Learned something new today

Most of the time that I've ever used a flush trim router bit has been to trim a melamine edge or something like that, I'm in the process of building an oak dining room table and chairs.
Decided to build the chairs by using a template to bandsaw the blank and then flush trim to shape. Needed 8 legs and fortunately I cut 9.
Took the first blank and using a 1/2" shank 3/4 x 1 1/2 flush trim in the router table proceeded to trim. Much to my surprise, actually scared the hell out of me, as I was trimming down the slender part of the leg, the bit dug in and split the leg along the vertical grain.
Seems I didn't pay enough attention to how close to the line I made the bandsaw cut. Got a little sloppy and some of the cuts were over 3/8" deep.
Needless to say I went back over the blanks and cut much closer to the line. No problems after that.
Vic
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I do the final cutting with a flust trim bit often. If I leave much more than 1/8" to be trimmed and expecially on oak I often see tear out beyond where I want when flush triming against a template.
To solve this , back route, go in the opposite direction. CAUTION the bit WILL try to yank the work out of your hands so do this with a firm grip. And naturally, the less material you have to remove the easier the procedure will be. The cuts end up very smooth after you make the final pass in the correct dirrection.
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Thanx Leon, that's what I wound up doing and it worked like a charm.
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I do the same ops with a shaper with a 2 5/8" trim cutter.
Yes, the less material to remove the better cut and less chance of chip out Yes do a climb cut of difficult section or at the exiting end Yes, create a fixture with a zero clearance exit if possible to stop blow out
Shapers can also be reversed (the motor and the cutter) so you can cut with the grain at both ends. Kind of a lot a work to do. Especially in my case since I trashed my reversing switch during a refurbishment process and I hve to actually switch wire to revere the motor.
I have found that in some cases I became so carfeul and experienced with my bandsaw cut that I didn't need to actually do the trim. Just sanded.
On a router you might look into a spiral cutter. Actually even more dangerous in some regards (they like to grab) but cleaner slicing removal of material because you always have a cutter in the material instead of the bang bang of a straight cutter.

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"Climbing cuts" (going the wrong way with your macrouter) are pretty safe if you are careful, don't take too much off at one time, and are experienced in doing it.
I don't mind doing it, but as Leon cautioned, it can be very dangerous. A 2 1/4 horse router doesn't seem to powerful until it had a handful of your project.
If I were going to suggest something to the less experienced, I would suggest this one, or its relatives:
http://tinyurl.com/ydaogqq
They have the family on this page, at the bottom, about the last 6 - 7 bits. They are called "flush trim plunge" bits.
http://www.toolstoday.com/c-416-flush-trim-router-bits.aspx
Look carefully at the bit. You can take off tiny amounts at a time by adjusting the depth of your cut, making sure the bearing rides on your template.
This differs from the normal flush cut bits that don't let you choose how deep you cut, which in turn makes the bit take a big bite. But note as well that for a 1/2" collet router head, you can get a 1 1/4" depth plunge at a very reasonable price of about $20. That should easily cover a 1" thick piece of stock.
Or you could index your template, flip it over, and cut from the other side and get about 2+ inches form the bit.
I use the bottom bearing flush cut bits for laminate work, but for pattern work/woodwork I always pick the top ride bearing style. You have a lot more control and you can adjust your cut/bite on the fly by eye if you want. It is safer and easier for me.
Of course, YMMV....
Robert
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