# Router table modifications for using a lock miter bit.



## johnnie52 (Feb 16, 2009)

If you followed my build thread for the first Baileigh contest you saw me have to change plans when I attempted to use a lock miter bit for the first time.

If you didn't well, the results were not worth trying to use.










Total crap. Good thing I wasn't using the project wood.

Anyhow, I decided that I really needed to figure out some way to actually use the bit and achieve good results so that the next time I want a lock miter I can actually make it happen.

So, after watching every video on Utube that I could find, I set about making some modifications to me router table.

First up was a more solid fence since one of the issues I was having was the workpiece wanted to move into the gap between the fence halves. The fence was simple enough, I just cut a piece of 1/2 Baltic Birch ply to size, cut out an opening for the bit, and (using longer bolts) attached it to the existing fence. I added an perpendicular top piece to the fence to add not only stability against warping, but to provide a base for a sled to slide on.

I next built a sled to firmly hold the work piece for the vertical cuts.

This is pretty simple also. Its just more of the 1/2 ply glued and screwed to a piece of 2x2 poplar with one of those locking clamps attached that is positioned to clamp the work against the 2x2 poplar rather than the fence.










I only used 1/2 materail for this and 1/2 material for the work pieces. I'm not sure how it will work using 3/4 material in the work piece. I may need a different sled for that.

Final piece that I had to make for this project was some kind of a stop stick to "remember" how far back the fence needed to move to reach the bits final cutting depth. For now, all I did was to drill holes in a piece of scrap walnut let over from a Christmas present build a couple of year ago. The holes accepted carriage bolts fitted into the slide tracks for the main fence and I used a couple of knobs for ease of adjustment and/or removal.










The next thing to do is to prevent the work piece from being thrown away from the spinning bit. For this I used my double stacked feather boards which I had made for a previous project. This is why the sled was made from 1/2 rather than 3/4. The sled must pass the feather boards during the cut. So the sled has to be either the same size or smaller than the work piece.










I won't go into great detail here, but set up is rather simple. Set the bit height, set the cut depth, secure the work piece and have at it.

Once everything is set properly, you can take several bites rather than just one big bite and end up with this.










Far better than my first attempt.

The next step is to make matching cuts in the adjoining pieces. I ended up needing a temporary ZCI because I could not figure out a way to hold a rather small piece (only 4" long) in place so it would not move as the bit toughed it.










Something just 2 inches longer would not have had the problem.

Even with the hold down issue and the need to reset the fence depth of cut because of the added ZCI, This time the joint came out very nice.










I know I still need to work on getting everything set up better, but compared to my first attempt, this is a perfect joint and makes a very nice mitered cornered box that comes off the router table square and also holds itself up nicely.










Morale of the story is:

To use a router bit in making a lock miter joint you must have the proper bit set up, a solid fence over the bit, and good method of holding the work piece, and the patients to do everything needed to "get it right."

As you can see the results are rather nice. Except now I have this odd sided box made from poplar to find a use for......


I'll think of something.


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## Dave Paine (May 30, 2012)

Good job figuring out a way to make this bit work. Good explanation. :thumbsup:

I purchased a lock mitre bit at a Woodworking show in the mid - late 90's because the manufacturer was offering a big discount on all their bits. Not a good purchase for me. Like many others I got home and started to attempt to figure out how to use it, then decided too much effort.

So the discounted price turned out to be a bad investment for me. The bit has remained in my drawer for all these years.

At the time I did not have a table saw, only radial arm saw, and it was not going to be accurate enough to cut the mitres.

I now have a good table saw, good mitre gauge. These days if I want to make a mitre joint, I would reinforce with splines.


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## fire65 (Apr 27, 2013)

Got a brand new one still in package. I saw to many horror stories after buying it so I just never got it out.


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## Al B Thayer (Dec 10, 2011)

I used it once just to prove it to myself it could be done. Could have made hand cut dove tails faster. Bought mine in the 90s too. Must have been the same sale as others found. Prolly the only way they can sell them. Too bad there isn't a spot on the bit hat could be used to cut a profile.

Al

Friends don't let friends use stamped metal tools sold at clothing stores.


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## johnnie52 (Feb 16, 2009)

I've had this one for a while also. Maybe its just me but I simply refuse to allow any tool to sit in a drawer unused because I give in to defeat or lack of patience trying to use it. It took me a total of 4 hours to figure it out and build all the needed additions. It then took all of 15 minutes to actually make the box shown. No way I can hand cut dovetails in that amount of time. :laughing:


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## Woodenhorse (May 24, 2011)

This is a jig I built to use for lock miter joints. It holds both pieces of the joint for a simultaneous cut. To sneak up on the cut I add supplemental fences and remove each fence piece for each successive cut. That allows me to use just one fence setting and avoid chip out. Since the pieces are held snug against each other and a backer there is no tear out. It is also adjustable for various board widths between 3/4" and 5"




















The screws on the back side are above my router table fence so they do not interfere.


