Z Zeros at 200mm

I am getting sooooooooo close that I can taste wood chips!!! :slight_smile:
But I am having a problem with a 200mm Z Axis problem. I am not Sure if its my SKR Pro? or if its Estlcam? or if its Repetier??? (Skip past all the junk until you get to my question. I wanted to make sure everyone knew what I have for a machine.)


Ok, so I am following all of the V1Engineering tutorials/forum pages/and any net info. I have a SKR Pro TMC2209 with the same steppers that V1 sells, on DOM pipe.
I have stock LowRider with endstops firmware, no changes. Endstops are connected with 3 wire endstop boards and hanging off the table. My settings are the ones I am following on the V1 site and I have the sweet V1 touch plate. Most important thing!!! I gave up trying to crimp my own wires!!! I bought extensions.






Question:
How do you change the Z Axis Height to not be 200mm when Zeroed? When I do a G28 x y z and Zero all my axis’s I get a X at 0, Y at 0, and Z at 200. My Lowrider can’t even do 200mm and it crashes into the table and pulls the sides off the table. (side note: I am going to have to buy new couplers as mine are turning into slinkies.) I tried moving my machine until the lead screws came out of the nuts (click click) but I can’t get it high enough for it to not crash into the table.
I did get it to work once when I was in the LCD settings and I zeroed the Z under advance or custom… Not sure who on V1 Forums wrote that. But as soon as I “restarted” the machine again, Z was at 200 on the LCD screen and on Repetiers move tab.

(Just to be clear! My machine is not at 200mm, it can’t ever get to 200mm as its not long enough. instead my machine is all over the place! where ever I unplug the power is where the new 0,0,200 will be when i plug it back in. Which means if the carriage is already touching the table when I unplug it, then it will try to go down 200 from there when I hit Play in Repetier.)

I am assuming this is a 3D printer thing. as my Prusa has a 210mm lead screw. However, I am working with as stock of a Lowrider as I can do!!!

My first goal is to get the “crown” image drawn. But its hard to do that when the sides are off the table.

Um, It just occurred to me that maybe it was meant to be 200mm off the table. So I can use the V1 touch plate to zero. However, I have the clamp biting the plate and it doesn’t do anything. (its not plugged into the Plus pin) same as picture in SKR Pro setup page. So maybe that not correct either.

I have a feeling this is a stupid setting that is super easy to change, But because I am so new to all these things I can’t find it.

Thank you all for your help!!!

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I just learned about this today from Jeffbe3 in another post. Reading between the lines, this 200 is an arbitrary number that is intended to be higher than your LowRider will go. When Homing up, your machine has no idea of your bit length, so it has no idea how far it is away from the spoil board. The whole purpose of Homing up is to square the Z axis. So in order to setup to cut your stock you can do one of two things, lower your router “by hand” (electronically) and then execute a G92 Z0 before beginning the cut, or you can use a touch plate to set the height. When probing downward on a LowRider, the G38.2 command is used.

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Yep. Robert has it right. You haven’t done anything wrong. The 200 comes from the default size of Z in Marlin. It homes up and assumes that is the top of the space. You don’t then zoom down to zero, you would jog to the surface and set zero using G92 (or one of the lcd options).

Interesting!
I have to say this really messes with my head!!!

Take 1
Connect to Repetier
xyz shows 0,0,200
load the file and click Play
(The LR2 then tries to go down 200 to get to 0 on Z. )
Cancel print and I wait a bit for it to quit… after its crashed into the table and does the next command. Then I move the z back up to the top.

Just so I am always doing the same steps, I disconnect and restart Repetier. ( I get weird values if i don’t, shown below in take 4-5)
Take 2
Connect to Repetier
xyz shows 0,0,200
load the file and type G38.2 z-1 (-1mm thickness of the touch plate) and Enter.
(Because i don’t have any tools attached, i just click the clamp to the touch pad to make the Z stop.
xyz shows 0,0,200
click Play
(The LR2 then tries to go down 200 to get to 0 on Z. )
Cancel print and I wait a bit for it to quit… after its crashed into the table and does the next command. Then I move the z back up to the top.

