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1
Andre,
The 'machine home' is the furthest left and down (toward you) it can go.  'Homing' is an automatic function on most mills and routers, simply by clicking on the 'home' button.

However, home is NOT necessarily the zero/zero point of your workpiece.  After homing, you should carefully position the cutter at EXACTLY the lower-left corner of the workpiece, and set that as the 0,0 point of your job.

Lloyd
2
hi i am starting to learn cambam and i have some questions

 the machine origin is that i the fysical zero pont of the machine(homing/ starting point ) so when i mill something he begin to calculate from that point  in relation to the origin from cambam and/ or is the start point the start point calculated from the origin/zero point from my workpiece i am looking for a clear right definition that it expain what it does. and what is the function  of the stock offset what does it?? can someone me a clear explanation? i'am a relative newbie!!
3
Couldn't get the last pic in.
4
Hi Kelly

The Homing and soft limits are in G53 "Machine Co-ordinates"
There are what they call workspaces, for you the important one's are
Machine c-ordinates and part or work piece co-ordinates.
The homing switches being where they are is ok, as this would (after an homing operation)
move the machine a convenient place so that you can load and unload the stock unencumbered.
where the co-ordinates are\can be  set to zero in G53 they don't always have to be zero, and could
be the tool changer co-ordinates.
This page has a reasonable amount of info directly related to what your doing now.

https://github.com/gnea/grbl/wiki/Grbl-v1.1-Commands
Quote
If you are using soft limits then you may have to set these parameters:
Set your $130,$131, and $132 max travel settings if you plan on using homing or soft limits. It's recommended to enter something approximately close to actual travel now to avoid problems in the future. Note that $130,$131, and $132 max travel parameters correspond to the 'Machine coordinates' parameters in grblControl.

It's ok for the homing to be where it is at the back of the machine.
this position is not the work piece x0,y0,z0.

If ok for you to have your drawing co-ordinates XYZ=0 at the lower left hand corner.
You then place the work piece in the upper right hand quadrant.
In the picture I've made a blue rectangle in my start up template.
This represents the machine work envelope.
This is a visual cue for me to place anything outside this area. else you'll hit the limits

If a new user fails take this into account and there’d followed the recommended set up for the machine and drawing
procedure may not  realise that some tool paths can dip in to negative territory triggering the hard or soft limits. I have my soft limits turned off for the grinder and laser, but if you do want to use then then you have to set them in your controller as above.

Side note: I very seldom on the mill use homing,(because I start my drawings from a template)
 I just indicate stock in and smash that start button.
I went and had a look at your blog it was a good read.
I do have some thought's about the cad, If you are happy with the terms and conditions for fusion
then it would be the one to learn.
If you want a “buy once” parametric modeller then there are a few of those too.
If you want a free one then freecad is a good choice, I use the linkstage version not
the downloadable current version.
Here is a pic of the freecad linkstage screen displaying a model that I 3d printed in various
sizes.
There is a shreen shot of GRBLMachine running the manifold file with live up dates to the CB drawing screen,I will post the CB file that is running in GRBLMachine as well.

Dave
5
Perfect, thanks :)
6
Kelly, The front-left corner of the WORK is 0,0,0.   That's NOT the 'home' position.

This I understand. What I don't understand is this: If I jog X+ the spindle moves right and Y+ is away from the front of the table. After I home in the back left corner of the table, when I jog back to the front left corner, the DRO says the position is (-34".xx,-34.yy"). So I understand Y= -34" and change because I jogged the spindle in the negative direction from home just about to the limit of travel, but why does X = -34.xx"?

Isn't machine zero supposed to be where you are homed and work zero where I call G92 X0 Y0 Z0? The origin of my CB part is offset in the stock such that the lower left hand corner of the stock is 0,0,0. Isn't that location what you would expect it to be placed at the G92 command? What appears to be happening is that is indeed the case but because the machine thinks I'm at -34,-34, all the machine work is outside the limit of the work space beyond the far right corner of the machine, resulting in error.

The front-left limit of travel is usually past the corner of the work, in both directions. My two bed-router machines 'zero' at about -9" in X and about -5" in Y from the front-left of the work-piece, assuming a 4'(X) x 8'(Y) sheet of stock.

The advertised XYZ work space on the machine is 35 x 35 x 3.75. The router spindle overshoots the front edge of the table/wasteboard by a couple inches but I could extend the table surface several inches forward beyond the machine framework if I need every inch of workspace travel.

Best,
Kelly
7
Kelly,
The front-left corner of the WORK is 0,0,0.   That's NOT the 'home' position.  The front-left limit of travel is usually past the corner of the work, in both directions.

My two bed-router machines 'zero' at about -9" in X and about -5" in Y from the front-left of the work-piece, assuming a 4'(X) x 8'(Y) sheet of stock.

My milling machine zeros about 2" left and 2" below my customary placement of the work, which might be any size up to 18"(X) x 12"(Y).

