Problems with setting up “pen down” height correctly

[tokefrello]

Whenever I setup my pen in the pen holder, I do it the following way:
1. Set pen holder in “pen down” position, let’s say at 55%
2. Put pen in pen holder so that it rests on the paper
3. Fasten the screw

Now, in theory this should mean that I can now draw without problems. However, the pen usually “misses” the paper in the middle of the drawing area, i.e. it doesn’t go all the way down to the paper. I have to lower the “pen down” position with an additional 6-7% to make sure the pen doesn’t miss any parts. This isn’t a big problem, but it makes it difficult to get a light touch with my thinnest pens, since they have to be pressed down quite firmly.

Does anyone else have this problem? Or is it just the only way to do it? I’m quite sure my drawing work area is level and even, and I can’t see any obvious malfunctioning in the machine.

[Windell Oskay]

That is definitely not a calibration procedure that should be expected to work. We would recommend that you follow the procedure from the user guide instead — start with the pen up, and make sure that it has enough vertical range to touch the paper everywhere.

The AxiDraw’s cantilevered geometry means that there is no guarantee of a consistent height between pen and paper over the entire plotting area. Even if your paper is perfectly level, the AxiDraw may not be, and it can even lean forward a bitThat’s one of the main reasons that we have the “floating” Z stage, which is tolerant of a variable Z height. The floating Z stage *does not* apply a different amount of pressure depending on the pen-down position. It applies exactly the same amount of pressure whether you have the pen-down height set at 55% or at 25%.

[tokefrello]

Thanks a lot, Windell, that clears things up. So to make sure I understand the guide correctly:

If the pen is ≈ 5 mm over the paper with the UP position being at 60%, it should (in most cases) hit the paper evenly if the DOWN position is at 40% – and the pressure applied to the pen won’t be different from having the DOWN position at, say, 41%?

[Windell Oskay]

Yes, that’s correct.

[Author]

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