Take 3
everything is the same but this time after G38.2 z-1 I also do a G92 z0.
xyz Shows 0,0,200
click Play
Works!!! Z goes down 1mm which is the “z-1” in G38.2.
xyz shows ~,~,199
When its done it goes back to where it started.

Take 4
I didn’t restart or disconnect. Left all values where they were
xyz shows 0,0,200
click play
Works!!!
When its done it goes back to where it started.

Take 5
This time I left everything the same, didn’t disconnect or restart.
But I reloaded the file
xyz shows 0,0,0
click play
Works!!!
When its done it goes back to where it started.

Take 6
This time I do disconnect, restart and reconnect.
as expected everything is back to
xyz shows 0,0,200
type in commands g38.2 z-1 and g92 z0. otherwise crash.

Is this what you’re seeing too?
Thank you for showing me these commands.
Sadly, I assumed Robert was doing a G92 z0 OR G38.2 command. But a G92 z0 always needs to be done.
I haven’t tried homing yet. In the tutorial it says to find a place in the middle of your three axis so that you have room if something goes wrong. But it doesn’t matter, Z crashes every time I do not do a G92 z0 command.
I am curious about the LCD options???
Is there a way to just click a button and have the LR2 do all the typing for me?
Thank you

That is almost what I expect. The 200 in RH is annoying, but it isn’t what Marlin is thinking. You can probably learn a lot by sending M114 at various places to see what Marlin thinks the coordinates are. The trouble is that if M114 disagrees with the RH report, then any jogs from RH are going to not go where you expect.

You can set up some macro buttons for common scripts.

The one that doesn’t make sense is Take 2. I thought G38.2 did set the coordinates. I haven’t seen it with Z-1 though.

From https://marlinfw.org/docs/gcode/G038.html
it says the “z-1” or z-0 or z-200 is the distance away from bed or work surface… i think. I used a z-1 in my example above because the touch plate has a nice thickness to it. However, in practice it didn’t work as expected. ( I need to measure the real distance!) The first bit of material was a bit more than the lower layers.

I finally cut out something! WOOT!
I cut out a nice version of the router plate. My first one was hand cut from 3/4" pine. it allowed for my Bit to stick out 11mm from bottom of the router plate. I have a ton of Ikea junk boards all around and they are all about 20mm-3/4" thick! Then I spotted some junk laminate flooring… Oh this stuff is 12mm thick!
As you could guess I had to cut the rest by hand! But now I have a nice 20mm of cutting space! Time to cut the sides out of flooring tonight!

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Correction:
G38.2 Z-1 does not move the bit 1mm down. instead it moves it 1mm up. It is very hard to tell which direction 1mm is going.

I figured this out because I finally started to cut what I really wanted to cut. Cabinet doors!
The most simple design i thought i could do… which i guess is the hardest design i could possible do and didn’t know it. (plan doors with a couple 45 angles on the edges, done)

Before I go into my problems, does anyone know how to make this on ESTLCAM? or v-carve? wouldn’t this be called 2.5D or is it 3d?

Test one:
I imported a 3d cad file into ESTLCAM. Nifty way to make gcode! It was going great, except the CAM program would make a tool path that would cut the whole top board flat. And it would do it 5mm into the wood.
I would then type in G38.2 Z-6 G92 z0 to offset or have the beginning gcode cut above the surface for 30mins before it would finally cut into the wood. A waste of time but if it worked i would have done it.
(new problem i have waves in my table. :frowning: i guess its time to cut a bit off the top of my spoil board)
Anyhow, the bit, scratches the test wood i have as it is going around and around in Rectangle circles!?

I have thought about doing a bunch of ESTLCAM files. maybe four or more. Each one doing one rectangle at a set depth and finishing. I just don’t know how to make this cut out correctly.

Thank you as always! you all are so much help! I totally wouldn’t have a machine at all if it wasn’t for this Forum!!!

I vaguely remember a separate chamfer function in estlcam for these types of operations.

I figured out how to make my shape in ESTLCAM. Two rectangles.
#1 I add an engraving middle of the line down 1mm with a V Groove bit.
#2 Engraving @ 5mm down from top of board on outer rectangle.
Then I change tools… which is super hard!!! Getting one tool out while keeping the LR2 from not moving.
#3 then use the end mill to cut a “part command” 1mm down on inner rectangle
#4 and then all the way down with tabs on the outer rectangle.


