3D printer & CNC design

Hello everyone. I'm new at "DIY 3D printer" stuff and I would like to ask you a question about what design it should have. I want to build a 3D printer/CNC combo machine but that damn design is a problem here. First I taught that I should make something like a regular 3D printer ( the printing head moving on 2 axis and the bed on third) but an issue appeared..... is it ok to bring 1kg of wood or aluminium that high? (I want to build something quite big). After few research I've found this: https://www.youtube.com/watch?v=Dt7uyuZ4DJA . The problem with this design is the fact that it double the space required with at lest the printing height and I don't even know if the NEMA 17 motors that I have can handle the weight of the CNC drill.

Can anyone give me some ideas ? But please, don't say something like build 2 different machines because this is not an option

well there are quite a lot of different multi use printers out there for you to look at for design inspiration.

The main issue you face is how large a drill/motor you want to use for the cnc side of things.
Weight on the bed isn't as big an issue as you think. If you havea double z screw design with 2 guide rods at each end and maybe one at each side as well. Then the bed will stay stable with an awful lot of weight on it.
Also you'll be using 2 steppers in parallel, which doubles the lifting capacity.

Most multi use machines use a very small cnc head - often an adapted dremel type rotary tool.

Looking at the video - no reason you couldn't stick an extruder and hot end on that machine.

It kind of depends on which side you want the emphasis to be on: cnc or 3d printing.

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Originally Posted by curious aardvark

well there are quite a lot of different multi use printers out there for you to look at for design inspiration.

The main issue you face is how large a drill/motor you want to use for the cnc side of things.
Weight on the bed isn't as big an issue as you think. If you havea double z screw design with 2 guide rods at each end and maybe one at each side as well. Then the bed will stay stable with an awful lot of weight on it.
Also you'll be using 2 steppers in parallel, which doubles the lifting capacity.

Most multi use machines use a very small cnc head - often an adapted dremel type rotary tool.

Looking at the video - no reason you couldn't stick an extruder and hot end on that machine.

It kind of depends on which side you want the emphasis to be on: cnc or 3d printing.

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Yeah, that is a good idea and I thing I'll go for it.

Thanks for your reply :)

If going for lightweight cnc, then all you need to worry about is a dremel type mount.
Adding a laser engraver is also a good idea.

These bastard machines tend to give you the worst of both worlds. You get a flimsy, underpowered CNC router that can't handle much more than foam, and a slow clunky printer. Dremel tools don't make good CNC spindles; the plastic housings deform after about a half-hour of use and then they die. NEMA 17 motors are fine for printing, but too weak for more than the lightest carving work. I'd say start with a printer, and once you're confident of your DIY skills, attempt a dedicated CNC machine that's as rigid as you can make it, with a decent spindle.

Andrew Werby
computersculpture.com

While i know you said you didnt want people saying stuff like the above, he has a point. Cnc machines and 3d printers have totally different needs and opposing design philosophies. For a 3d printer you usually want fairly quick speeds, this means a light as possible gantry that only needs to resist forces from accelerations. Cnc cutters on the other hand want a rock solid (read:heavy) gantry that can resist cutting forces. The speed of your motion system is not a limiting factor.

At best you get a printer that doubles as a light duty mill that will do wood and maybe aluminium if you go super slow. Or a cnc that doubles as a slow printer. Dont get me wrong, id love a good two in one machine, but it wont be the best of both worlds.

If i were to make thr machine, i'd go for a replicator, ultimaker, corexy or other similar 'cube' form factor. Steer clear of prusa style gantries as the cutting forces when cutting in the y direction will do horrors to the vertical part of the frame with the torques they'll exert on it. Build it out of aluminium as a compromise between weight and rigidity, and use nema 23 where possible. And don't cantilever the bed.

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Originally Posted by awerby

These bastard machines tend to give you the worst of both worlds. You get a flimsy, underpowered CNC router that can't handle much more than foam, and a slow clunky printer. Dremel tools don't make good CNC spindles; the plastic housings deform after about a half-hour of use and then they die. NEMA 17 motors are fine for printing, but too weak for more than the lightest carving work. I'd say start with a printer, and once you're confident of your DIY skills, attempt a dedicated CNC machine that's as rigid as you can make it, with a decent spindle.