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## johnnie52 (Feb 16, 2009)

I like that idea. Cut both pieces at once with no tear out... great idea. It looks like you have to set teh bit high though for the sled to go under it without messing up the cut.


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## Al B Thayer (Dec 10, 2011)

Woodenhorse said:


> This is a jig I built to use for lock miter joints. It holds both pieces of the joint for a simultaneous cut. To sneak up on the cut I add supplemental fences and remove each fence piece for each successive cut. That allows me to use just one fence setting and avoid chip out. Since the pieces are held snug against each other and a backer there is no tear out. It is also adjustable for various board widths between 3/4" and 5"
> 
> The screws on the back side are above my router table fence so they do not interfere.


Smart Idea. I love it. Do you use them a lot? Do you cut the boards to the length needed or do you have to add something to make them come out the right length?

Al

Friends don't let friends use stamped metal tools sold at clothing stores.


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## Woodenhorse (May 24, 2011)

Al B Thayer said:


> Smart Idea. I love it. Do you use them a lot? Do you cut the boards to the length needed or do you have to add something to make them come out the right length?
> 
> Al
> 
> Friends don't let friends use stamped metal tools sold at clothing stores.


Everything is cut to size and final length. I like to keep things simple. If I have time I can make up a set up plans in SketchUp if anyone is interested.


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## Al B Thayer (Dec 10, 2011)

Woodenhorse said:


> Everything is cut to size and final length. I like to keep things simple. If I have time I can make up a set up plans in SketchUp if anyone is interested.


Thanks but the pics work fine for me if I need to build one.

Al

Friends don't let friends use stamped metal tools sold at clothing stores.


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## Greg in Maryland (Jan 6, 2011)

Woodenhorse said:


> If I have time I can make up a set up plans in SketchUp if anyone is interested.


I would be interested if yo you the time.

Thanks.

Greg


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## Burb (Nov 30, 2012)

I bought one of these bits about 2 years ago at the suggestion of a tool salesman. I never could make it work, though I did think I had an idea what to do. It just seemed like to much work. One of these days I'd like to figure it out.



Greg in Maryland said:


> I would be interested if yo you the time.
> 
> Thanks.
> 
> Greg



Me too. Thanks

Mark


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## bladeburner (Jun 8, 2013)

'Holy lock miter bit', Routerman! 
That bit is no more complicated than a drawer lock bit.....

Just remember that the top end, divides the bit between inside the fence and outside the fence. Once that's understood, then it's a simple matter of eyeballing (centering up/down) the locking cut, on the 45 degree miter. Because first of all, it's a miter bit.......with a locking notch.

I use a slap-on aux fence for many of my bits that work easier with a ZCI. In fact, it's the same fence and looks like this;










When I need to make leg stock from 1X material, I'll sometimes make them like this;(the joint lines are outlined in pencil for this pic)
I made this leg with the lock notches off center to prove to another woodworker it could be done!











Woodworking is easy.....even I can do it :yes:


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## One Ozark American (Jan 9, 2008)

FWIW, last year Fine Woodworking published an article showing how to use a height gauge to make perfect lock miters. Having tried multiple tips to accurately set the bit up I purchased an inexpensive digital height guage to give it a try. Perfect results on the first attempt with no test cuts. Don't remember the exact issue. I'll look it up. They may have the article on their Website, maybe even in the free section.


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## bladeburner (Jun 8, 2013)

When you saw how easy it is, did you feel a little sheepish? I've shown folks and they always say they were trying to make it too difficult.


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## woodnthings (Jan 24, 2009)

*this photo?*



bladeburner said:


> When you saw how easy it is, did you feel a little sheepish? I've shown folks and they always say they were trying to make it too difficult.


tos 


Just remember *that the top end, divides the bit between inside the fence and outside the fence.* Once that's understood, then it's a simple matter of eyeballing (centering up/down) the locking cut, on the 45 degree miter. Because first of all, it's a miter bit.......with a locking notch.

I use a slap-on aux fence for many of my bits that work easier with a ZCI. In fact, it's the same fence and looks like this;











I don't understand this photo. It shows 2 separate things AFAIC, the finished joint in a clamp and the fence. I'm more interested in your fence setup than the finished joint which we all should know what it looks like... :yes:
Can you better explain the set up and how the pieces are laid on the table ....which side up and so forth? Thanks. :smile:


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## bladeburner (Jun 8, 2013)

That's an old pic, but when I get back I'll take some more. But in the meantime, I can tell you that it's simply a sheet of MDF that has the outline of the bit(s) cutout so that the bit(s) can expose just the amount of cutting surface I will use. Oh yes, and there's printing on the fence itself to remind me which workpiece rides vertically on the fence. Also unreadable in the pic, are notes to myself concerning each bit opening. BTW, the inside of workpiece (inside of the box) is face against the fence/table. Sides of the box are run vertical, ends are horizontal.


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