Looking at building a CNC - What will this machine not do?

[pwatt01]

Hi all!

Being new to CNC there is a lot that i don't know so I was hoping to mine some of the amazing knowledge here. I am looking at making the machine in this link, but it seems a lot cheaper then other CNC routers that I have been reading about, so I was wondering what will be my limitations of using a design like this? I read about how stiffness is important, and squareness, but as I have no experience i don't know what to look for.

I plan to mainly work in wood, may put a laser on it for some acrylic or this mdf (and maybe even a 3d print head(??)) but as we all know plans can change quickly enough which is why i thought that if i could get told what it can't do, it will help me decide if it has enough flexibility. Also as I build are there thinks to look out for?

I was thinking on changing the z axis to a leadscrew, and upgrading the motors in x and y to NEMA 23s and eventually replacing the belts on x & y with leadscrews to help make it a bit more accurate/reduce the play in case you were wondering.

Thanks in advance for your help!

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[fretman_2]

Well...it looks a lot like the Shapeoko2 that I had and what it won't do is be rigid. There's an awful lot of flex in those aluminum extrusion, plastic V wheel systems. It'll be great for a laser, and if you keep your cutting loads light, it'll do ok with a spindle such as the one in the picture. If you intend to replace the belts with screws, you might as well build a new machine from scratch with low profile rails instead of the plastic Vwheels IMHO. I have seen the Vwheels break.

No need to replace the motors IMHO. I doubt they'll be the limiting factor. Your spindle power, and frame rigidity will.

[ger21]

It won't do what a more expensive machine will do. Well, maybe in some cases it will, but it will take a lot longer. It all comes down to if it's acceptable to you. It wouldn't be acceptable to most members here, by a long shot.

And when you start down the upgrade path, everytime you make one part better, it just exposes the next weakest link in the chain.

There's a reason that CNC machines can cost thousands of dollars. In most cases, you get exactly what you pay for.

When a decent 3D printer costs about $500, how well do you think a $300 router converted to do 3D printing will work? Not very well.

[wizard]

These machines are at best an educational toy. If looked at in that respect they are a bargain.

The question then becomes what are your expectations. I look a that machine and the only thing that comes to mind is that it wouldn't be able to do anything I would want to do with it as a router. You look at the size of the spindle motor on the machine and it becomes pretty clear that the capabilities are lacking. I'm not even sure it could handle my engraving needs.

If you want to build a machine you really should nail down what you expect it to do. For some it is the learning experience that counts. For others its is the need to do a specific thing. Others want a general purpose wood working machine. Nail down what you want and you can then fit a build to those requirements.