[csaw]

I hope this is the correct area for this. I am still struggling with the difference between 2.5 and 3d. There is quite a difference in price between the two softwares. I would like to see some pictures of complex 2.5d projects if you have any.

Most specifically I want to know about Dolphin Partmaster Pro.

Can hemisphere/dome or convex/dish machining be done with it?

Do all three axes move simultaneously?

Please excuse my ignorance, I have no experience with CNC at all, but want to.

Please don't forget pics!

Thanks

[M250cnc]

csaw

I know how you feel.

But 2.5D is a shape with a constant Z depth setting for the profile the only exception is when you may have a ramping motion set for the PLUNGE and then it runs X & Y at a constant Z depth

3D is any shape where all three axis may be moving at once

Then there will be a step up in price again for 4th axis and even more for 5th axis

Phil

[tobyaxis]

I can't help you with Dolphin but can make references to 2.5D and 3D.

CAD and CAM are different in the aspects of 2.5D and 3D.

This is a part created in a 2D CAD environment using various plains, 2D Geometry, with Solids.

This part will need a 3 Axis Mill to machine it.

[tobyaxis]

This one is 2.5D and has no need for 3 Axis Machining

[ger21]

This is a part created in a 2D CAD environment using various plains, 2D Geometry, with Solids.

That's not helping at all. A 2D CAD program can't do that part. It's created in a 3D CAD modeler. Help the guy, don't confuse him.

[tobyaxis]

That's not helping at all. A 2D CAD program can't do that part. It's created in a 3D CAD modeler. Help the guy, don't confuse him.

The second post is a 2.5D part. I separated the posts to avoid confusion.

You have a point with the software being used though. I might be able to find a BobCAD file that is 2D for a better example.

[Switcher]

Ok,

2.5D can be done on a 3 or 4-axis machine (X,Y,Z,A)

3D would be 5-axis or greater (A,C,X,Y,Z), rotary axis both depend on your machine (A,C-axis names).

It's really all about how you setup the part, you could cut a 3D part with 2.5D software, but when you go to index the part (by hand) you better have a good fixture on your machine to align everything.

I think your ?'s would be better answered If you post a photo of the part you want to cut.

[Switcher]

This one is 2.5D and has no need for 3 Axis Machining

How would you cut that part in your .pdf file with less than 3-axis?

[Switcher]

Vectric has a program called Cut3D, that you can use on a 3-axis machine to get very close to 3D.

Still it's not full 3D (undercuts, etc...), the program only supports 3-axis (X,Y,Z), I understand why they did this, much larger market of machines that are only 3-axis.

It's still great software.

[tobyaxis]

Here is a reference from the machinery's handbook on 2.5D vs 3D.

On the left is 3D and on the right 2.5D drawn in an isometric projection.

[tobyaxis]

How would you cut that part in your .pdf file with less than 3-axis?

The Reference 2.5D Machining means that you have X,Y, & Z but the Z Axis is only for Depth. A friend of mine has a Proto-Track VMC where the Z-Axis can only be used for depth, hence he can't not do anything requiring Full 3 Axis.

That shoulder harness was machined using a 2.5D method. There are no Z Feeds in the program, only Z depths

The differences of 2.5D and 3D can get confusing when asking about both CAD and CAM.

In CAD you can create a Square Box on a flat 2D plane. Place a Depth Dimension on that same box and machine it. Now you have a 3D Box or Cube.

No pun intended but your definition wasn't exactly great either, because it is difficult to explain to a person in words. Now if we were all in the same room next to a VMC we could do that in about 2 seconds and show great examples.

Like I said, it can be difficult to explain.

[Swag]

A friend of mine has a Proto-Track VMC where the Z-Axis can only be used for depth, hence he can't not do anything requiring Full 3 Axis.

Toby, A friend of mine has a Prototrak that does full 3 X work, he purchased the DNC key.

[BobWarfield]

I think the first definition is the clearest:

"But 2.5D is a shape with a constant Z depth setting for the profile the only exception is when you may have a ramping motion set for the PLUNGE and then it runs X & Y at a constant Z depth

3D is any shape where all three axis may be moving at once."

Another way to think about it is (roughly) what sort of tool paths can the program generate?

A 2.5D can drill holes, follow a profile at constant depth, or make a pocket at constant depth. That's about it. They will have some variations on that, but the emphasis is on constant depth.

A 3D will be capable of smoothly moving the cutter up and down to create smoothly flowing shapes. Most newcomers dream of 3D, but they get to building real parts and often realize an awful lot can be done with 2.5D.

