HF44 bench design - for the non-welder

[kasander]

Inspired by steevo and dbonne, but designed from 8020 to avoid the need for welding. Also, aluminum, so no paint required, it also comes in black anodize for extra $$.

I finally splurged and bought 2 HF44 boxes on black friday. One was in stock, the order had to be ordered so it should be here in a week.

I wanted a workbench similar to what steevo built, but also wanted it to be wall mounted as with dbonne's version. I also do not have a welder. I decided to design something out of 8020 since we use it often at work. It is not cheap, but I drew something up and priced it just to see how it compared to a welded frame. Considering welding time, 8020 is cheaper for me vs. hiring someone to do the welding.

Anyway, here's what I have designed to this point. I'm thinking about ordering the materials Monday while there is a sale going on. It's only 5% off, but every bit helps. I found a cheaper alternative to 8020 at www.tnutz.com so that is where the pricing came from.

Some details:

Workbench height: 37.75" + gap to floor, assuming 1" thick bench surface.
Workbench depth: 28" - debated on this and read many, many posts about this topic. In the end I wanted to minimize wasted space behind the 22" deep boxes, so I went with 28". 2" overhang + 22" box + 3" for 2x6 and aluminum extrusion + 1" gap.
Material costs: Around $750 for clear anodize, or around $800 for black anodize.

Anyway, some pics of the design. I used Autodesk Inventor to design it.

I added storage bins and upper cabinets to the design but those are things I may add later as my funds allow.

The pictures show a 24" diagonal support as that is what is available off the shelf from 8020. I'm going to see if I can get one at 30" length so it extends all the way to the front.

Static FEA with 6000 lb load applied to the lower horizontal supports approximately where the 4 corners of the box would rest. I will remove the casters and add a block so the box rests on the caster mounting surfaces rather than the perimeter of the box.

Max deflection of 0.130", exaggerated in the image so you can see it.

I will lag bolt the horizontal 2x6s to the wall studs, then lag bolt the 8020 assembly to the 2x6s.

I'm not to concerned about ripping it off the wall. If I decide I need to bang on something, I'll just wedge a 2x4 under the frame to make it stiffer. Having the vertical supports extend higher than the height of the boxes increases the supporting moment so the loads on the bolts counteracting the moment due to the weight of the boxes will be small.

What do you guys think?

 

[southalabama]

Looks good to me.

Well designed imho

 

[ScottsGT]

That's going to be really nice. Especially if you can build the frame around the box instead of dropping the boxes down into a pre built frame. That was my toughest nut to crack was getting the box in for the test fit and then back out all by myself. Even harder once painted so I didn't scratch it all up.

 

[matt_i]

How do you cut the 80-20?

I think in indutrial apps most extrusion is cut with a cold saw (slow turning HSS blade with coolant feed) for the "milled" finish, as opposed to bandsawing it rough and then having to put every single piece into the milling machine...

I'm not 100% clear on whether its all going to hang on the wall or have feet, but I would make sure the feet are all independently adjustable (leveling feet).

 

[kasander]

No feet is my plan. Wall mounted. You can cut it with a chop saw but I am ordering everything precut and machined for anchor fasteners. They are the strongest fastening method.

 

[matt_i]

What kind of pullout force are you modeling on the upper fasteners (presumably to the studs)?

It seems like if you hung this over drywall the back lower corners would crush into it due to the reaction there. Edit: see the horizontal timbers (?) those should help.

I would say its not out of the question to get 500 lbs of stuff in each of those toolboxes once they're loaded up.

 

[QwikKotaTx]

The pre-cut 8020 looks way nicer than doing it yourself. I don't know what they use but it's sweet. That stuff is expensive though.

Is that SolidWorks Sim or an old version of ANSYS?

 

[kasander]

What kind of pullout force are you modeling on the upper fasteners (presumably to the studs)?

It seems like if you hung this over drywall the back lower corners would crush into it due to the reaction there. Edit: see the horizontal timbers (?) those should help.

I would say its not out of the question to get 500 lbs of stuff in each of those toolboxes once they're loaded up.

