1/2" VHB tape and 1/4" racks.

Should I put the racks side by side, attach the tape and slice apart?

Is it better to put the tape on the rail, then the rack on the tape?

Any suggestions on how to make sure the rack goes on straight?

Thanks

I used 2x2x3/16" and followed the area of the tube that was flat (thicker tube has rounded corners). My plans said to run your tape 1" or .5" from the top of the tube. Draw your line with a square or run a chalk line. I put my tape on the tube and then laid the gear rack down. I tried drilling and tapping the gear rack, but the was a royal PTA!!!!!!!!! I used the 3m tape from mcmaster and that stuff is crazy good. I never thought it could stick that good. I cleaned the tubes real good and have had no problems even with the humidity in Mississippi. You can buy pre drilled gear rack also. I have also seen where people tacked on the gear rack. I have to remove the gear rack on my X axis I put on too high. The plans changed for the tape line and I did not pay attention! It will have to be cut of with a cut off wheel. I did purchase an extra roll of tape just in case I messed up.

[Rambozo]

1. How do you remove the pinion gear from the shaft on the motor? I need to put a larger set screw in the Z axis, and I cant get the pinion gear off.

Is it pressed on, or did the set screw put burrs on the shaft? You might need to use a puller.

2. The table is cutting the part backward. Is that normal?

What do you mean by backwards? If you mean the X and Y are swapped, that is because of how you labeled X and Y. X is usually the long axis, but I believe you made X your short axis. They are just arbitrary labels, so if you want you can just leave it that way. It is nice to have the part match so that it looks the same on the screen as it does when you look at the table, but that all depends on what side you access your table from. If the part is reversed on one axis, it's because of your zero origin and the sign of the numbers you are using. Again you can put your part anywhere in this imaginary space and work in those axis. To make all your numbers positive you typically put your zero in the lower left corner. For some parts it's easier to have zero in the middle of the part. The CAM software can work with it anywhere, but people follow it easier when it makes sense. At first it's nice to line up your parts with X and Y, but later your software will spin them all around for best fit on the sheet. It conserves metal, but makes it almost impossible to manually edit anything.
It's hard to describe in words, maybe I can draw something that will help.
The machine will do just what you tell it. It's up to you to understand where things need to be. If you post your Gcode and what you think is wrong, I can tell you what it's doing.

Here is something on the coordinate system. That site also has a lot of other tutorials that you might like.

http://www.cnccookbook.com/CCCNCGCodeCoordinates.htm

[SeanMurphy265]

I've been trying to figure out how to make positive. I currently have it set up in the upper left hand corner. I will try the lower left corner and see how that works. I guess what I mean by backwards is this.. I am cutting out the letters S A M and that is how they are drawn and scaled. The machine cuts them out M A S. I realize that I can just flip it and it will be fine. I was curious if I had something set up wrong.

[Rambozo]

Is the S reversed or not? M and A don't really tell me what's going on.


If it's reversed than you have the sign wrong on X and need to flip that axis, if not then it's just the moves between letters that are wrong.

I know some people really want to know what's going on, while others just want to make parts. Sometimes I really wish I could do the latter.

[SeanMurphy265]

no the S is not reversed. If you look at it down from the table top SAM is backward. If you crawled under the table and looked up SAM is correct.

[Rambozo]

In order for SAM to look right from under the table, the S would have to be reversed looking from the top of the table.

[Rambozo]

Here is a simple part that uses the basic moves, so it's easy to follow what is happening. There are no Z or torch commands, this just moves the table around.
Here is the part:


And the

(With zero in the lower left:)
G0X0Y0 (Rapid to zero home position)
G1X0Y1F20 (First line vertical @ 20 inches per minute)
G1X1Y2 (Angled line)
G2X1Y0I1J1 (Curved line)
G1X0Y0 (Last line horizontal)

(With zero in the upper left:)
G0X0Y-2
G1X0Y-1F20 
G1X1Y0 
G2X1Y-2I1J-1
G1X0Y-2

(With zero in the middle:)
G0X-1Y-1
G1X-1Y0F20 
G1X0Y1 
G2X0Y-1I0J0
G1X-1Y-1

[acourtjester]

You may try changing the setting for the motor direction see attached.
That will change the motor direction for its axis. This is in Mach 3.

[SeanMurphy265]

I have a felling that I will probably have to end up changing the motor directions if want the bottom left corner to be 0,0. I did a little playing around this afternoon until it started raining. I was going to make my first real cuts until the rain. I also need to get my slats done, right now its a pain trying to strategically place a piece of metal on the table.

I have the machine set 0,0 in the far right corner. This allows the cnc to move in a positive direction. The Z axis I have set +0 is the torch dead on the table. Any negative -1.-2,-3, etc has the torch moving up (safe Z).

I still have some motor tuning to do, it sounds rough because the IPM are pretty low. When I jog the table using the hot keys everything sounds fine.

[SeanMurphy265]

Here is a video running some G-Code