Author Topic: Building an eggbot type laser  (Read 5119 times)

Zax

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Re: Building an eggbot type laser
« Reply #15 on: February 13, 2018, 06:07:10 PM »
That's exactly what I was going to suggest, although the active follower is certainly possible.

SteveK

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Re: Building an eggbot type laser
« Reply #16 on: February 14, 2018, 03:40:57 AM »
In case I would ever want to do one with a range finder do you think it would be difficult? Not the mechanical part, I think that would be pretty straightforward. The electronics would be difficult for me. I know I have seen an arduino laser range finder shield somewhere but not sure just where. Have never written a sketch but it seems a simple if/then script would be necessary as well.

Stevev

ggallant571

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Re: Building an eggbot type laser
« Reply #17 on: February 14, 2018, 07:17:42 AM »
Depends on where you put the range finder code. You could:

 1. Modify the embedded GRBL code but the the Z axis would be confused if there is nothing detected.
 2. Change the host application (if you have the source) and add a option/mode control.
 3. Add another Arduino for just the Z-Axis with its own application.

I'm open to almost anything. Especially ideas!!!!
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Zax

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Re: Building an eggbot type laser
« Reply #18 on: February 14, 2018, 10:12:18 AM »
I would design it as a completely separate module, independent of Grbl.

A non-contact proximity sensor, or 2 if you use the cheaper IR (fixed focus) type.

Something like this:
https://create.arduino.cc/projecthub/jenniferchen/distance-measuring-sensor-900520

Use the feedback to drive the stepper and maintain a position. It should be fast enough in most cases, unless the object has drastic changes in height. In that case you'd want to integrate it which is more complex.

SteveK

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Re: Building an eggbot type laser
« Reply #19 on: February 14, 2018, 03:13:15 PM »
I did have time to get the laser wired up today and played with it a little. I think maybe now the real work starts. It seems to me the y axis is much too fast and the x axis may be a little slow. On this machine the y axis is the rotation and the x is the laser travel. Also, the aspect is all wrong. I really won't get another chance to play with it until maybe next Wednesday or Thursday. I believe I'm going to have to change some feed rates and other settings but I don't want to affect how T2 works with my other machine. Can I created a profile for one machine and a different profile for a different machine?

Steve

Zax

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Re: Building an eggbot type laser
« Reply #20 on: February 14, 2018, 04:01:06 PM »
If you are only talking about parameters like feed rate and power, yes they can be stored in a profile.

The steps and other parameters are saved on the Nano, so you can setup each machine independently.

SteveK

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Re: Building an eggbot type laser
« Reply #21 on: February 21, 2018, 11:35:33 AM »
Okay, I tried calibrating my machine a few times today and haven't had any success to this point. Not sure if I'm on the right track or not. I shot a little video to show what I'm doing and I appreciate any help offered but I would ask to make the explanations as basic as possible, it's impossible to make it too simple. Not a bad carpenter but I've much to learn about these kinds of things. 
Thanks to any who respond
Steve

https://youtu.be/opGoQTL9eHM

ggallant571

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Re: Building an eggbot type laser
« Reply #22 on: February 21, 2018, 11:54:15 AM »
Please dump and post the grbl parameters.

On my rotary lead screw (8mm 4 start) one rotation is 8mm linear. 1 rotation of the motor is 200 steps. With the microstep set at 16 this is (200 x 16 /  8) or 400 steps per mm. What are your leadscrew, motor, and microsteps?
« Last Edit: February 21, 2018, 07:55:58 PM by ggallant571 »
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SteveK

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Re: Building an eggbot type laser
« Reply #23 on: February 21, 2018, 02:37:19 PM »
Please dump and post the grbl parameters.

On my rotary lead screw (8mm 4 start) one rotation is 8mm linear. 1 rotation of the motor is 200 steps. With the microstep set at 16 this is (200 x 16 / 8) or 400 steps per mm. What are your leadscrew, motor, and microsteps?

thanks for the reply. I think I saw somewhere that 3200 steps were a rotation on my motors, I also think that's maybe normal?

Is this what you wanted as far as the grbl?

