1. 4th Axis Question

Can BobCAM create GCode from a solid model that is rotated/indexed cut? Meaning, I would start with a cylinder stock, which would fully "contain" my model, and by indexing a small amount around the X axis, I would remove one "tool width" at a time along the Y axis, varying Z depth.

I can "easily" do multiple setups at different indexes to get this effect, what I hope is that instead of me manually doing the indexing, BobCAM should be able to do it on its own...

Does this work in BobCAM?

I know you can wrap a "flat" image around a cylinder, but what I am talking about doing is much more detailed and the starting model is 3D (no way to "unwrap" that to 2D).

2. No.

3. If your 3d part is symmetrical, as in a revolved surface, it would be easy to create the surface to machine as 4th axis.

4. Originally Posted by BurrMan
If your 3d part is symmetrical, as in a revolved surface, it would be easy to create the surface to machine as 4th axis.
Nope, not simple at all... : (

Why is 4th axis so difficult from CAM software to do? Seems like it should be easy in a stepped/indexed mode. I understand that having more than 2 axes moving is tough, that that's not needed. All I want is to index A, then make a path using X and Z, go to next index on A, another path using X and Z, loop to last A index.

I could do this myself, by importing a bazillion models with the solid rotated "an index" in each one, and just make a single pass of GCode - but that would take FOREVER to do. I will try it with 8 indexes, and machine a "patch" at each surface, and see what I get, but why cant BobCAM just do the index iteration already?

Another option would be index X, then machine a full revolution using A and Z, then index X, machine a full revolution using A and Z, loop to last X step.

Neither option seems (to my admittedly naiive self) to be much/any more complicated than the XYZ code that is generated now. What am I missing?

5. Originally Posted by mcphill
Nope, not simple at all... : (

Why is 4th axis so difficult from CAM software to do?

What am I missing?

A symmetrical revolved part? completley simple and able to do in BobCad as is. Take your curve that creates the revolve and extrude it as a surface the length of the cylindrical stock and machine it with a 3d toolpath like slice planar.

BobCad has been planning a "Full 4th Axis" for awhile. It just hasnt materialized yet. I suppose the difficulty is in the math. Just doing simple indexing is not the answer. You may be able to fake something, but the results may be less than desirable...At least, you wouldnt want to engineer this into your application.

Usually, a true 4th toolpath would look like a motion around the rotation axis with the steps into it.

6. I understand that a revolve is easy, and I understand how to do that. That is not what I am discussing.

As stated, sounds like with BobCAM I will need to go with indexing and see what that gets me. Not really needed at all right now, I am just building a 4th axis and wanted to know what my limitations were due to the software. You have answered that, thanks.

I did this with "4 indexes" (just rotating the block on a channel I had milled to hold it in place) in the demo version of Cut3D, so it's not "so bad" to do multi-index work, but it would be nice to have all the GCode generated at once (this was 8 separate programs, a rough and a find for each face).

7. Nice picture.

8. really impressive mcphill. so which version do u have of bobcad? i am planning to buy it ver 23. but not sure if i should go for bobcad or mastercam..

9. Originally Posted by virdi
really impressive mcphill. so which version do u have of bobcad? i am planning to buy it ver 23. but not sure if i should go for bobcad or mastercam..
I used Mastercam for 10 years, from Version 4 to Version 9.2. I have been using BobCAD for 2 years now. I always will prefer MC, but that is because of familiarity and it wasn't my money buying it.

I am amazed at what BC can do in 3d and Solids for the price you pay. You could not go wrong with BC. It has some "quirks", but most, for me at least, have been just getting used to new techniques. V23 has been a real good upgrade.

That's my 2 cents. Take for what it is, an opinion. "Everybody has one."

10. Originally Posted by virdi
really impressive mcphill. so which version do u have of bobcad? i am planning to buy it ver 23. but not sure if i should go for bobcad or mastercam..
I have v23 Pro.