What is the size of the up/down axis on the cnc machine? Is it like the others in that you can expand it?
Recommended max is 4". It starts getting too floppy much higher.
floppy? In what way?
That is a compound axis meaning it’s length has a more significant effect on rigidity. Something like 1/2 the length is 4X more rigid. 2.5-3" is good, I usually do 2.5" now. If you need more room make a table that allows for thicker material, do not make a taller machine.
is 2.5" a cutting depth or just how tall it can go up? is the max cut distance 4" before it gets wobbly, or just how tall it can go up, would putting the machine on higher feet let it cut deeper?
How about you try it this way. Find the endmills you want to use and link them and we will tell you how tall you need to make it. Or describe some of the projects you want to do and we can guide you. Asking for hard numbers will not get you an answer. It is not as simple as 3.9" works, and 4" is a no go.
The have been built up to 3’ tall but that does not mean you should.
I don’t have anything specific in mind really, i just want to be sure that if i get a cnc machine, that it will be large enough for anything i do. The things i was thinking of would be things like gears, micro fluidics (in which you would need a fine bit to do the small water paths), and shorter things, but i also wanted taller things, maybe like topography models of mountains, or smallish parts like wheels or projects on thingiverse. Things taller than 4 inches tall.
Unfortunately that is not a good thing to do. Build it small like the instructions say, learn it only go bigger if you need it. You will see why it says 2.5" is excessive. typical 1/8" bits are 3/4" DOC, so you only really need 1.5" Z.
Make your table adjustable, no the machine.
What do you mean make the table adjustable? how would that increase how tall you can cnc things?
Not to hijack, but the cut calc says min Z is 2.87 inches. Understanding this is third party but are you saying it can go smaller?
Does the loss in rigidity come from taller legs or from extending the tool down lower when its mounted high, or both?
I’m trying to make one as compact as possible. My legs will be mounted flush on a piece of plywood but a 0.75" piece of spoil board (MFD) will be mounted to the plywood as well. Max height of parts I plan on making is 1.25". So I’m at 2" Z + tool length?
Extending farther down has a larger effect than the length of the legs. You can prop up the workpiece but it is usually recommended to build it shorter to start with and cut a hole in the table.
1 Like
ohhhh i see now, thanks a lot
This table is what he means. You can drop the table down in a couple inch increments.
so 4 In. is how tall the legs can be, but the tool head can go down further than that?
I think what he means is that the end mills aren’t going to cut deeper than an inch or two depending on the length of the end mill, but if you want to carve thicker pieces, having the work table section, the part where the work is mounted, adjustable so you can lower the table in the middle and fit thicker pieces under the router and bit, the length of the z axis will still be 4 inches (or less) but since you can drop the work surface area, you can fit thicker material under the mill head.
Ultimately, you will only be able to carve down a couple of inches max, the question is how much travel down do you actually need and where can you add additional depth for the work piece that doesn’t affect the z axis height to maintain rigidity.
Hope that was clear.
1 Like
If i wanted to build it at 4 In. would i have to do anything different?
Nope. I think mine is right around 4 inches. I’ve run my z axis tubes into a carving because I didn’t take them into account. You can only carve as deep as your endmill is long. I have around 8 inches of travel total, but only move 2 or 3 inches for anything.
so ultimately you can only cut out 4 inch tall objects? (3d objects like say, a half sphere)
Less than that. A normal bit just over 3/4" bit. A long one is 1.5". You could cut something like a wedge deeper using one of those buts, but you can’t pocket that deep. The collet and the router will hit the sides. How far down can a pattern or follower bit go? Those are available in up to 1/2" shank sizes too. This is going to be much more shallow.
What are your goals? If you’re expecting to carve deeper than a couple of inches, you may need to rethink your process or your tool. If you really need something that thick it may be worth stacking shallow cuts, ie, cut 1/4 inch thick “slices” of your contours and stack and glue (at least for wood) them together to get the shape you want.
Again, this all depends on what you want and what you’re doing.
1 Like