Lock Miter Router Bit - Any Experience?

Rennie Heuer

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I have a project coming up that has as a main part a tapered mitered four sided tube. I made a small taper jig that I can use to cut a 45 bevel on the tapered sides, but gluing those four sides together, even using the masking tape method, looks like it might be a real strain on my limited patience. :rofl: Also, although the jig worked well, I could see where it might have some small accuracy issues.

So, I started looking at lock miter router bits. Read lots of reviews and they tend to be either hate or love, very few in between. It seems that the overwhelming majority of negative reviews dealt with the time involved in set up and the finickiness of the miniscule adjustments necessary to get a good joint. What I did note is that the people that had the worst time with set up were using a trial and error approach. Looking a little deeper I found a number of companies that make set up blocks or jigs to take (presumably) the mystery out of the set up and give you a good joint with less time and scrap.

Right now MCLS is selling their smaller bit (for 1/2" to 3/4" stock) and offering their set up block for free. That is quite a savings. $38.50 for both. The sale runs through January.

So, Who here has used these bits and what has been your experience? Is the set up block the answer to most of the woes cited in so many reviews? For under $40, can you go wrong?:huh:
 
Well, I don't think they are worth the time and money. Set-upblocks are something you can make when you finally have the darn thing dialed in. So wonder they are free! Unless you plan on making a bunch of items with them or plan on getting all your money back on this one project, I'd use your jog, with which you already have experience.

As for gluing up, invest in some wide rubber bands. Using them as clamps, at least you can see what you are doing as opposed to the masking tape.I'd even consider gluing one edge at a time in turn and drying clamping the other edges, keeping the whole in alignment.

FWIW, I co red them very briefly in my book, but I spent a considerable amount of time trying to come up a fool proof way to make the investment worth the money. Failed miserably, so these things are not my first rodeo.

Save your money.
 
I've only used mine once on a humidor (https://goo.gl/photos/spCMxKAe7wcKhmVDA). I do recall it being a pain to setup, but once I got that done it worked perfectly. I did all the corners and the top so there was no end grain on it showing. I do recall cutting a 45* filler to go on the outfeed side of the bit to help hold my work as it fed through, but may not be necessary.
 
OK, Count me as in between.

It's a bit of a beast to set up, but once setup it makes a nice joint. Lot of glue surface area for a miter joint.

It has been a long time since I last used it.

Honestly I forgot I had it.

I'm not going to rant and rave either way.

I will probably use it again. I would not "buy" it again. I would use it again because I have it, and it is kinda cool.

Cost justify it? Nah not even gonna try that! Heck, for that matter I'm not going to try to cost justify a night out with Diane for a dinner and movie night. If you wanna try it and play with it and enjoy the time in the shop - go for it. If you need to cost justify it - save yer money.
 
I have a small one (wood up to 1/2 inch) and a big one (1/2 to 1 inch, if I remember right). I don't use them a lot, but....

It has been a long time, but what I recall ... recognize that you have a mortise and tenon in the middle of a miter. Be sure you have exactly the same amount of miter above and below the lock stuff. (If you have it right, you can flip one board over and join it to the other.) In this first alignment, the fence is only used roughly to keep from cutting too deep. Once the height of the cutter is set, don't touch it any more. The second cut is against the fence rather than the table, so adjust the second cut only by moving the fence, not the height of the cutter.

Fine Woodworking had an article years ago that was absolutely wrong - they even apologized in the letters to the editor several issues later. If you are putting together four pieces called A, B, C, and D, cut both sides of A and C on the table, both sides of B and D on the fence. Fine woodworking said to do the first side of each on the table, second side of each on the fence, and the result was as hard to glue up as if you had just done plain miters.

If you do the lock miters right, you only have to clamp in one direction. You can also use it to join two boards side to side or end to end, with both cuts on the table.

Hope I remember the details right!
 
I've looked at them, but am too cheap to buy. To strengthen miters on boxes, I use a spline along the length of the miter or a contrasting key across the miter in 2 or 3 places to dress it up.
 
I've got one - somewhere. I bought it maybe ten years ago, used it a couple times, but got frustrated with its being so finicky. Haven't used it in a long time.

Regarding Carol's suggestion for using large rubber bands as clamps. I do that all the time, but an even better alternative if you've got a medical supply house nearby is surgical tubing. It's relatively inexpensive; comes in several sizes (elastic strengths) and really works well for holding odd shapes together while the glue dries. I've never looked, but I'd bet Amazon has it, too if there's no medical supply house nearby.
 
I have the set, and bought the Infinity set up thingy. It really does solve the set up problems....or at least it did for me. In the pic below is a the very first test joint I made with the bit. I had never used one before, and this was the first pass. It's not perfect, but very, very close. That said, the jigs aren't exactly cheap, but if you plan on doing a lot of work with the bits they are probably worth it.

LM.jpg
 
I have the bit, I do not have the setup block/gauge. Setup takes a little time but once done, it works great. I use shims along the router fence to lessen the size of the cut on each pass and progressively remove them to get to the final depth. Minimizes any tear out and just makes it easier to keep the wood moving. I used large hose clamps and some blocks for glue up.

P1010904.JPG P1010901.JPG P1010935.JPG P1010906.JPG P1010030-1.JPG

Having said this, I have also had good luck using splined miters. I even used the jointer to make the miters dead flat/even.
P1011336.JPG P1011333.JPG P1011338.JPG P1011339.JPG P6130037.JPG

Either way, the joints are strong and tight. Good luck.
 
I have that exact set with set up block. Still a bit finicky. I did get a real good fit and finish after much fooling around. Would I buy it again - NO. Wasted to much time setting up. Better to use a different method.
 
used a set some rennie without the jigs, but now have the infinty setup like fred mentioned once you get it set up it glues up fine,, used that joint on the hoosier and sever cabinets in the past..
 
I have the lock miter bits and the Lock Miter Master gauges from Infinity Tool to set them up, but I have mixed emotions about using them because I frequently get too much tear-out in the center of the cuts when making them. I think trying to remove that much wood in one pass is the main cause of this, and I have experimented with ways to make the cuts in two passes at increasing depths, but it's just so much easier for me to just make and use splines, so it's been several years since I've even tried to use my lock miter bits.

I now make cross grained splines using my Delta tenon jig set so that the spline is actually the off cut between the jig face and the saw blade. Once set correctly I can then make a spline from each face of a board, then flip the board end for end and make two more splines. I cut them free using my miter saw with a stop set to cut the splines to the correct length for my needs. What would usually be the created tenon in this process becomes scrap. I can make 4 splines on a board and then cut them free, then go back to the table saw and tenon jig and cut 4 more splines from the same board and all of them will be within a few thousandths thickness for a perfect fit to whatever blade kerf that I made when cutting the spline slots in my mitered corner joints. I do this because long grained splines, although much easier to make, do not increase the strength of a mitered joint nearly as well as the cross grained splines do.

Charley
 
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