New (CNCd) box beam workbench, with Festool holy system!

[fritter63]

I've been planning to build the "3rd generation" of my workbench box beams for quite some time and finally got the time in between guitar builds. This time I decided to use the CNC machine for all the holes.

These started based on a radical design from FWW (http://www.finewoodworking.com/2008/12/01/forget-what-you-know-about-workbenches), but I've been modifying it every time to suit my needs and improve it as I see fit.

Here is the 2nd gen (which as you can see has not been demoted to an outfeed table for the TS):

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Two rows of holes on the top, one on the side, and I left the bottom off thinking I didn't really need it. But as my mechanical engineer nephew pointed out, they weren't as strong without the bottom part, and indeed they have sagged between 1/32" and 1/16" over the years. Also, those interior partitions were ALWAYS in the way. Everytime I went to clamp something, there was a partition in the way of the festool clamps.

So I decided to do them up as proper box beams, with a bottom, and create cutouts so I could still use the Festool clamping elements knobs to secure them. I also made them based on a multiple of 32 mm dimensions, 3 rows of holes in the top and 2 on the sides. I used dominos for alignment during the glue up, and then just glued everything without any other fasteners.

Note that decided to use 1/2" ply for the top this time just to save weight. I'm surprised at how much lighter they are actually. One last thing, I chose to laminate the tops in formica (bright green of course!) to make them resistant to glue and chemicals.

Here are some pictures, and a CNC video about how I did the holes. Kudos to Peter Passuello of the CNCNutz youtube channel for the basics of how to CNC an 8 foot long board on a 4x2 machine.

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And finally, here's the video of the CNC process:

 

[Whatsupdoc]

That is cool.  Thanks for sharing.

 

[leakyroof]

I think the Green color improved it far more than the Box Beam construction..... [wink]
all kidding aside, looks great and surely will provide you with superior clamping and assembly work down the road.

 

[Kbuild]

I really like the green top! I almost ordered that for mine but chickened out at the last minute and went with graphite to match my cabinets in my shop. Are the holes chamfered at the top?

 

[DashZero]

Nice video an explanation.  I wish I had a CNC.

 

[Mario Turcot]

Wow that's a really nice boxbeam. I don't know exactly the situation you use it, but were not you tempted to offset the holes on one side, just for more versatility.

 

[Jruks]

[member=10223]fritter63[/member]

Great bench and I’m looking to do something similar, though shorter and wider than Finn’s bench and drilled out with the parf guide system and incorporating some 8020 tracks.

Do you find that without any internal partitions your beams are holding up well from a bending/twisting/sagging perspective? Any twist or issues getting the two boxes co-planar when putting them together and trying to do a glue up that spans both tops?

 

[fritter63]

[member=10223]fritter63[/member]

Great bench and I’m looking to do something similar, though shorter and wider than Finn’s bench and drilled out with the parf guide system and incorporating some 8020 tracks.

Do you find that without any internal partitions your beams are holding up well from a bending/twisting/sagging perspective? Any twist or issues getting the two boxes co-planar when putting them together and trying to do a glue up that spans both tops?

Sorry, just saw this!

No issues so far, they are very true. The bottom part is key which keeps it a true torsion box for strength.

 

[mkasdin]

[member=10223]fritter63[/member]

Great bench and I’m looking to do something similar, though shorter and wider than Finn’s bench and drilled out with the parf guide system and incorporating some 8020 tracks.

Do you find that without any internal partitions your beams are holding up well from a bending/twisting/sagging perspective? Any twist or issues getting the two boxes co-planar when putting them together and trying to do a glue up that spans both tops?

Would the cross sections on 3/4” Baltic Birch make the box stronger? 5/8” is fine but 3/4” will keep its rigidity. Why not an MDF top instead of BB.  It’s cheaper and machines well plus sacrificial. Building as such you wouldn’t need an affixed bottom. If you were putting a lot of weight then that’s doable, otherwise for sags shim out the top ?

 

[Dane]

What are the dimensions on those beams?  Any reason you chose a certain size?