Hi everyone,
I've been playing with my fresh assembled polargraph for a couple of days now, but I am having trouble printing images straight. Here are some images I printed. Note that at the end the image is much more narrow than the up side. How can I configure the machine to fix that?

Sure!!

I will try to recalibrate it and see the results. Thanks!!

Helpful pics again, thanks. The position of the motors is fine I think, as long as the width you have measured is the distance between the two sprockets, and not the width of the board or something like that.

So it should be 720mm between the closest points of the two sprockets - bit difficult to judge from the pic, but looks like it could be about that.

Main thing that jumps out as being off is the steps per rev and the step multiplier though: 800 steps per rev and step multiplier of 1 does not correspond with any standard polargraph setup.

Steps per rev – should be 200
Step multiplier – should be 8

I've just added a section to https://github.com/euphy/polargraph/wiki/Building-a-Polargraph-from-a-vitamin-kit about the proper settings for the controller app. These were already noted down in http://www.polargraph.co.uk/setup/polargraphsd-controller-application/ but they should be in the wiki too.

That kind of explains some issues (the size really), but perhaps not the distortion. Have a go and see if it helps. The drawn size will never be exactly perfect, but it really should be within a couple of millimetres of what you've specified in the app.

sn

Your excellently straight drawing (congrats!) evoked this response from me:

(Thanks to Craig, I can't see the photo you used without hearing, "OOOOoooh!")

hahahaha, thanks for the compliments!! And now I can hear the OOooh every time I look at it as well ... thanks for that too!!