# I need help with choosing a double bearing flush trim bit



## tdale (Feb 18, 2012)

I'm buing a flush trim bit, with both top and bottom bearings, and I need it to cut 2". 

I found these three bits, but can't decide which one to choose. Katana and MLCS also have the bits as a kit, with some extra bearings, for overhang routing, while the Rockler bit comes as a kit. I don't really need the overhang option, since I'll be using it for flush trim, but who knows...maybe I will need it some day. Anyway, I'd appreciate to know which brand you guys prefer.

Any tips on which one to choose? I haven't bought high quality bits before, expecially not from the US, so I don't know the brands at all. 

Katana® Rabbeting Router Bit Kits, Round Nose / Core Box Router Bits, Flush Trim Router Bits

MLCS Flush Trim and Shear Angle Flush Trim Router Bits

Rockler Trim Router Bit Kits - Rockler Woodworking Tools


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## bobj3 (Jan 17, 2006)

Hi

If you are going to put out 40.oo for a trim bit I would select the Katana one, a bit for many jobs but if you are low on funds then the Shear one from MLCS..
But

I will add one to your list, it's great bit for trim work but it's only 1 1/4" long cut but it will do 2" thick stock also. but the 1/4" shank works the best ,it will get in the corners or round the sharp corners easy.

Spiral Flush Trim Router Bit
MLCS solid carbide router bits

only 17.oo with free shipping ▼
Solid Carbide Flush Trim Router Bit- Spiral Upcut - 1/4" Shank - Yonico 14121 | eBay
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tdale said:


> I'm buing a flush trim bit, with both top and bottom bearings, and I need it to cut 2".
> 
> I found these three bits, but can't decide which one to choose. Katana and MLCS also have the bits as a kit, with some extra bearings, for overhang routing, while the Rockler bit comes as a kit. I don't really need the overhang option, since I'll be using it for flush trim, but who knows...maybe I will need it some day. Anyway, I'd appreciate to know which brand you guys prefer.
> 
> ...


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## Drew Eckhardt (Aug 2, 2008)

tdale said:


> I'm buing a flush trim bit, with both top and bottom bearings, and I need it to cut 2".



Amana 47097. 2" long, 3/4" diameter, down-shear, about $50

Amazon.com: Customer Reviews: Amana 47097 FLUSH TRIM DOUBLE BB 3/4 DIA
http://www.amanatool.com/routerbits/down-shear-trimmer-47094.html

Or the Rockler for $85; it's a down-shear bit too and may work a bit better at a full 1" in diameter.

The MLCS double bearing and 2" flush trim bits don't have shear angle and will be less friendly when they encounter grain reversals.


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## tdale (Feb 18, 2012)

I'm a bit curioius about the spiral bits... What are the advantages compared to a regular straight or shear bit?


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## Mike (Nov 22, 2004)

Read the sticky threads Tommy.


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## bobj3 (Jan 17, 2006)

HI Tom

For me, they are solid carbide router bits they will stay sharper longer than the norm.


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tdale said:


> I'm a bit curioius about the spiral bits... What are the advantages compared to a regular straight or shear bit?


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## tdale (Feb 18, 2012)

Maybe this is what I need? It hasn't got the top bearing, which enables me to turn the work piece, with the template still attached, so avoid tear outs... but the spiral bit doesn't tear that much, does it?

RFT5200 SOLID CARBIDE 2 FLUTE UP-CUT SPIRAL FLUSH TRIM ROUTER BIT 1/2 DIA X 2" CL X 1/2" SHANK: Amazon.com: Home Improvement


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## ggom20 (Feb 1, 2012)

Hello!

spirals:
Easy example,say that motor stays at top of the work , like a press-drill:
- the usual spiral drill-bit it pulls dust or shaves upwards,
nicely taking shaves out of the hole but it also will pull up surface wood and cause
chipping at up -side thats a upcut.

Down-cut will push chips, shaves or dust downward rxaxtly contrary.This will cut a 
nice surface at motor-side, and a bad at end side.

Some got upcut and downcut to keep both sides clean.

