Toolpathing an edge treatment

[CanisLupus]

I have an irregular shape (kidney bean-ish) and need to create a slot on along the edge of the shape. A sketch is attached for reference.

Can this be toolpathed and safely done on a CNC? I'd use a slot-cutter or similar profile but without a bearing.

For those about to ask, yes, I could use a handheld router or router table but the workpiece is already mounted on the CNC.

[ger21]

Is it mounted so that no clamps are interfering with the edges?

Yes, you can do it on the CNC, but the preview will not display it properly, because it's an undercut. And, you need to start and end the cut away from the part, so the slot cutter doesn't plunge or lift through the edge of your part.

I prefer to do a slot like this by hand, as it will tend to be more accurate, unless your part is absolutely perfectly flat, and uniform thickness.

[Rcnewcomb]

I would definitely do that on a router table. The time to create an accurate toolpath for the CNC exceeds the time it would take to do it on the router table -- unless you are doing 100 identical pieces.

[adze_cnc]

For those about to ask, yes, I could use a handheld router or router table but the workpiece is already mounted on the CNC.

Was this shape cut via said CNC? Or is it some pre-existing item that you mounted onto the machine?

[CanisLupus]

For those about to ask, yes, I could use a handheld router or router table but the workpiece is already mounted on the CNC.

Was this shape cut via said CNC? Or is it some pre-existing item that you mounted onto the machine?

The piece will be cut on the CNC at the same time as three or four other toolpaths, including a profile toolpath to create the bean shape.

[mtylerfl]

I don’t know how large the bean shape is. But, it seems to me after you cut the shape out and remove the outer waste (leaving the bean edge clear of material all around), you could run a slotting tool around the edge and use lead-ins and lead-outs along a suitable offset vector. The bean would need to be secured in position (maybe screws or vacuum?).

[CanisLupus]

I don’t know how large the bean shape is. But, it seems to me after you cut the shape out and remove the outer waste (leaving the bean edge clear of material all around), you could run a slotting tool around the edge and use lead-ins and lead-outs along a suitable offset vector. The bean would need to be secured in position (maybe screws or vacuum?).

The overall dimensions are around 24 x 24 inches.

I'm looking at workholding options which might include strategically-placed screws and/or clamps inside the shape by taking advantage of some cutouts.

I think this will be an exercise in tool sequencing and workholding more than any complicated machining processes. The toolpaths - except for the slot - are routine profile, drilling, and pocket toolpaths.

[mtylerfl]

Sounds good, Scott!

[kstrauss]

I frequently do cuts like this and also chamfering the bottom edge of the stock. As others have mentioned the only challenging parts are workholding and using a sufficiently long circular leadin/leadout to clear the cutter during the plunge.