How do I do this...

New user here with V27. I am working on a simple 2-1/2 D encoder wheel. I want to mill this from 1/4" stock and create a central hub with the encoder slotted disk milled down to .1" Here is what the part looks like superimposed in the stock:

Attachment 253512

What I'd like to do is a milling operation with a 1/4" end mill that removes the material outside of the larger central circle to create what would look like a boss in this first operation:

Attachment 253514

Ideally, I'd like to spiral in from the outside to remove all that waste material but any solution would be fine. I tried a few things but they all resulted in a "slot" cut around the central circle. I could draw concentric circles and mill each one of those but that's a brute force approach. Any suggestions?

cheers,
Michael

I meant to include this. There seems to be a profiling operation that looks like what I need to do:

Attachment 253516

But when I create this operation, it doesn't actually mill away that excess stock, it simply traces the feature, leaving a slot.

Here's my choice(more than 1 way to do this for sure)
I did in V26,but it should get the idea across.I did not set -up speeds or speeds or other little stuff.
It is Advanced Pocketing.

Hey thanks jrmach. I see that you used the adv pocketing but how/where did you specify to pocket "outside" of the internal circle rather than pocketing inside it?

Ah, I see it, you actually drew the stock border and made that part of the selection!

I think I found another way also:

Attachment 253526

Attachment 253524

I don't quite understand the relationship between Stock Remaining and Passes. It also is less efficient than your method as this would "cut" more air.

Thanks!
Michael

Advanced Pocket is the best thing since sliced bread for "open pockets"
The dashed lines tell the software that it is OK to "violate" that space.
If you want to get into the profile tool path as you were mentioning above "I don't quite understand the relationship between Stock Remaining and Passes." just start a new thread.And also try and make the title so it will be searchable in the future for other users.


Here is another example of the advanced pocket tool path, with advanced rough also,notice where the dashed lines are

Thanks, I'll start a new thread for my other question.

Meanwhile, I haven't been using BobCAD, I do my CAD in Rhino. Is the dashed line a feature of BobCAD or can I convert a line in a DXF file to dashed? I do plan to spend some time learning the CAD since it would be convenient for a lot of my parts.

cheers,
Michael

If you're working off of a 3d model, you can just extract the edges of the model in Bobcad and then convert the geometry at the appropriate edge to a dashed line. I don't bring in many 2d entities anymore as it's often just easier to pull the geometry needed right off the 3d model. If I need a boundary, I often offset the geometry in Bobcad as needed. I don't start thinking as much about the CAM workflow needs until I get to Bobcad, and the few things you need to do are pretty easy to get efficient at in Bobcad. Otherwise, like you, I do all my actual modeling grunt work in other applications.

Thanks mmoe. In this case, it is a 2D drawing. I do most of my drawings for parts like this 2D, just the way I currently work. That might change.

From what I see the only way to get the spiral cut from outside in on the step down cut area of fingers is to, make that area a solid, which I feel is necessary because at .100 thick the finger will probably not have much rigidity. All other cuts that I have done are not in 3D. On the slots I did a clean a profile with a Finish pass. Would probably have to add a profile cut to outer edge of hub after spiral cut.

This sample is not to any spec.

This is just an idea in the way I might approach the job. Hopefully the fingers will be rigid enough for the cut, maybe trial and error.

Best of luck
RAF.