Cross Lap Jig
#10
  
I am looking for a cross lap jig.
Planning to build a Torsion box and that jig will save some time

Did some search and could not find any DIY Cross Lap Jig. Found some jigs but was not sure if they can do multiple cuts on a cross bar.

Found this Rockler jig for  $ 35.00  looks like this might work

Rockler jig

Before I buy this want to know if there are any other similar jigs.

Thanks
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#11
  Re: Cross Lap Jig by Jack01 (I am looking for a c...)
It's really the same sort of thing as a box joint jig except the space between the key and the blade is wider. You can find any number of box joint jig plans and modify them to suit.
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#12
  Re: Cross Lap Jig by Jack01 (I am looking for a c...)
Build one, not that tough.  I use a sled, not a miter gauge but both will work. And for a torsion box, you will not to have slip fit joints.  Cut the gap a bit thicker, just press the pieces until they are flush.  When building furniture, I get real close then go to a plane or scraper to get a joint with no gap.  You will not have to get that fine.
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#13
  Re: RE: Cross Lap Jig by DaveR1 (It's really the same...)
(01-03-2019, 10:01 PM)DaveR1 Wrote: It's really the same sort of thing as a box joint jig except the space between the key and the blade is wider. You can find any number of box joint jig plans and modify them to suit.

Thank you very much for the tip.
Soon I will start building the jig  let you know the updates.
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#14
  Re: RE: Cross Lap Jig by Jack01 ([quote='DaveR1' pid=...)
Jack,  I have built a number of torsion boxes, and i don't know if cutting laps will save any time.  I normally just staple the tops of the cross pieces together.  While I didn't realize it at first, the strength of the torsion box comes from keeping the top and the bottom the same distance apart -  that is why you see some industrial torsion boxes made with cardboard as the spacers. I don't think the stiffness of the  web itself adds any rigidity.  On on the ones I have made, while the core had a ton of sag in it when stapled together, the torsion box was a rigid as a pool table once glued up.
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#15
  Re: Cross Lap Jig by Jack01 (I am looking for a c...)
I have built many, many torsion boxes.

I just use the miter gauge with a Dado blade set up. 
A small stop on the rip fence is all the measuring needed. 
Set the fence, cut all of the parts of a length on both ends at that setting, then move the fence and repeat.

The “egg crate” inside the box will not be seen so minorvariations do not matter.
What IS important is that the slots are all in the same place across the ribs.

It is also not critical that the halflap cuts fit snug.
Ralph Bagnall
http://www.woodcademy.com
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#16
  Re: Cross Lap Jig by Jack01 (I am looking for a c...)
I built a 4'x 8' torsion box out of mdf 7 years ago. I glued and pinned the slats together, no half laps. It has been sitting on 2 saw horses in the garage since then and is as flat as the day I made it.

Mals

Mals
You can educate the ignorant - You can't fix stupid.
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#17
  Re: RE: Cross Lap Jig by handi (I have built many, m...)
(01-05-2019, 10:39 AM)handi Wrote: I have built many, many torsion boxes.

I just use the miter gauge with a Dado blade set up. 
A small stop on the rip fence is all the measuring needed. 
Set the fence, cut all of the parts of a length on both ends at that setting, then move the fence and repeat.

The “egg crate” inside the box will not be seen so minorvariations do not matter.
What IS important is that the slots are all in the same place across the ribs.

It is also not critical that the halflap cuts fit snug.

So have I. That is because it is amazing how strong they are. Here are a few T-box shelves that I built for the shop about 12 years ago,:
   
   
These shelves are about 16" x 42". They weigh at most three pounds apiece. They never sag. I weigh 195 lb and stood on top of them when suspended at each end. There was no bend that I could detect. They are in service today.


Attached Files Image(s)
   
Rip to width. Plane to thickness. Cut to length. Join.
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#18
  Re: RE: Cross Lap Jig by Edwin Hackleman ([quote='handi' pid='...)
(01-08-2019, 09:28 PM)Edwin Hackleman Wrote: So have I. That is because it is amazing how strong they are. Here are a few T-box shelves that I built for the shop about 12 years ago,:


These shelves are about 16" x 42". They weigh at most three pounds apiece. They never sag. I weigh 195 lb and stood on top of them when suspended at each end. There was no bend that I could detect. They are in service today.
That is great.
Thanks for sharing
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