Andrew Werby
computersculpture.com

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I got your point and I must say you are right. I've made some research and I have found that is not a very good idea but I taught that it could do some lite work (only few mm in wood) but I think that the TRAKYAN's idea with the laser engraving is better than cnc.
P.S. Even I said I didn't wanted to hear this, this reply has an explanation so it's welcomed :)

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Originally Posted by Trakyan

While i know you said you didnt want people saying stuff like the above, he has a point. Cnc machines and 3d printers have totally different needs and opposing design philosophies. For a 3d printer you usually want fairly quick speeds, this means a light as possible gantry that only needs to resist forces from accelerations. Cnc cutters on the other hand want a rock solid (read:heavy) gantry that can resist cutting forces. The speed of your motion system is not a limiting factor.

At best you get a printer that doubles as a light duty mill that will do wood and maybe aluminium if you go super slow. Or a cnc that doubles as a slow printer. Dont get me wrong, id love a good two in one machine, but it wont be the best of both worlds.

If i were to make thr machine, i'd go for a replicator, ultimaker, corexy or other similar 'cube' form factor. Steer clear of prusa style gantries as the cutting forces when cutting in the y direction will do horrors to the vertical part of the frame with the torques they'll exert on it. Build it out of aluminium as a compromise between weight and rigidity, and use nema 23 where possible. And don't cantilever the bed.

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Be sure that I didn't wanted to make something like prusa. I don't like the their performance even at 3D printing mostly because that bed...... But I think that I'll go for laser engraving ( it was something like a backup option. until now) as you said :)

Thanks for reply

Or you could just buy one like this... or if you must DIY build maybe use this as a template.

https://www.amazon.com/BIBO-Extruder...+printer&psc=1

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Originally Posted by KrYpTOCiD

Be sure that I didn't wanted to make something like prusa. I don't like the their performance even at 3D printing mostly because that bed...... But I think that I'll go for laser engraving ( it was something like a backup option. until now) as you said :)

Thanks for reply

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The laser was CAs idea, so I can't take credit. But now that you've mentiomed you only want to work with a few mm thick wood, I would say something like a 5w diodr laser mounted instead of an extruder would be your best bet as laser cutting and 3d print both dont need to endure cutting forces, and would work fine on the same machine. Be sure to enclose the printer though to protect yourself from the laser, it's dangerous and its an invisible threat if it reflects off something.

Also make sure that you have something laser proof under whatever you are cutting.
Printing surfaces are not usually laser proof.

And don't forget the smoke :-) Some kind of extraction hood and exhaust to outside is a good idea, and easy to do. You could get away with something as simple as a computer case fan and an expanding tumble dryer tube.

The only things I've engraved are very small peices of leather and woodfill filament. Fortunately i like the smell of burning leather and i don't think the filament gave off any noticeable smoke.

That was with just a 1000mw laser though.

Commercial laser systems are totally enclosed and shielded. If yours isn't, you had better be extremely careful not to let the laser hit anything shiny. A stray reflection can easily blind you.

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Originally Posted by awerby

Commercial laser systems are totally enclosed and shielded. If yours isn't, you had better be extremely careful not to let the laser hit anything shiny. A stray reflection can easily blind you.

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The most important piece of advice for the machine itself. CA's point about fume extraction is also very important for the actual use of the machine. I'll admit it's not so bad with wood and leather, but vinyl, acrylic and PVC which I've seen people cut on these self made machines will put out something real nasty when hit by the laser. All three of those (and more) contain chlorine, so when they burn (which is what engraving or cutting with a laser does, it burns through the material), they create chlorine gas. That stuff is nasty, I'll leave it at that.

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Originally Posted by curious aardvark

Also make sure that you have something laser proof under whatever you are cutting.
Printing surfaces are not usually laser proof.

And don't forget the smoke :-) Some kind of extraction hood and exhaust to outside is a good idea, and easy to do. You could get away with something as simple as a computer case fan and an expanding tumble dryer tube.

The only things I've engraved are very small peices of leather and woodfill filament. Fortunately i like the smell of burning leather and i don't think the filament gave off any noticeable smoke.