Lloyd



8
"I'd really like the front left corner of the machine to be 0,0,0 for several reasons with X+ to the right and Y+ away from the front."
------------------------------

That's the correct way to view any CNC machine.  CB is perfectly-capable of making that the origin.  I do -- most of us do.

Most folks don't make the exact 'limit of travel' to be 0,0,0, but pick the spot at the very front-left corner of the work as being that.  Most machines travel sufficiently past both edges of a work-piece in both X and Y, such that there's a bit of 'over-travel' available in order to cut clear to the edges.

Lloyd

That's good to know because I think that means I either have conflicting instruction from the machine manufacturer or I'm misinterpreting the instruction. In my mind, you could home in any corner and as long as the direction of travel was correct, seems like it should be fine after the G92 call, right? But, and I know you can do it with the G54 and up commands, but for the sake of simplicity, if you wanted to intuitively send the spindle to a table position, doesn't it make more sense for the front left corner to be 0,0,0? and if so, dont the limit switches need to be there? FWIW, the machine is supposed to back off the homed position 4mm in each axis after homing.

Still scratching my head a bit.

Best,
Kelly
9
"I'd really like the front left corner of the machine to be 0,0,0 for several reasons with X+ to the right and Y+ away from the front."
------------------------------

That's the correct way to view any CNC machine.  CB is perfectly-capable of making that the origin.  I do -- most of us do.

Most folks don't make the exact 'limit of travel' to be 0,0,0, but pick the spot at the very front-left corner of the work as being that.  Most machines travel sufficiently past both edges of a work-piece in both X and Y, such that there's a bit of 'over-travel' available in order to cut clear to the edges.

Lloyd
10
CamBam help (General usage) / Re: First Post, First Project, & Some Questions
« Last post by Tool-n-Around on August 02, 2021, 23:37:37 pm »
Hi Kelly.....As your just starting out with GRBL you should consider this plugin below as it'll save you a lot of grey hairs, it's tightly integrated with CB and works well and is really one of those must have plugins if you have an GRBL powered machine.

https://cambamcnc.com/forum/index.php?topic=6482.0

Happy cnc'ing. Dave

So I read all 12 pages of that, most of which is over my head but gathered it's a plug in that would allow me to run my GRBL machine directly from CamBam via th eplug in, correct?......and it would replace what is now UGS, correct?

I'm a little skittish about doing so but at the same time would like to simplify life where possible. I got the EMI issues sorted but now I'm struggling a bit with the machine set up and may have some XY+- travel convention errors. I posted this at the machine forum but it is pretty thinly traveled. Seems like a silly thing to be hung up on but any help would be appreciated.

I went through UGS set up wizard and tried to cut the demo file that cuts the Mill Right Name/logo and was getting soft limit errors and (air) cutting that didn't occur over the stock. As I recall, I believed the issue was wrong direction of travel designated on the Y axis. I swapped that in the set up wizard and after issuing a G92 X0 Y0 Z0 command with the cutter at the front/lower left corner of the stock, the demo file cuts just fine and still does now. However, now that I have created some of my own gcode files (from CamBam), I'm once again getting soft limit errors because the stock is in a different place than expected by the machine.

All the following reads from the convention of standing in front of the machine. The front of the machine is looking at the gantry from the side of the z-axis rails and router mount. For the avoidance of doubt, my machine homes to the back left corner when standing in front of the machine, because that's where the MegaV assembly video showed the limit switches.  But the beginners guide says when you execute $H the machine will home/move to the back right corner. ??? How can that be if both the X&Y limit switches aren't located there?

So as I'm set up, my machine happily homes to the (my) back left corner. It jogs with X+ being movement to the right, but Y+ is movement away from the front whereas the quickstart/beginner's guide says movement away from the front should be Y- (z- is down and Z+ is up so that is fine).

After I am homed, if I jog the spindle to the front left corner the DRO says I'm at about -34"(x), -34"(y). So isn't the homed location supposed to be 0,0? and Y axis aside, why isn't the front left corner X=0 if movement to the right is supposed to be X+?

The thing I don't understand is, if I issue G92 X0 Y0 Z0 with the spindle at the lower left corner of the stock near the front left corner of the machine, the demo file runs fine with the machine set up as is but doesn't run properly on any other file I download. It wont cut the demo file is if change the Y axis convention to that stated in the guide (Y- away from front). Do I possibly have two things flipped?

I'd really like the front left corner of the machine to be 0,0,0 for several reasons with X+ to the right and Y+ away from the front. First, everything I have drawn and have seen has the XY origin in the lower left corner of the screen with positive X+ to the right and Y+ upward and to me and my brain, that corresponds to the front left corner of the table, with X+ to the right and Y+ away. So to achieve this, would I need to move the homing switch to the front left corner and get the +/_ convention set properly with X= to the right and Y+ away? Would that do it? The other reason is the front left seems to be the most convenient for tool change but I suppose it could always be moved there for such.

I must have the cnc twisties and may need to change my screen name to dyslexia....or is that Lysdexia? LoL.


Best,
Kelly
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