miter lock bits

[tjbnwi]

45 deg cut with your track saw and a quick series of dominos.. would that not work? Once fitted the edge should look identical. I have used this technique many times resulting in very strong joint, with less set up time, and a beautiful edge.

So what would be advantage with the lock miter joint?

Speed.

We run about 250 feet of lock miter per job.

Tom

 

[Roseland]

If you use a lock mitre bit with ply, as I do, it is almost essential to use a zero-clearance fence to stop tear out.  I use a piece of 1/2” MDF screwed to the front of my normal fence. With care it can be removed and reused, both as the fence and as the set-up guide.

Andrew

 

[HowardH]

45 deg cut with your track saw and a quick series of dominos.. would that not work? Once fitted the edge should look identical. I have used this technique many times resulting in very strong joint, with less set up time, and a beautiful edge. I think these are some solid advantages being on the festool platform. Sorry I am assuming you have a track saw and a domino. Surely the bit is a lot cheaper.

Is there any other advantage with the lock miter joint?

Sort of.. MT55cc and a DDF40.  ;D. I also like the decorative aspect of the joint.  Also, the boxes I am building are really small.  Maybe 2.5" tall and the material is 3/8th thick.  Too small for a domino -maybe the smallest size would work - but the DDF40 has an attachment for a single dowel that might work.

 

[HowardH]

If you use a lock mitre bit with ply, as I do, it is almost essential to use a zero-clearance fence to stop tear out.  I use a piece of 1/2” MDF screwed to the front of my normal fence. With care it can be removed and reused, both as the fence and as the set-up guide.

Andrew

Excellent idea! 

 

[Svar]

45 deg cut with your track saw and a quick series of dominos.. would that not work?

Or 45 deg miter, then lengthwise slot and spline. Sure, more cuts, but saw cuts way faster then router and no fiddling with lock bit setup. The downside of router cut lock miter on plywood is high risk of tear out.

 

[Kevin D.]

Just for fun........


Tom

A video on how NOT to do it!

 

[HowardH]

I ended up getting the Veritas version and it works great.  There was a little bit of trial and error to get it dialed in but the resultant joint was perfect on the test piece.

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I also learned that it's fine on the flat grain with maple, walnut and purple heart. However, to make the mating piece on the end grain, it does not work with well with very brittle woods like Purple Heart.  It just splintered  and somewhat disintegrated.  I think I'll use the the walnut and maple. 

 

[Michael Kellough]

[member=7466]Kevin D.[/member]  Assuming you watched the video (I just scrolled thru) why do you say not to do this? Besides the fact that the diameter of his vac hose was too small.

 

[Cheese]

FWIW...all the older JBL speaker enclosures from the 60's to the 90's were constructed with miter lock corners. The reason being that it was the strongest fabrication method and prevented unwanted resonances from occurring because of weak joints.  [cool]

 

[Michael Kellough]

Clamping a box made with lock miters is sooo easy.

If the vertical piece is solid wood you can bring the router fence forward a bit and so moving the miter joint away from the actual corner, making the corner cleaner looking.

 

[martin felder]

Very nice video made by a really nice and knowledgeable guy.  He teaches courses on how to use a shaper.  I attended a course. Called Alpine workshop.

 

[tjbnwi]

We use spring clamps to draw up the lock miters.

You do have to be carful with the glue, you can get enough in the joint where it will hydraulic lock the joint.

Glue is applied, then brushed to even it out.

Tom

 

[FestitaMakool]

FWIW...all the older JBL speaker enclosures from the 60's to the 90's were constructed with miter lock corners. The reason being that it was the strongest fabrication method and prevented unwanted resonances from occurring because of weak joints.  [cool]

That would have been the enclosures for the tweeters then  [big grin]
- Cool.. I can see it perfect for “dead” joining.

Thanks, it has been interesting to follow this thread.

 

[HowardH]

Very nice video made by a really nice and knowledgeable guy.  He teaches courses on how to use a shaper.  I attended a course. Called Alpine workshop.

The title of that video should be "how to cut an accurate lock miter with a $25000 shaper"  ;D

 

[Cheese]

That would have been the enclosures for the tweeters then  [big grin]
- Cool.. I can see it perfect for “dead” joining.

Actually, JBL recommended lock miters for the entire speaker enclosure. Both the L100 & the L300 systems came from JBL with lock miters.

JBL also produced a "Speaker Enclosure Design Guide" that was a 3/8" thick folder with specification sheets inside and construction tips including internal bracing techniques, damping materials & methods, grades of MDF, speaker mounting directions and port sizes/volumes. It was like the bible of speaker enclosure construction.  Very  [cool]

 

[HowardH]

To follow up on this, I use a CMS-GE router table system. The piece that is laid flat on the table is no issue since I have the set and use the sliding table and fence along with the vertical stock support to keep the piece secure while it is being pushed through the bit.  However, like I mentioned, the vertical side is getting chewed up since I don't have any stock support system to keep the piece pushed tight against the main fence.  What are the work arounds since there isn't a way, AFIK, to attach a separate feather board to keep it tight? 

 

[Sparktrician]

To follow up on this, I use a CMS-GE router table system. The piece that is laid flat on the table is no issue since I have the set and use the sliding table and fence along with the vertical stock support to keep the piece secure while it is being pushed through the bit.  However, like I mentioned, the vertical side is getting chewed up since I don't have any stock support system to keep the piece pushed tight against the main fence.  What are the work arounds since there isn't a way, AFIK, to attach a separate feather board to keep it tight?

 

Suggest that you use a single sacrificial piece of MDF clamped to the CMS' fence while well back of the bit.  Then pull it forward gently to put the outline of the bit into the MDF. Adjust it appropriately to get the joint right.  Get busy with your joint-making.  [smile]