Pullout force on the top bolts is small. Assuming 18" CG of load off wall and upper 2x6 at 48" high, load is 2250 lbs. (Fx = 6000*18/48) With 12 lag bolts holding it up, that's 188 lbs/bolt.

A 5/16" lag bolt has a pullout force capacity of 209 lbs/ inch of thread engagement. I will engage them 1.5" so that gives me a capacity of 313 lbs.

I highly doubt I will ever have the toolboxes both loaded to 3000 lbs, so I think I am well within the capabilities of this design.

https://www.zillarac.com/Portals/0/Documents/PDF/Screw%20Pull-out.pdf

As I noted in the original post, I did the FEA analysis with 6000lb force. 3000 lbs per box.

The pre-cut 8020 looks way nicer than doing it yourself. I don't know what they use but it's sweet. That stuff is expensive though.

Is that SolidWorks Sim or an old version of ANSYS?

8020 is ridiculously expensive, a little better from Tnutz, 1.5" light profile is under $5/ft.

I used Autodesk Inventor and its embedded Analysis tool.

 

[rattle_snake]

Nice. Uni-strut could be used as well. Not as nice as the Al extrusions, although cheaper and available at HD if needed.

 

[kasander]

Nice. Uni-strut could be used as well. Not as nice as the Al extrusions, although cheaper and available at HD if needed.

Unistrut will not support the loads cantilevered off the wall. You can’t make strong right angle connections with unistrut either without extra bracing.

A 1.5” profile will support 1200 lbs at 6” away from the joint with the double anchor fastener.

 

[Farmall450]

Looks good. Like you said, don't whale on it with a sledge and I think you'll be alright. Use good lags.

 

[PugetDude]

Looks nice, but why are you cantilevering the benchtop off the wall instead of just mounting a conventional top on the benches? Seems like it would look the same and be a lot stronger?

 

[kasander]

Looks nice, but why are you cantilevering the benchtop off the wall instead of just mounting a conventional top on the benches? Seems like it would look the same and be a lot stronger?

The whole assembly is wall mounted, not just the top. I just like the floating look and want to be able to sweep under it if needed.

 

[mrvm]

The whole assembly is wall mounted, not just the top. I just like the floating look and want to be able to sweep under it if needed.

Appreciate the the math involved for design loads but short support legs would go a long way to remove load concerns or hammering from above while allowing an occasional clean sweep.

 

[mike93lx]

How much of a gap will you have under them?

I agree that it seems a little odd to not have even 2-3 short feet on the front. Would make the whole setup much more solid.

 

[56Mark]

We design lots of things with 8020 where I work. I like it too, but have one thought about making it without welding; for the cost difference of 8020 vs steel tubing, I bet you can buy a $500 MIG welder and come out of this with a "free" welder. Just throwing that out to think about.

 

[kasander]

How much of a gap will you have under them?

I agree that it seems a little odd to not have even 2-3 short feet on the front. Would make the whole setup much more solid.

Maybe 2-3" gap. I may add some adjustable feet later if I feel the need for it.

We design lots of things with 8020 where I work. I like it too, but have one thought about making it without welding; for the cost difference of 8020 vs steel tubing, I bet you can buy a $500 MIG welder and come out of this with a "free" welder. Just throwing that out to think about.

I am waiting on a final quote, but my cost is going to be around $700. I don't think I could buy all the steel necessary to build this for $200. I also prefer anodized aluminum to painted steel. Finally, my time is not free and the time it would take for me to weld a square frame to build this would not be insignificant.

 

[jimkinney]

Interesting design, but I would worry more about the wall than your bench/box support structure.

I didn't see you commenting about your walls, but most stick built structures probably won't survive. Wood studs are only attached with a couple of 1/8" nails, top and bottom, and metal studs have even less attachment. Walls are designed for a vertical load, not a large overturning moment.

I know if I hung my Suburban (5300 lbs) on my garage wall, regardless of the number of lag screws, it would be on the floor really quickly, along with the room above the garage.

Just a thought.

Jim

 

[PugetDude]

Interesting design, but I would worry more about the wall than your bench/box support structure.

