# Egg measurment

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• #20076
cbhills
Participant

Does anyone have a list of px vs inches?  IE 700px = 2 1/8 inches?  Is there another way to check the size perimeters without using up eggs?

Thank you,

Claire

#20765
Windell Oskay
Keymaster

There is no such list, because pixels correspond to angles, not to inches.

For each motor, a movement of 3200 pixels corresponds to one complete revolution.   If you are printing on an egg that is one inch in diameter, then 3200 pixels corresponds to 3.14 inches– in the horizontal direction.    If you are printing on an egg that is 3.5 inches in diameter, then 3200 pixels corresponds to about 11 inches– in the horizontal direction.   If you are printing on a ball that is 3.5 inches in diameter, then the distance scales in both the horizontal and vertical are 11 inches per 3200 pixels.
If you are printing on chicken eggs, the total vertical range available to you is about 800-1000 pixels.  If you want to test your range without “using up” eggs, just set your pen in high enough that it doesn’t touch the egg when in the down position, and run a test print that way.
#20766
cbhills
Participant

So if I had a design that was 2 inches tall and 1 inch wide and wanted to print it on an egg that is 4 inches tall how do I let the Inkscape program know how tall I want the design?

#20767
Windell Oskay
Keymaster

There’s no straightforward way to calculate that with the amount of information that you’ve given.

The coordinates in the horizontal direction are absolute.  As I said: 3200 pixels corresponds to one complete revolution, so if you know the circumference of your egg, you can easily calculate how wide the design should be in Inkscape.
In the vertical direction, the exact scaling depends upon a number of factors including the shape of the object and pen motor position.  I can give you some starting points, though:
– If you are printing on a sphere, put the pen motor in the top position, and the horizontal scaling is equal to the vertical scaling.
– If you are printing on a chicken egg, put the pen motor in the center position (halfway between top and bottom positions), and reduce the drawing size by about 1/3 in the vertical direction.  (Or, stretch it horizontally to about 1.5 X the initial width before calculating the proper horizontal size.)
#20768
cbhills
Participant

Thank you. I’ll give it a try. :-)

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