# Question about flush trim/pattern bit



## LBrandt (May 9, 2006)

Hello,

I plan on building a bookcase using 3/4 inch stock. I'm going to cut a radius at the top edges of the bookcase sides, so that they will slope back slightly. Since I want the curves on both sides to match perfectly, I plan to make a template with a jigsaw (probably out of 1/4 inch MDF), then with that on top of the side, use a router with a bit to cut the curve. I'll do the routing by hand, and I want to put the template on top of the piece to be cut. 

I have a few questions:

One, do I want a pattern bit or a flush trim bit, or are they both the same? 

Two, assuming that the template is 1/4 inch MDF, does the size of the bearing matter?

Three, does the length of the cutter matter?

You can tell that I'm still somewhat of a novice about routing, but I have done some. I'll be using a Bosch 1617EVSPK router. 

I guess that what I'm asking for is a recommendation of what bit to use. I prefer Freud bits, and I prefer 1/2 inch shanks, so if you know the number of a Freud bit that would work well for this, please advise.

Thanks,
Louis


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## rweerstra (Feb 9, 2010)

http://ecx.images-amazon.com/images/I/3118BN8XXJL._SL500_AA300_.jpg

Check this one out. I tape the pattern on top, a top bearing bit and you are good to go. You obviously will not want to use the plunge feature


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## rweerstra (Feb 9, 2010)

Sorry, I think the number is Frued 50-101.


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## LBrandt (May 9, 2006)

Thanks, but when I looked at that link, it stated that it has a 1/4 inch shank. I prefer a 1/2 inch shank. Can you recommend one with a 1/2 inch shank?

Thanks.
Louis


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## Marco (Feb 21, 2009)

#7804 Might be what you are looking for.......... not Freud but a good bit for 9 bucks

MLCS Flush Trim and Shear Angle Flush Trim Router Bits


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## LBrandt (May 9, 2006)

Thanks. That bit looks like it has the bearing on the bottom, and since I intend to have my template on the top of the work, I think that I'd need a bit with a bearing on the top. I noticed that they do have flush trim bits with bearings on both top and bottom, so I assume that type of bit would work for me. 

I'd still prefer a Freud bit.

Thanks,
Louis


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## jschaben (Jun 21, 2009)

LBrandt said:


> Thanks. That bit looks like it has the bearing on the bottom, and since I intend to have my template on the top of the work, I think that I'd need a bit with a bearing on the top. I noticed that they do have flush trim bits with bearings on both top and bottom, so I assume that type of bit would work for me.
> 
> I'd still prefer a Freud bit.
> 
> ...


Hi Louis - I think this is what you are asking for:
Freud 50-122 Top Bearing Flush Trim Router Bit

Unfortunately, I don't think that bit will work for you with 1/4" thick template. I looked for a dado cleanout bit but all I could find at the Freud website were dado saw blades. 
Why not a 1/4" shank bit?


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## bobj3 (Jan 17, 2006)

Hi Louis

If you use the brass guide in your router table you don't need to buy the high price bits, just put your template on the bottom  it's that easy.. 

http://www.routerworkshop.com/multipleguides.html
========


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## LBrandt (May 9, 2006)

bobj3 said:


> Hi Louis
> 
> If you use the brass guide in your router table you don't need to buy the high price bits, just put your template on the bottom  it's that easy..
> 
> ...


Hello BobJ3,

Thanks for the reply, but (A) I don't really understand what the brass guide is or how to get one, and (B), it looks like it would be more complicated to use than a simple flush trim bit with a hand-held router. Again, I'm still a router novice, but that's just what it looks like to me.

Thanks,
Louis


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## LBrandt (May 9, 2006)

jschaben said:


> Hi Louis - I think this is what you are asking for:
> Freud 50-122 Top Bearing Flush Trim Router Bit
> 
> Unfortunately, I don't think that bit will work for you with 1/4" thick template. I looked for a dado cleanout bit but all I could find at the Freud website were dado saw blades.
> Why not a 1/4" shank bit?


