[Patrick2by4]

What is 2.5 d work? I have been assuming that this is relief work where the a multi layered object is cut out sort of like a picture or carved drawing, but laying flat. Am I correct?

2d would be sort of like fret work or cutting out parts that are one thickness and the item being cut is also laying flat.

True 3d work would be like a statue, where the item is being cut upright or suspended in a 4th axis. I guess the object could also be standing upright and cut with a 5 axis router.

[ger21]

I don't know the exact definition, but what you called 2D is 2.5D. When the cutter doesn't move up or down during the cut. Just go to the desired depth, and make a 2D cut. Make sense?

Any time your Z-axis is moving during the X and/or Y movements, it's 3D. You don't have to cut all the way around to be 3D.

[sol]

Yeah, 2.5D means that the Z axis has only 2 positions...cutting and not cutting.

[duluthboat]

A 2D CNC machine has 2 axis that are capable being numerically controlled simultaneously and one or more operated manually. A 3D CNC machine has 3 axis that are capable being numerically controlled simultaneously and maybe more operated manually. A 2 1/2D CNC machine has 3 axis that are capable being numerically controlled but is only able to move 2 axis simultaneously. (XY, XZ, YZ) Most 3D objects can be machined in 2 1/2 D it’s just not as efficient.

Gary

[sol]

And here-in lies the rub...a Google search will find each of these different definitions; different manufacturers will give different versions as will different software vendors....and lets not even get into what mathematicians have to say about it.
So what do we call a machine that has motors on X and Y and a two position solenoid on Z, all of which can be moved simultaneously?
In Gary's definition (in post 4) I need help understanding what is keeping the 2½ D machine from moving its axes simultaneously, software or hardware. In other words could more robust software turn a 2½ D machine into a 3D machine?
This is a sincere question, not nit-picky flame-bait.

[sol]

I just realized we are talking process and product versus machine here as well; so we may be talking past each other. By one definition a product would be called 2½D (a simple cut-out or lettered sign) and it could have been created on a 3D machine, a 2½D machine or even a 2D machine and there would be no way to tell what kind of machine was used. Likewise, given enough patience, a 2D or 2½ D machine could create a 3D product such as a statue or intaglio or cameo.

[Patrick2by4]

hmmm, I guess I have to readjust my thinking on the matter. Thanks for your help

[duluthboat]

Sol,

You won’t start any flame war asking good questions like yours. I spend most of my time here looking for answers. When I respond to a question I give my opinion and that is all it is unless I attach something to back myself up.

3D machining WAS mostly a hardware problem; the controllers were as big as the machines themselves. Today most of the restrictions are in the software, generating good 3D tool paths takes a lot of number crunching.

Patrick,

I have for 30 plus years made a living as a machinist, for me, 2 1/2D, 3D only describes the process used to machine a part. Before CNC that part might have been done mechanically or manually.

Gary

[ynneb]

From what I can understand from all the comments here is.

2D is cutting is for example cutting a sheet of material and the cutter is always been at the same level.

2.5D cutting is cutting the same sheet of material but been able to hop from one section of the material and start another cut.

3D cutting is the ability to do full or partial depth cuts anywhere on the sheet.

Is this correct?

[chuckknigh]

Precisely. If you've ever used a pen plotter, it's 2.5D. There's a pen up command, and a pen down command...and not much else. It either draws, or it doesn't.

WRT a router, it's the same thing. It either cuts, or it doesn't, with a 2.5D system.