I didn't see you commenting about your walls, but most stick built structures probably won't survive. Wood studs are only attached with a couple of 1/8" nails, top and bottom, and metal studs have even less attachment. Walls are designed for a vertical load, not a large overturning moment.

I know if I hung my Suburban (5300 lbs) on my garage wall, regardless of the number of lag screws, it would be on the floor really quickly, along with the room above the garage.

Just a thought.

Jim

Good thought.
This is one of those situations where I'd take empirical evidence and common sense over free finite element analysis on the internet.

 

[dfiler2]

Interesting design, but I would worry more about the wall than your bench/box support structure.

I didn't see you commenting about your walls, but most stick built structures probably won't survive. Wood studs are only attached with a couple of 1/8" nails, top and bottom, and metal studs have even less attachment. Walls are designed for a vertical load, not a large overturning moment.

I know if I hung my Suburban (5300 lbs) on my garage wall, regardless of the number of lag screws, it would be on the floor really quickly, along with the room above the garage.

Just a thought.

Jim

I agree with this and if it doesn't happen quickly, it will happen over time.

 

[kasander]

Good thought.
This is one of those situations where I'd take empirical evidence and common sense over free finite element analysis on the internet.

Who's using "free finite element analysis on the internet."?

Interesting design, but I would worry more about the wall than your bench/box support structure.

I didn't see you commenting about your walls, but most stick built structures probably won't survive. Wood studs are only attached with a couple of 1/8" nails, top and bottom, and metal studs have even less attachment. Walls are designed for a vertical load, not a large overturning moment.

I know if I hung my Suburban (5300 lbs) on my garage wall, regardless of the number of lag screws, it would be on the floor really quickly, along with the room above the garage.

Just a thought.

Jim

Got me thinking on this. I agree in principle about your point in the design of a wall, but not sure the loads are that excessive. The nails securing the top plates to the stud will have no problem holding this load. Summing the moments about the bottom of the stud and solving for the shear force on the top nails yields F = 6000*18/117 = 900. (117" long studs) That's 923 lbs distributed over 6 studs, 154 lbs per stud, 2 nails per stud, 77 lbs per nail. Shear strength of a 16D nail is > 100 lbs. This is assuming you just had studs sticking up in the air and held by nails. Obviously, the weight of the roof, wall sheathing, and hurricane ties all increase the strength of the wall and improve it's resistance to the moment load.

I don't see a couple of wall-mounted tool boxes bringing my garage crashing down...

As to mounting your suburban to the wall, the CG of it is a little more than 18", assuming you were mounting it with the tires on the surface of the wall. (29" from what I found on google)

Here's my FEA with wall studs added. The bottom surface of the bottom plate is fixed, and the top plate is allowed to move vertically and side to side, but fixed from moving out from the wall. All mating surfaces are assumed to be bonded together, I didn't model the nails...

Maximum displacement with the 6000 lb load is less than 3/8". Here's a graphical representation with the displacements amplified so you can see them.

Here's a stress plot, where red is greater than 30ksi stress. (There is very little red, except around some small corners of the aluminum extrusion).

I am very curious about how accurate the FEA is for something like this. I'm tempted to try to install the frame and load it with weights and measure deflection to see if I can correlate the model to reality. I've never really tried to use FEA with wood materials, not sure how well it correlates.

 

[PugetDude]

One thing consistent on these GJ threads is someone taking a simple project and making it exponentially more difficult, often to the point of paralysis by analysis.
Subscribed for the actual build.

 

[kasander]

One thing consistent on these GJ threads is someone taking a simple project and making it exponentially more difficult, often to the point of paralysis by analysis.
Subscribed for the actual build.

I think that describes all my projects.

Decided to make it two separate mounts, then I can decide later if I want to spread them out and have a workspace between them.

Materials on order.

Picked up my second 44" box from HF which was a pre-sale from Black Friday. My first box was SKU 64133 which I have already filled with tools. This time they only had 64281 and 64134. I thought the 64134 was the same as 64133, so I took it home. Got it unloaded, unboxed, and sure enough, it is the other style with the drawers that don't fully extend. After getting my pregnant wife to help me load it back up and straining my back in the process, I took it back and returned it. Now I am waiting for them to get more in the store until I find the 64133 SKU. They said they will honor the BF price, hoping to get the second box in January. I will post an update once I have something to report!

