# Tag Info

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 ...

13

The sagulator will give deflection values for horizontal shelf spans using various materials and thicknesses. Unless you are working with extremely heavy loads (more than the weight of a countertop with people dancing on it), 3/4" material for the (vertical) cabinet walls should be more than adequate. As you make the walls thinner, they will still remain ...

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 ...

6

Firewood stacks pretty well, so there shouldn't really be any load acting sideways on the upright supports, even with a much wider (longer?) rack. Additionally, you're only making it taller by about 5 inches (~10%), so it's not a huge change in that direction. A lot of people stack firewood without any supports at all. Putting some numbers into the ...

6

TL;DR: Maybe, but I don't think we can tell you. This probably cannot be answered, at least fully. It depends if you want to think like a woodworker acting as an engineer, or an engineer acting as a woodworker. Can a specific construction support ~160lbs? It depends on what you mean by "support", because it depends on what forces are applied. What ...

5

You haven't shown the leg arrangements, so a more immediate problem might be racking forces. That is, depending on how the legs are attached and arranged, a ~300lb. weight on the top may cause the entire table to swing like a pendulum and maybe even fold up where the legs meet the table. However, it is my guess that, even at a nominal 1-inch thick, this ...

4

I see three inherent weaknesses, two of which critically compromise the strength of the bed. I'd suggest looking at commercially-produced solid wood bed frames for some design ideas (don't look at cheap futons, etc.). The support beam running down the middle is inherently weak at the ends because the top half transfers the load to the outer frame, but the ...

4

TL;DR: Use a metal pole. Commercial dowels are not a good material to use for pull-up bars. The supports for the metal pole can be wood. I'm going to take the unpopular opinion and suggest that random oak from a big-box store is not going to work. Or, at least, it'll work until it doesn't, often in a spectacular manner. And it isn't really about the ...

3

Your design raises some interesting issues and requires additional consideration for connections. Each shelf is supported at only one location and the actual load on each shelf is not the only consideration. The only way I can thin k of to evaluate the design is to actual test the assembly. You may want to make a mockup of a single shelf and test it before ...

3

I don't know how to calculate it, but it passes the sniff test when compared to parallel bars used in gymnastics: These are made of (unspecified) wood, are 11.5ft long and 2 inches thick. They are of course made to support people who weigh more than 200lbs, doing very dynamic movements (literally jumping off of the bar and landing back on it. There are of ...

3

Rob's concerns are important. When you calculate the load that the main beams will carry you must ignore the depth of the notches and calculate the sag/load based only on the depth of the continuous wood below the notches. I would also caution you regarding the use of the 3-way miter. This is not a joint for beginners. It will need to be tight, so unless ...

3

What you have described is a swingset with a mattress connected below.To design this hybrid fabrication you must first consider each function separately. For the swing, consider the designs for children's swingsets: a beam at the top to support the swing's load and a triangular frame at each end to carry the beam. The triangular frame shape is the simplest ...

3

I would not recommend using this table for a fish tank. There are too many potential sources for failure. If the tank rests upon the 3/4" top instead of extending to the width and length of the metal support frame, the risk of failure increases due to the potential weakness of the MDF board itself. The ability of the metal apron to support the load depends ...

3

You want the grain/growth lines to be oriented vertically to maximize strength. Most 4x4 posts will have curved annual growth lines. Choose the orientation that is most vertical. As a caution, note that professional balance beams are made from laminated wood and are much deeper than the 3 1/2" in a 4x4 post. If your daughter is going to do any gymnastics ...

3

While your concept can certainly work, there are several considerations that will help it perform well. Wood species. A softwood is not nearly as strong and will be more prone to splitting especially if the molding is attached with screws (as shown). Consider using a hardwood for both the molding and the 2x6 parts. If you use a hardwood, you could use ...

3

As long as you still plan to use the slats, you can go pretty thin with whatever material you put over them to smooth out the spaces between the slats. 1/4" plywood should would work fine.

2

I would suspect that a 3/8" would be enough. If you want to screw your slats to the bottom of the plywood, you could use the 1/4" plywood. 3-4 slats would be enough to stiffen up the 1/4" to handle most of the abuse you'll be likely to throw at it.

2

You can always take the Calvin & Hobbes approach!

2

Are any structural concerns with making the table this long? No. Even with a top much thinner than you're going to end up with you can have a >100" span. Would the table need to be reinforced underneath with hidden brackets? Not at all, the interlocking box joint is very strong (lots of surface area for the glue) and the table will be naturally stiff. ...

2

First of all, the 110 pounds they say for that desk almost certainly is being very conservative, it will probably actually hold at least twice that. That being said, we can look at the ways it can fail and help mitigate each of those. Looking at the specs on that desk , the top material is probably the weak point. Putting a lot of weight over the middle ...

2

It's unclear if this question fits within the purview of "woodworking", and we are only guessing that you are asking "will this walnut stave top split under load or because of fasteners?" With that in mind: The table is fine. It isn't going anywhere under a static load twice what you've put on it. If you attached the legs with appropriate ...

2

I would like them to lay flush against the steel flats This will be the role of countersinks you make in the steel rather than determining what screw to use. Note however that if you decided to use coach screws (which are essentially a type of bolt) they can't be made flush because the head is too large and doesn't have a countersink. What kind of ...

2

How do I go about figuring out how much weight each shelf can support? Based on what follows this becomes sort of irrelevant, but if you did want actual numbers the only way I can think of realistically is to make sample shelves (note, not just one) and test them, see how much weight they can take before A) bending too much to be acceptable, B) fracturing ...

1

In evaluating if the members in an assembly will be adequate, it is important to consider both the individual pieces, the connections and geometry of the entire project together to determine if it is adequate. Perhaps the word 'breaking' is not the best term to use, but rather 'failure' works better. The project won't necessarily fail because of a single ...

1

You will be making these in batches of some sort, even if it is an evening of 2-3 items. Semi-regularly you pick one at random and test it using a test platform of some kind. Ideally you want to know the safe deflection mass, the mass under which it deforms and stays deformed, and the complete failure mass. Keep track of this and then you can see how your ...

1

You can model each dowel and the shelf itself as beams. The dowels would be like a uniformly distributed load cantilever, while the shelf would be a simply supported beam. You can look up the material properties for your material type and input the parameters of your shelf in the calculators below. https://www.engineeringtoolbox.com/timber-mechanical-...

1

Looking at the plans they use carriage bolts to attach the bed frame to the uprights. These are very resistant to sheer loads. The article on the website also shows a strength test with a full sized adult. Your idea of adding supports is the same principle of jack studs in house framing. You can screw and glue the "scrap" 2x4s cut to 29 3/4 inches they ...

1

Assuming your vertical pieces (standards) are on studs, I would drill through them and run a long screw into the stud. It should hide everything. If you want to use the brackets from Ikea for decoration, you could but I don't think you'd have to.

1

I can see two ways this table could fail under load. Either the leg joints could fail (resulting in either racking or the legs splaying) or the surface could bow and break. For the first issue, I would reinforce the joints by adding diagonal braces going from the legs to the top. I'd probably try two braces from each leg, 4-6" away from the joint. This ...

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