Not afraid to admit… I have NO Idea what I am doing… I’m just kinda Faking it til I make it.
Today I finally had the chance to try to cut something. Got the M4 set up, got the bit in it. Turned the Dewalt on ( set to #2) Lowered the Bit to just above the Media. and pressed Play!
The M4 lowered the bit slightly, and drug across the board. then Dove into the material and just started Smoking!!!
What Did I do Wrong? I would like to start doing some Cutting. but could really use some guidance!
what was it supposed to do (can you post the gcode you were trying to run)?
That looks like the bit wasn’t cutting well (and/or the sled wasn’t sliding well) causing the sled to tip as it was being pulled, then the movement stopped and the tension/cutting caught up with the sled’s position (letting the sled go flat) and everything then stopped with the bit still against the wood, causing it to burn the wood and heat up.
what was your feed rate and cut depth for this.
Teacher Gift.nc (254.9 KB)
Ok, there was a lot of other movement that was supposed to be happening, were
there any errors in the log shown?
David Lang
Brad wrote:
Today I finally had the chance to try to cut something. Got the M4 set up, got
the bit in it. Turned the Dewalt on ( set to #2) Lowered the Bit to just above
the Media. and pressed Play!
you should have set Z=0 after lowering the bit and before hitting play, did you
do so?
David Lang
yes I did
I don’t know When it started smoking I Hit Stop, closed my laptop and hit the Estop
Sounds a lot like my first cut attempt, I forgot to hit the Define Home button after lowering the bit to the wood, and when I hit play it started driving to the start position and buried the bit. I was just cutting a small piece of 7/16" OSB, so it just dragged it around until I turned it off and didn’t burn too much.
Did you do a dry run with no bit and the router turned off? That’s the first thing I did to make sure the movements were what I expected before trying a cut.
Absolutely. being that Its all new to me, i was trying to see what size it was, and that it wouldnt go off board.
Here is how I go about setting the Z zero. I retract all, and flip maslow upside down. Then I move it up or down and use the wrench to find zero. Kind of like setting up a router table. Then I move it up 1mm.
Once you flipped your router over, you messed with my mind. I am assuming you used the wrench to span the gap and found zero by adjusting until the bit just touched the spanner…er, wrench. Then you moved “up” 1 mm. With the router upside down, which way do you mean? Is up retracted or extended?
I have been doing this:
I’ve only done a few cuts, but here’s my approach to homing the Z axis…I take care of Z before I attach the belts.
I first prop the M4 up on a 2x4, drive the z axis all the way down until it bottoms out on the steppers, then go to Setup and hit the Zero Z button, that lets the M4 know where the absolute zero limit is. In theory, this shouldn’t be necessary, but I worry that if there’s an Emergency Stop during a cut the Z Position might not get saved, and it doesn’t take a lot of time or effort.
Then I raise the z axis up until the bit clears the sled. Then set the M4 down on a scrap of wood and lower the bit until it’s almost touching. Then turn on the router and lower in 1mm increments until I hear it cutting into the scrap, then back up 1mm and hit the Define Home button. Hitting the Define Home probably isn’t needed at this point, but it makes me feel good.
Then I retract all/extend all/apply tension, then move to where I want to start the cut and hit the main Define Home button, making sure I don’t accidentally hit the STOP button.
Then I look at the serial messages and find the G54 that sets the home offset:
[G54:0.000,0.000,27.180]
Those are the X, Y, and Z coordinates of the home that I just set. I copy and paste those into a text document for future reference. If those were my real numbers, I’d know as long as I haven’t changed/moved the bit the next time I just need to move the Z axis to 27.180 and set the home.
Also, I had a cut randomly stop yesterday, no indication of an error, but it was clear that the Emergency Stop had triggered. I power cycled the M4, moved the Z axis to get it out of the cut, did the retract/extend/apply tension thing again. Then I drove it to the coordinates from the G54 command and set the z axis to the z from the G54 command, hit the main Define Home button, and told it to run the file again and the cut turned out perfect. I could barely hear the bit cutting until it caught up to where the first attempt failed. So that seems like a pretty reliable/repeatable way to get back to the start point.
Russ wrote:
I first prop the M4 up on a 2x4, drive the z axis all the way down until it
bottoms out on the steppers, then go to Setup and hit the Zero Z button, that
lets the M4 know where the absolute zero limit is. In theory, this shouldn’t
be necessary, but I worry that if there’s an Emergency Stop during a cut the Z
Position might not get saved, and it doesn’t take a lot of time or effort.
it should be needed, as the absolute Z position matters for belt length.
There should be a difference between absolute zero and bit zero.
David Lang
My thinking is that since the Z position is now saved in non-volatile memory once Z=0 was set once it wouldn’t need to be set again unless the position was lost. I could be wrong on that. Either way, I’ve made it part of my startup routine since Bar mentioned that it wouldn’t get saved if the M4 was powered off during a cut, for example.
The Z zero (workpiece origin) is changed all the time depending on what z plane you want to start your job. Often people raise Z well above the surface then set it to zero and run the job for a minute or so to get a visual sense and confirmation that the job is running at the trajectory and feedrate that you expect. Then you lower the bit and set it to where you will actually cut.
Yes. And bit zero will not always will be set at the plane where the bit touches the workpeice.
.
Sorry, it gets confusing when there’s more than one zero. When I said Z=0 I was referring to the absolute zero where the z axis is bottomed out on the steppers. So my understanding is that as long as the z axis location is saved between sessions, that absolute zero should not need to be set again. But I do it anyway since there can be situations where the z axis location isn’t saved between sessions.
Russ wrote:
Sorry, it gets confusing when there’s more than one zero. When I said Z=0 I
was referring to the absolute zero where the z axis is bottomed out on the
steppers. So my understanding is that as long as the z axis location is saved
between sessions, that absolute zero should not need to be set again. But I
do it anyway since there can be situations where the z axis location isn’t
saved between sessions.
As of a week or so ago it was not being saved, I know Bar is working on it, but
I don’t know if that got into a more current update.
David Lang
My assumptions are based on this note from Github:
V0.73 adds a system to save the z-axis position automatically in non-volitle storage before the machine shuts down and then it loads that position again when the machine turns on meaning that it will always be adjusting the belts to match the machine’s actual position.
I still think it’s a good idea to set it every startup, since we can’t be sure it was saved if there was a crash in the previous cut.
I’m still very happy with where things are now, and the ability to repeat a failed cut given the original home x,y,z coordinates. And I’m sure it’s only going to get better from here.
