I am a newbie to builds (disclaimer). I want to build an X,Y,Z system that can be used not only for milling, but also as a 3D printer (by changing the head. I know that a milling/router system has to be rigid so I'm wondering what configuration will give me a good solid support for the router. I've seen some commercial small router/mills, and some have a moving base (Y axis) and others have a fixed base with a moving gantry. I'm wondering if there is general advice regarding the rigidity of these two configurations. They all seem to move the router z axis on a single rail which is mounted to a carriage on the gantry which moves in the X axis. In my design, I'm thinking about fixing the router on the Z axis rail, and moving the whole rail up and down, this way the rail won't interfere when 3D printing tall parts. For size, I'm thinking about using 500 mm rail which should give me around 13-14" travel after you subtract the carriage width. I'm also a bit concerned about the stability of the router when "dangling" from a 500mm rail. Not sure if C-Beam and V-wheels are rigid enough for this. Thanks in advance for any advice you can provide.
Normally I stray away from giving advice on dual purpose machines (other than don't do it) but as it sounds like you're going into this with a level head I'll offer a few suggestions. Based on where you're wanting to go with this the dual Z-axis concept with a moving bed is probably the way to go. While I'm not a big fan of moving beds, to get decent rigidity out of dual Z-axes they're going to need to be solidly fixed at the base. This just means having to design the instabilities out of the moving bed. For the dual Z-axes I would suggest a pair of 500mm C-Beam® Double Wide Gantry Actuator Bundle. The vertical length of the double wide gantry plates will reduce potential for X-axis roll due to the weight of the router. For the Y-axis I would suggest inverting the common logic and rather than having the gantry plate riding on the rails, have the rails riding on the gantry plate (ie. the gantry plate is affixed to the base and the rail is affixed to the spoil board). This eliminates the issue of the router pushing down on fore and aft cantilevers of the working surface. The bit will always be pushing down on a properly supported surface. For this I would suggest a 500mm pair of either C-Beam® XLarge Linear Actuator Bundle or C-Beam® Double Wide Gantry Actuator Bundle with the drive screw mounted between the two units. (Note, this will require a custom plate to mount the drive assembly but it'll be simple bar stock so it won't be the least bit difficult.) For the X-axis a 6 wheel version of C-Beam® XLarge Linear Actuator Bundle would be a good choice. Best suggestion going forward would be for you to work up a concept in Sketchup or other design software and post it for suggestions.
I can see this being possible, but routers are so dirty and you need "clean" for a 3D printer. You may be able to make a machine that can do both things, but will it do both things well? 3D printers move relatively fast and are light. You will be trying to throw a lot of mass around at high speeds, or you will be printing slow. However, I see nothing wrong with trying. If you do not get the results you want, you can always modify the parts into the machine you think they would work best with, and buy or build the other.
Randy, the question also is 'what are you planning to cut with the router?'. It makes a difference. If you are just going to make PCBs, for example, or light engraving, the router can be very small and therefore light. It will determine the needs for high rigidity as mentioned by Rick. I used a Brushless motor as spindle with great results. It's way lighter than a trim router. Also, the question of using a fixed or moving base may be a question of space. A moving base need more space than a fixed space for the same work area. 3d printers have a moving base since most non professional printers have a printing area of between 200mm to 230mm. Some have bigger but most not. This size make the printer compact and easy to store. Having a cutting area of 500mm will make the machine bigger than 1200mm where as a fixed base machine may only be 700mm on the same axis.
I was actually thinking I would interchange the "tool" (router or direct drive extruder) onto the Z axis rail, but that would be a lot of tinkering each time I wanted to switch between mill and 3D printer. A dual Z axis, with both tools installed permanently would be a much more efficient setup, and probably well worth the cost of the extra axis in the long run. I don't really understand this section (w/o a diagram). Y axis is front/back correct? This is the base axis in a setup with moving base. I don't understand description of "gantry plate". My thoughts are that the gantry plate is the plate that moves in the X axis direction along the length of the gantry, so I don't see how you could mount this plate to the base. I think what you're saying is that the gantry supports are mounted directly to the base (in which case this would be a moving base design). Can you clarify this section (please) thanks.
Though it through and basic concept attached. Was having difficulty achieving balance on the Y-axis with the inverted plates so took another approach, using outrigger wheels in line with the X-axis run. Anyway this is not my best work but should achieve what you seek. Around 13x13x8 for routing and 13x13x10 for printing. You won't succeed at routing anything hard at 8" up but should be okay with softer materials. Sketchup model attached. Forgot to put the 1/8" shim plates under the gantry plates but you'll see the gap in the model so just assume they should be there. Also in retrospect I'd probably put a stabilizing cross beam between the uprights near the top to add rigidity but then again I'd also probably try it first without one. Past my bedtime though so this is as far as I'm taking it. Gotta get up early in the morning.