John,

Thanks for your reply, but I don't understand why you're saying that the bit wouldn't work with a 1/4 inch thick template. Why would that be a problem? 

As far as why I want a 1/2 inch shank bit, it's just that most woodworkers seem to say that 1/2 inch shank bits are more stable, and I've already bought a few 1/2 inch shank bits, and I'd like to have more of them. 

Thanks,
Louis


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## jlord (Nov 16, 2009)

Hi,
Just go to a local Home Depot. They carry Freud bits & get a 1/2" shank Pattern bit it will have a top bearing. You might want to route with some scrap ply underneath so you don't route into your table top. If no scrap available just hang over edge & work your way around. You can also use flush trim bit with your pattern just put pattern on bottom instead of on top.


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## LBrandt (May 9, 2006)

Thanks James,

I still have two questions. First, I still can't understand why John said that he didn't think that the Freud bit that he mentioned would work with a 1/4 inch template. What difference does the thickness of the template make?

Second, you mentioned a pattern bit, then you mentioned a flush trim bit. Aren't they the same thing? Or do you call it one name when the bearing is on top and another name when the bearing is on the bottom? 

Remember, I'll still somewhat new to routing, so be patient with me.

Thanks again,
Louis


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## jschaben (Jun 21, 2009)

LBrandt said:


> Thanks James,
> 
> I still have two questions. First, I still can't understand why John said that he didn't think that the Freud bit that he mentioned would work with a 1/4 inch template. What difference does the thickness of the template make?
> 
> ...


Hi Louis. With the top bearing bit and a long cutting length , your bit will be buried in the stock before the bearing comes near the template. That bit would work with a 1/4" template given two conditions, one - you were starting on an edge and not trying to plunge and two - your plan was to make the entire 3/4" deep cut in one pass.


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## jlord (Nov 16, 2009)

If you go to Home Depot look at the bits. You can find them with different length cutters. You can also use a mortising bit. It is basically the same thing as the pattern bit but the cutter is short. They are mainly used for mortising for hinges & you don't need to cut very deep, but if the cutter is a little short just increase the depth & make another pass. 

If starting in the middle of your material & not near an edge just drill a starter hole larger than the diameter of your bit to start. No mater what the length of the cutting edge of your bit is you just need the bearing to come in contact with the pattern to start. If you use the mortising bit & you need to increase the depth below your pattern your bearing will ride on an area that was trimmed even with the pattern from a previous pass.

A flush trim bit has a bearing mounted on the bottom & the cutter is usually the same diameter as the bearing trimming you piece flush with what ever the bearing is riding on. A pattern bit has the bearing mounted on the top (shank side) & the cutter is below & on the bottom able to leave you a flat bottom as when routing out a dado etc.


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## LBrandt (May 9, 2006)

John and James,

Thanks again. I see what you’re talking about now, with respect to the length of the cutter and the thickness of the template. 

I don’t think that will be a problem though. My plan is to first use a jigsaw to cut the curve in the 3/4 inch stock. But I’ll cut it “strong”. The pattern bit will just be used to trim it perfect to the template. I’ll also put a piece of scrap material underneath the stock, and it will also be cut first with the jigsaw. 

I don’t expect to have to use a plunge cut, just start somewhere along the edge and cut the entire 3/4 inch in one pass, since all I’ll be doing will be trimming the piece to the template pattern.

I realize that you could just tell me to just do all of the work with the jigsaw, then sand the curve smooth, but I’d like to do it with the jigsaw and the router. It will also give me more experience using my router. 

Don’t you think that this would work with the bit that was 
mentioned above?

Note: After I wrote this, I looked at another Freud bit online, which has a bearing on the top and the bottom. It's Freud number 50-509,and it looks like it would also work for me. And it has the capability to do both pattern and flush trim work, so maybe it's the bit that I need.

Thanks,
Louis


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