DIY Pen Plotter with Automatic Tool Changer | CNC Drawing Machine

[yifandianzi]

May I ask how to set the tool table above the Y-axis? After setting, the pen position in the tool table is negative, and all the tool tables in the pictures are in the negative direction of the Y-axis

[svenhb]

Tool table positions must be set in machine coordinates - homig of the plotter is needed (or manual "homig" via hard reset on lower left position):

[yifandianzi]

The above image is set by me, and the following image is set by me referring to another producer

[svenhb]

Just change the 277 to 0

[yifandianzi]

1694698454095.mp4

Hello, this is a demonstration set to 0

[svenhb]

You are right, there is a bug and the offset is not shown, but processed during streaming. Will fix it soon.

[svenhb]

You may try this version: https://github.com/svenhb/GRBL-Plotter/blob/master/GRBL-Plotter_Setup_1_7_0_2_i.exe

[yifandianzi]

output_multi_video_1694780403069_1694780417484_VI.mp4

Hello, there is another issue now, which is that it can return to its normal position when returning to zero. When starting to work, the Z motor will rotate in the opposite direction, and then it can surprise the next step normally

[svenhb]

I don't exactly understand this issue. I assume the problem is the servo-position, when PWM is off.
Compare behavior of PWM on/off here:

Compare behavior of PWM low/high here:

[svenhb]

Now I could watch your video on a PC - it's not a servo...
I thing you need to "Zero Z" your Z axis before starting streaming.

[yifandianzi]

Hello, I have reset all X, Y, and Z here to zero, but when starting work, they still rotate in the opposite direction. I think it may be due to incorrect settings elsewhere, and it should not be rotated without selecting a pen

[svenhb]

It is normal that the Z axis move to a save position on start.
Example code after importing a simple line:

Line 14 G00 Z2.00 move Z upwards to save position
Line 17 move to start position
Line 18 G01 Z-1 move Z down, to start drawing
Line 19 draw the line
Line 20 G00 Z2.00 mive Z upwards

[yifandianzi]

Did I make the right changes here

[svenhb]

I don't know your hardware, I didn't saw a servo for a gripper...
Do your gripper opens with M3 S100?

Did you check my site? https://grbl-plotter.de/index.php?id=auto-pen-change&setlang=en

[yifandianzi]

Hello, I have looked at your website and it is slightly different from the position where I lifted and clamped the pen

[svenhb]

Looks like the Z-stepper should turn for a half turn maximum to move from lowest Z to highest Z.
Did you setup $102 correctly?

[yifandianzi]

Should I set $102 correctly to $40?
https://www.youtube.com/watch?v=ZxeStwRespc&list=RDCMUCJHZY4Tl6ovsnBrNocdDbAg&start_radio=1&rv=ZxeStwRespc&t=65
https://www.youtube.com/watch?v=The following link is mine_4S9PE

[svenhb]

Last video is not visible. I don't know your driver settings for micro-steps.
Usually a stepper-motor needs 200 steps for a full turn, If I interpret your design correctly, you have a half turn for about 20mm Z-change. With full-step-mode you may set $102 = 5 (100 steps/half-turn divided by 20 mm)
If you have half-step mode: $102 = 10

If your Z axis is spring loaded to keep it up, you may have a problem with step loss at the Z motor.

[yifandianzi]

https://www.youtube.com/watch?v=ZJZuB_4S9PE
Hello, setting $102=10 and $102=5 will prompt an error, while setting $102=40 will not cause an error

[yifandianzi]

I have set these three places in the firmware

Do you think it's correct

[svenhb]

I don't understand how your z-axis works, in your video time 0.04, the stepper is moving, but the z-wagon is not moving....
Also I don't see an end-switch for z. So you can't use homing for z.
You need to set: #define HOMING_CYCLE 0 ((1<<X_AXIS) | (1<<Y_AXIS)) if you have end-switches there

[yifandianzi]

https://www.youtube.com/watch?v=NDZsdDLbDDo
Normally, it should start working after resetting to zero, and then X Y starts moving to the pen selection position and Z starts lifting. The problem now is that when the start button is clicked, the Z stepper motor has already started working, and then the Z limit is set off

[yifandianzi]

https://www.youtube.com/watch?v=ZxeStwRespc&list=RDCMUCJHZY4Tl6ovsnBrNocdDbAg&start_radio=1&rv=ZxeStwRespc&t=65
The author's point is that the Z-lift motor does not work when starting work after resetting to zero

[svenhb]

The main problem is, that pen selection positions are machine coordinate, which needs homing.
Also the linked video shows a working z-homing - you need to change your mechanics...

[yifandianzi]

Thank you for your great help. When you pointed out the location, I also raised the Z limit position to zero. Now, just as I was preparing to start the work, the Z stepper motor continued to raise and then raised again, triggering a limit fault

[yifandianzi]

https://www.youtube.com/watch?v=QQNdMw_KsNo
After all X Y Z are reset, the execution starts at 0:53, and the Z stepper motor continues to rise

[svenhb]

After Z-homing, Z stays at top position which you may want to have at +2mm in work coordinates.
After Z homing move 2mm down and press "Zero Z".
Also important the choosen travel way for import - small enough for your hardware?:

[yifandianzi]

Hello, where is the white area set and where can I reach the coordinates

[yifandianzi]

https://www.youtube.com/watch?v=qdFgPm4bOkc
This is my complete operation steps, but there are still problems and I don't have a clue now

[svenhb]

Looks good so far.