( Generated by T2Laser )
( SketchGcode for Grbl )
( Start Point: Center  )
( Frame Mode : Abs.    )
( X Maximum  : 93      )
( Y Maximum  : 50      )
( Laser Max  : 255     )
( Vector Rate: 500     )
( Rapid Feed : 2000    )
G21
G90
F500
M05
G00X0Y0F500
G92X46.5Y25
G90
G01 X30 Y32 F2000
M03 S0
X56.75 Y32 M03 S255 F500
X56.75 Y9.75 M03 S255 F500
X30 Y9.75 M03 S255 F500
X30 Y32 M03 S255 F500
X71.25 Y25.75 M03 S0 F2000
X70.975 Y23.275 M03 S255 F500

Steve

Zax

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Re: Building an eggbot type laser
« Reply #24 on: February 21, 2018, 03:07:12 PM »
On the Machine menu, click Display Grbl Parameters. You can also enable debug mode and type $$ (does the same thing).

SteveK

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Re: Building an eggbot type laser
« Reply #25 on: February 21, 2018, 03:25:17 PM »
On the Machine menu, click Display Grbl Parameters. You can also enable debug mode and type $$ (does the same thing).


Connected COM3 115200
Grbl Ready
$0=10 (step pulse, usec)
$1=25 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=0 (dir port invert mask:00000000)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=3 (status report mask:00000011)
$11=0.010 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=0 (hard limits, bool)
$22=0 (homing cycle, bool)
$23=0 (homing dir invert mask:00000000)
$24=25.000 (homing feed, mm/min)
$25=500.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$100=80.000 (x, step/mm)
$101=80.000 (y, step/mm)
$102=80.000 (z, step/mm)
$110=5000.000 (x max rate, mm/min)
$111=5000.000 (y max rate, mm/min)
$112=5000.000 (z max rate, mm/min)
$120=500.000 (x accel, mm/sec^2)
$121=500.000 (y accel, mm/sec^2)
$122=500.000 (z accel, mm/sec^2)
$130=500.000 (x max travel, mm)
$131=500.000 (y max travel, mm)
$132=500.000 (z max travel, mm)

Steve

SteveK

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Re: Building an eggbot type laser
« Reply #26 on: February 21, 2018, 04:03:32 PM »
I believe one rotation is 4 mm

Steve

ggallant571

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Re: Building an eggbot type laser
« Reply #27 on: February 21, 2018, 08:07:30 PM »
The icon with the face should be "divide by 8".

There are two things to resolve., rotation and the linear motion. I thought your rotation was ok and that the major problem was along the linear axis. How far does one rotation of the lead screw move the carriage carrying the laser? With 8mm screws you can get "single" or "quad" start with corresponding nut. With single start threads, one rotation advances the nut 2mm,  with quad start 8mm.

I'm assuming that the X axis is wired to the rotation motor and the Y axis drives the lead screw, Assuming a 4 start leadscrew you want to change $101 to be 3200.
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SteveK

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Re: Building an eggbot type laser
« Reply #28 on: February 22, 2018, 03:34:00 AM »
The icon with the face should be "divide by 8".

There are two things to resolve., rotation and the linear motion. I thought your rotation was ok and that the major problem was along the linear axis. How far does one rotation of the lead screw move the carriage carrying the laser? With 8mm screws you can get "single" or "quad" start with corresponding nut. With single start threads, one rotation advances the nut 2mm,  with quad start 8mm.

I'm assuming that the X axis is wired to the rotation motor and the Y axis drives the lead screw, Assuming a 4 start leadscrew you want to change $101 to be 3200.

One rotation of the lead screw motor is 4 mm, the lead screw is my X axis and the rotation is the Y.  Not sure what you mean by the "icon with the face" and also not sure what is a quad start or single start lead screw. When the motor spins, so does the screw.  I appreciate the info about changing the $101 value to 3200 but would really like to know how you arrived at that number.
thanks again


Steve

Zax

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Re: Building an eggbot type laser
« Reply #29 on: February 22, 2018, 05:08:21 AM »
T2Laser can take care of all the calculations, using either rotary mode or the calibrate distance features but I can explain the calculations (you can also see them in the rotary axis setup screen).

The motors are 1.8 degrees per full step. Since there are 360 degrees in a rotation, 360/1.8 = 200 steps for full rotation.

The drivers use microstepping, which is a method to get more resolution from the motors by partially indexing them. You get lower torque but higher precision. The standard drivers are fixed at 1/16th microsteps (others allow you to select from 1/4 to 1/256). So this means you have 200*16=3200 steps per rotation.

Not applicable for a rotary axis, but say it's a Y-axis and you are using a 10 TPI (turns per inch) leadscrew, 32k steps will cause 1" of travel or in metric (what Grbl uses) you would have 32k/25.4 = ~1260 steps/mm.

So with your 4mm per rotation lead screw, it would be 3200/4 = 800 steps per mm. That is the value you would enter.

As I said though, T2Laser will figure this out and update the correct $ entry automatically.