Router bit slot cutters - can the 'blades' be stacked? (Update)

Henry W

Senior User
--- Update below in thread ---

Eons ago I used to stop by the DeWalt Repair Center on Capitol Blvd, and check their bargain bin. At one point I picked up a Porter Cable slot cutter arbor and several 'blades' - 3 wing, carbide tipped cutters in widths of 1/4", 1/8". and 1/16". I have used a few times awhile ago.

I can't find much info online about these - I THOUGHT that these 'blades' could be stacked for intermediate thickness slots (i.e. 1/8 + 1/16 to get a something approximating 3/16"). In fact I have several very thin metal washers (shims?) that were supplied with these - suggesting to me that these could be stacked.
I haven't used in some time, and now I can't seem to get the arbor to fix the 'blades' in place, they just seem to rotate about the shaft, even with the arbor nut quite tight. So clearly something is amiss.

I am trying to cut a slot for the plywood panel in a shaker style door - nominally 1/4" but of course nowhere near that thickness.

Anyone have helpful info/advice or real life experience with these slot cutters? I would rather use these than a dado set on the table saw because I don't want to cut a through slot on the stiles, only on the rails; creating a stopped dado on the TS requires machinations that I am not willing to go through. These slot cutters create a much smoother line than I get with just a 1/4" bit (which is also too large really). I don't have an 'undersized' bit for this thickness (3/16" nominally).
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Corporate Member
Yes but you have to alternate the teeth just as you would a dado blade. My set came with several shim washers in different thicknesses. I've used this for shaker stile doors


Corporate Member
I purchased this inexpensive set is slot cutters a couple of years back and it has served me well. I too have found that today's 1/4" ply has shrunk to be more like 3/16" thick. This is the set of slot cutters I have been using when routing rails and stiles for panel doors.


My set doesn't include spacers/washers. You can stack the cutters, just ensuring that the carbide teeth don't touch each other in the stack (like table saw dado stack setup). The Arbor nut does secure the stack pretty well in this configuration.

(Just wondering how thin this plywood will go before they rename 1/4" - 3/16"!)

Henry W

Senior User
Thanks Fred and Wayne.
I bought a new 3/16" blade and an arbor at Klingspor's WW shop. Having used my set so infrequently, I forgot (or did not realize) that stacking order was important. My problem was that I have the bearing in the wrong spot - it needs to be farthest from the arbor nut (or closest to the router collet). Once I corrected that it worked - stacked- just fine (on old PC or new arbor). I now have two arbors and a selection of thicknesses, from 1/16, 1/8, 3/16, and 1/4". When I remember how to use this, it is fantastic.

What I really like about this slot cutter setup is the work piece can be set flat on the router table- and then pressed down onto table, and into the fence (and or bearing) while being machined.
THis is far preferable the alternatives I had:
- running a piece with a dado stack on a TS (at least it is for stopped dadoes),
- running apiece on edge using a spiral router bit (and I did not have the right size bit for 'undersized' plywood)
- using the same router bit (improperly sized) in my horizontal router table.

The forces of cutting this groove in the edge of door frame parts are (for me) far simpler to manage with this orientation. The cuts are cleaner than any other method I tried, except the TS dado. Stopped dados on the TS were the issue I had - I WON'T 'drop' a piece onto a moving bit or blade, and raising the blade into the piece just seemed fraught with inaccuracies.

So I have a method I am happy with. The new 3/16" blade stacked with the old 1/16" PC blade (doesn't add up to 1/4 because the 'set' of the teeth of the two blades overlap) provided the right slot for the nominal 1/4" plywood.

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