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¿What joined wood connection is more weight support?

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Forum topic by dinkifin posted 03-01-2017 04:03 AM 1491 views 0 times favorited 7 replies Add to Favorites Watch
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dinkifin

4 posts in 291 days


03-01-2017 04:03 AM

both cases panels are MDF (30cm x 30cm) but different thickness (16mm first case and 10 mm second case)

Case 1: Three rows of MDF thickness 1,6cm, Total 48mm

Case 2: Four rows of MDF thickness 1,0cm, Total 40mm

It goes without glue and I need to know what is the most effective way to support weight.

(In the example there are only 8 screws but every hole is going to have screws, I don’t know if it’s too much or not enough to make it more stable, any tip are welcome)

Thanks a lot in advance.


7 replies so far

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Rich

1984 posts in 428 days


#1 posted 03-01-2017 04:24 AM

I’d go with case 3.

-- No matter how much you push the envelope, it'll still be stationery.

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dinkifin

4 posts in 291 days


#2 posted 03-01-2017 06:06 PM

I am also thinking on a case 3 but I dont know much about this. Any tips?

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Rick_M

10640 posts in 2219 days


#3 posted 03-01-2017 08:08 PM

Assuming the same orientation as the screenshot and this is a cantilever, the top boards will be in tension, the bottom boards in compression: In Case 1, the load will only be transferred by the metal plate. In Case 2, the load is more evenly distributed and doesn’t depend as much on metal fasteners which don’t hold well in MDF. Of those 2 choices, case 2 will be stronger

-- http://thewoodknack.blogspot.com/

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TungOil

747 posts in 334 days


#4 posted 03-01-2017 09:06 PM

Please explain the application in a bit more detail and how the parts will be loaded. how much weight, where, etc.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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dinkifin

4 posts in 291 days


#5 posted 03-03-2017 12:23 AM

Thank you Rick M, Case 2 seems to be the strongest choice but I am redoing all the project with a Case 3 torsion box because all this is a waste of material and screws so I’ll just redo everything and come again if I get stuck in some point.

TungOil, The project was to make a shelf capable of support heavy weight and mountable without glue so its width, height, or thickness could be changed if needed. In the picture you can see the original design where it is supposed to hold a big freezer full of food plus 2 fat guys of 120kg (260pounds) so like (350kg)750 pounds without breaking, plus more so it is not in the limit, best would be 2000 pounds. I don’t know anything about weights or structure limits, I am completely noob so that’s why those two models, I will try now with torsion box so maybe I come up with something that is not a completely failure.

Thanks to all for all the help.

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TungOil

747 posts in 334 days


#6 posted 03-03-2017 12:38 AM

2,000 lbs? dont even consider MDF for the application shown. You need steel here, this is not a woodworking project. To put that load in perspective, that’s about the weight of an old VW Beetle.

The good news is your diagram represents a fairly straightforward beam calculation. The formulas are easily found on the web. Run the calcs with a 2,000 lb point load in the center.

With that kind of load and people nearby, consider having a structural engineer at least review and stamp your design for liability reasons. This is one of those areas where you can get yourself and your company into a lot of legal trouble.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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dinkifin

4 posts in 291 days


#7 posted 03-04-2017 04:06 AM

I will try to go in different directions like with the racking, metal skeleton.
http://www.firststoragesa.co.za/wp-content/uploads/2015/07/Pallet-Racking.jpeg

Thank you for all the tips,

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