How would you make this?

[tjb]

I'm trying to visualize the most efficient way to make the part in the drawing attached below. I'll need to make several, so the closer I can get to assembly-lining the process, the better. Accurate measurements are more likely the metric values.

I'm thinking something along these lines:

1. Make a sacrificial plate that's slightly smaller than the overall diameter - 7-3/4" - 8" or so. I have a piece of 3/8" aluminum that will work perfectly.
2. Mill a hole in the center of the plate to accommodate the center hole and the six slotted holes.
3. Center-mount the plate and a slightly over-sized blank onto my 12" rotary table, clamping on all four slots.
4. Mill the interior hole and slots. The slots are actually on two-alternating diameters. It would be simple to determine the diameters and make alternating internal and external holes, but the slots would probably easier.
5. Move to the outside diameter and mill by removing and replacing one clamp at a time.

Any feedback or suggestions for a better approach?

Thanks in advance.

Regards

 

[Janderso]

I’m sitting here thinking about my DRO and the bolt circle feature. No, you don’t need it.
You have a pre set dimension in the X axis to drill down through the material then move out for the desired X slot distance, move back to zero, move the rotary table 60 degrees, rinse and repeat.
Regarding the clamps, you can’t do this in one set up without moving them? Did I miss something?
Sounds like you got it.

 

[tjb]

Yes, I have the bolt circle feature on my DRO as well, but I agree it'll be much easier to just move along the X-axis since I can easily determine the radii. I don't think you're missing anything on the movement on the clamps - unless we both are. I can't visualize any easier way to set up the process. The ONLY possible streamlining I can think of is stacking three or four pieces at once and milling them together. That may be worth a try. Thoughts?

Regards

 

[Janderso]

Yes, I have the bolt circle feature on my DRO as well, but I agree it'll be much easier to just move along the X-axis since I can easily determine the radii. I don't think you're missing anything on the movement on the clamps - unless we both are. I can't visualize any easier way to set up the process. The ONLY possible streamlining I can think of is stacking three or four pieces at once and milling them together. That may be worth a try. Thoughts?

Regards

Of course, milling more than one at a time is the way to go. If your equipment can handle it.
How deep are your passes on the slots? I get kind of greedy and it bites back
I like to finish pass on slots so I allow for a clean up on both ends and side to side. Maybe .005”

 

[tjb]

Don't know what you mean about how 'deep' are the passes on the slots. The material is about a sixteenth of an inch thick, so milling the holes should be rather uneventful if the blank is securely stabilized.

Also, Jeff, I may have misread your comment on clamps in your first response. The only way I can think to clamp the part is with four toe clamps on the outside perimeter - easy enough with a 12" rotary table. I can move the X-axis to the appropriate position and mill to a given toe clamp / remove it / proceed past it / re-clamp. That's essentially one process but four interruptions. Is there an easier way?

Regards

 

[7milesup]

Sacrificial wooden plate underneath. Toe clamps on the outside perimeter. Mill some/all of the slots and use those holes as points for fasteners into the sacrificial wood plate. Continue to mill the center hole and if there are any remaining slots. Remove toe clamps and mill outer perimeter. That is one way I can think of doing it. The outer perimeter operation will have to be slow and it will be loud due to lack of hold downs. You might be able to "walk" the outer perimeter hold downs around as you mill, but probably not by much.

 

[Inferno]

Waterjet cutting.

 

[tjb]

Sacrificial wooden plate underneath. Toe clamps on the outside perimeter. Mill some/all of the slots and use those holes as points for fasteners into the sacrificial wood plate. Continue to mill the center hole and if there are any remaining slots. Remove toe clamps and mill outer perimeter. That is one way I can think of doing it. The outer perimeter operation will have to be slow and it will be loud due to lack of hold downs. You might be able to "walk" the outer perimeter hold downs around as you mill, but probably not by much.

Good idea, Neil. I'll study that.

Thanks

 

[tjb]

Waterjet cutting.

Got a feeling that would not be cost effective.

 

[ChazzC]

Sacrificial wooden plate underneath. Toe clamps on the outside perimeter. Mill some/all of the slots and use those holes as points for fasteners into the sacrificial wood plate. Continue to mill the center hole and if there are any remaining slots. Remove toe clamps and mill outer perimeter. That is one way I can think of doing it. The outer perimeter operation will have to be slow and it will be loud due to lack of hold downs. You might be able to "walk" the outer perimeter hold downs around as you mill, but probably not by much.

MDF makes an excellent backer for this type of work: very flat, no grain (ir knots).