- July 1, 2016 at 1:07 am #14215
Hi everybody, just a new post to share to the community an idea for big projects. My real work don’t let me time to do that (i don’t build the new Z tower yet, really frustrating), so i say it there, maybe somebody could want to do this or discuss about :
Imagine a moving surface at the bottom of the machine -actually static – (on Y axis for example, but it could be X axis if you prefer) with a second ramps and 2 parallel motors (or using the extruder stepper maybe not to have to put a second arduino-ramps to save money).
You are still limited by the width of your mpcnc but you can have the lengh you want on axis Y, depending of the space you have in front and back of your machine.
You put 2 bars on left and right along Y axis, inside the foots (like aluminium angle), perfectly parallels, and for example 3 x Y lengh (or whatever you want-can). So you have bar going out the mpcnc in front and back (exactly the same distance). Along them there are bearings. You can also add bearings on a third bar in the middle just in case, depending the thickness, the width and rigidity of your flat surface. You cut your surface exactly to the width between left and right bar and put it on the bearings (of course the middle bar is under the surface). The two new motors are near the front foots (under actual Y tubes) on each side, with gum wheels or something like that. They are upper the moving surface and can move it on Y axis. Near the back foot you can put two wheels to keep the surface compressed between them and the bearings which are under. So if your surface is 3 times your Y lengh, you can double your Y working area. If you have space for 5 x Y lengh, you can triple, ……
In your softwares you divide your project (illustrator and estlcam for me) in parts equivalent to your usual working surface. You engrave (or whatever) the first, after you ask to the two new motors to move X steps (with an accurate calculation) equivalent to your working area Y lengh. Now your surface moves to its new position and you can engrave the second part.
It is like a kind of plotter. For paper it could be easier because no need space and bearings. You keep left and right parallel bars but they only need to have your Y lengh. You put a roll of paper on the back of the mpcnc (parallel again, with a tube and two bearings) and your 2 new motors on the front (outside the mpcnc this time) with a tube between them (to roll up paper with adhesive tape at the beginning). You also need to have two bar at the back and front on X axis over the paper to keep it flat on your surface and also a blocking system somewhere to be sure the paper will not move.
So you can have drawing or cutting project (on paper) only limited by the width of your machine 🙂
Note : for drawing and cutting perfectly i actually use a leveled bed of glass of 450mm x 500mm and 5mm thickness, it works great. I have a bigger on (900mm x 600mm) not tested but i know i need 6 point for leveling this one (thickess 5mm is not good for this size, 8mm could be better). It could be added easily to the new system under left and right bars.
It is shared with my beautiful english from France, let me know what you think (sorry no time to do a 3d simulation, I expect i’m understandable), and if somebody have time to do that, i’m really curious to see if it work 🙂July 1, 2016 at 3:16 am #14217
The biggest problem with this is moving the weight of the table. The table is going to have to be built out of some really beefy whatever to keep it flat. Then you’re going to have to have something equally beefy under that to hold your bearings and whatnots that move the table. So now that you’ve got this big beefy table built, you may as well build a standard gantry style cnc router.July 1, 2016 at 3:41 am #14219
@Barry Yes for sure it could be heavy and must have beefy supports. It needs to be supported on a biggest table obviously. I’ll look closest gantry cnc, but the idea is to update mpcnc without many money and without changing your habits on it. It is about just having more options like a “big plug” in this case on a standard mpcnc.July 11, 2016 at 8:19 am #14727
A simpler solution might be to just do one section of cutting, and manually move the workpiece after cutting the first area. If you have a fence (edge) that is perfectly aligned with one of the cutting axes, you can just make sure to fit snug against that edge when you move, and then it’s just a matter of moving the exact distance your gcode expects.
You could make some holes with the CNC to align the fence with the axis, and depending on the workpiece, drill some holes in a scrap area and insert a dowel to register the other axis.July 12, 2016 at 2:03 am #14757
Yes of course this is the idea but an “automatic” version 🙂 I like the idea of holes, but not possible for some projects. I think first of all i’ll try like this, and if it is a good way (i’m sure it is), i could put motors tu gain accuarcy
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