Thin Groove in wood

Hi all,
I am trying to cut a groove in wood that is 1.5mm wide with a depth. Basically this is the thickness of my stock. I’m having difficulties finding a bit that will accommodate the depth. Any suggestions .
Thanks John

I often run into this problem, and here is what I do. I modify them…

Here is a 201Z Cutter that I use for deep slots and cutoffs in 2x4s… you can see that I relieved the shank down to allow for some clearance (so it doesn’t rub)

Here is a 2mm cutter that I modified to cut deeper when I was making a stainless steel watch (body)

How I do it: I own a few cheap Chinese Diamond ($15) grinding wheels, and I place the cutter that I need to modify in a cordless drill and grind it while spinning the cutter. It does NOT need to look pretty…it just needs to be a little smaller than the cutting diameter.

NOW to cut 22mm deep with a 1.5mm cutter…that is REALLY deep (Greater than 10 times the Diameter (10D)). I would do that in steps. Start with a standard cutter as deep as it goes, then another cutter with a relieved shank to (about) 10D, then 15D.


@RichCournoyer Love the idea of relieving the bits…just a little goes a long way.

@John3 Is the groove straight? I ask because I have had problems on deep curved cuts with bits sticking on withdrawal in a curve, and then throwing off the Z - and the next plunge heads to the center of the earth.

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Yes it straight. I was cutting thin strips to insert into the grooves.

I will have to order some bits and try grinding them down. Thanks for the suggestion.

You can get to 20mm with one of these, but it will most likely snap.

One possible alternate approach is to cut 12mm deep (much safer) and then flip over the stock. You’d have to be very accurate in the way you arranged the stock so the flip worked. But the ridge (there will be a ridge) will be halfway through the stock and probably not visible.

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Without fully understanding it…let me ask, could you do it as a pocket cut, instead of a single contour and get deeper with relief always on one side?

Yes I though about that. I was just concern about the alignment.

The issue is the bits they sell does not have the depth I require. Thanks

Are you cutting all the way through?
It might help to explain what your end goal is.

Oh my. It feels like that tool would snap by just looking at it the wrong way :sweat_smile:
It would be an interesting exercise in feeds & speeds AND chip evac/dust collection to slot down to 20mm depth with it though.

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