The seatbelt clip Toby shows, for example, looks smoothly flowing, but with corner rounding endmills and such, is a pretty easy 2.5D part.

Now 4-axis says we want to rotate on one axis as well, usually the X. And there are 2 styles there too:

1. I want to rotate for indexing only. I will stop and lock the rotation before cutting.

2. I want to rotate while cutting.

Case #1 is largely (but not exclusively) handy so you can get at more sides of your part without having to remove it from the machine and reposition it.

Case #2 is less often important, but has cool applications. For example, engraving a shape that smoothly wraps around a cylinder.

5-axis rotates 2 of the linear axes, such as x and y. It's all about being able to reach into crazy places without refixturing. Porting a cylinder head, for example.

Each step up that list seems to multiply the cost of the software by 2x, so we seldom see 5-axis among amateurs. Though there are some wonderful exceptions:

http://www.cnc-toolkit.com/

Cheers,

BW

[cyclestart]

BobWarfield's explanation for the win (imho)

And then I'll play devils advocate to be a jerk

Spiral cutting a counter bore would be an example of simultaneous 3 axis motion resulting in a 2+1/2 D profile.

A hemisphere is 3d but the general shape could be cut with a 2+1/2D strategy. I've never used a control that will do cutter compensation in the x-z plane however so most people would resort to 3D CAM.

.

[cyclestart]

A OT question.

Years ago I worked with a conversational Mazak (Mazatrol) control that could do fairly complex 2+1/2D work. Have the newer conversational controls moved into 3D ?

[BobWarfield]

BobWarfield's explanation for the win (imho)

And then I'll play devils advocate to be a jerk

Spiral cutting a counter bore would be an example of simultaneous 3 axis motion resulting in a 2+1/2 D profile.

LOL!

So, I'll pose this question (at the risk of being a jerk back, LOL), does the helical interpretation g-code have to "know" it is a 3D operation in the same way that most 3D g-code does?

Likewise, a ramp would be similar.

Of course the answer is the g-code makes it look like just another 2 1/2 D op.

I haven't seen any conversational 3D but would be fascinated to hear of some.

Cheers,

BW

PS For something like the hemispheres, or other very regular shapes, it isn't hard to hand program the g-code. I like to use Excel to do odd things like that (even though I have a 3D CAM). Calculate the coordinates and then use string formulas to create the g-code. Cut and paste and you are there.

[Switcher]

I haven't seen any conversational 3D but would be fascinated to hear of some.

I ran this conversational software for about 8 years on a Schutte WU305 5-axis tool grinder, Windows NT at the Siemens Control.

It's wild to watch the g-code file on the monitor, while the machine is running the full 5-axis simultaneously (example: the rake on a ball end-mill), the text file scrolls so fast it's just a blur


.

[fabconv]

hi everyone
another explanation on this website

http://www.shopbottools.com/3-d_work_v2.htm

[ger21]

Here's some 2.5D mouldings I cut the other day. All just straight X axis moves. You can do curved parts like this too.
http://www.cnczone.com/forums/showpo...&postcount=181

I don't think anyone mentioned it yet, but using 2D toolpaths for parts like this usually result in much smaller file sizes and much faster run times.

Basically, 2D or 2.5D is cutting in X and Y only, with Z movements between cuts. 3D is X, Y, and Z all moving together, but sometimes just X and Z or Y and Z, depending on the CAM software and the paths it generates.
And there are inexpensive 3D packages, like MeshCAM and Cut3D, but they may not be the right option for some applications.

[cyclestart]

LOL!

So, I'll pose this question (at the risk of being a jerk back, LOL), does the helical interpretation g-code have to "know" it is a 3D operation in the same way that most 3D g-code does?

I was just up to some mischief, your explanation was excellent. The spiral routines in simple CAM go from here-to-there following a canned strategy as you explained. Good enough for a vertical wall. Blending shapes in 3 dimensions and understanding tool shapes is more complex.

A conversational control (question and answer) could be thought of as a type of CAM without the usual CAD method. The questions for 3D would get complex pretty fast

For something like the hemispheres, or other very regular shapes, it isn't hard to hand program the g-code. I like to use Excel to do odd things like that (even though I have a 3D CAM). Calculate the coordinates and then use string formulas to create the g-code. Cut and paste and you are there.

Maybe that could be thought of as a kind of single purpose CAM ? There have been a few examples posted in these forums of hemisphere tool paths created without using CAD software.