Do you have your homing Is your home position set to upper right? All of your gCode is moving to the +X,+Y part of the work surface, so your 0,0 should be set in the lower left of your work piece...is that what you are doing?
Thanks MG, Its starting to make sense after your explanation. I have downloaded GRBL panel but not used it, just a little nervous of it as it does not appear to have a visualiser but will give it a try and mimic how you do it and see if that helps. I have downloaded Camotics and ran the file through it, to be honest I wish this was a GRBL controller software as visually it is much better. The file ran ok within Camotics from start to end, I had to speed it up as it was really slow probably for the reasons you mentioned, but other than that I am not sure what else I should be checking for within the program. GRBL is confusing the backside outa me and this working in minus makes no sense to me as well.
Hi again Ferreri, No, I thought you could reset zero anywhere and that is where you wanted the cutting to start from and I have been setting it in the center of the table. So you are saying as is MG, that my 0,0 position should be -X, -Y bottom left which seems to make sense but also conflicts with what most people advise. As I used Sketchup to create this little file it seems a bit weird that it has put the 0,0 at bottom left or have I done something wrong in Sketchup? Anyway, somehow you guys are starting to make things a little clearer for me and hopefully close to getting it solved, this has been frustration in the extreme.
My GRBL workflow: 1. Home machine (top right) 2. Jog to my desired work zero (usually lower left or center of workpiece) 3. G10 L20 P0 X0Y0 (sets current position as work origin) P0 is the first system, G54 4. Jog to Z0, and set that G10 L20 P0 Z0 or just use G92 Z0 because the Z changes with bits and such 5. Run the job The advantage tousing the work coordinate systems (G54,G55, etc) is that you get a permanent work zero offset from home. If you home by hand, your job is not repeatable. If I lose connection, break a bit, kick the plug, or need to go change a diaper, I can always get back to that exact same work zero. One advantage to having multiple work coordinate systems with their own origins is that you can create jigs that are set at specific locations on your table for different reasons. I think $# always reports your offsets in mm unless you changed $13 to 1.
If you have limit switches at both ends of your axes, you can simply change the GRBL setting "Homing Dir Invert Mask" to make the X and Y axes move the opposite direction. This will home at the left front of your machine and make life a whole lot easier. Your position numbers will be large negative numbers (=your x and y max travel - homing pulloff) after a Homing Cycle. This is where I just disconnect and reconnect with GRBL Panel to zero everything out. Don't know how or if you can do that with UGS. In Camotics, you will see a large red, green, and blue 3D cross, this is the origin of your code. It should be in the upper right corner if you are sticking to that home position. If you are using the lower left corner for home, the origin should be lower left. MG
Your work zero can be set anywhere. You Gcode had everything in the +X+Y which means your origin was set (in the design) at the lower left. "Homing" should be thought of as ONLY a way for the machine to know exactly where it is. It really doesn't matter where you home. The WCS handle your work.
I don't necessarily agree. I home lower left, zero the machine, and set G28 button to that position (0,0,max). Then I jog to the corner of my work, and set G30 to that location. Then I zero the machine again, set Z, and start the job. If power fails, I simply home, zero, G30, zero, and I'm back at the correct position to restart the job. If the job finishes correctly, I just reload another workpiece (if I'm doing more than one) hit G28, and it's ready to go again. I have to admit that this is because I find it impossible to understand the G54-G60 co-ordinate system and how it is supposed to work. If you ask 10 machinists, 9 of them will say they don't know how it works or why it's done that way either. I find it just eliminates a lot of frustration to do it my own way. MG PS - There is a way to get GRBL to home to the left front with 0,0 on X and Y. However, it involves changing a compiler directive and recompiling the source code. I tried it, and it didn't seem to work, but I'm no programmer. I'll have to enlist the help of a nerd buddy...
I have had problems looking at some gcode file formats in Camotics (can't remember which). I know it is due to my lack of paying attention to how Sketchucam saves it, but I am too lazy to re-save it in a format Camotics will open. So, here is another place to check your gcode. It doesn't require a download and will use any file. Just open your gcode in notepad and cut and paste it in. g-code simulator
This is a lot of confusion. Its seems to me that one would want to home to top right z max, which should be 0,0,0 to the machine after the home, then jog to whatever x,y starting position and jog to Z 0.0 then save that move (how do you save this?). Then you can reset this point to zero (g 0.0x 0.0y 0.0z? or "reset zero" button on UGS). Now you're ready to begin. Now if you halt part way what you saved from the jog move from home to the 0,0,0 starting point, should get you back to the starting point by doing a Home and then a recall of that saved jog move (what command does that?), use the UGS "reset zero" button. This seems logical to me, but I do need some help identifying the exact commands.
