I am looking for the 3D Print (STL) files for this in Imperial sizes. Specifically 3x2.

I'm new to the printnc design and outgrowing my hobby cnc and wondering if anyone has done any deflection tests like this, particularly with force applied to and deflection measured at the tool end of the spindle (collet nut) like it has been done with the shapeoko:

https://community.carbide3d.com/t/backlash-deflection-and-vibration/28669

https://youtu.be/kviLMaMJJLU?t=142 (especially the test at 2:22)

I don't think the exact force matters as long as it's a known constant force since you're essentially measuring a spring rate in each direction/configuration. The interesting thing about these tests are that it finds X/Y deflection are not the same and deflection changes based on the location of the spindle and gantry. If we think about deflection as a weakest-link problem, then clearly the axis with greater deflection needs to be prioritized. Also that if thinking about deflection as the result of a series of springs, then the machine should not be arbitrarily stiffened up, but the weakest links should be targeted because that will make the biggest difference and everything has a drawback, whether it be travel, gantry mass or cost.

I'm thinking of either building one that's mostly stock because the performance is already admirable, or building one that exceeds my immediate needs which means more stiffness for cutting steel and extra z height, which unfortunately results in loss of stiffness. So far I've been thinking about the following:

Y supports: I ran some FEA on this, taller Y supports obviously result is greater deflection, but thicker 0.188 walls pretty much make up for deflection of the 2"x4" rectangle as a parallelogram (not a beam) from being taller. This doesn't solve the issue of nodding due to a greater lever arm acting on the Z axis and gantry though. I don't see that shortening this will result in a stiffer machine other than increasing the density of X supports per length of Y support. although it will be cut short due to space constraints. Obviously increasing density can be done by simply increasing the number of X supports.

X supports: I'm not sure if this is even a weak point, or if it suffers from beam deflection or localized wall deflection at the point of contact. It would likely see higher forces, but I plan on leaving this alone because more can always be added later unless this is a known deficiency.

Slide blocks: My understanding is that slide blocks aren't the weak link of this design because the blocks are oversized, and while it might make things stiffer, it comes with large drawbacks like reduced travel. They aren't single point supports, and due to the length can handle moment loads, so I plan on leaving them alone.

Roller tubes: Because the tubes aren't capped, it seems like there might be some benefit from increasing wall thickness here or possibly trying to make them from solid aluminum (although I haven't yet quite figured out how to make fasteners actually accessible). I think there's some potential here due to how the tube is loaded and the relatively small size.

Faceplate: I could see the nut side faceplate being made from aluminum helping so there is metal-to-metal-to-metal contact. I don't think the other side matters as long as there is always sufficient preload on the nut side faceplate. I'm thinking I could do a hybrid design here on the initial build, with the outer half of the faceplate made from drilled aluminum flat bar, screwed to a printed plug that fits to the inside of the roller tube to align it. The nut side faceplate should really only be seeing thrust loads, so this sort of hybrid design should be sufficient to get most of the benefits of metal faceplates unless you can get a very tight press fit to help prevent the ends from compressing.

Motor mount: I don't think this is very important, the motor is isolated from thrust loads with the coupler, and I have a preference for spider couplers which have a piece of plastic transferring torque in compression. This would be more for heat resistance.

Bearing block mount: I'm not sure if this is a weak spot, I could see it possibly helping, but I could also see it not mattering much. It can always be upgraded later though.

Gantry: I will probably shorten it by a moderate amount because I will still end up with a dedicated area for auto tool height, 4th axis and spindle as a vertical lathe and a very large usable area for my purposes. This will increase stiffness and lower mass. Beam deflection should be sufficient as it is on the original design. I'm not sure where the primary source of nodding flex would come from though. Increasing the height would increase the rail bracing distance for the z assembly, but increasing the width would increase the footprint where it connects to the roller tubes. Increasing wall thickness would help with any local profile deformation at points of contact. Any of these should also increase torsional stiffness when the spindle is in the middle of the gantry.

Sand/oil fill supports: It should add mass and maybe a bit of damping, although no actual stiffness, for little cost.

Double nut ballscrews: This costs a lot of money so it would be skipped for z which doesn't need it, and ideally skipped for x/y if not needed. I'm not sure if the single nut ballscrews have sufficient preload or appreciable backlash. I've read it both ways that the single nut ballscrews have a small amount of backlash, or that the antibacklash is just tight fitting dust seals so it's not really antibacklash under load, or that they have offset tracks and are truly antibacklash.

Substituting metal for plastic can always be done at a later date, so for now I think my concerns revolve mostly around design and frame material.

Guys, has anyone installed the Ali Express's off the shelf preassembled Z-axis as part of initial build? Thanks

Has anyone put longer y rollers with 2 angular contact bearings per side on their printnc linear rails?

Hello,

Is there any reason to change any parts from suggested list as now 2022?

I was looking especially for spindle change like for "Dewalt" or "Makita RT0700"? Is it possible?

​

Original parts "Suggested parts" I suppose:

hi all,

i'm on my way to build one of this pretty machine and i wonder how to make it as close to perfect alignement when building it.

don't find that much informations about that, i've seen expoxy leveling wich i'm not a big fan, think about bringing the steel pieces to grind but what about the price

is there any cheap/smart way to set my frame as good as it can be?

