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Author Topic: Polargraph Optimiser
yasirhawk
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Posts: 13
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Post Re: Polargraph Optimiser
on: March 23, 2020, 15:06
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Quote from yasirhawk on March 21, 2020, 15:45
thanks,,, perfect..... 🙂
sandy can you share your email kindly ,i want to mail you???

yasirhawk
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Posts: 13
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Post Re: Polargraph Optimiser
on: March 25, 2020, 15:18
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latest polargraph controller gives error while open in processing 3.
its open well in processing 2.whats reason?
Image

yasirhawk
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Posts: 13
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Post Re: Polargraph Optimiser
on: March 28, 2020, 06:54
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reply me?

yasirhawk
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Posts: 13
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Post Re: Polargraph Optimiser
on: March 28, 2020, 15:27
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[sandy can you configure that reason for draw square bottom skew,,,
i have change my string pulley and even mm per rev but its still draws the narrow bottom images.....whats reason that ? how can it be improve?

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sandy
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Posts: 1424
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sandy
Post Re: Polargraph Optimiser
on: March 28, 2020, 17:06
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Polargraph Controller only works in Processing v2.2.1.

Distorted drawings - narrow bottom
The drawing tapers as the pen moves down the page, and has a concave bottom row.

Usually: The pen is actually slightly higher up the page than the machine thinks it is / The strings are slightly shorter than the machine thinks they are.

Maybe your home point is physically higher than you have told the controller, or the pen was actually higher than the home point when it was calibrated.

Less commonly: Bad specification. The pen is in the right place, but the machine is physically narrower than it thinks it is.

So the machine thinks the distance to the home point is 800mm (for instance), but it's actually only 750mm.

Solution: Measure, fix, re-upload machine spec!

Do a bit of diagnosis by doing set home then physically moving the pen 10mm down, and see if that makes the distortion better or worse. Select an area in the controller and do Draw outline selected to quickly sketch out a rectangle for testing.

https://github.com/euphy/polargraph/wiki/Distorted-drawings#narrow-bottom

yasirhawk
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Posts: 13
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Post Re: Polargraph Optimiser
on: March 29, 2020, 17:31
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ok, there are some questions ...
1 - is there any ratio or formula for setting home point exact position based on machine size /area from top of machine???
2 - what is the calculation for measure the pulley size for stepper based on size of machine?? because my machine area is large in meters amd pulley size is 10mm inner and 20mm outer but when machine start to draw it only draws usually or 1/4 of area ....

sandy
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Posts: 1424
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sandy
Post Re: Polargraph Optimiser
on: March 29, 2020, 19:05
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No ratio - the position of the home point is arbitrary. I put it where it is because that was easy to measure, kept the pen off the drawing paper until it was actually drawing and did not put too much strain on the motors while they were holding the cord stationery.

For very large machine where I can't reach the top easily (without a stepladder), I make the home point down at the bottom.

Pulley size, stepper size or step count and machine size are not related.

Important value:
mm per rev – This is the length of string dealt out by one revolution of the motor.
Steps per rev – This is the number of whole steps that the motor is capable of making.
Step multiplier – This is the default microstepping value. This one depends on which motorshield you're using, and how you've set up the firmware.

What does the inner and outer of a pulley refer to?

sn

yasirhawk
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Posts: 13
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Post Re: Polargraph Optimiser
on: March 30, 2020, 18:51
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its setting with my machine drawing area , 1300 width , 850 height ,with setting home at 300 and also put home at different position , but still need to be perfect . and cannot find a perfect way to quick and accurate home point .even home is too down position then a little change in draw square better the previous. my pulley size is 10mm diameter
all polargraph machines require too down home positions if we increase width ?? problem is just to find accurate and close home point position....
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sandy
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Posts: 1424
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sandy
Post Re: Polargraph Optimiser
on: March 31, 2020, 21:11
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Hello,

The only requirement for the home point is that it is in a position that the motors can hold still. So the angle of the cord going to the gondola is the thing that really matters. That's why very wide machines usually have lower home points.

You need to set your mmPerRev. As stated, this is the amount of cord that the spool will let our in one revolution. It is not the diameter. If your bobbin there is a standard sewing bobbin, then the core is probably about 8mm across. However, since the cord is so thick and the bobbin is so small, the diameter of the core of the bobbin will change rapidly as line is wound on and off the spool.

10mm diameter might be ok as the average. Now, when you unwind that spool one full revolution, you'll find about 31mm of cord is let out, so your mm Per Rev is 31.

Note that you will never have a very accurate machine because the diameter of your spools will be changing constantly with such small spools and such a large machine.

You have your machine set to 1450mm wide, so your motors must be 1450mm apart from one another. Because your cord is leaving the underside of the spool, your distance measurements should be from the outside edge of the spools. The 1300 is the size of your paper, and is not a relevant measurement for calibration.

Your drawing is skewed to one side, so this shows that your centre line is not actually central. It should be exactly in the middle.

(see pic)

Your stepMultiplier is set to 4. This is unusual. This depends on what microstepping setting you have configured in your firmware and your hardware.

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