1. set your travel ranges via $130, 131, 132. https://github.com/gnea/grbl/wiki/Grbl-v1.1-Configuration#130-131-132--xyz-max-travel-mm
   This will influence your homing machine coordinates:
   

After this you go to setup and take over the ranges:

[svenhb]

Here you need a value, close to your homing Y-value = ca. 350:

[yifandianzi]

[svenhb]

You need to seperate between "work" (big digits) and "machine" (small digits) coordinates:

The origin of Work coordinates can be set with the buttons "Zero XY" etc.
The origin of machine coordinate will be found during "Home" and can not be changed.
Tool change position must be given in machine coordinates, to be independent of "zeroing" the origin.

I hope this helps: https://grbl-plotter.de/index.php?id=auto-pen-change&setlang=en

[yifandianzi]

Hello, this is the coordinate for resetting the machine to zero

[svenhb]

So this is your configuration? And Position as shown in screen shot?

Then you can take over this values vor the shown machine area.

[yifandianzi]

Yes, this is my configuration, X \ Y is like this, but after following your prompt and configuring it, it looks like this

[svenhb]

You took the wrong numbers - you need the small numbers for machine coordinates

[svenhb]

Then you move to your tool change position, read the machine coordinate for use here:

[yifandianzi]

Hello, I've finished setting it up. Here's how it is

[svenhb]

Ok, now you need to adapt your pen holder positions:

[yifandianzi]

Hello, I changed the X coordinate of the tool to 0, but it still shows in the common color area

[svenhb]

Just compare your screenshots - pen holder graphic moved to the right direction.
Now change X to ca. 800 and Y to ca. 350:

[yifandianzi]

Hello, where is this not set correctly? When the fixture in front of the pen is moved after zeroing, Z is lifted to the limit position and then moved to the pen position to start gripping the pen. When writing, Z is almost lifted to the Z limit position. After writing, when placing the pen, Z is lifted again to trigger the Z limit position
https://www.youtube.com/watch?v=YUySwfs-eN8

[svenhb]

you need to set new origin for the Z work coordinate: move Z a little bit down (at least the "Save Z" value + the $27 value), then press "Zero Z".

At the moment the work "0" is too close to the end switch.

Also, you may adapt $132 to the real mechanical dimensions, I assume Z can move 20 mm at all? But is not so important for the moment.

[yifandianzi]

Hello, the pen clip got loose while writing. Where do I need to set it up
https://studio.youtube.com/video/-ziqMox3jBs/edit

[svenhb]

Perhaps you changed something else?
Can you show your G-Code?
Which scripts do you use here - and did you modify them?

[yifandianzi]

Hello, this is the script I am using

[yifandianzi]

[svenhb]

And the G-Code from the edit-box?

[yifandianzi]

Hello, the problem I am currently facing is: when selecting the pen for the first time, I can correctly grip it to write. However, when gripping the pen for the second time, there is an error in Z, and Z cannot fall to the specified undetermined value during writing. When gripping the pen for the third time, it cannot touch the paper at all. Can this offset value be adjusted

[svenhb]

So you have step loss on Z because your mechanical range is too small.
You may adapt Z movement in scripts to your needs:

[yifandianzi]

Okay, thank you. Thank you for your help. I will continue to make adjustments

[yifandianzi]

Hello, I suddenly reported a malfunction while writing. Is it a problem with the driver

[svenhb]

ALARM:1

During your plotting process an end-switch was triggered. Perhaps your drawing is too big?
You need to press "Kill Alarm".
You may disable $21 to avoid hard limit alarm. https://github.com/gnea/grbl/wiki/Grbl-v1.1-Configuration#21---hard-limits-boolean

[yifandianzi]

Thank you for your help

[yifandianzi]

Hello, I find this watercolor a bit interesting. Do you have any relevant information? I would like to try making it

[svenhb]

It is my foldable plotter: http://svenhb.bplaced.net/?CNC___Klappbarer_Plotter
Together with some settings - Note the values in the screenshot may not the same, used in the video:

• Accurate PWM setup for different height positions
• Drag tool compensation for the brush
• Split original moves to insert water-color refresh script

[yifandianzi]

Okay, thank you. I'll refer to it

[yifandianzi]

Hello, is the sound emitted by the servo motor an electric current sound? How can I eliminate it
https://www.youtube.com/watch?v=prI3imqAP7Q

[svenhb]

This looks very good!!! I'm happy that you solved all problems!
You can speed up everything by:

• Use higher acceleration, perhaps 500 or 1000 for $120, 121
• Use higher XY-Feedrate in GRBL-Setup

The servo noise is normal: the servo is trying to reach its target position when grabbing the pin, but the pin is in the way. Maybe adjust the grip position value a bit.

[svenhb]

For the gripper value try "S10" or "S20" or higher, you need to figure out: