Bike Bench/Stand design question

[Jbone]

So... before I begin reassembling my 748, I wanted to build a proper bench/stand for it. There are a lot of examples of good solid wood DIY benches out there and I've come up with, what I think is a solid and straight forward design based on what I've seen others using.

However, one thing has me re-thinking the design a bit. Basically, the design calls for 6 18 inch 4x4's as the main upright supports. However, after making a run to Homedepot for the materials, they were out of 4x4's. Now... I could go to Lowes (25 minute drive away vs. 500m drive with the Depot) but I bought enough 2x4's to get 6 18 inch pieces extra to use for the uprights instead of 4x4's. I guess what Im asking is, would the 2x4's be enough to support the weight?

Im thinking yes, as once its all put together it should really be pretty solid.
Here is a basic scketch of my design. Note: 3/4 inch plywood will be screwed down onto the top as well as two seperate peices of plywood undeneath for shelf space.

Any thoughts and or concerns () are more than welcome as the workbench is next!

[Ritlee]

Should be good, might even get away with just 6 2x4's. But 12 2x4's would personally keep my mind at ease if it were my bench.

[DaC]

Originally Posted by Jbone

Any thoughts and or concerns () are more than welcome as the workbench is next!

First off, I am NOT a structural engineer!

That said, here's how I would go about looking at your problem. The first thing you need to know is the weight of your bike, as well as the sheet of 3/4 plywood that it will support.

Next, what material is the 2x4 made of? Obviously a soft wood, but is it Douglas Fir? Yellow Pine? It's a big difference.

The Fir gives you a LOT more compressive strength (the load will be on the gain). 7,000+ PSI for Fir, vs. ~4,500 for White Pine, vs. 8,000+ PSI for Yellow Pine. The material makes the difference.

What does a 2x4 have for surface area on the end grain? Call it 5 square inches?

If your stand ends up weighing 150lbs, and your bike another 450 lbs...that's 600 lbs of weight. Using 6 2x4 would give you 30 square inches of surface area...so 600 / 30 = 20 lbs per square inch. Hmmmm..OVERKILL

Of course there are a lot of other factors floating around in my head as I type this, such as the stiffness and bending strength of the wood, but your 2x4's will be so short that I think it's a moot point. I'd also check to see what 3/4 birch plywood is rated at and keep in mind that your tires have a small contact patch. You obviously want a wide safety margin when looking at how close you come to the rated limits, but I as far as the 2x4s are concerned, I'd work it out using the above logic.

As I see it, in relation to the 2x4 vs. 4x4 question, you've saved yourself some money.

[mlukason]

I make a lot of sawdust in my spare time. The strength of lumber inline with the grain is extremely strong. Suppose you build the stand with 6 2x4's and have a top that will transfer the weight to all six supports...Let's say you have a 1000 lbs of bike, top surface, and some tools....that's still only 167 lbs per leg. Not at problem at all.

The key is keeping those supports from leaning or twisting. Make sure they are braced securely at the top and the bottom.

Here's a photo of an aquarium and stand that I made...the entire weight (about 1,000) is supported by 6 supports made from 1" dimensional lumber.
Turtle Tank | Flickr - Photo Sharing!
Three years with about 200 gallons of water and not a change in dimension.

You will be fine with 2x4's

[Gilly]

I agree with all on the 2x4's being short enough and strong enough. What I would look into is a leg support that would prevent a collapse. With the legs secured at the top, and straight bracing at the base, you could still have a collapse if say you are loading a bike up onto it, and running it into a wheel chock. (I would fit it with a wheel chock from Harbor Freight).

Anyway, the weight of the bike, has enough downward force to prevent the legs from sliding when you hit the wheel chock, but the force may be enough to cause the top portion of the unit to move forward, while the legs hold their place.... collapse.

Angled cross bracing will distribute any lateral force equally and make a collapse proof design. It is not that you may have an issue loading a bike the first fifty to a hundred times... it's the cumulative force that weakens the structure over time.

I couldn't find a specific image... but this is the idea...

[Ricoyam]

Are you talking about a bench to build your whole bike on or assemble components?
If the whole bike, you might want to consider one of those inexpensive lifts that Harbor Freight sells. They're rated at 1000 pounds but I wouldn't put anything over 500 on one but for your Ducati or BSA they work very well and give you the advantage of being a real lift.
I bought one from a friend who thought he could put a Harley on it.

Not as nice as the K&L lifts I use at work but great for my collection at home.

[Jbone]

Well, after some thought, I've decied to over engineer this thing and double up the 2x4 uprights...which would essentially give me the same as 6 4x4's
In the end, I suppose that 6 2x4's would hold, especially since they'd be short and braced properly.... but Im all for overkill ; )

BTW...thats a nice job there Mlukason! I don't think mine will turn out anywhere near that nice lol!

As for buying a lift... in time. This projects all about saving money. Just moved from overseas AND bought a house AND started anew job.... so the pay needs to catch up some before I can justify a new 500$ lift in the garage to the wife (That said I spied a nice Termi half system for $500 the other day.....Hmmmm?)LOL!

[apagios]

Holy crap with the compressive load strength on 12 2x4s doubled up (as 6, 4x4 posts) you should easily be able to park the same weight as an F-350 on there!

But at $2.49 per 8' stud for a 2x4 at Lowes/Home Depot, over engineering is cheap!

My dad built his deck with 2x12 joists, in case he ever wanted to enclose it as a summer room. I pointed out that even the entire house is built using 2x10 floor joists, I am pretty sure we could park a few trucks on his deck and be fine!

Gilly has a good point. Use diagonals, and you can get away with 1 on each side, rather then the X on each side. On say the left side run a long diagonal 2x4 from the top of the front to the bottom of the rear. and run it the opposite way on the right side of the stand and, so if you look through you'll see an "X" but with only 1 diagonal per side. Make sense? That will be plenty of diagonal bracing!

[SP3]

Holy crap, I thought I overbuilt mine way back (it WAS, for sure) but that's nuts. No flex or creaking with any of my Ducs on it. The only thing I'd do different if I were to make another is make it another 6" wider.

[velocidave]

they are all overbuilt unless you are running a shop from your garage. Check out this thread, we built three of them in a weekend, the guys and myself have had 600+lbs on them without hesitation, and they are stable as you can imagine, You could taper the plywood from the outside a bit to make it pyramidish if you're worried about stability when you're standing up on it or whatever, and maybe most importantly, unless you have a 3000Sq ft permanent work space, they break down and store in a small footprint.

Check it out before you start hating.

Plywood stands