 

[ScottsGT]

One thing consistent on these GJ threads is someone taking a simple project and making it exponentially more difficult, often to the point of paralysis by analysis.
Subscribed for the actual build.

You say that like its a bad thing.

 

[kasander]

Finally received my parts. Originally received silver anchor fasteners even though I specified black. They shipped replacements so now I'm ready to go. I assembled the frame, just haven't mounted it to the wall yet. I guess I will temporarily mount it, then take it down when I'm ready to add drywall...

Still waiting on my local harbor freight to receive a matching 64133 SKU box. The other 2 SKUS are the other style with the drawers that don't quite fully extend.

 

[kasander]

Modified my design and building as two separate frames so I can experiment with how far apart I want the boxes before I permanently mount them. Haven't bolted it to the wall yet, but here's an updated 3D model of what I'm planning.

 

[Growlertdi]

I like your design, but again think that if you are only going to have a 2-3" gap below your boxes, why not put a foot on each corner at the front. Will still give you ample room to swing your dust mop below the boxes for cleaning (and that area will collect schmutz over time) and will also completely support the front end of your boxes and worktop. do you have any short pieces of your extrusion or did you only order exactly what you needed for the HF box frames and no extra shape to play with.

Either way, looking forward to more updates

 

[kasander]

Finally got my first toolbox mounted. Just need to load it up with tools and get the other one up and make a bench top for them. After calling for months trying to find a 64133 SKU number to match the first one I bought, they had one last week so I snapped it up and went back for a $100 refund during the parking lot sale this past weekend.

 

[Growlertdi]

Looks great! and the hover conversion does make it look extra interesting

 

[mudcat]

Great design. I am an automation machine builder and work with extrusion almost daily. I really like the stuff and have built 2 desks, 2 workbenches and a shelving unit out of extrusion for my area at work. I have butcher block tops on the desks and workbenches. Look into dust covers for the slots. They really help keep the frame looking clean. They make it in different colors. I use blue dust covers on my black extrusion frames.

 

[Gentleman Adventurer]

Nice work! Thanks for posting the the thought process and analysis behind the build.

I'm still paranoid though and would probably put some front supports in. Just in case something heavy gets put on the bench, or who knows what happens. (then again I tend to over build, that's why I was never an aircraft structures engineer, LOL.

Keep up the good work. I had no idea about 8020, great introduction.

 

[cyclic]

If you add a flat panel to the outside and bolt it with t nuts around the perimeter it will seriously add some major strength to it.

 

[ericlar80]

If you add a flat panel to the outside and bolt it with t nuts around the perimeter it will seriously add some major strength to it.

This is a really good idea.

I think I would probably put one or two small legs at the front of this one to prevent deflection in the wall. Depending on what is on the other side of the wall, drywall or stucco for example, 1/4"+ of deflection like in the FEA could cause some problems. Small legs could be done that would barely even be noticeable once installed.

 

[kasander]

I may put some feet halfway between the wall and the front of the box They would eliminate the pull-out forces on the studs and still not be visible from the front. Adding flat panels around the perimeter would not serve any purpose as it is already stiff enough.

The wall is an exterior wall of the garage so the other side is OSB (as you can clearly see) and fiber cement siding.

 

[ptgarcia]

I see you're in CA. Did you account for seismic loads?

 

[pbon]

Looks nice! In my last garage, I simply put 3 of the 44s on their casters in a row across the back wall with a wood top over all 3 and it worked great.

 

[kasander]

I see you're in CA. Did you account for seismic loads?

Um, Wilmington, NC is not in California, thank goodness.

 

[gtsgarage]

I like they way my Newage Pro cabinets mount. Bolted to studs but weight bearing on adjustable feet. Nice and simple. The tool cabinets just sit on feet and have a top across them. I didn’t even bolt those to the wall. Took one day to install by myself.

I commend anyone who invests time, money and interest in projects they are passionate about so fantastic work.

Look forward to seeing the final product.