This worked great on my samples. But getting all the angles at the right depth (z height) was impossible. So I broke up the Gcode into 4 files.

This didn’t work because no matter what I do I can not get my LR2 to home. Example: if I use a G92 x0 y0 z0 and then tell it to home. it will move about 10~ units in x to the right, 10~ units in y forward. Z0 doesn’t move which is so great as I have millions of problems with z crashing into my table and not knowing where z really is.
There is no way to get it back to its starting location when something goes wrong. With 4 files, something will go wrong!
Below I tried 4 times to get the v groove tool back in the right place. Instead, I got a big spot in the middle and then my y became out of line. It was futile and I gave up.


This full sized drawer face plate lost about 4 steps because the y axis clogged with dust… So, I need to print those covers that “some old guy” made. the amount of dust that fills that area is unreal! But as you can see, I don’t have a vacuum yet.

By the way, I am using Repeater Host and not the LCD. Should I be using just the LCD?
I have noticed that RH will not stop for maybe 5 commands. which means it has crashed and its trying to kill its self and then its about to destroy itself and then it stops. I have moved to pulling the plug when something starts going wrong. However, i really do not like this option because pulling the plug could be bad on my board and there is no way to home.

Any suggestions? Thank you again for all the help!!!

G92 X0 Y0 Z0 tells rhe machine, “this is your home”.

G28 (or any of the homing buttons or options), tells it, “go until you find your endstops switches, those are your new home”. If you don’t have endstop switches, then they look triggered and the machine thinks it already is on the switches and then back away trying to get off of them and then complains.

G0 X0 goes to zero. But that will probably drag your bit across the worl piece, so it would be better to say G0 Z10 or just jog up, then G0 X0 Y0 and the. G0 Z0.

You should be able to run 4 files without skipping steps. But bit changes do add risk. If you had dual endstops, you could home and then drive to a specific spot and reset the zero.

This is because of the buffer in Marlin. The buffer reads and accepts a few moves ahead, so the planner doesn’t starve. That means that when RH wants to pause, there are still a few commands in the planner waiting to play out. The lcd will do the same. There isn’t an official way to fix this, pulling the plug is the best way. I don’t think it will hurt the board.

Jamie made some code to stop the steps on an external switch. There is also an “emergecy parser” that will read a few special commands out of order and one of those is an emergency stop gcode. Then you’d need to convince RH to send that command on a pause/stop.

I bought a pack of those little red 3d printer endstops.
image
The V1, SKR Pro Page told me this dual endstop CNC wouldn’t work without them. So I bought these as they were meant for this board. They also have a cool little light when triggered (feedback). I have also noticed that both lights work. the Driver light as well. Which I like! (Double Feedback).
but what your telling me is that these are the wrong way. Normally open or Normally closed or whatever. its the opposite of what it should be. meaning the CNC thinks its triggered and moves away. LOLOLOL
Thank you for bringing that to light!!!
I will need to fix my endstops before continuing.

I am finding that Marlin has some short comings for CNC’s. Is there a way to fix these in the future? The 200mm Z and buffer adding extra moves? I totally understand why this is a thing for 3d printers. I also totally understand that these boards were not made for CNC’s. (I know that a 3d printer is a CNC but it doesn’t use the same rules.)

Thank you so much!!!
I have endstops to figure out and get working. :slight_smile:

I know someone else on the forum used these switches. He had to “rewire” them. You might be able to just pop the metal connector out of the white connector for the green wire and move it to the open slot. Alternately you can make the change in the firmware. By default the endstop code in the firmware expects the switches to be wired normally closed. That way if a wire ever breaks or a connector is pulled loose, the homing will just stops rather than running until physically stopped or the power is turned off.

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I disagree. The buffer is necessary for CNC. Otherwise, it would stop at the end of every command and it would take a lot longer. The same is true with cnc firmwares. The 200mm is really my fault, but I don’t see it as a problem. The coordinates don’t matter until you set the origin, and you won’t be doing that with the Z endstops.

W.r.t. those endstops, you can reverse the logic in the firmware (search for invert in the configuration.h). Those little red boards have caused people problems before. You can remove the switch and just use the switch, or you can just buy the bare switches for about a dollar each.