Need suggestion cutting deep

Have a project where I need to cut a 2” deep profile in a wood slab.
Assuming a long 1/4” uncut spiral bit?
Only cutting in 1/8” deep passes but concerned about chip extraction after passing deeper then the flute height?
Thinking too much or is this a potential problem ?
Also is 1/8” too shallow a cut?

are you truly doing a .25" slot or is it wasting a wider section?

You’re overthinking it, so long as your bit is long enough and you keep your feed rates within reason, there is no issue with deeper cuts and chip extraction.


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I am cutting parts out of 2” thick slabs
Thanks I have a 3” long 1/4” with 1” flute inserting 1/2” gives me clearance
Thanks as I have 10 to do

@Fly_capt - recommend you use an upcut bit. As @MindOfMcClure recommends, if you keep your speeds reasonable, you shouldn’t have a problem. If you can, maybe pocket the profile instead, reducing the likelihood of chatter and some really catastrophic issues at depth.


What does pocket the profile mean?

@Fly_capt - hopefully this make sense. Instead of doing a very deep profile cut, where the cutter is likely engaging both sides of the deep walls while cutting, establish an additional offset profile outside the main profile about [edit] 1.5x-2x the diameter of the cutter. Then use the main profile as one boundary of the pocket, and the offset profile as the other boundary of the pocket. The pocket operation will remove the material along the main profile, and more material along the offset profile, creating a cleared area for the cutter to operate. That way the cutter is cutting deep, but only engaging on one wall of the material rather than two. You waste a little material and a little time, but removes the probability of the bit chattering and potentially failing when it is deep into the cut.

(if the bit starts to chatter, it creates perpendicular vibrations on the bit while cutting. The vibrations cause the cutter to bounce between both sides of the profile, taking cuts from both sides rather than only one. Since the opposite side is catching the ‘back’ face of the cutter, the cutter grabs the material rather than cutting it, likely causing the cutter to dig deeply into the opposing face resulting in a failed operation. Some times the ‘grabbing’ of the material is very violent, causing the cutter to break. It’s a little complicated and hard to visualize, but I’ve been there and can confirm it’s easy to do in a deep profile cut with a machine that is not too rigid).

Hope this helps.


Okay that makes sense
So offset the profile and cut out the trench around it
What advantage does 2.5-3.5 bit diameter give over 1.5x
Also should it cut the relief channel first before engaging the final profile?
It already is a long cut time for this big piece
Thank you so much for your help, this is a great board for help.

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@Fly_capt - sorry, 1.5x is perfectly fine (I was doing three things at a time while drafting my response and mixed some things up). In fact, just about anything greater than 1.0 works.