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Discussion Starter · #1 ·
Can someone explain to me the why's and which of buying a flush trim bit depending on application your using it for. I have some 5/8" maple plywood with solid edge trim I glued on it 1/4" thick. The trim was stock at 3/4". So I need to remove the overlap to make it flush. I see 3 or 4 sizes of bits with end bearings. All in all I am trying to peel away 3/16" on a 1/4" thick material. My router is 1/4" shank. I was told I can't do this on 1 pass.
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John
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Can someone explain to me the why's and which of buying a flush trim bit depending on application your using it for. I have some 5/8" maple plywood with solid edge trim I glued on it 1/4" thick. The trim was stock at 3/4". So I need to remove the overlap to make it flush. I see 3 or 4 sizes of bits with end bearings. All in all I am trying to peel away 3/16" on a 1/4" thick material. My router is 1/4" shank. I was told I can't do this on 1 pass.
Thanks for the reply's
Hi - I'd go with a 1/2" flush trim bit (or the largest you have). Size isn't terribly important with flush trim -- larger than the amount to be removed if possible. My own feeling is that the larger diameters give a smoother surface because they are attacking at a shallower angle. Just my opinion, no research or anything to back it up.:smile:
I don't know why you couldn't do that in one pass.:blink:
 

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With a 1/4" shank I wouldn't go any bigger than a 1/2" cutter. In fact, I don't know that I've seen them bigger with that shank size. If the cutter outsizes the shank by too much it can produce bit wobble - especially with 1/4" shank bits - which leads to the bit overcutting the bearing.

The only things I use 1/4" bits for are flush trimming laminates or for running very small profiling bits like small round overs, coves, etc. You should be ok flush trimming 1/4" thick wood edge. Is your solid edge maple too?
 

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Discussion Starter · #4 · (Edited)
Solid edge is maple. I would buy the 1/2" shank bits but my router a 1/4" Ryobi has been a work horse and I love it. I started with my 3/8" flush trim bit but it was tearing the wood up in places. So I stopped. Right where the thickness varied to 3/16" overlap. Where the overlap was less it worked flawlessly.
 

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Old School
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I use ¼" shank ½" diameter flush trim bits quite a bit. Three flutes cuts very smooth. For the wood edging, I allow 1/16" overhang, which is easy to trim. If you don't push the router, ¼" shanks hold up well. Those bits come in different lengths, and if you are using a short cutting length, it doesn't give much room to adjust the bit up or down to use fresher edges.

If you use longer bits, you have to be careful not to tip the router (if using handheld), or tip the stock (on a router table), as the bit will mill off at an angle due to how far down the stock the bit is riding. You may find some of the face being sheared off.

I use ½" shanks with the long ½" diameter cutters, and some with double bearings. You may find that using a 3/8" diameter cutter on wood edging works pretty good, as it doesn't have as much wood to rout. With the thin bits like that, you have to have a gentle feed rate.






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gowings said:
Solid edge is maple. I would buy the 1/2" shank bits but my router a 1/4" Ryobi has been a work horse and I love it. I started with my 3/8" flush trim bit but it was tearing the wood up in places. So I stopped. Right where the thickness varied to 3/16" overlap. Where the overlap was less it worked flawlessly.
It's possible that - assuming your bit is sharp - the wood edge tearing out is more due to the difficult nature of routing maple than it is to the bit being used. If the grain direction is running against the feed direction of your bit, it's going to tear out no matter what kind of bit you're using. Whenever I run a profile in maple, I run the router backwards to prevent the cutting flutes from digging into the grain. You have to be very careful in doing so, as the router will want to take off on you.
 

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I use a 1/4" down cutting spiral bit to trim solid wood banding with no tearout on even the toughest of grains (I use it in a Bosch Colt Palm router)

edit: I replaced my "high end name brand bit" that I dropped with this Yonico that I had never heard of but read good reviews on and surprisingly it cuts just as good at half the price.

http://www.ebay.com/itm/Flush-Trim-...679656015?pt=Routers_Bits&hash=item564e3aae4f

 

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John
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I use a 1/4" down cutting spiral bit to trim solid wood banding with no tearout on even the toughest of grains (I use it in a Bosch Colt Palm router)

edit: I replaced my "high end name brand bit" that I dropped with this Yonico that I had never heard of but read good reviews on and surprisingly it cuts just as good at half the price.

http://www.ebay.com/itm/Flush-Trim-...679656015?pt=Routers_Bits&hash=item564e3aae4f

http://s29.photobucket.com/user/MrMarv/media/Stuff/IMG_20130702_171317_zps2ae885d5.jpg.html
Just half the price?? :thumbsup: I just picked one of those up last week. Haven't had a chance to use it yet but I have several Yonico bits that I have been pleasantly surprised with. :smile:
 

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Discussion Starter · #10 ·
It's possible that - assuming your bit is sharp - the wood edge tearing out is more due to the difficult nature of routing maple than it is to the bit being used. If the grain direction is running against the feed direction of your bit, it's going to tear out no matter what kind of bit you're using.
:thumbsup:I think you hit the nail on the head here. I was thinking it was grain related also. I had 12 lengths of 8 foot maple edging to router. Out of those 12. Ten worked great the other 2 now have some tear on them. Good thing is the tear is against the backside of the veneer plywood and not noticeable since that edge is 3 inches off the floor.
 

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Just a thought but could you put a larger diameter bearing on the bit so you take less material off in the first pass then switch back to the original bearing and make another pass to get a flush trim. Like I said just a thought. :)
 

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Just a thought but could you put a larger diameter bearing on the bit so you take less material off in the first pass then switch back to the original bearing and make another pass to get a flush trim. Like I said just a thought. :)
I've done that. It's a PITA. You could just lay up a spacer for the bearing to ride on, for the first pass. Then remove the spacer.




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Discussion Starter · #15 · (Edited)
This maybe the ticket for my plunge router job. Can you buy a spiral bit with a 1/4" shank and length of approx. 3.5" I need to reach inside 2" to the bottom of a round circle 3/4" template I made to remove 1 1/4" of plywood material with my sleeve collar. I figure 2-3 passes.
P.S. I'm stumped, what's the diff on up cut or down cut bits for application purposes.
 

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John
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This maybe the ticket for my plunge router job. Can you buy a spiral bit with a 1/4" shank and length of approx. 3.5" I need to reach inside 2" to the bottom of a round circle 3/4" template I made to remove 1 1/4" of plywood material with my sleeve collar. I figure 2-3 passes.
P.S. I'm stumped, what's the diff on up cut or down cut bits for application purposes.
I think I see a couple of issues on this one. At least I think so. By "3/4 template" are you saying the template is 3/4" thick?:blink:
I suspect you will run out of plunge depth and/or have the collet nut in contact with the guide bushing (not a good thing) before you get the desired depth of cut. Let us now a few more specifics and maybe get some other suggestions.
Upcut vs. downcut - That simply defines the direction the chips get pulled. The upcut pulls them toward the collet, the downcut pushes them away. Downcut is generally preferred when doing things with veneered stock as it will tend to reduce tearout along the cutline. Downside is if you are doing a non-through cut, it will pack the chips in the bottom like you wouldn't believe. Personally, I have found single edge O-flute upcuts to do just as well as the downcuts in those situations without the packed chips and resultant heat buildup.
I have a suspicion you may be in market for a 1/2" router and just haven't realized it yet:laughing:
 
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