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Discussion Starter · #1 · (Edited)
how thick of wood can u flush trim with a pattern

once i trim my pattern can i remove them pattern and set the bit deeper for more cut depth example i dont have a band saw and need to a pattern for the bottom feet for a tresle table build and i am using 4*4 oak post milled lumber here is a pic of the table
 

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crosseyed & dyslexic
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With a pattern/top bearing bit you could do that. I would be worried about hogging out that much material, you would have to make quite a few passes slowly increasing your depth. Since you don't have a band saw, which would be ideal to get you close to your mark, what about a jig saw with a long course cutting blade? Those flush cutters are really only designed to take no more than half the diameter of the bit.
That's my story and I'm sticking to it! Good luck.
 

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Discussion Starter · #4 ·
i will be using a 1 inch long bottom bearing bit so once i get the 1 inch flush cut done i can just raise the bit and the bearing will ride on the first pass cut and i will use a jig saw to take most of the material out first
 

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I guess the travel of your router also has to be taken into consideration.
I think I have a 2 inch bit for trimming two pieces of mdf glued up for a router table.
 

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You probably need 2 bits to do this and they both probably need to be 2", you may be able to get away with 1.5". The thing you do not seem to be accounting for is clearance above the cutter. If you start with a flush trim bit and the pattern on the opposite side of the workpiece, the rough cut stock would interfere with the shank of the bit, preventing you from following the pattern. If the cutter diameter is enough larger than the shank diameter, you could use it, but the total length of the cutter and the exposed shank would need to be at least 3.5" just to reach the pattern. Keep in mind that the bit would have to be more like 4.5"-5" to have enough length to cover the full workpiece and have enough shank to mount it in the router. The pattern bit would have the same problem (except since the pattern is at the top, no issues with shank to rough cut wood interference).

So, the way to do it would be to use a pattern bit for the first pass(es), and use a flush trim from the opposite side for the final pass. This prevents you from having to get one bit to stretch across the entire workpiece. Another option, would be to mount a spindle sander drum into your drill press and sand to the final shape. (Just don't try to mount a spindle sander drum in your router table, the speeds are too high.)

(Note that when I reference top, it is based on free hand router operation, even though you plan to do this in a table.)
 

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You will need a shorter pattern bit to get started, since you need a bearing surface on the pattern before the cut begins unless, you drill out most of the waste first. Which is what I'd do; then treat it like a routed bowl. And of course, like a routed bowl, you'll need a bit extender to increase your reach and a 3/4" pattern bit to clear the bit extender's collar!

As a practical matter, you may find it cheaper to buy a jig saw and a sanding drum.
 

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If you use a router guide bushing you can use a longer cutter. I had to cut 424 couch sides from 1 1/2 inch thick red oak, I used the bushings and had no problems. You will need a good heavy duty router though a small router will get hot and fast. Another thing is the longer the bit the more the chatter.

We had to make multiple passes, too much bite and it will smoke a small router.
 
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