Canvas printer design hurdle

[Azazyel]

I'm designing a inkjet printer that will print to canvas. But I can't decide between two different designs in my head.

One design has the y axis on the gantry (print head scan) and the X axis done by moving the canvas. The canvas will be fed from a roll of canvas to another empty roll and two servos will keep the tension in the canvas. I will have a roller before the print head with a linear encoder on it to find out how mucht eh canvas has moved. I might need a small amount of motion in the x axis on the print head to get more accuracy if the canvas is hard to control.

The other design is a more common flat bed, with the canvas layed out and pinned down stretched. The head moves in x and y.

I'm thinking the advantages of the first are a smaller, cheaper machine.
The other one is more multi purpose (Change inks and print on less flexible substrates for printing PCBs or photovoltaic cells).

Any suggestions?

[blackbeard52]

I have a little experience with Screen printing and I see a little problem with the ink transferring to the underside of a rolling senerio...or am I missing something. I dont see the advantage of the roll unless it is a large print. Space saving would only be an issue if it were say a 4 x 4 print or larger in my mind and how often would this be done? And lastly the electronics for the rolling setup would be more than twice the expense of the build

Just my worthless wooden nickle

Bob

[Azazyel]

Yeah, I'm starting to think the flat bed may be better. Though it should be cheaper to make the other one, as there doesn't need to be a large flat bed, and I don't need some huge, accurate, rack and pinion system. The electronics are easy enough, I specify a torque, and the controller maintains it. If I want to go forward, the power is increased to one motor and the other one has to give to maintain the constant torque.

I'm going to get some inkjet canvas, comes in 60" by 40' rolls, and you print on the top of it.

[blackbeard52]

That is a great idea for a build. I would be very interested in the progress... gutting an old injet destined for the graveyard!!!!...Would you be adapting a flow setup for the ink? Or does it require a special ink for heat setting into fabric? I have lots of old laser steppers begging for a specific use...they are too small for routing builds but may be suited for this application.

Bob

[Azazyel]

I want high quality prints, so I'm thinking of getting an 8 colour Epson high quality printer and modifying it.

It will be really easy if I can rejig the linear encoder and have it accept the longer y axis. I might need to modify some hard limits in the firmware. Otherwise I'll need to find the protocol for the head and make my own USB print system for it.

I'll give it another month before I look at starting the body, maybe someone will find something wrong with my cheap system and I'll have to bite the bullet and fork out for a large table and moving gantry...

[blackbeard52]

Hmmm...might be a challenge....i have seen where users have modified the height but not the length. I will do some googling and see what we can do about that.

Bob