Moving beyond straight end-mills

[freman]

Hi,

I have a job cutting a cylindrical section out of a block. Ideally I would do this with a ball-nosed tool but FreeCAD does not yet handle this and I can't think of trick to get around this.

In this case I have decided to use a straight end-mill since the finish is not too critical and I can accept a staircase approximation. However the 0.5mm steps means the job is taking about 2.5h to run !!

Is there a workaround I have missed?

If not if someone can point me to the relevant part of the code, I may have a look and see whether I can do something to move this forward. Is anyone actively working on this already?

Thanks.

[RatonLaveur]

Hi freman,

Without a picture, diagram or model it's quite hard to identify exactly what you want to do.
In this blind context I'll assume I understand what you want and suggest the following answer:

What you want to do is a surfacing OP. which means 3D machining (not 2.5D).

A search in these here forums will yield answers with the following keywords in any combination: drop cutter, waterline, 3D machining, 3D surface, OpenCamLib, OCL.

You'll find that users such as Russ, Sliptonic, JoshM and many others have worked on solutions to this problem, and you'll also find that, depending on the part you're trying to machine, this seems achievable.

That should get you started:
https://forum.freecadweb.org/viewtopic. ... d1fd19b401

Good luck!

[freman]

Thanks Monsieur Laveur.

I was not expecting a specific solution for this piece but if it helps see the point, here is the model I'm working on.

I've just cut this path and it seems that the diameter is slightly less than the 80mm in the model, so may be overlooking something in using a straight mill. Offering it up to my 80mm spindle ( accurate 80mm ) it only touches at the edges , there is about 1mm clear of the spindle body in the middle.

I'll have to think about that again.

[herbk]

Hi freman,

Is there a workaround I have missed?

do you got OpenCamLib running?

If yes, you can use 3D Pocket with bigger stepdowns for roughing and 3D Surface for a finishing path.

[freman]

Ah thanks! That sounds a lot better. Especially if I need to do another pass, I will not spend 2.5h cutting air !

I do have OCL, but I only seem to have 3D pocket, where do I find 3D surface?

[RatonLaveur]

Lookup 3d surface in the freecad wiki.

Lookup Experimental Features.

The thread i pointed to has russ's latest python scripts in the original post.

These three points of action will get you sorted!

[freman]

Many thanks, well hidden. I'd read about experimental features and thought it was enabled from prefs but couldn't find it. Nice to have a mechinism for adding this kind of work, very flexible.

Russ' comments seem to suggest this supports ball end tools, I'll give it try. Murky buckets

[Russ4262]

...
do you got OpenCamLib running?

If yes, you can use 3D Pocket with bigger stepdowns for roughing and 3D Surface for a finishing path.

Great suggestion Herbk.

ping

Just a few things related to Herbk's dual operation suggestion.

1. 3D Pocket only supports and produces paths based on end mills [Other FC users please correct me if I'm wrong].
2. 3D Surface works with: end mills, ball mills, bull nose mills, chamfer, and engravers. HOWEVER, all these except end mills have limited testing and feedback. Therefore, we may need to adjust some translation settings from the FC tool manager to OCL. That said, proceed cautiously with non-end-mill cutters and their paths; detailed feedback to make adjustments for non-end-mills in 3D Surface would be helpful for improvements.
3. The FC path simulator also is limited to end mills [Again, correct me if I'm mistaken].

WIKI NOTE to self:
-- add list of FC to OCL translated cutters into the 3D Surface page
-- make note that simulator only uses end mill [unless otherwise informed
-- make note in 3D Pocket that it only uses end mills for path generation unless otherwise informed].

UPDATE 2019-06-21 20:58 CST: Wiki has been updated per wiki notes here.

Still on holiday,
Russ

[freman]

Thanks Russ, I followed herbk's excellent idea. It's only half done but it looks good. It's also a very long run time since I needed to run 10% overlap with my 6mm ball-end, but the result on 3D-surface it better than a staircase with an end-mill.

Many thanks to herbk for pointing me to this I did not realise this was working , even if a little untested.

3D Pocket only supports and produces paths based on end mills

Yes, IIRC. sliptonic told me somewhere that 3D Pocket calculates all tools as though they were straight end-mills.

I selected the cylindrical surface in the attached file and ended up getting a path which covered the upper faces as well. Is that intended or just something which has not been ironed out yet. I was expecting to just cut the cylindrical face.

[Russ4262]

I selected the cylindrical surface in the attached file and ended up getting a path which covered the upper faces as well. Is that intended or just something which has not been ironed out yet. I was expecting to just cut the cylindrical face.

I'm on a smart phone out of town with no FC around. That said I'm imagining some type of trough-like part. No matter, the fact is the 3D Surface op has no face or area selection/limiting capability at the moment.

Sir, your name will be added to the long list of those requesting this particular, very-useful improvement. The feature list is already lengthy and I have no timeline to speak of nor with which to project forward. "Is that intended," yes for now.

Thanks for the feature suggestions.

A suggestion:
Should this venture be one of importance or intended learning, consider the following in light of FC being the unique software that it is.
If you have the desire and time, a little creativity in part design(segmentation or assembly) and job augmentation will allow you to isolate only the cylindrical surface portion of the part and then apply the 3D Surface op only to that isolated object in a separate job. This would mean two or more jobs overall. One for the roughing of the entire part, a second with the base part being the isolated trough portion - for finishing just that area. If necessary, create a third job for the rest of the finishing ops if they can not be inserted into the first job after the roughing ops.

Thanks to all those who have achieved great projects, start to finish, with FC even when it had less functionality than it does today. Your creativity and varied approaches to successful part design and milling completion continually encourage me to think differently and explore greater possibilities I could not see without your support.

Catch ya on the roughing pass,
Russ