HELP- Lock mitre router bit

[Dave Tinley]

I have the Jessada lock mitre bit and just cant get it right. I did a setup and it matches up great. My problem is cutting the piece that is vertacle against the fence, it just does not cut smoothly and when it gets to the end of the cut it jumps off of the fence.
If anybody has a good fence setup or a better way, please let me know.

Thanks

Dave

T-storms in Waco

[Bob Lasley]

Dave,

Two things that might help: One, cut a 45 on your piece with the table saw first, Two, use featherboards to hold the piece against the fence.

Good luck,
Bob

[Tim]

Hi Dave,

Those lock miter bits can get pretty large. I'd suggest making sure you use more than one cut, if you aren't already. You could set the fence to make 3/4 of the cut first, then setup for the final pass and it should be clean. Make sure to use a backer board on end grain.

Bob's suggestion to cut on the TS first is also a good one and should help. Featherboards are always a good idea on the router table as well.

[Ted Shrader]

Originally posted by Dave Tinley
I have the Jessada lock mitre bit and just cant get it right. I did a setup and it matches up great. My problem is cutting the piece that is vertacle against the fence, it just does not cut smoothly and when it gets to the end of the cut it jumps off of the fence.
If anybody has a good fence setup or a better way, please let me know.
Thanks
Dave
Dave -

I have that bit and have used it successfully. I don't quite understand what you mean it "jumps off the fence".

When I use it, I have guide boards clamped to the table so it won't move anywhere except sideways during the cut. You have to be careful not to push it down into the hole in the top where the bit is. I make vertical cuts both edges of two panels and then horizontal cuts on each edge of the other two panels. You have to make the cuts in a single pass - you can't sneak up on it. I don't cut an initial 45^o because you can't take enough off to make any difference and still have the full tounge.

Ted

[Garrett Lambert]

You can see a step-by-step demo at http://www.woodshopdemos.com/cmt-lm5.htm. If you back up to the main page and look under the routers section, there are a couple of other lock-bit articles as well.

The attachement is a How-to file with info from Jesada that was in the Badger Pond archives.

Cheers, Garrett

[Garrett Lambert]

The attachment was dropped from the previous post. I'll try to e-mail it to you.

[Tim]

Originally posted by Ted Shrader

You have to make the cuts in a single pass - you can't sneak up on it.

Hi Ted,

What is it about the lock miter that you can't sneak up on it with the fence? I haven't used one, so was just offering general router advice for larger bits.

Thanks,
Tim

[Ted Shrader]

Originally posted by Tim
Hi Ted,

What is it about the lock miter that you can't sneak up on it with the fence? I haven't used one, so was just offering general router advice for larger bits.

Thanks,
Tim

Tim -

You can sneak up on the cut on the piece that is cut vertically. Just set the fence and bit height to get the proper cut. Then move the fence about ¼". Make a pass with the vertical piece(s). Move the fence back to where it should be and make the rest of the cuts.

I don't do it this way because it is very critical to get the fence re-positioned correctly and doing the cuts in one pass has been successful for me.

More info is available at Locking Miter Setup (http://www.woodshopdemos.com/cmt-lm5.htm) in Woodshop Demos.

Ted

Edit:

I didn't see the link had been posted above also. Sorry.

[Ray Carpenter]

Hello Dave,
I have the CMT version, but I imagine that they are pretty much the same. On Sommerfeld's video, he shows using a scrap piece of wood as a fence in front of the router bit, similar to a featherboard. I have used this method and it works well for me.

Regards,

Ray in Central Nebraska