That was with just a 1000mw laser though.

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Can you tell me what depth and speed were you cutting?
And thank you for laser proof tip :)

Has anyone here made their own cnc? Our makerspace made a cheap (<$100 with stuff lying around) cartesian that is... ok.

Not yet, but I am planning to. Mine will be low cost, no more than a couple hundred dollars and 1-0.5m square cutting area. How big was the CNC at your makerspace? I don't imagine it could be too big for <$100.

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Originally Posted by emwest

Has anyone here made their own cnc? Our makerspace made a cheap (<$100 with stuff lying around) cartesian that is... ok.

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If it worked at all, that's quite an accomplishment for that budget. You can expect to pay a lot more for the parts of a half-decent CNC router, if you don't have a lot of the required components lying around. Depending on size, figure $1000 - $4000 for a medium-duty machine, paying yourself nothing for your labor. For more help and inspiration on DIY CNC, check out CNCzone.com .

I think you can do cheaper than 1k on a self sourced machine. Chinese machines with aluminium profiles and leadscrews can be found for 200-600 in various sizes. You could build something like the xcarve for a few hundred dollars worth of import parts. Granted, quality wont be amazing and you wont be milling steel, but woods and aluminium (slowly) are doable.

I wrote a big long post with responses to a number of quotes but then realized that it was overkill.

We really don't know what it is you want to cut with the CNC router part of this.

You could do some very nice wood carvings at a very slow speed with a hybrid machine, but forget about aluminum.

If you could give some more details and perhaps some pics of the cad files of what you want to make and what you want to cut exactly, the advice would be more relevant.

Trakyan, you are overly optomistic. Also, when you bump up to a router, things cost alot more. The speed of a filament printer is slow compared to a proper CNC router and very very slow compared to a commercial laser. IMO, filament printers are not made as spartan as they are in order to increase speed, they are made this way to reduce cost, and because beefier components aren't necessary to achieve the goals.

Unless you are talking about an XY area that is very large, I don't see an advantage in combining the two machines, and I think you would be better off to keep them separate.

Check out the MPCNC (mostly printed CNC).
It has been through a few revisions and is very capable and totally DIY so you can customize. The tool holder uses a mount that you can put a print head of any size, a laser, or like on mine a dewalt cutter for spindle that can cut wood, plastic, metal. It uses RAMPS boards for control and a modified marlin firmware so that all the printing functions can remain intact.

I used stepper motors from a previous 3d printer and the ramps board, I only had to buy pipe, belts, dewalt dw660, bolts and nuts and then print the parts.
The site has a full parts list down to the bolts.
Check it out on www.vicious1.com

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Originally Posted by Don McLean

I wrote a big long post with responses to a number of quotes but then realized that it was overkill.

We really don't know what it is you want to cut with the CNC router part of this.

You could do some very nice wood carvings at a very slow speed with a hybrid machine, but forget about aluminum.

If you could give some more details and perhaps some pics of the cad files of what you want to make and what you want to cut exactly, the advice would be more relevant.

Trakyan, you are overly optomistic. Also, when you bump up to a router, things cost alot more. The speed of a filament printer is slow compared to a proper CNC router and very very slow compared to a commercial laser. IMO, filament printers are not made as spartan as they are in order to increase speed, they are made this way to reduce cost, and because beefier components aren't necessary to achieve the goals.

Unless you are talking about an XY area that is very large, I don't see an advantage in combining the two machines, and I think you would be better off to keep them separate.

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People can and have milled aluminium with converted 3d printers. I'm not saying it was ideal, I'm just saying it's doable. Check out thomas sanlader's video where he converted his mendelmax to a cnc. The "router" was the bit that gave out in the end, since he was using a rotary tool not proper router. That being said, you can do better than a mendel style frame for milling. And I don't know what sort of desktop routers you're thinking of that have higher travel speeds than 3d printers, they usually go a fair bit slower as they have to cut through material as they move, 3d printers don't face any noticeable resistance when they move. That aside, a lot of them are powered by lead screws of some sort (acme, ballscrew) which limits their speed compared to belts.