Home › Evil Mad Scientist Forums › Egg-Bot › 400 steps / revolution steppermotors higher speeds than 1000 steps per second › Re: 400 steps / revolution steppermotors higher speeds than 1000 steps per second
Good catch on the coding.
Using “hard-coded” values in (any) code is a ‘pain in the neck”.
It’ is used “all over” in the inkscape extensions,
I have changed most of my extensions where I need higher default values – like in the
“Render – Parametric curves” the max value for the independent variable “t” is 1000,
if I use the “degrees” option this will plot less than three “revs:” I have set it
to 100000 in the “param_curves.inx” – I then store the extension files in my %appdata%
folder (“C:UsersRagnarAppDataRoaminginkscapeextensions”on my win7 system)
– the files here will not be deleted by uninstall / install of Inkscape.
You can do the same to increase the too low step/second value in the eggbot.inx file.
Having experimented with higher step values in my standalone driver program my motor fails to move fast as it is not accelerated or ramped up/down.
How do you overcome this?
For the pen arm play you will have to ‘design out” the play.
I agree that the original design is “clever” and very simple doing a very good job.
Two changes to the original design would be beneficial.
In the original design the pen tip moves along an arc when the pen is lifted, when changing pens the getting the “new” pen height just a tiny fraction different from the previous pen height will introduce a “large” offset along the X-axis. I am working on a design where the pen moves straight up/down when lifted/lowered to remedy this. (there are already one in thingiverse).
Another “problem” in original design is that it’s possible to “twist” the pen along the x-axis as the hinge part is not stiff enough. (using the optional “stiff” hinge almost eliminates this problem though).
I use extra force (provided by a rubber-band) to keep the pen down as some of my pens require this “extra” force to work.
The RC-Servo does not “like” the constant force provided by the rubber band in the up position.
I try to come up with something “simple” that can be mass-produced using the existing technology (laser cutter) of EMS.
Currently I have a design on my napkin using a wedge (moved by the servo) lifting the pen.
Another change I would like is to move the pen arm servo off the pen arm to reduce the “moment of inertia”.
By having the servo link operating in the center of the pen arm motor axis the servo can be attached to the eggbot frame.
Good luck “pimping” your eggbot ;-)
Thanks to the EMS team for providing me hours and hours of fun!