mouse following plotter

[oozmaq]

oozmaq

hi
i am making a mouse following plotter which plots whatever u draw on a GUI. i have done all the programming and electronics bits but am stuck in the mechanical design. need help.....its supposed to b able to draw on standard drawing sheet ( about 71 cm x 55 cm)

 

[salamander]

Hello,
wouldn't it be easier to use a old pen plotter. This devices are very cheap today and you could simply connect to your computer with the serial port.

salamander

 

[Ahmed Ragab]

Well you said you you done all the programming and electronics but stuck in the mechanical design !!!
Which part of it are you stuck with? and what sort of problems didi you find ?!
I imagine that doing such a plotter mechanically is quite easy
or are you designing the mouse itself ?!

Considering the plotter you may find a board for a start and then place two screws one horizontal and the other vertical
each screw will be rotated by a stepper motor ( for better accuracy )
now lets see, what is missing now is to design the movable part which will plot your drawings.

Emmm... you will need 2 rods that will be place on the board one horizontal and the other vertical

The vertical rod will be tied using a bolt to the horizontal screw and vice versa
this way .. when the horizontal screw rotates... the bolt will make the vertical rod move to the left or right ... and when the vertical screw rotates the bolt tying it to the horizontal rod will cause it to move ypwards or downwards.

So what's remaining?! Yes the drawing pen, e need it to move upwards or downwards so as to make it draw only in the places its supposed to do so, and not mess the whole drawing board while moving.

I'll think of something and get back to you soon.

Any inquiries just feel free to ask.

 

[oozmaq]

thanx ahmed
actually what i've designed so far is almost exactly the same as what u have suggested. the problem is that one bar has to move over the other bar. one bar just rotates, the other moves and rotates. i've already designed an electromagnet arrangement for moving the pen up and down. its seems as if u have already done or seen a similar project. it would b really helpful if u cound just skecth wat u saw and upload it>:| i took my design to a workshop and they told me that the design was not practical!!!!!!!!

 

[jonw0224]

oozmaq,

most plotters move the paper.

if you insist on moving the carriage (with the moving bar), the biggest problem is that you have to move both sides of it (if you apply your force on one end, it will produce a torque on the other sliding contact and tend to try to put it in a bind -- one way to get around that is having three points of contact for the carriage -- another way is to move both ends using two rotating bars).

Why did the workshop say the design wasn't practical?

Oh, by the way, you can buy X-Y tables on the internet or on catalogs. That is essentially what you want to build.

 

[Ahmed Ragab]

Well to be quite honest with you I never did make such a thing as the plotter you requested , but I'm generally interested in mechanical designs and motions.

Now back to your work,
The idea depends on having 4 rods, 2 are screws only rotating, and the other two will not rotate but will only move left or right , upwards or bottom.

So let's imagine this, you will have your board with the paper above it, right above it place your first screw horizontally along the board at the bottom of your board. anf tie it using a bolt to a rod placed horizontally right above it.
this way when the screw rotates the vertical rod will move right or left
Above this place the vertical screw at the right most of your board and on top of it tie the horizontal rod using a bolt to it. this way when your screw rotates the horizontal rod will move up or down.

Whats left is to tie your pen between the vertical rod and the horizontal rod

I'l try to skecth something and pm to u as soon as possible

Hope i did really help.
Regards