New Machine Design Advice

[cncJim]

Hi everyone,

I am looking to make a small machine that can draw using a marker pen.

A3 kind of size
I would like it to be fast
light weight
Wall mounted
Small Z movement - only needs to lift the pen from the drawing surface
Control - I would like control the machine using something like an arduino - just drawing predefined images.
The machine will be on display so the final look is important.
The drawing "head" of the machine needs to be able to move out of the way so the view of the finished drawing is not obstructed.

Any advice/ideas/links where to start? I was thinking something like a Delta Robot (is this the right term?) type of thing would be good - fits the looking interesting requirement! - looks very complicated mind....

Any input appreciated! :)

Jim

[EddyCurrent]

I think you've just described something like an XY Plotter, mybe the guts of this would do ?

http://www.ebay.co.uk/itm/CalComp-Mo...item19f29e9262

[cncJim]

Cheers Eddy - yeah I guess I did kind of describe a plotter! Thanks for the link - Might be a good place to get me started.

Still tempted by the delta type machine or some kind of 2 motor arm? Does anyone know of any resources that deal with Delta robot type calculations?

[EddyCurrent]

Does this give any ideas ?

http://orangenarwhals.blogspot.co.uk...-now-with.html

I used to have a similar thing years ago for a BBC micro only it was an input device. Two perspex arms joined with a potentiometer and both attached to a table with another potentiometer. As the extreme end was moved about over a drawing surface it created a digitised image on the screen. Mapping from the two pots. was quite simple using sin or cos calculations I remember.
So I was thinking about the reverse, two motors, one attached to the base driving a 'shoulder' the other driving an 'elbow' all moving in the horizontal plane over an A3 drawing area.

[cncJim]

yes! that's the kind of thing - Thanks!

I think the two motor arm idea would work very well - Also could look very nice/interesting. Also the entire arm could be positioned so that the view of the drawing area is clear.

Material wise, I will be looking at using brass (or aluminium) with wood for a kind of retro/steampunk look. Would be great to use something like servos but not sure they would be up to the job? Maybe small steppers might be better.....?

[FatFreddie]

Any advice/ideas/links where to start? I was thinking something like a Delta Robot (is this the right term?) type of thing would be good - fits the looking interesting requirement! - looks very complicated mind....

Delta forum for 3d printers...
http://forums.reprap.org/list.php?178

The usual software is I think Marlin running on one of the 3d printer boards based on an Arduino (Melzi / Ramps etc). That's probably the cheapest way to get it going because they're commodity items now (a UK sourced Melzi which includes the stepper drivers is less than £50 and there are cheaper alternatives). They read fairly standard g-code with some extensions and some restrictions so shouldn't be difficult to control.

I've heard complaints that the arduino is a bit slow for a delta because the position calculations are more complex than a linear xyz design but there seem to be plenty of people using them.

[cncJim]

Delta forum for 3d printers...
http://forums.reprap.org/list.php?178

The usual software is I think Marlin running on one of the 3d printer boards based on an Arduino (Melzi / Ramps etc). That's probably the cheapest way to get it going because they're commodity items now (a UK sourced Melzi which includes the stepper drivers is less than £50 and there are cheaper alternatives). They read fairly standard g-code with some extensions and some restrictions so shouldn't be difficult to control.

I've heard complaints that the arduino is a bit slow for a delta because the position calculations are more complex than a linear xyz design but there seem to be plenty of people using them.

That's great - Thanks for the link and information - Lots of info to digest! I would like my machine to be fast ,and by fast i mean be able to draw quicker than a person would do, but not anything crazy. Maybe something Arduino based would still fit the bill?

Thanks,
Jim

[FatFreddie]

That's great - Thanks for the link and information - Lots of info to digest! I would like my machine to be fast ,and by fast i mean be able to draw quicker than a person would do, but not anything crazy. Maybe something Arduino based would still fit the bill?

I think it should be fine for that - if you're using a marker pen, that will probably set the upper speed limit.

A delta machine for A3 will be fairly large but it will also be quite impressive :-)

[Neale]

I know that it's not entirely relevant, but just for fun: robotic painting machine

[cncJim]

Ha that's a clever idea - I would be interested to see the result if they isolated the machine noise from the the processing.

So after thinking about it, the delta type robot may be on the back burner. I think the resulting machine will be just too big and I cant see how it would make so the machine does not obstruct the view of the resulting image.

The robot arm idea has legs though!

Something like this....