What's The Difference Between These Bits?

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Forum topic by Mean_Dean posted 03-02-2010 03:52 AM 5423 views 0 times favorited 7 replies Add to Favorites Watch
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6418 posts in 3114 days

03-02-2010 03:52 AM

A pattern bit, and a flush-trim bit?

It seems to me that one has a bearing on top, and one has a bearing on the bottom. So what’s the difference between them, and which one is best for what use?

Thanks in advance!

-- Dean -- "Don't give up the ship -- fight her 'till she sinks!" Capt James Lawrence USN

7 replies so far

View Alexander's profile


193 posts in 3077 days

#1 posted 03-02-2010 03:54 AM

I don’t know either. Maybe it is, one for a hand held router and another for a table mount router. I’ll be checking back to find out.

-- John at Sugarloft Mountain........Don't argue with an idiot; people watching may not be able to tell the difference.

View bigike's profile


4050 posts in 3255 days

#2 posted 03-02-2010 04:28 AM

a flush trim bit is good for flushing edges to one another a ptern bit is good for template routing and both can be used in either handheld or table mt routers.

-- Ike, Big Daddies Woodshop,

View tooldad's profile


660 posts in 3681 days

#3 posted 03-02-2010 04:32 AM

just a classification difference. I use a flush trim bit when I make a pocket hole face frame. I oversize it just slightly then it can be trimmed exactly flush.

a pattern bit is used when you double stick tape a pattern to a blank and router the shape. this way the pattern can be on top.

when we make adiorndack chairs in the shop classes, we use screws to hold the pattern down, so we use a flush trim bit (bearning on bottom) with a router table. this way the student can see the pattern and the screws are on top and not holding the board up.

View Ger21's profile


1074 posts in 3097 days

#4 posted 03-02-2010 05:28 AM

Also, a pattern bit can cut mortises, a flush trim can’t. Both do basically the same thing, but different. :-)

-- Gerry,

View SnowyRiver's profile


51457 posts in 3447 days

#5 posted 03-02-2010 05:47 AM

A pattern router bit has the bearing on the top of the cutter, and a flush trim bit has it on the bottom. A flush trim bit works best for triming the top of lets say a counter top flush with the edging, where a pattern bit like it says can follow a pattern that can be clamped to the top of the work piece and trim the lower piece to the pattern detail.

-- Wayne - Plymouth MN

View closetguy's profile


744 posts in 3858 days

#6 posted 03-02-2010 07:17 AM

I use a Rockler bit with bearings on both the top and bottom. I use it for flush trim and pattern following. With bearings on both ends, you have a choice of using a pattern on top or bottom of the piece.

-- I don't make mistakes, only design

View Alex Lane's profile

Alex Lane

500 posts in 3857 days

#7 posted 03-02-2010 03:21 PM

As an electric guitar/bass builder, I know that pattern bits (with the bearing between the cutter and the shank) can be used to rout the cavities/pockets that house the electronics and the pickups. They also can be used to make the cavity that houses the neck on instruments with a bolt-on neck design. These are blind (or stopped) cuts that don’t go completely through the thickness of the wood I’m routing, therefore I need the bits that only have the bearing on the top.

I’m usually a proponent of avoiding templates and patterns when building my pieces, but when it comes to features that need to be a consistently standard size, pattern bits and a template can be very useful.

-- Lane Custom Guitars and Basses

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