First Plot Results and How to resolve issues
2018-07-02 at 22:14 #20245
My first plot ==>
Did a Generate Art / Hilbert Curve Fractal (order 6)
1.) It did not lift the pen after it finished the plot. (I have checked my pen up/down and calibrated its ok)
2.) there is a bow in the design more pronounced at the top compared to the bottom
Nema 17 1.8/200
GT2 Belts / 16T Pulley
Rumba with Firmware v7.15.5
Running Software v7.16.1
MW 537.0 (this is from the right end of pulley left to the left end of pulley right)
Accel 2000, Draw Speed 2000.
PEN UP 180
PEN DOWN 120
LIFT DELAY 50
A3 Paper Landscape
// motor details
#define MICROSTEPS (16.0) // change this. microstepping on this microcontroller
#define DEGREES_PER_STEP ( 1.8) // change this. as advertised by the stepper motor maker
#define NORMAL_MOTOR_STEPS (360.0/DEGREES_PER_STEP) // 360/0.9=400. 360/1.8=200.
#define STEPS_PER_TURN (NORMAL_MOTOR_STEPS * MICROSTEPS) // default number of steps per turn * microsteps
#define PULLEY_PITCH (2*16.0) // 2mm per tooth, 20 teeth.
#define THREAD_PER_STEP (PULLEY_PITCH/STEPS_PER_TURN)
#define MICROSTEP_PER_DEGREE (STEPS_PER_TURN/360.0)
Thanks for any suggestions
Rob.2018-07-03 at 00:39 #20246
Finally getting some better results
The improvements are settings Paper 10.5 from top and Pen Home 23.5 from top.
The bow has completely gone but the lines that should be straight in the upper half are noticeably curved but it gets better as you get lower.
Not sure how to resolve that one.2018-07-03 at 01:23 #20249
That is odd. I normally get better quality higher up. If you draw a 10cm line in any one direction is it actually 10cm?2018-07-03 at 01:26 #20250
I will try that now and report back, but so far dimensions are outputting the same as in the GUI
I’ve slowed it right down to 500 Accel/Feedrate and this is the results so far ==>
Cheers Rob.2018-07-03 at 09:10 #20254
fwiw, I have been doing experiments with adjusting acceleration based on machine size and plotter position.
Acceleration sideways can be higher when the plotter is near the top of the drawing because the V shape of the belts is much wider (more stable).2018-07-03 at 19:04 #20263
Ok so I have done my homework!
I used inkscape to draw a 200mm line and some text, object to path and exported as a DXF as that is what the GUI seems to like best.
Here is my results
My concern is how I have measured the Machine Width and not certain I have done it correctly and that is affecting the Math of the output.
Centre to centre of my stepper motors is 547mm, The Radius of my Pulleys is 5mm (16T pulley, so 2×16=32mm circumference) so I set 537 as my Machine Width (which is the right most side of my left stepper to the left most side of the right stepper i.e. groove to groove)
is this correct?
Cheers Rob2018-07-03 at 19:54 #20265
I would have used 547.
As the plotter moves around the belt changes position on the pulley. this is *really annoying* if you want precision. On the M5 the belt is usually touching on the bottom inside screw of the motor, which keeps it mostly under control. I say usually because in the very bottom corners of the drawing area the belt can lean away from the screw. If it were always at exactly that spot the image quality would be even better.2018-07-03 at 20:13 #20267
SO i am just trying 547 now
It does seem slightly better, It is bowed because my home point will need to change with the width change
I did find some standoffs and longer bolts in my parts bin, so would the width measurement then be taken from
them points? i’ll try that next.2018-07-03 at 20:20 #20268
I have a feeling you are going to invent new and interesting ways of making even more accurate pictures, and I welcome your efforts.2018-07-03 at 21:20 #20269
I have added the standoffs as suggested
It’s taking me some time to get my page in the right spot and find the correct home position to avoid the Smile or Frown at the top of the drawing.
Cheers Rob.2018-07-03 at 23:19 #20270
I have now found the correct paper placement and home position again after adding the guides, its pretty much bang on the homing template that you provide!
So i did another Hilbert Curve (soo bored of this test pattern right now!)
i’ve slowed the accel/speeds down to 400 & the pen has had its day 🙂
it’s getting better but not producing perfectly straight lines, is this the best that i can hope for?
Cheers Rob.2018-07-04 at 00:50 #20271
That is pretty good! Without a way to further stabilize the pen (reduce wobble) that’s about as good as it gets.
One suggested way to reduce wobble would be more contact points on the wall (2 points + pen tip).
Another is to double the belts so they hold both ends of the pen.
Both would require experimentation.2018-07-09 at 01:06 #20326
Thanks so much for everything, you are an amazing person. Your Software/Firmware/Development is outstanding!
Also I think i’m getting the hang of this 🙂
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