I am considering buying an Acro 2020 kit (or custom 2040?) to use as a large-format plotter and I would appreciate input on my intended use (i.e.: Am I overlooking a better approach?) I am a metal sculptor and my current process typically goes like this: --Design sculpture in CAD program (Rhinoceros) --“Unroll” the surfaces to create templates --Print templates on paper using a 36” wide HP Deskjet printer --Glue paper templates to sheets of aluminum (typically 5’x10’) --Cut parts using jigsaw or bandsaw (most of my parts have simple curved outlines, so cutting them is relatively easy) --Disk-sand edges to clean up irregularities --Assemble parts, weld, etc. . . . In the past, I have paid to have pieces laser- or plasma-cut, but the economics are not great for one-off parts, so I switched to the above method. It has worked well, but now, I would like reduce the number of steps. I have considered buying a 5’x10’ CNC plasma-cutter (or router), but I don’t want to tie up that much floor space for a tool that I may only use a few hours per month (and they are expensive, . . . and the learning curve . . . .). A large-format plotter, like Acro, would speed up my process and I could hoist it up to the ceiling when not in use. My questions: 1. Is it feasible to make a custom 2040 Acro as a pen plotter, or would the 4 meter rails be problematic? I am assuming that I could add a center support to the inside face of each long rail. I would mount the whole unit to a stiff aluminum frame/table. 2. Is there a different approach that I should consider for my described use? For context: I have limited CNC experience, but I have a 3D printer that I assembled from a kit and I have used it enough that I have occasionally made modifications to g-code. I have reviewed videos about assembling an Acro machine and it looks straightforward. Thanks
You've solved one of the two largest problems. The other would be belt sag over the 4m distance as the belt hangs below the bottom side of the extrusion. You may need to redesign the plates to put the motor on the top side to where the belt lays inside the channel. Wire length may be an issue but that's really not my area to comment on.
I can see it leading to accuracy issues. Would be fairly minor so depending on the required level of accuracy this may not be an issue. Additionally, some of this accuracy error could possibly be removed through calibration.
Accuracy will be important in my intended use. If I mark, then cut out a part with a 3-meter edge, it will need to match another 3m edge in assembly. If one is a few millimeters shorter than the other, or if they are both too short or too long, I could run into problems with cumulative errors. I have wondered if a belt-driven machine might not be a good choice for large-format marking. If I just need to calibrate occasionally, that should be OK. Is belt stretch likely to be an ongoing problem with a 4-meter belt?
They’ve been redoing the menu structure so it’s probably an oversight. Easily found though with the search bar. OpenBuilds ACRO System As for your earlier question, the potential error is likely under a millimeter but it’s hard to say as you’re getting into uncharted territory.
Thanks Rick 2.0. As far as the "uncharted territory" is concerned, will I have any problems getting the controller to recognize the double-length Y-axis, or will that be taken care of in the set-up process? Also, FWIW, on the issue of rigidity, I am thinking that I will attach a 4"x1/8" aluminum bar (or angle) to the inside of each long rail. That should add considerable rigidity without too much additional weight.
Honestly, just an angle bracket support at midspan on the inside face of the long rails will do the trick. As for the controller, you can easily input the new limits.
I didn't explain my thinking about the reinforcement very well. I would like to NOT mount the unit to a table, so that it will be easy to raise to the ceiling for storage. I'll place the material-to-be-marked on the floor, lower the Acro frame to surround the material, make the marks, then raise the Acro frame. I'm thinking the long reinforcement will help for that approach (perhaps overkill?), but I understand that angle brackets would provide a lot of stability at very little cost for a permanently mounted arrangement.