SERVO lifts and lowers the pen when the arm strikes the attachment screws??

[Alan Nelson]

I don't get the way the servo moves the pen. Is the arm attached to
the servo supposed to be loose?

As the servo moves the arm hits the screws that secure the arm to
the servo plate and that lifts or lowers the pen when it strikes the
screws.

Shouldn't the arm be fixed so it doesn't flop up and down?

[bre pettis]

The arm relies on gravity to have the pen on the paper, this makes it so that it can handle small variances in the paper.

It won't flop up and down!

Bre

MakerBot Industries
http://makerbot.com
Recent Press: http://bit.ly/cbsmakerbot

[Matt G]

Actually, this arrangement not only makes the issue of getting good
pressure on the paper mechanically easier to solve (given slight
variations and height -- driving the pen down would require a lot more
feedback on precise distances of paper to avoid tearing or missing)
but also grants this pen plotter a more natural "hand" than many pen
plotters: the pull of the paper on the nib leads to more natural lines
and curves rather than a lines and curves stepped at the resolution of
the steppers.

The servo is mostly involved with pen lifts, actually.

Matt

On Oct 28, 10:27 am, bre pettis <brepet...@gmail.com> wrote:
> The arm relies on gravity to have the pen on the paper, this makes it so
> that it can handle small variances in the paper.
>
> It won't flop up and down!
>
> Bre
>

> MakerBot Industrieshttp://makerbot.com

[Alan Nelson]

but this floppiness doesn't work to focus a laser cutter.
what I will do is pin the arm to the disc to control the pen depth and
then remove the pin when I want to plot.

[Matt G]

Um....please be careful with lasers! this scenario kinda gives me the
weebie-jeebies (is that how you spell it?) as the potential for
disaster or eye/body injury is quite a bit higher than, um, drawing
things on a drawing surface with a pen.....

One of my colleagues suggested that you take this project (or at least
the parts of the lasercutter assembly you have completed) to the
Thingiverse.com and MakerBot Operator google group communities to see
if you can get some help or make adjustments to other mounting
projects to get a safe, firm grip for your laser. You can still re-
purpose the plotting tools for the drawings themselves.

And how about putting up some protective filters on the open walls of
your makerbot so you don't die! ;-)

Matt

[Alan Nelson]

First there are specific glasses for the laser I have. It is powered
from the same board as the plastruder.

I have attached the laser to the side of the plastruder and etched
designs before.Paper plotting is nice but I can laserprint a lot
faster.
the idea that I can etch into materials flat or otherwise at this cost
is intriguing.
the unicorn that I just modified will allow a fuller range of motion
of the laser to focus the beam at various depths.

By the way, I am a state licensed engineer and have been one since the
early 70s (1970s) so I kinda think I know the issues.