This is interesting, and thank you for the picture,and the sketchup model. Yes, I've always wondered how rigid the base is when it's only riding on a single C-Beam. Why don't you (or people in general) attach wheels to the underside of the base which ride in the V-slots of the base? This would give maximum rigidity in that direction because the wheels would be far apart from each other. If you mounted the wheels on an adjustable height standoff, you could level the base with the wheels also. Then just move the base with a floating acme screw and anti-backlash nut. No center C-Beam required. Just the screw, nut and end supports. I like the triangular braces stabilizing the gantry vertical members. This is probably one of the biggest concerns for rigidity because of the long lever arm there. Overall I like this design, and will put together my own model of it. Thanks for the input. Greatly appreciated.
I took your model and tweaked it a bit. I'm running the base "outrigger" wheels directly in the base tracks. I removed the C-Beam from the center, using just a "floating" acme screw. I might decide to keep the C-Beam because it's not really that expensive and I'll need chunks of C-Beam at the ends anyway. I also rotated the C-Beams for the Z axis thinking if I can make my own plates, I can combine the Z axis plates and the gantry end plates into a single piece. I like this orientation better because it loads the z axis wheel bearings the way they are intended to be loaded. It would be nice if I could use the "double plate sandwich" assy on the gantry plate, but this would limit travel in the X direction (along the gantry) as the back-side plate would hit the Z-axis. But that could easily be solved by simply increasing the width of the whole machine (Base and Gantry X axis). If I oversized my base, I could mount the 3D printer extruder on the back-side gantry plate and have a dual purpose machine ready to do either task (router or 3D printer) without any setup.
is a bad idea, unless you're building your bed from very wide aluminum extrusion, maybe with some C-beam lateral supports. I don't recall seeing the dual-Z on a gantry router like a printer setup, but it could be an interesting experiment. Looks like an antique metal planer, which modern bridge mills came out of. Could be a pretty rigid setup, you'd just have to be careful about depths of cut and driving your gantry into workholding. Printing, of course, doesn't have those problems. And for the record, the general idea is to have as few axes in any given chain as possible; tolerances and flex stack, so having a separate X/Z and Y like this is slightly more mechanically ideal over the standard Y/X/Z single-chain gantry setup. It allows over-building of the columns to reduce Z/Y-induced rotation about their mounting points and maintains full support for plunges, just like a table/knee mill. Downside, as mentioned, is footprint- but increased rigidity always correlates with footprint, so that's something individual circumstances dictate.
OK, I'm realizing now that there are nearly infinite possibilities depending on how you join members etc. This is where I'm at right now. With a moving base, that is tracked on the outside rails, and the triangular reinforcements on the Z axes, and the cross brace above the gantry, i think this will be quite rigid. The only "weird" thing I'm doing here, is how the bed axis is attached to the frame at only one point. I did it this way to provide clearance for the bed wheel brackets which run on top and bottom of bed rails. I could add more bracing for bed C-Beam, but it would have to be below those wheel brackets. Another "tricky" aspect is having to attach the Z plates to the gantry end plates. Could potentially make both out of one custom plate, but I haven't actually seen any of these parts, so might not work because it looks like they are different thickness. Another issue is this gantry will be heavy, especially if I leave the router installed when 3D printing. All of these axes are acme screw. Wondering if I'll be hating that when printing due to slow axis movement. I see these actuators are "rated" at 8000 mm/min which is 133 mm/sec. I think that's quite fast for 3D printing, but not sure if they can do it with this heavy load.
You're most likely going to reducing the quality of the 3D prints by trying to sling around this much weight on the gantry. Typically, one of the goals of designing a good 3D printer, is to reduce the weight of the gantry as much as possible. With that much unnecessary weight on the gantry, you're either going to have a lot of quality issues, or you're going to have to slow speeds down so much that print time may be unacceptable.
What if I removed the router motor from the gantry cart when 3D printing. This would be similar to 3D printers on the market, except maybe that my structure is a bit heavier with C-Beam instead of 20mm x 40mm gantry rail. One contributor suggested that I would burn out my z-axis because 3D printing makes many Z-moves during a print. I have not worked with any 3D hardware or software yet, so wondering if Z axis moves up and down within a single print layer (for example when it stops printing, and moves to another spot in the same layer). My assumption was that Z axis stays fixed for the whole layer and printing is controlled by X,Y and filament feed. I'm thinking the nozzle shouldn't need to raise up to avoid dragging on previous layer. Thoughts? I could also mount the 3D extruders on the open side of the C-Beam and remove both the router motor and it's gantry plate/wheels when 3D printing to further reduce weight, but would then have to come up with a (quick) way to attach the router plate and motor since the current design uses screws that run all the way through both plates and both sets of wheels.
I would go nuts if I couldn't run a 15 minute task on my CNC router while my 3d printer is churning away on on a 2 to 10 hour print. A $200 Ender 3 or similar may cost you much less than the extra parts required to modify a CNC to make it also behave like a 3D printer.
Just picking up the commercial 3D printer is what I did. Ender 3 Pro, $230, done. DIY is fun, but there's a line. Unless you specifically need extremely large format 3D printing- direct-to-fabric, for instance, it's almost certainly not worth the hassle of trying to produce a multi-purpose machine. Even in that case, a lightweight maybe vertical machine would probably make more sense. Many people have tried to get the grail of a machine that actually does everything well, and other than combo routers/diode lasers for cutting and marking in one setup, it has just never worked.
