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I see router bits marketed as flush trim bits, pattern bits, template bits, but they all seem to be similar in design. The cutting edges are exactly lined up with a bearing, so that an exact copy of a piece can be cut.

For example, Rockler sells a flush trim bit:

flush trim bit

and a pattern bit:

pattern bit

and Amazon sells a template bit:

template bit

They all seem to be identical in function (although the linked pattern bit is shorter, so it can't cut as deep of a copy as the others can), so is this just a marketing thing? Rockler's flush trim bit I linked is even listed as a "Pattern flush trim bit".

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  • The top link I would read as a Pattern, flush trim, bit. So it's a pattern bit as already mentioned, just specifically a flush-trim type (which may or may not imply there are other types that don't trim flush).
    – Graphus
    Commented Aug 25, 2017 at 6:27

2 Answers 2

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A flush trim bit has the bearing at the bottom of the bit. This is so that it can trim a layer of laminate (i.e. Formica) that has been attached to the top of a smaller substrate (i.e. MDF or particle board) flush to the substrate.

A pattern or template bit has the bearing at the top of the bit (between the shank and the cutting blades.) This is so that it can follow a template attached to the top of a larger workpiece, cutting the workpiece to match the template. I believe that the terms "pattern bit" and "template bit" are interchangeable.

Your first picture is incorrectly labeled. That is a pattern/template bit, NOT a flush trim bit.

Also worth mentioning, some flush trim bits have cutting surfaces on the tip of the bit to allow plunging it through a laminate. (These typically have a flat reference surface instead of a bearing.) This is useful if you've laminated over a hole in the substrate that you want to remain open.

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    My understanding mirrors yours, with the caveat that I don't think the terms are interchangeable. On the other hand, language evolves, so there's always the possibility/likelihood that meanings have shifted. At any rate, the difference is where the template goes. Note, too, that their functions swap when you put them in a router table.
    – Katie Kilian
    Commented Aug 24, 2017 at 18:38
  • noob here, what is a "top laminated surface flush"? I imagine top means that the piece to be cut is top. But the other words, what do they mean? I can't google them specifically, I just need to know what are they, then I can find the rest for myself.
    – Santropedro
    Commented Feb 2, 2019 at 22:05
  • @Santropedro A clearer way of saying that is that it can trim a layer of laminate (i.e. Formica) that has been attached to the top of a smaller substrate (i.e. MDF or particle board) flush to the substrate. This is a fairly common operation in the world of laminate counter tops. I've edited my answer to be more clear.
    – SaSSafraS1232
    Commented Feb 4, 2019 at 17:15
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The second bit, labeled "pattern" bit, could route along a pattern/template mounted to the top of a workpiece without going all the way thru the workpiece. Using successively deeper passes, this bit would eventually not require the template at all, instead running it's bearing along the surface it just routed. This allows for routing rabbets or dadoes of various depths that must follow a template. The bit's shallow depth allows it to handle thinner material.

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  • ....so how is this pattern bit different from the other two varieties mentioned in the original question?
    – gnicko
    Commented Jul 13 at 16:49
  • The other two varieties are much longer (deeper) and are better for cutting patterns all the way through the wood. The shorter bit is better for patterns not intended to go all the way through the wood, recesses not holes/openings.
    – Nico Cortez
    Commented Jul 14 at 19:56

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