Hello everyone, a buddy and i are wanting to build a large format CNC for 3d printing and needle cutting sheet material. i was thinking of buying a MPCNC kit to start and than finding a way to increase the z dimension by potentially having the entire machine climb.
i have a perfect table to use for this. its a steel rectangular cuboid made from 1"X2" 18 gauge steel tubing and its on casters. it has a 36" x 60" base and a 73"x36" hard wood top. it stands 3’ tall. my plan is to mount the machine underneath and use the structure of the table to reinforce the machine and maybe use some printed mounts to secure some conduit to the verticals.
after taking a second look at some pictures i think i might be able to adapt some of the existing z dimension parts and maybe but a lift screw on all four corners… doable?
I’m wondering if any of you see anything inherently wrong with this idea or if any hurtles jump out at any of you that I’m not thinking of. thanks in advance to any of you that take an interest in helping me figure this out.
so those are the dimensions for the table top. the actual foot print would be something more like 55 x 35 and it would be located under the table so that i can use the structure of the table (which amounts to a large rectangular steel cube) as support to stiffen up my machine and allow for the larger footprint. the actual working area is going to wind up being much closer to the recommended max for the mpcnc. potentially in the 30x40x30 range. its the “x30” at the end there that I’m going through all this trouble to achieve. which is why the lowrider, while considerably more practical for the 30x40 part, wont work for what I’m trying to do. though i will absolutely post videos of my failed contraption wobbling and jerking its way around should that be the outcome. and in the end if it fails ill still have a bunch of pieces and i can still build something functional.
my idea after having slept on it, is to use 4 sets of the pieces that make up the z axis to place a lead screw on all four corners. these masts would be secured at the top and bottom so I’m going to have to do something clever to make sure they’re aligned. they would be attached by belts to a single stepper motor this would all have to fit inside the mentioned 56x36 with a max height of 30" for the final footprint.
Way too big for an MPCNC style design. You would hate it.
Large format printers exist, and the designs for those are very different by necessity.
A large area needle cutter would be a good modification for a lowrider,
Lowrider is unsuitable for a 3D printer in general, but in particular for Z heights above about 80mm.
no im looking to print large scale and the area the machine needs to fit into has a maximum height of 30". the actual working space for the machine will be much smaller. if any cutting was to take place it would never be deeper than what you might expect from a standard build. just maybe done at different heights to the working deck. i.e. an 1/8" pass made 6" off the deck. the z axis that the tool would be mounted to would never go beyond standard range. most likely there would never be cutting done that high but id like to be able to print that large. my idea is that x and y axis would be mounted within a framework that could lift it to a given heigh so that you could effectively do any work within an area roughly 40x30x20. again those dimensions are rough guesses as id need to see how much space the additional axis would add to everything. as i said the original space allotted for the overall footprint is 56x36x30. some of that can be altered but the maximum machine height is a hard 30" max. i cant change that.
I am not sure I am completely following along here but just to be super clear we are all willing to help, but we also do not want you to be super bummed right off the bat. It really sounds like you might need two machines here.
Can you be more specific about what you are trying to make so maybe we can help better.
You are trying to print large things and separately might do some cutting?
do you have any suggestions on where i might start if i wanted to build something that could do work on that large a scale? i was hoping to use v1e parts for this project because of the ease of access to technical support and replacement pieces.
However if what I have in my mind right now is correct you don’t need a larger machine, you need a drop section in your table. That way you can keep the machine as rigid as you can make it, but you’ll have a section of the table that will accept a larger piece. It doesn’t matter how tall the piece is, if you’re only machining the top inch of it.
The primo mpcnc is not (imo) a very rigid machine to start with. It works fine but it has it’s limits. The longer you make any axis the less pressure it takes to provide a large amount of torque, and any torque to the tool head give you at best angled cuts.
yeah sorry for the confusion. you are correct. i want to print large scale but id like the machine to be capable to performing other processes if possible.
i think @Nathan_Doty has exactly what im picturing in mind. my idea was, was to use the double shaft and lead screw design used for the z axis of the mpcnc and adapt it to mount on each corner in order to lift it from the deck. the rails would be secured to the to the legs of the table i have, so those would be as rigid as they could be. if the basic design of the mpcnc wont work well for what im trying to do. would you guys have an idea of where io should start to build a printer that could do what im looking for. id really like this machine to be able to perform more processes than just printing. im trying to draw something up right now so you guys have a basic visual of what im looking for.
Hit the search (top right) and look for ‘drop table’. There is a bunch of threads. I had a 3/4 removeable center to mine, far less than what you’re looking for so my stuff won’t do the job. I’m not too familiar with the rest of them but I know they’re there. The overall idea is to leave the machine alone and just move the work piece itself up and down so the machine can stay rigid. Once the machine itself starts moving you lose a lot of that and I think you would spend most of your time cussing and chasing problems that might not be solveable.
There is also (if memory serves) a guy on the lowrider side that did something so he could mill big ice blocks, it might serve your purpose as well.
thanks for the help guys i truly appreciate it. so maybe instead of moving my x y axis i could mount the machine high within the allotted space and build a deck that could slowly lower away from the tool. i know the picture i drew isn’t the most accurate thing on earth mostly because I’ve never actually put hands on any of these pieces but i tried to give an idea of what i meant about using some z axis parts on each corner. i think @Nathan_Doty is onto something though about moving the deck down though. i just need to be able to do it incrementally as part of the printing process because this machine would be primarily if not exclusively printing
Back in the 2015 time frame, I built several 3’ x 4’ and 4’ x 4’ MPCNC’s for needle cutting. The MPCNC had become my development platform of choice and I used it almost exclusively during years of needle cutter development in my long-running thread in the Flitetest forum.
I have no idea why I built them with such a tall Z-axis but my late RC flying buddy and I cut “miles” of fan-fold bluecor and DT foam sheets with them. We built and flew an entire fleet of “foamy” RC aircraft – demolition-derby style – in my pasture. What a blast!
MPCNC’s at that size are flimsy, of course, but can serve well as needle cutters, as the cutting forces are quite light. Later, when I started playing with lasers, I mounted them on the MPCNC as well. In spite of the limitations, you may find the MPCNC useful, where the tools and loading are light.
it will primarily be a 3d printer but i want to be able to attach a router or needle cutter. in those cases it would never be moving on the z axis beyond the normal amount you’d expect from a standard build. i think the point made earlier about lifting and lowering the work to the tool is going to be the way i go. in that case i could in theory use a lowrider with a track for the free end to ride on and just build a lift table with leadscrews to raise and lower the work surface. thank you @Dreyfus and @dkj4linux both of those threads are helpful and i appreciate the incouragment.
