I’ve been pondering about a pen plotter for a while now. I want to make dedicated machine for plotting (and perhaps laser in the future). I’ve got many tubes and parts from the burly and other projects lying. I want to make this as cheap as possible, with easily available stuff. My CAD-skills are as a four year old, so I want to borrow some parts from v1. (I won’t sell or license anything, if anyone wants I’ll share the parts, but of course in the right manners!)
The red plate will borrow the x rollers from lr2 for the X direction, using 25mm pipes I’ve got. For Y I want to get linear bearings and use 16mm aluminium tubes. (They are quite cheap and rigid). I want the work area to be at least A3 (approx 30x40cm). I’m hoping to figure out a way to run this with corexy design.
My question is - do you think this is feasible? I’ve been thinking about using the new zenxy as basic setup, but I think it’s more complicated than necessary. My main worry is how much wobble there will be on the Y, in terms of size and tube specs.
It’s definitely feasible. I’m not sure if your goal is to have a project that will stretch your design skills, or to have a working pen plotter.
If you’re interested in designing and building your own machine, then this is a good project to do that. I would definitely take a look at some of the other machines out there to see what they learned and try to incorporate that. But ultimately, drawing with a pen with a few stepper motors should be an achievable goal.
If you’re interested in just getting a plotter, then you should look at what is already out there. There is a lot of knowledge and experience soaked into those designs that won’t be completely obvious when you start. The cantilevered laser engraver would be a good one to try. Or there are a bunch of open source machines. A lot of machines that @dkj4linux uses for needle cutting would also be good. Or, just make an MPCNC . The axi draw is a pretty popular machine I see on #plottertwitter.
I also made some chicken scratches on how to make something like a corexy cantilevered design at one point. But when I think about how to actually route the belts, I think may be some problems there.
I totally understand the idea of making your own design though. Even if it doesn’t work well, it’s yours.
Thanks for kind replies. I’ve looked into quite a few variations out there. There are two main goals for this project: making a functional plotter AND using as many already owned parts as possible. Using aluminium extrusions would certainly be simpler, but I’d like to give it a shot. I shouldn’t be THAT difficult. A nano with a cnc shield, a4988s and two nema 17 and a servo/solenoid. I think you are right @jeffeb3 that figuring out the belt would be the most tricky part.
Look at things like the eggbot/spherebot (and the proliferation of redesigned arms) for ways to hold and lift various writing/etching instruments. Don’t lock yourself in to a particular model of pen. Include some spring tension to hold the pen on the work piece. You may not need CNC control of height while running, but you’ll probably want to be able to adjust across a pretty wide range depending on the range of tools (pens) you’ll want to mount.
There are many nifty ways to control the pens, both using servos, solenoids and simple motors. I’m mostly worried about the stability of the physical build - but again, it won’t be as important with a super precise z, when the retraction is 2mm, and the pen is spring loaded. Stability in x-y-direction would on the other hand be obviously needed.
And I’ve enjoyed using https://www.thingiverse.com/thing:2933276 on my Burly. You can wire it in to the probe connection and it will automatically zero your Z height.
Oh yeah, that’s a good drawing. The whole gantry has to slide though? Hmm. Not exactly what I was thinking. But that would work, and it would need half the belt of a regular corexy and still have two stationary motors.
A new worry has come to mind. Will the aluminium tubes wear out too quickly?? I cannot use them if they’re not rigid enough, but if they wear out, it’s no good anyway.
I’m assuming that a little play shouldn’t be too much of an issue. There’s not a lot of forces on the tip of a pen that’s riding on something. And there’s 0 forces on a laser, although any play and the laser would wobble.
Z doesn’t matter, but x and y should be somewhat precise. I guess the alloy type of the aluminum would matter a lot. The webstore doesn’t say anything about it.
Yes, you are really going to not want to use aluminum tubes. Pretty much any aluminum alloy is too soft for the pressure the rollers put on it. They will turn into wiggly triangles after a short while…
. The axi draw is a pretty popular machine I see on 
What do you think about my (very immature) plans?
