Dear Chris: I purchased your system at Hamvention and wanted to know if you have a means of stacking another board on top of the base? Any advice?

Thanks again, John in Ohio.

 

Dear John in Ohio:

It’s relatively easy to build a two-layer/double-stack WorkBench.

The basic approach is:

  1. Use a WorkBench 1007 Base or 1010 Base as the foundation for the stack.
  2. Use a WorkBench 1107W Base for the upper layer/s.
  3. Space them out using 8-32 hex (female-female) standoffs of an appropriate length for your project. You will need four.
  4. Attach the hex standoffs using 8-32 truss-head machine screws.  You will need eight.

The key to success is using the right hex standoff.

While many options are available, I consider some things to be imperative and other things are highly recommended.

  • You must use a standoff threaded for either an 8-32 (Imperial) machine screw, or an M4 (metric) screw. These screws match the size of the hole in the secondary matrix in the WorkBench.
    • In the US, of course, the 8-32 is more readily available, both for the screws and the standoffs.
    • You don’t have to use a truss-head screw, but I strongly recommend it. The truss-head will spread the clamping force of the screw over a broader area on the Plexiglas of the WorkBench Base, minimizing the chances of cracking the plastic.
    • Optimal length of the screw is 1/2″ or 12mm.
  • There are different diameters of standoff. The same principle applies here: use the largest diameter you can fit into your design, to help spread the clamping load more broadly on the plastic of the WorkBench Base.
    • While you can certainly use round (tubular) standoffs instead of hex, I prefer the hex because they are easier to tighten.
    • My favorite diameter is a 3/8″ (across the flats); closest metric equivalent would be the 10mm. This always feels like the right balance to me.
    • When you tighten the screws into the standoffs, do not overtighten. This is especially important if you’re using a smaller-diameter standoff. Just hold the standoff between your fingers and gently tighten with the screwdriver.
    • If you are in a high-vibration situation such as with robotics, try using a bit of chemical threadlocker (Loctite brand or similar). I’d suggest using the medium-strength blue grade; higher-strength grades can be difficult or impossible to remove.
    • The remaining variable is the length of the standoff. While that depends on your project, the right answer is: Choose the shortest standoff that will just clear your installed components.”  This gives you the most rigid setup.
  • Finally, choose a material. I prefer aluminum: it’s usually the cheapest of all options, plenty strong, yet lightweight.  Unless you have a special requirement for brass, stainless steel or nylon, aluminum is the best bet.

You are now ready to venture into the wilderness of McMaster-Carr.  You can find standoffs in many other places, often cheaper, but I like McMaster because they have a consistent supply of high-quality components at reasonable prices. (We are not a McMaster-Carr affiliate. We make no money from this recommendation. )

If you use this link, you will find pages and pages of standoffs and no good way to filter them (Sorry!).

  1. Scroll down to the aluminum
  2. Find the 3/8″ Hex Size section in the right-hand column.
  3. Choose a length; note that you can go all the way to a 6″ long standoff, but unless you really need that, go shorter.
  4. Make sure to choose the right thread size (8-32 or M4, if you’re going metric), put four into your cart, and off you go.

In addition to the standoffs, you will need eight truss-head machine screws. Be sure to match the thread size you chose for your standoffs. I get small quantities at my local Ace Hardware. They have a good selection and common hardware like an 8-32 truss-head screw is rarely out of stock.

Now, a couple of notes on the assembly:

  • The 1107W is a flat WorkBench Base (no folded legs) designed for use in a BUD Industries NEMA box.
    • It is slightly longer than the equivalent-size folded-leg Base, which is the 1007.
    • That means that when you stack them, the 1107W Base will be offset by one row of holes to one side or the other of the 1007 Base.
    • The only impact is that the Cover will not fit on a double-stack, but that was probably going to be iffy anyway due to the height of the components.
  • Note the markings on four of the holes in the corners of the secondary matrix (the small holes) on the 1107W.
    • These holes are inboard by one row from the left and right sides; they have a circle etched around them to indicate the best choice for standoff placement.
    • Place your standoffs in these holes.
    • The outermost holes in the secondary matrix of the 1107W are slightly larger diameter to adapt to the BUD Industries NEMA case. You can use them, but it’s better to use the marked holes.
  • To simplify things, work from the top down. First, attach the standoffs underneath the 1107W at the marked holes in the corners.
  • Then align the standoffs on the 1007 (or 1010), run the remaining four screws through from the bottom of the Base, and you are ready to deploy.

Of course, it goes without saying that attaching a second layer really restricts your access to the first, but you already knew that.

Keeping the standoffs attached to the 1107W Base means you can pop that off and set it on your desktop as you finish or adjust the lower layer.

Happy building!

C