Pocketing vs Part Cutout

When using EstlCAM, I almost exclusively use the Peel strategy for pocket cuts. It makes nice clean cuts with a good stepover for efficiency, and as a bonus it’s fun to watch. I rarely have any problems with chatter or stress (going by ear only).

If I use the same tool settings that I use for peel/pocketing for simple part cutout, I frequently get a lot of extra noise and vibration to the point where I’ve had to shut it down mid cut before in the interest of caution.

Is this a common issue? Do you guys typically have a different tool setting for pocketing vs cutout (my current solution)? Is this an indication of something not being quite right with my build?

For reference:
Primo
1/8" single flute upcut bit
Pocket cuts: 24ipm (10mm/s) feedrate, 4mm depth per pass
Part cuts: 19 ipm (8mm/s) feedrate, 2 mm depth per pass

Is the chatter/etc on the first pass or on the second pass?

I noticed that I have chatter when doing conventional milling, I can see it very well for linear clearing pockets. From X- to X+ there is chatter, when going in the other direction, there is not. Hardwood, 3mm DOC, 1000mm/min, 20000 RPM.

Same thing happens with my planing endmill. It would be nice if you could tell Estlcam to only clear in one direction.

Funnily enough the Sororec App gives me lower values. :scream:

I just cut something using parallel cutting instead of linear and the surface finish is a lot better, also it goes only in the climb direction. Pretty neat. :slight_smile:

During a part cutout, it happens to some extent on each pass. I’ve not noticed it being any worse on a second or third pass. Sometimes I get brave and let it go, but sometimes it makes me nervous and I stop it. It depends on how deep the material is and if I want to take a chance on another pass.

I have no issue with cutting pockets. It’s when I’m doing a part cutout and the bit is cutting on all sides (except for the back, obviously).

Like this:
image

Hmm, okay. Do you have a video of it?

1 Like

I don’t want to hijack this topic to much, but have a quick question.
Wouldn’t that give you chatter all the time? Or did I misunderstand this?

I was stupid, chatter with conventional…

I got double-bit-width chatter because the core was super loose when milling plywood. Works great in foam because there is no load, but it makes lots of foam fuzzies when carving with a 60 degree bit. If I tighten the core, then it fries my stepper because it binds… must be time to rebuild.

This seems to be a pretty common problem: chatter because too loose or binding. I found the mistake with mine, but it is still a pretty close call between binding/not binding and being too loose.

I think the binding comes from the foam milling without dust collection building up on the conduit and bearing surfaces and stretching the PLA to crack or binding and then once cracked, they are loose and retightening them makes them bind more. Which leads to building new printers to print more parts so it won’t bind, but that rabbit hole has yet to lead to new parts…

That is because when you are cutting out, that is a slotting cut, 100% engagement. A peal is 10-40% step over.

You can usually leave all the settings the same, just do less depth of cut (half as much should be good). That will get the chips out of the way.

2 Likes

Ryan beat me to it. Slot cutting is harder because the chips can’t escape and the bit is 100% engaged. So I would expect to be able to use more aggressive settings in a pocket.

I was hoping this topic would be about the trade offs between cutting holes and combining layers vs pockets. I always like the idea of building layers for projects instead of big pockets.

Not sure what you are saying about layers and holes… intrigued :thinking:

1 Like

I’m assuming like this.

You create multiple pockets that are smaller, then stack them together and glue. You get two advantages 1/ Your pockets are shallower so your bit can be shorter 2/ you can do undercuts like in the example image. You wouldn’t be able to mill that with our machines in one piece (not a challenge)

2 Likes

I have done 3D as 2 sided cuts that is a similar to that just i think of it as sliced so just semantics :+1::heart_eyes:

Makes total sense. 2mm DOC seems to work alright for the slot cutting. As far as pocket peeling, I actually think I could go to 4.5 to 5 mm DOC and not have too much of an issue.

Do you guys have any thoughts on a 2 flute bit to help clear the chips during a slot cut? I have some on hand so it might be time for a test…

2-flute makes CNC go faster. NEOOOOOOOOW.

Yes, a single flute. We run at Single flute RPM. So at that RPM a single flute will be best to scoop out chips, 2+ flutes are too close together.

2 Likes