miter lock bit,,,

[jeff oldham]

maybe im doing something wrong,,i have had 2 of these bits bought from amazon,,one which was 1/4 shaft and bent,,which i sent back,,then i reordered a 1/2 in shaft one,,,and used a backer board in both cases and maybe im doing something wrong but these are really dangerous bits,,,one bent and the other would not cut the material all it did was raise up,,,,if anyone can tell me what im doing wrong or the results they have had with this bit it would be appreciated,,,,if you watch the you tube videos on these bits you dont see these problems,,,

[Mel Fulks]

The larger ,approx. 4 inch diameter shaper cutters work much better. If you are getting a lot of tear out ,you can stop that by rounding
over the corner that will be removed...with a “round-over “ bit run with “ climb-cut” ,pocket knife , or even sandpaper.

[Brian Runau]

maybe im doing something wrong,,i have had 2 of these bits bought from amazon,,one which was 1/4 shaft and bent,,which i sent back,,then i reordered a 1/2 in shaft one,,,and used a backer board in both cases and maybe im doing something wrong but these are really dangerous bits,,,one bent and the other would not cut the material all it did was raise up,,,,if anyone can tell me what im doing wrong or the results they have had with this bit it would be appreciated,,,,if you watch the you tube videos on these bits you dont see these problems,,,

Jeff, I used to make drawer boxes with these vs dove tails and apart from getting it set up so I get the right joint overlap, they did work for me. When you machine are you going with or against the grain of the wood? I used a Freud bit. I had to make a sled to do the vertical cut on one piece for the mating pair. If memory serves me one runs through flat 90 degrees and the mating half runs through on the sled vertical. Could you show us pictures of your set up and how you are running them in the router? Brian

[al ladd]

I did a run of boxes in difficult material once a few years back with lock miters. I precut with something like a bevel miter on the table saw first to minimize the material removal from the router bit, and that made for a much more relaxed, accurate router cut.

[Ray Newman]

Lock miter bits are probably one of the biggest PITA bits to set up, but a set up gauge will really help! The below gauge was designed by a member of this board and works very well: https://www.infinitytools.com/lock-miter-master-jigs

[Thomas McCurnin]

+1 for Ray's comment. I tried to use one once and spent an afternoon for set up. Never again.

[Alan Lightstone]

Yup. Get the Infinity version with the setup gauge. Makes all the difference.

Still a PIA, but looks nice when completed.

[Dave Sabo]

The infinity setup jig works with just about any lock miter bit. It is not exclusive to infinity’s version.

[jeff oldham]

what would the bevel setting be on the table saw for precutting the miter

[Jay Rasmussen]

Is it a quality cutter? I have Woodcraft brand, cuts very cleanly. I haven't used it in a while but don't remember any problems.
Do you have any photos of your setup?

[Jim Becker]

what would the bevel setting be on the table saw for precutting the miter

45º. Do keep in mind that pre-cutting the miter to make the cut less work for the lock-miter tooling can get you into complicated sizing calculations if you need to have a "box" of a particular dimension. The reason being that there are portions of the profile that stick out farther than the bevel. So you have to cut long for material relief to pre-bevel. It may be easier to pre-cut with the lock miter tooling but holding back the material slightly before making a final pass at full depth. That's likely relatively easy for the horizontal cut with the material on the table, but harder for the vertical piece which really does have to be supported by a jig/fixture for best results.

I have the good Infinity cutter and setup block. Despite that, I got frustrated with the touchy setup and to-date haven't pursued it much at all.

[Mel Fulks]

Jeff, round off the bottom corner. That will stop the small tear-out and big flying pieces.

[jeff oldham]

thank you mel,,,very helpful

[Jim Becker]

Jeff, round off the bottom corner. That will stop the small tear-out and big flying pieces.

That's an excellent idea, Mel. Thanks!

[Mel Fulks]

That's an excellent idea, Mel. Thanks!

I worked in a large custom mill ,about 3 years, that had a shaper mitre head. But all the guys there ripped 45 degree and just nailed and
glued. Obviously they got a lot of complaints from buyers. I asked them to buy a mitre head and they told me they had one! But they
“didn’t work, tore out big pieces”. I showed them it did work. The basic idea of climb cut rounding before making difficult cuts was once well known.
Im pretty sure it was killed by safety stuff . I did the rounding on the shaper with the feeder on the highest speed, so it didn’t add any
time to do the rounding . Far less time and material are used than getting the material out 3 or 4 times ! And then trying to patch them up.
The climb cut rounding can be done on the highest feeder speed ...yes the one you have to switch the gears to use.