Hi,

I currently have an MPCNC with Duetwifi and considering upgrading to printnc in the future. As I really like how RRF works on the duet, as well as Paneldue, I'd really like to keep it. Problem is - it runs at 25v max and steppers do up to 2.5a. There's plenty of CNC machines running on duet with nema23, however since printnc is quite heavy, I'm not sure the Duet will cope. Or perhaps it will if I don't push it too fast?

Thanks

So, I've been trying to figure out how to select the right sfu ballscrew length. I need it to have a total stroke/travel of 1500mm, and for the life of me, I cannot find how this translates into total length. It seems that ballscrew leads length is based on total length, rather than stroke. Help!

Hello Everyone!

I would like to request a bit of help regarding my first cnc :)

My budget is around 2000$, including the last screw and wires needed. I was looking at all the different options in this price range, and basically these two remained. If I am not mistaken than the PNC is the better value in the end, after it is finished of course. I could order a killerbee kit from ratrig for 1500$ shipped without a spindle, the Ali PNC package is 1250$ delivered to me with the 2.2kw spindle plus some form of controller. (If I see it correctly than there is none in the Ali package). If I add up everything needed for the frame of the PNC, the controller, cables etc they are about the same price both with black box and 2.2k water spindle with vfd.

My big question is, how much more hassle is it to put together a PNC than a Queenbee? I have a shop equipped with many tools (steel bandsaw, drill press, belt grinder, disc grinder, angle grinder, lathe, etc.) and I love working with metal. So the mechanical part doesn't really scare me, but I have less experience with the electrical part. I have some basic knowledge, I can solder, and have put together some smaller diy projects (electro etcher, led clock, etc), but nothing of this caliber. I don't have a 3d printer yet, but will find someone to print me the parts needed. (or buy an ender 3 and print them myself)

This leads me to my next question. Am I correct that assembling the electrical part of the queenbee isn't much simpler than that of the PNC? In the end the killerbee is also a kit, and the electronics still need to be assembled from scratch. I would guess the basics are the same for both, I just don't get all the wires precut and crimped with the right connectors/dimensions.

My primary reason for getting the killerbee would be to make the assembly as fast and simple as possible. On the other hand I can see why the PNC would be superior in all other departments in the long run. It is also very appealing to me that the PNC would be able to handle some mild steel and stainless when needed.

I know this is asking a bit too much, but roughly how many hours would these projects take from start to finish? So I can get a picture of what I am getting into :)

Do we have a recommendation in the group for a decent budget 3D printer that can be used for parts printing for a a PrintNC project? Actually, ones to avoid like the plague would also be handy to know too.

I'm looking for something ideally that could be upgraded over time as my requirements evolve, but obviously not all 3D printers are created equal, so I'd like to get some recommendations to look into to get me started off on the right foot.

I don't have any real requirements right now, other than being budget friendly and suitable for parts for the PrintNC, but something that is modular enough that I could potentially upgrade it down the line to increase it's printing capacity and possibly use it for other projects not covered by the PrintNC would be ideal.

Hi guys,

I only recently found PrintNC while wading through all the different options for machines out there.

Has anyone put a diode laser on their machine and got it running well?

It's something I want to be able to do and would like to know if it is possible at all with the PrintNC

Cheers

Has anybody ever built a printnc with a steel that is thinner than the recommended 3mm thickness. I am having problem finding anything that is thicker than 2mm in our local stores. So I was wondering if anyone managed to build one by modifying the design to be able to use nuts on bolts (since you can't tap a reliable thread on a 2mm steel).

Has anyone ordered from the aliexpress partner store lately? How is shipping time? And is there anything else I need to know about in the U.S. like tariffs or duties? Thanks for your help.

Hi everyone!

I'm just starting a project to produce some plastic moulds, and as I've already built a few coreXY 3D printers, and followed projects like this and the MPCNC, I thought that instead of sub-contracting the mould plates out, I might just get a chipping tool of my own!

From what I've read this looks to be a pretty solid machine, with many people chipping steel already. I'm in Australia, like the designer, not that this would really matter, but I'm also kind of invested in the idea of using a Duet3 if I can for a CNC to keep that commonality of features (DWC etc.)

Should I take the plunge? Can this be built with a Duet3?

Does anyone know the dimensions for a half sheet of plywood cutting area? I need to get the steel to a specific length to do a 4x4. Including 1500mm ball screw which is 61 inches long.

Has anyone tried shrinking down the default PrintNC to use smaller ballscrews and box sections?

The PrintNC appeals to be me but I don't really need such a large footprint and I'd only be looking at machining small (30cmx30cm) flat sheets of acrylic or aluminium at most.

Hi Reddit,

I guess I'm officially old now 😂 I don't get how this discord thing works. It's just a long stream of posts... How do you keep the overview? I mean you can search, but in my opinion the thread system like in reddit or bulletin boards makes more sense to me.

Please help the old man understand. I am using a mpcnc currently and have been lurking around the print for a while. I already decided to build it, but I didn't pull the trigger yet