# Different diameter flush trim bits



## losttree (Oct 2, 2010)

I'm new. I got my router to work on a project building loft beds for my kids. To help me do 2 at a time, I got a flush trim bit which was really helpful. 

My question is this, why are their different diameter flush trim bits? I understand different lengths and bearing position but why would anyone need a 3/4 inch diameter bit versus a 3/8 inch for example? 

Thanks,

Adam


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## losttree (Oct 2, 2010)

ps this probably belongs in the bits group instead of here. I just realized I goofed, sorry.


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## Mike (Nov 22, 2004)

A very good question Adam. The larger bits remove a lot more material so they are faster cutting. For tight corners you need the smaller size to manuver, but they cut a lot slower. Make sense now? Keep asking, we all learn from the process.


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## bobj3 (Jan 17, 2006)

flush trim bits

Just my 2 cents, heat kills any router bit the bigger the trim bit the less heat you will build up on the cutters, sometimes you need the small ones but it's best to use the bigger ones if you can.

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## Mike (Nov 22, 2004)

Good point BJ, I agree.


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## losttree (Oct 2, 2010)

Thanks for answering, those reasons make sense to me. I hadn't thought about the smaller corners. Would you run the router on different speeds based on how big the bit diameter is or adjust feed rate or would they be more or less the same.


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## bobj3 (Jan 17, 2006)

feed rate and speed, It's more or less the same 

I should note the one I like to use more than all the others I have is 1/4" shank one with a 1/4" diam. cutting head but it must be replace all the time, it will make the tight turns that I do a lot of the time.

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losttree said:


> Thanks for answering, those reasons make sense to me. I hadn't thought about the smaller corners. Would you run the router on different speeds based on how big the bit diameter is or adjust feed rate or would they be more or less the same.


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## Pete_Judd (Oct 19, 2010)

I use a bunch of dif dia's, from 1 inch down to 1/4 depending of the curve dia.


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## Phil P (Jul 25, 2010)

I find the smaller the bearing diameter the shorter the life of the cutter and with laminates especially the more likely the cutter is the clog up with contact adhesive squeeze-out


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## bobj3 (Jan 17, 2006)

Hi Phil

You can replace the bearing with one of the sq.ones with Teflon cover and it will help with the life of the bit and it will not clog up with contact adhesive..

http://www.mlcswoodworking.com/shop...l/pages/katana_bits4.htm#laminate_trim_anchor
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Phil P said:


> I find the smaller the bearing diameter the shorter the life of the cutter and with laminates especially the more likely the cutter is the clog up with contact adhesive squeeze-out


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## Phil P (Jul 25, 2010)

Thanks Bob. I've tried them, but they're still not generally available over here in the UK (certainly not where I live/work). One day, maybe.


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## bobj3 (Jan 17, 2006)

Hi Phil

That's strange I was sure you had them in the UK, they have the europe name "Euro " Trade Mark like many of the items from over the pond..



Whiteside Router Bits from Woodworkersworld.net--Laminate trim, bevel router bit


A Euro Square Bearing added to a quality Whiteside Trim Router Bit. 
The square bearing stop spinning as soon as it touches the work piece. 
Then the side of the square simply slides along the work piece edge. 
Compare this to a regular bearing that rolls along the edge, building up more glue and reside with every revolution. 
Plus the square is made of non-stick Teflon, so it wipes clean and won't mark your work piece. 
These bits are designed with a slight taper on the cutting diameter. 
This allows up or down adjustment to achieve an exact blend, even after sharpening.

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Phil P said:


> Thanks Bob. I've tried them, but they're still not generally available over here in the UK (certainly not where I live/work). One day, maybe.


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## istracpsboss (Sep 14, 2008)

I was intrigued when I first saw them advertised, some months ago. I deal with vendors in the UK and Germany as well as North America and I've never seen them anywhere in Europe either.

Cheers

Peter


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## Phil P (Jul 25, 2010)

Hi Peter

Like you I've found them difficult to source. I bought my one and only from the USA but when it was dropped on a concrete floor the bearing cracked so that was that because the cost of shipping from the USA was ridiculous. I've just found out that CMT do sell a triangular bearing bit called a 3-in-1 which I might give a try especially as it's on offer. For most laminate work I still use either this sort of cutter (with the pi;ot dipped in Vaseline from time to time), or a straight cutter in the GKF600 (Colt) with the bearing guide.

For heavy flush trimming work, such as template routing in 18mm (3/4in) plywood or MDF I've been using Wealden Multi Trim replaceable tip bits for 4 or 5 years now. The replaceable tips are a boon and the 19mm diameter means they are less harsh on MDF templates


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