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Ramped & Curved Slot Machining

adamlee2727
Contributor

Ramped & Curved Slot Machining

adamlee2727
Contributor
Contributor

Hi all, 

 

Looking for some help on the correct strategy to machine the slot in the attached f3d file. 

 

The slot travels around 90 Degrees but also has a ramped bottom. A ball bearing would be used to travel in the slot so i wanted to rough it out and then finish with a single cleanup pass using a 10mm Ball Nose Cutter for the curved base.

 

Any ideas? I am struggling to find a strategy that will stay parallel to the slot and also follow the ramped base.

 

Regards Adam 

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randyT9V9C
Collaborator
Collaborator
Accepted solution

In your model create a three point construction plane by selecting two point at one end of the slot and a point at the other. This will make a an angled plane that follows your loft. Next create a sketch that is the center line of your slot. I approximated it in the attached model. In CAM select 2D trace and select the center line. The trace will now follow the Z path.

 

When I mill slots like this I create a 2D arc and then manually add the Z value to my G2/G3 arcs in g-code. I rarely bother modeling it. Old school hand coder, some habits die hard. :winking_face:

 

Update: I just realized I forgot the axial offset to reach the bottom. Make sure you give it a negative axial offset equal to your radius, ie -5 mm.

 

ramped0.PNGramped.PNG

 

 

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adamlee2727
Contributor
Contributor

Hi Randy, 

 

Thanks for the help. That is exactly what i was looking for.

 

I thought it may be the case that i would have to add some construction geometry to create a selection for the Trace operation. My only issue with that is, like you said, it makes modeling the actual slot a pointless exercise. 

 

Surely there must be some method that uses the modeled geometry? Maybe not.

 

Thanks Adam 

 

 

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randyT9V9C
Collaborator
Collaborator

You don't have many options using the 10mm ball mill besides trace. If you used a smaller end mill, say 5 mm you could do a 3d adaptive to clear the bulk of the material and then 3d finish with ball mill. A lot slower for sure. Generally, when I mill a slot like this I'll ramp down into it with a flat end mill and then finish the bottom with the ball mill. I sometimes relieve the middle with a smaller end mill.

 

Design for manufacturabilty, you may find a flat bottom to work equally well for your application and will save machine time and tooling. If you need it radiused, than it may be possible to only go to partial depth, similar to a bearing race. Easy to machine and still effective. Food for thought. I don't know your application, just throwing out ideas. :winking_face:

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adamlee2727
Contributor
Contributor
Accepted solution

Hi Randy, 

 

This is a simplified version of what i was trying to achieve but thanks for the input, appreciate it. 

 

I received a reply from an Autodesk employee this morning that has a few more options of how to machine the slot depending on the finish required. 

 

See attached file if you are interested... 

 

Thanks, Adam 

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randyT9V9C
Collaborator
Collaborator

Nice. Project works treat in this application. Learned something new. Thanks for posting his file. :slightly_smiling_face:

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adamlee2727
Contributor
Contributor

Had a chance to go through the file i was sent this morning and i realized they used an 8mm BallEnd mill in the 'Project' example. Changed this to a 12 (Full slot width) and it screwed up the tool path.  

 

After a look at the model i realized the geometry they had created for the slot wasn't really concentric. I suppose its more of a model fault then CAM fault. 

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