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18

There are many hidden reinforcements you could use - biscuits, dowels, or more complex hidden joints such as these: Mitred corner dovetail joint Mitred blind dovetail joint ... but I wouldn't recommend them unless you have a lot of skill with a chisel, and a lot of time on your hands. Both of these images are from here which is a really excellent site ...


16

The 4x4 posts used for the legs support virtually "infinite" weight longitudinally. Now, of course, given a naive design, each leg would only transmit force onto one 4x2 beam (which are then maybe nailed together with some kind of ledge or so), which isn't optimal. You most definitely want to connect the beams with a dovetail batten or a similar construct ...


14

When determining the load bearing capacity of any structure, you'll need to take into account several different factors: Acceptable deflection Maximum allowable bending stress Column compressive and buckling strengths For calculating deflection, @rob's suggestion of using the Sagulator is a good start. You don't need to have an in-depth grasp of all the ...


11

Just to find the load bearing capacity of the horizontal bench top, I'd treat it like a shelf and run the numbers through some sort of load-bearing calculator like the sagulator. The load-bearing capacity will also depend on whether the weight is mostly toward the center or if it is evenly distributed. Ideally you would laminate (thoroughly glue) several ...


9

How might this joint be constructed so that it is strong enough to prevent racking but still appear to be a miter? It's not racking that is the major concern here, it would be (probably sudden!) failure of the glue line in one or both of the mitres. The answers from WhatEvil and Matt cover many of the solutions. There are a number of variations on blind ...


7

In terms of compression strength, I wouldn't want to park a big car on top of it - but even a couple of drunken teenagers jumping up and down should be fine. As others have commented, racking side-to-side might have been a concern if you didn't have walls either side. That could easily be addressed by attaching a plywood skin to the back (but it doesn't ...


6

I've thought about this some more and have come up with an alternative solution. If I had to make this bench and be sure that the joints won't break over time, I'd want to look at some real reinforcement... how about a steel substructure? So you have your basic bench structure which is made by lamination of smaller timber boards: The fact that it's made of ...


5

While I may (justifiably) be shunned for bringing it up, it is possible to get right-angled dowels. http://www.fastenersplus.com/90-degree-right-angle-furniture-dowel-pkg-3.html This will prevent any motion of the pieces, but it's not what you call a purist approach to woodworking.


4

Each shelf is capable of holding the load that you are intending with shearing or sagging. Where this design fails is in racking, both front to back and side to side. Traditional shelves are built with solid sides and a back. This serves to hold books, or items onto the shelves, but this really is only a secondary function. Primarily, the solid sides and ...


4

The weakest part of the design is how your substantial load is being carried to the uprights. There's not that much you can do for those joints as drawn... I'd suggest you add actual 1x2 members beside your existing uprights that will carry the weight of the frame (perimeter) of each shelf. It's easy to build this way, and will look a little less spindly. (...


4

Metal Brace This is not my area of specialty at all but if I had to guess I would say that there are some metal brackets hiding underneath the joins that we cannot see. Quite possibly in conjunction with what ever joint is hiding in there. Just as long as they are a strong metal. Not like the cheap ones made that are zinc plated you commonly find in ...


3

The easiest improvement I can think of is to insert a metal sleeve (or bushing) in the opening for the axle. This should eliminate a lot of the wear and tear caused by the bolt axle on the wood in the opening. I have used copper pipe or electrical conduit inserts with success. If you rotate the table a lot, then a more precision fitting would be desirable. I ...


3

I plan on using 3/4 plywood (.706 or so) with 3/8" dowels and some pocket screws (as well as titebond). I don't want to over or under engineer it. Actually you should seek to over-engineer this, or at least err on the side of stronger than you think you need, because it can't hurt given the dynamic forces this might be subjected to over time. One key thing ...


3

The easiest way to prevent racking would be to replace the slats at the head and foot of the mattress supports with a solid piece of plywood approx 1' wide that is solidly connected to the three sides of the bed frame it contacts. I would also suggest that the pocket screws could be replaced with solid dowels as well. If you have a table saw and a dado ...


2

You can always take the Calvin & Hobbes approach!


2

The sagulator calculates a sag of 0.03 in over 24" for a 50 lb uniform load on a single 1x2 of (Ponderosa) pine laying on its face. So your 4-board shelf should be stable given that weight load. A 12" 1x2 on its side can support in excess of 1000 lb, so no worries about the shelf supports breaking, either. Note that, although each shelf could hold the ...


2

This is intended to be my main workbench, and will be used for all of my hand tool work A rock solid desk that doesn't shake or wobble would seem to be a requirement for hand tool work of any kind. It's the defining difference between a desk used to hold things, and a desk used to work on. Your design has no support for lateral movement. When you apply ...


2

The weakest point ended up being the half-laps (as predicted by @SaSSafraS1232):


1

If the occupants of the bench rock to the left and right, the wedge will apply a large force on the end of the pegged tenon. The expected failure point is marked in the image. A combined weight of 150lbs, doing moderate rocking, could cause this failure in a few seconds.


1

While this is a great design overall, I'd be a tiny bit concerned about the pocket screws resisting side to side racking. If you could make one (long) side out of a single sheet of ply, the other side could be pieced together. In place of pocket screws, you could probably find a strong mechanical connector -- one for each corner, so 8 in total -- that ...


1

I own the bench along with the matching table. It is a simple frame constructed with 2x3 dimension lumber; a simple reclaimed board veneer with miters.


1

Besides mitered versions of various types of other sufficiently strong joinery methods, you could use non-mitered versions of any of those, and more (dovetail, dowels, Domino, mortise and tenon, box joints, dadoed/housed joints, knock-down hardware, etc.--perhaps even butt joints with countersunk lag screws), using any sufficiently strong material. Then, ...


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