Why not go maximum depth?

CNC Machines Shapeoko
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Sorry if this has been discussed before, my Google-fu is weak.

From my novice understanding of speeds and feeds, you can increase your depth of cut by slowing down your feed. But that makes me wonder, why not always cut full depth? All of the starter tutorials/guides/videos and even Carbide Create seem to do things in multiple depth passes. I’ve always wondered why.

Also, from what I’ve heard, max depth of cut should be better for tool life, as it uses more of the overall tool length, rather than focusing wear on just the tip.

Thanks!

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This requires rigid tooling, and a rigid machine, such as are used in industry — for an example of what purchasing such looks like see:

Alternately, it can be done using special toolpaths — search terms for this are: “adaptive toolpath” and “trochoidal toolpath”.

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Are the forces on the machine not the same between the two scenarios? Maybes that’s what I’m missing. I assumed that by reducing feed rate the forces would be reduced as well.

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Yes, but when you slow down, you may not be moving fast enough to create a proper chip. If this happens then you end up rubbing more than cutting, which creates friction and heat. That ends up hurting tool life and creating a poor quality cut.

It’s better to move at the correct speed to create a good chip and then set the depth to get the correct cutting power.

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Thanks for the explanation. Very clear now. :+1:

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If you would like to dive further down the rabbit hole of feeds and speeds and depth of cut, this may be of interest:

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