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I want to use a router to cut a 1/4" slot (in poplar) to make a panel door with 1/4" plywood. (In the past I've use a table saw.) I need to buy a bit. I'm choosing 1/2" shank so it will be stouter.

I see that these slot cutters come configured with the bearing above or below the cutter. Is there a reason to choose one or the other, bearing above or below the cutter?

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  • The reason for bits to have a bearing at top or bottom is covered in previous Q&As, but if you're just cutting a groove you only need a conventional straight-cutting bit (no bearing top or bottom).
    – Graphus
    Commented Jan 19, 2022 at 23:02
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    This question may help
    – Ashlar
    Commented Jan 19, 2022 at 23:21
  • ok, makes sense - I thought it might offer some stability
    – rebar
    Commented Jan 20, 2022 at 0:14
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    The advantage to above or below depends on what your particular need is at the moment.
    – FreeMan
    Commented Jan 20, 2022 at 14:56

1 Answer 1

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I see that these slot cutters come configured with the bearing above or below the cutter. Is there a reason to choose one or the other, bearing above or below the cutter?

Router bits with bearings are meant for following a pattern of some sort; the bearing rides against the edge of the pattern and guides the path of bit, so that the bit cuts the workpiece to a similar shape. Sometimes it's easiest to put the pattern on top of the workpiece, other times it's easiest to put the workpiece on top of the pattern. That's why some bits have the bearing close to the shank, while others have it at the end of the bit. Neither is better than the other, they're just different styles for different situations.

I want to use a router to cut a 1/4" slot (in poplar) to make a panel door with 1/4" plywood. (In the past I've use a table saw.) I need to buy a bit. I'm choosing 1/2" shank so it will be stouter.

It sounds like you don't need a bit with a bearing at all. If you're talking about forming a dado along the edge of the rails and stiles to hold the panel, you just need a straight bit with no bearing. This is really a job that's best done with a router table and a fence, so that the fence will guide the workpiece over the bit; you can attach a fence to a handheld router, but even with the fence it's hard to hold the router exactly in line with the workpiece so that you can make a clean cut because the edge of the workpiece is so narrow. If you must use the router handheld for this, clamp the workpiece to something more substantial, like a workbench or a piece of 4x4, so that the edge you want to rout is flush with the top surface. That'll give the router base a wider surface to ride on. Use a fence on the router to determine the bit's position on the edge of the workpiece.

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