Using the Lock Miter Router Bit

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Forum topic by Chris posted 2193 days ago 14477 views 1 time favorited 11 replies Add to Favorites Watch
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1867 posts in 2618 days

2193 days ago

Topic tags/keywords: router router bit lock miter lock miter bit

Do any of you have experience using a Lock Miter router bit?

I have one and tried it the other day; that was a very scary bit. I found it very hard to control the pieces of wood safely.

I think it could be a very useful addition to my arsenal if used properly; but how ?

-- "Everything that is great and inspiring is created by the individual who labors in freedom" -- Albert Einstein

11 replies so far

View bhack's profile


348 posts in 2347 days

#1 posted 2193 days ago

I have one and have never been able to set it up for anything less than 3/4 inch stock. I got a set up block from Rockler but unfortunately the bit was not from Rockler so no help there. I suppose a lot of patience would pay off.

-- Bill - If I knew GRANDKIDS were so much fun I would have had them first.

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11295 posts in 2501 days

#2 posted 2193 days ago

I got a bit and a set-up block from MLCS, but I haven’t tried it yet.

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1867 posts in 2618 days

#3 posted 2193 days ago

my bit came from MLCS tool. I think….

-- "Everything that is great and inspiring is created by the individual who labors in freedom" -- Albert Einstein

View fredf's profile


495 posts in 2336 days

#4 posted 2193 days ago has a pretty good method of setting up. once you get it right save a sample to make it easier the next time!!!!


-- Fred, Springfield, Ma

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John Nixon

189 posts in 2690 days

#5 posted 2163 days ago

Hi Chris,

Although my bit isn’t from MLCS, the setup procedure is the same. The first video in my pool table series covers the setup of the Lock Miter bit:

-- John Nixon - Buffalo, NY -

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1867 posts in 2618 days

#6 posted 2163 days ago

Thanks for the Link John!

-- "Everything that is great and inspiring is created by the individual who labors in freedom" -- Albert Einstein

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1867 posts in 2618 days

#7 posted 2163 days ago

Skeez… I like your method; it’s far more economical than purchasing a dedicated coping sled or other such jig.

-- "Everything that is great and inspiring is created by the individual who labors in freedom" -- Albert Einstein

View botanist's profile


150 posts in 2165 days

#8 posted 2104 days ago

I was a little late to this discussion, but I thought I might add my 2 cents. I recently found an article about using lock miter bits to create quadrilinear posts in the mission style, but I can’t find it in my files. Here’s a link to the article:

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Thos. Angle

4435 posts in 2589 days

#9 posted 2104 days ago

WoodShopDemos. John Lucas has the technique you need. Works every time.

-- Thos. Angle, Jordan Valley, Oregon

View Jim Jakosh's profile

Jim Jakosh

11297 posts in 1732 days

#10 posted 1732 days ago

Hi Chris. I found this site by looking for Lock Miter instructions that I could post in my shop. Anyway I have had an MCLS lock miter bit for years. I tried to use is on my old router table and it was a bust. The boards moved too much during cutting and took away too mch material. NOW I have a new router table with a true fence and a Woodpecker Quick Lift router insert. I have used it to make a nice box for my wife’s woodburner using 1/2” stock. I recentley made 3 drawers for my daughter using 3/8 stock and had to brorrow a smaller one from my good friend , Tim the toolman!
Using the MCLS bit was frustrating because I did not have set up instructions or a set up block. This 3/8 cutter I borrowed had instructions and I’d like to share some learnings to make it faster to set up.

First, to rough set the bit height, line up the center of the cutter with the center of the thickness of stock you are using. I found that the center of the bit was the bottom edge of the finger coming out( for lack of a better term on the cutter).
Then set the fence by getting the top edge of the stock to just intersect the 45 degree edge of the cutter- by eye is good enough.
Now cut two pieces of scrap stock of that same thickness laying flat and sliding along the fence through the cutter. Flip over one piece to see if they come together perfectly aligned. If not, move the cutter up or down to achieve perfect alighnment. Then the cutter height is set and needs no more adjustment.
Now cut two more scrap pieces on the table and against the fence to make the joint. Check for corner alignment. If they are off, just move the fence to gain perfect corner alignment. Use two new pieces for each trial because the fence controls both cuts. One you get it aligned, save samples for set up next time!!

I have found that you cannot trust the edge of the wood on the vertical cut to be the same after the cutter, so I clamp a board very tightly to the board and slide it along the top of the fence to feed the board through the cutter. This insures a straight on the edge. I could not do this on my old router table and it always dropped a little and dug in cutting away too much wood. I use a pusher to hold the board against the fence throughout the cut too.

Good luck!! This is now an enjoyable joint to make for me….................Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View Bret's profile


162 posts in 2121 days

#11 posted 1732 days ago

I just found this guide, which looks to be an ideal approach and it echoes what I was trying to do myself, trying hard to apply my degree (mathematics) to this basically geometric problem.

While I was using two scrap pieces planed to the thickness of my actual stock, this guide takes one piece, cuts a bit off the end and flips it to test, but the approach is the same:

Once the height is set so that two pieces cut flat on the table mate perfectly, the fence can be adjusted so that two pieces cut flat against the fence also mate perfectly. At that point, it should be safe to make a setup block of the location and proceed to routing your miters.

Dang. All that math just came in handy!

-- Woodworking is easy as 3.14159265358979323846264338327950288419716939937510...

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