You can read mike here:
http://www.routerforums.com/router-bits-types-usage/28685-spiral-vs-straight-bits.html#post237388

In practice, its necessary to finish a flush trim by a little chamfer, a laminate nicely
cut at 90° is cutting like a real blade, you can cut your skin on it.

Regards


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## billg71 (Mar 25, 2011)

I like the Freud 50-509


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## tdale (Feb 18, 2012)

It's hard to decide! I got one guy telling me that 2" tall bits will wear out almost at once, if I use them on a guitar body (almost 2" thick") and that even 1/8" or less wood after rough cutting, will be to tough on the ibt and router. He recommends a top bearing bit, which I raise about 1/4" for each pass in stead. 

I would really like to have a 2" spiral bit, to do the job in one pass.....why do they sell these bits, if they won't work properly?


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## ggom20 (Feb 1, 2012)

Hello!
Many nice bits in your list now!
Withch way are you going to work?
table router or hand-held ?
*IMHO*
About taking 1/8 , a solid carbide will take it easy ! , the only thing is the more
you take , the more the bit will catch and destroy wood surface, depending on wood fibers direction. leaving more trouble for finishing, like sanding. 
Get this nice solid carbide , and when it sounds difficult, have a look why, reduce feed.
Maybee file or hand saw a little.
Some woods are better than other for this kind of works too.

Regards


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## tdale (Feb 18, 2012)

I'm going to use it in a table. Now the challenge is to find the right (cheapest/best) spiral bit...


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## ggom20 (Feb 1, 2012)

hello!
IMHO:
make a list of what is your choice in 2 inches long:

Spiral = 85 $ to 89$

Straight= 40 $

A spiral unless it is a compression spiral will chip a lithle on one side.

Didnt find compresson spiral at 2 " cut.

I'll go for a katana #18816 with 3 bearing size , one can make a progressive approach
to the patern.Those bearings are designed it.
Katana® Rabbeting Router Bit Kits, Round Nose / Core Box Router Bits, Flush Trim Router Bits
You can probably buy bearings to fit on collet-side too.
35 pc. Bearing Repair Kit Details
And about edge- chipping , never seen a guitar with straight edge, so it will disapear in
rounding or chamfer operation.

By the way, what's the wood you plan to use?

Regards
(I once made a straight edge so straight it did cut a bit in my finger, so now i round or chamfer every edge.)


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## tdale (Feb 18, 2012)

Thanks. I've looked at the Katana bit, but I think I' going for a spiral bit. Mainly alder, basswood and some ash for the 2", and maple, but only 1" thick...


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## ggom20 (Feb 1, 2012)

Hello!
IMHO:
Try a solid cabide spiral if you fell its better!
You still can add bearing beteewn the collet and the cutter , like the katana.
It's easy to find various bearings and stop- rings, it could give you the advantage
of changing cut direction if grain direction changes.
Please, show us this guitar body when done!

Take good care of wood selection I don't know much about guitar making , but sure I know some woods are very likely to move too much.
Regards


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## gav (Oct 12, 2009)

How about the ultimate spiral pattern bit.


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## billg71 (Mar 25, 2011)

gav said:


> How about the ultimate spiral pattern bit.


Good call, Gav. I forgot about that one! 

Here's a link

Wonder where you can get it sharpened?


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## ggom20 (Feb 1, 2012)

Nice!
Just needs a second bearing on top.

And true it looks like difficult to sharpen need for elaborated machinery.
A straight carbide is easy to sharpen with diamond.
Material is hss cobalt, not bad but not carbide.

Do they make them with forced hight pressure air-duct at center of bit for forced
air chip cleaning and cutting edge cooling ? (for the latest bosh plunge router prototype.)
The red laser pointing device is a very cool new feature too.

Regards


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## gav (Oct 12, 2009)

Do you have a link for this new Bosch router prototype ?
I couldn't find any information about it.


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## ggom20 (Feb 1, 2012)

hello!
About a link, no link, sorry it' s prototype.
Engineers try things but not always show or put in the market.
It has to be seriously tested before, but the cooling air-flow can reduces
cobalt migration due to heat at the cutting edge.
Getting cutters to last 30% longer.

Regards


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