lock miter bits

[billconner]

Building some newel posts for a small stair per attached dketch. They will support a 3'x4' landing about 3' above a floor as well as guard and hand rails. Planning on cherry (a lot of rough sawn at the very best price - free). Approx 5"x5".

Never used a lock miter bit but seems to be a good fit for this project. Thinking each side might be a stile and rail panel. Any experiences here to share?

 

[jar944]

They are a pain to setup, but work well once you do. Depending on how I'm feeling I'll lockmiter or miterfold.
Lockmitered



Miterfold

 

[billconner]

Thank you.
Not grasping miter fold.
Also have seen and am considering this:

 

[jar944]

Thank you.
Not grasping miter fold.
Also have seen and am considering this:

It's just a 45degree bevel cut, and tape.

 

[BMW Rider]

I've used the lock miter bits before and as mentioned, they are fussy to get set up accurately. You will have to use a router table for them, they cannot be used in a handheld router. The joint they produce is very strong compared to a plain miter joint, but is also a bit challenging to glue up and clamp. I get the posts assembled and then wrapped them tightly with bungee cord to hold until the glue set.

For what you are doing, I'd likely use a smaller structural post and wrap it with the decorative cherry using the miter fold method. You could glue up three sides and slip it in place and then glue in the fourth to complete the box.

 

[R.Bolte.Jr]

You'll want a router table, and a speed control if your router doesn't have one.
The first time I fired one up at about 19,000 rpm, it sounded like a P51 taking off. Shut it off and read the package, it wanted to max out at like 1/4 of that. lol.

But yes, it worked really well on 3/4" oak veneered MDF.

 

[strutaeng]

It's a pain to setup. I bought one of those bits and tried, but gave up. Wound up using a drawer lock joint instead (for drawer use).

Maybe buy the matching setup blocks they sell? IDK if they are all the same or not.

 

[billconner]

For what you are doing, I'd likely use a smaller structural post and wrap it with the decorative cherry using the miter fold method. You could glue up three sides and slip it in place and then glue in the fourth to complete the box.

I thought about this. Build a cherry post 3/4" smaller, butted corners, and then apply 3/8" thick cherry onto it to simulate the stile and rail look. Feels wrong, cheating, but may make sense.

 

[Sumboodie]

You'll want a router table, and a speed control if your router doesn't have one.
The first time I fired one up at about 19,000 rpm, it sounded like a P51 taking off. Shut it off and read the package, it wanted to max out at like 1/4 of that. lol.

But yes, it worked really well on 3/4" oak veneered MDF.

Thanks for the info, I bought a set for my table, would have figured it's rated for normal RPMs

 

[rkevins]

I have a lock miter from MLCS, they have a new name now, with a setup block. use a scrap piece until you get the feel of set up and keep the final set up as a guide. also trimming off some of the corner on the tablesaw will help by removing some of the material you have to remove with the router. Remember set is determined by material thickness so be sure your scrap is the same thickness as the material you are using.

 

[cos]

Great joints NO Nails. I would never try with a router even with a good long table. Use a shaper with long offset fences. Make caulks out of scraps to fill joint to protect sharp edges, they are delicate. The stiles don't have to be same thickness. I make face frame stiles 13/16" and wide end panels with 3/4 plywood. People try find joint and look at where they come together but actual joint is back on plywood 1/16". Good Luck

 

[jar944]

Great joints NO Nails. I would never try with a router even with a good long table. Use a shaper with long offset fences. Make caulks out of scraps to fill joint to protect sharp edges, they are delicate. The stiles don't have to be same thickness. I make face frame stiles 13/16" and wide end panels with 3/4 plywood. People try find joint and look at where they come together but actual joint is back on plywood 1/16". Good Luck

I don’t think the op has a shaper, and you wouldn't want to offset the fences even if you did. There isn't a full profile cut, so no need to pull one fence out of alignment. It's better with a continuous fence.


As for different thickness, sure but you cant just flip the horizontal and vertical cuts then. You end up having to reset the fence.

 

[Git]

There are two steps to setting up a lock miter bit.