Well sorry guys, have tried all the suggestions from you all but nothing works. The machine just wants to run off the rails whatever I try and whatever ever I use, so whisky where are you!. If someone has a small gcode file that is known to work fine on their Ox that would be a of help so that I can at least start discounting some things. Any help would be apprecieated.
A thought...sorry I didn't mention it before. Are your steps per mm set correctly? If you tell the machine to jog 100mm to the left, does it move 100mm? If your settings are too high, your machine will move farther than it "thinks" it is.
Did you try these yet? What should I do next? They are smallish and except for the Shapeoko one, the zero is bottom left. The shapeoko zeros in the middle. You can see this in the pictures. Put a piece of wood on your machine, move the bit to the bottom left (Front left) corner of the wood. Zero the bit (Z0) to the top of the wood. Then zero your X and Y at this lower left (front left) position for the star and the calibration example. All cuts for these two will be positive (away and right) from the zero. For the Shapeoko, zero in the middle of the material. If your settings are right, everything should end up on the material.
Maybe you should get rid of the homing until you can get the machine to start cutting at your zero point. I have yet to install homing or limit switches, but have not had any issues cutting what I want where I want. If I do start homing, I will try to figure out a way to do it at the front left since that is where I do most of my cutting. I have switches installed at each end of the various axis. I just haven't hooked them up yet.
You nailed it!!!. I had previously set these values up but somewhere in my utter confusion and messing with GRBL I had put my maximum travel distances in the step/mm values which as you say made the cnc move further than it should. I really appreciate you steering me in the right direction and solving what has been a real hair pulling experience. Wow, what a learning curve this has all been but well worth it. Thanks again.
Thanks for that Craig, I had to setup the homing and limit switches as the way I had it wrongly set up (which thankfully is solved now) I had the carriage bashing into the side rails and if it continued I would do some serious damage. As MG said as well, I think homing to the bottom left seems more natural and I will probably adopt that method but at the moment I am just relieved to have it working as it is meant to.
Thanks for everyones advice on this thread. In getting to the solution everyones input has helped me learn a hell of a lot more and proved more beneficial than reading endless pages of text. I didn't realise when undertaking this project the steep learning curve involved, without this forum and the help of posters on here I think it would have ended up in the bin followed by divorce proceedings from my other half whom I have driven mad with my frustration. Cheers
No problem... Glad you're up and running! By the way, I've enjoyed using Chilipeppr as a controller and recently I've been trying CNC (needs a better name... Search "cncjs". It's pretty slick.
Don't forget to calibrate you steps/mm. Find a good metric SS ruler. I use a small machinists square to make a pencil mark on the top of the v-slot. Then move 300mm (or whatever your ruler is), and make another pencil mark on the rail the same way as you did the first one. Then, measure the distance between the 2 pencil lines. It should be exactly what you commanded the axis to move. If not, simply use a ratio to determine the new steps/mm. (Commanded distance / Measured distance) * Current steps/mm = New steps/mm MG
Hello Dears, How can I run a specific line mumber from gcode file. Wich software had a "run from hete" function? I want to select some line and machine continue work from there.
Thanks for the info, They look really good visually but appear a bit complex to install, not sure if my brain can handle it atm. Perhaps when the old grey matter is working again I'll have a go. Cheers.
Thanks MG, I have set those up as best I could. Milling good, size is as per design and all square with good circles, only problem I have is that it is not cutting as deep as it should, probably about 50% less. Any ideas?
Are your settings right for the lead screw for the z axis? The steps/mm will be different than the belts I believe.
Your probably right, I will check those tomorrow, have been reading up about it tonight and I suspect the Z axis values are wrong. Cheers
For a 1/8 step setting on the stepper driver, I use 200 ppmm with the OB lead screw. With 1/16 step setting, I start with 400. Simple to check, put a ruler alongside the axis, tell it to move 20mm, measure what it actually moves. MG