The secret, (at least for me), is to figure out where the center of the bit is. I use a digital height gauge and measure the distance between the two horizontal 'flats' of the bit. So on my Bosch bit, the distance is 0.354 so the center of the bit (that actually does the cutting is .177" down from the top flat.

You want to align the center of the bit with the center of the thickness of the board. If the Board is .75" thick, center would be .375" either up from the table. I have already worked this out with my router bits and shaper cutter, and I know if I am working with a true, 3/4" board, the top flat of the router bit should be at .552 above the table



Next you set the fence. Put one of the boards on edge, up against the fence along with a straight edge. Position the fence so there is just a tiny gap in between the cutting edge of the bit (90 degrees straight out) and the straight edge.



To check to see if you have the proper bit height, take two test pieces, lay them flat on the table and write UP on one of them. Run both pieces through (flat on the table, not on edge) and then mate them together, with the UP piece UP. If the UP piece is higher than the other piece, the bit needs to be lowered, about half the distance of the step up.


It seems like a pain, but you only have to measure your bit once and then make adjustments for the actual thickness of the lumber you are using

 

[jar944]

There are two steps to setting up a lock miter bit.

I use a digital height gauge and measure the distance between the two horizontal 'flats' of the bit.

That helps if you have a bit/head with a flat. Some have no flats and only angles/radius.



There still seems to be some fiddling no matter what.

 

[billconner]

You're talking me out of it.......

 

[rharman]

Depending on the bit, you can get a setup jig for it. See Rockler.

https://www.rockler.com/router-bit-set-up-jigs-for-22627-45deg-lock-miter-bits

 

[billconner]

Depending on the bit, you can get a setup jig for it. See Rockler.

https://www.rockler.com/router-bit-set-up-jigs-for-22627-45deg-lock-miter-bits

That makes sense. Thanks.

 

[purplezr2]

It's just a 45degree bevel cut, and tape.

So do you really think there is a benefit to Lock Miter when it comes to wood, it seems miter fold is much quicker and with plenty of glue surface I really don't see a down side to Miter Fold. Now with the PVC trim I see the benefits of Lock Miter.

 

[jar944]

So do you really think there is a benefit to Lock Miter when it comes to wood, it seems miter fold is much quicker and with plenty of glue surface I really don't see a down side to Miter Fold. Now with the PVC trim I see the benefits of Lock Miter.

If the stock is perfect (dead flat) and 3/4" or thicker, not really. If it's got any curve/bow/twist/belly or under 3/4" thick the lock miter will close up and straighten out a lot easier.

Trying to pull together 2 stiles so that you can initially tape them when each have 1/8"+ of bow in the opposite direction (after ripping the bevel) can be frustrating.

The lock miter is better if you are gluing on the 4th side after (like a post wrap) it allows straight on clamping.

 

[rharman]

Depending on the bit, you can get a setup jig for it. See Rockler.

https://www.rockler.com/router-bit-set-up-jigs-for-22627-45deg-lock-miter-bits

That makes sense. Thanks.

I forgot to add that you could also get your lock bit setup just right for whatever size stock(s) and use a piece of that stock to make your own jig(s).

Rockler also sells a miter fold dado set that makes it pretty simple to do that joint as well.
Not exactly a cheap date @ $380 - on sale 20% off for $304 right now. There's almost always a 20% off deal at Rockler.

https://www.rockler.com/rockler-miter-fold-dado-set-plus

 

[jar944]

I forgot to add that you could also get your lock bit setup just right for whatever size stock(s) and use a piece of that stock to make your own jig(s).

Rockler also sells a miter fold dado set that makes it pretty simple to do that joint as well.
Not exactly a cheap date @ $380 - on sale 20% off for $304 right now. There's almost always a 20% off deal at Rockler.

https://www.rockler.com/rockler-miter-fold-dado-set-plus

That miter fold dado set is for sheet goods. The idea is to cut and fold a continuous sheet into a box, without cutting completely through.

 

[rharman]

That miter fold dado set is for sheet goods. The idea is to cut and fold a continuous sheet into a box, without cutting completely through.

I haven't researched it, but I assume if you made one long rip type pass on something like a 1x6, you could fold that into an L for a leg profile. Or, one edge of a sheet and make a drop - like a waterfall top/side.

I could be mistaken but it sure makes sense.