Playing with MicroRAX slotted aluminum framing

MicroRAX is a mini-slotted aluminum building/prototyping material, similar in concept to 80/20 and MakerBeam. Extruded aluminum beams are formed with an X shaped cross section and bolted together using nuts and other fasteners that fit into the slots. This sort of T-Slot is common in machine shop tools and other fixtures. It is a great way to quickly build a frame without having to custom cut and drill parts.

MicroRAX cross section 10mm x 10mm

I was putting in an order to Sparkfun and decided to add a MicroRAX Medium Kit to build some frames. Shipping on my order was already expensive (once over $100 it HAS to go UPS, which is roughly $50 to Maui), so I figured adding in the microRAX would be offset the expense. The box arrived yesterday and today I got a chance to play with it.

MicroRAX Medium Kit

MicroRAX Medium Kit from SparkFun

There isnt a lot of documentation on how to use it – none provided in the kit. MicroRAX just recently (late 2011) opened up a MicroRAX Wiki which may build up more info over time. Their YouTube channel has a few decent videos. They have an ok overview and another on how to do joint assembly – and some other treats…

Basically you join the beams together using a cover plate, a nut plate and several M3x5mm screws. The kit came with three different types of cover plates – L, Corner and Truss. There are two ways to put these together. The videosays to screw the nut plate to the joining plate and then insert into the beam….

Inserting a nut plate screwed to L-Joining Plate into a MicroRAX beam

This works ok sometimes. However I found that the nut plates can be difficult to get into the slots. Perhaps its a tolerance issue, perhaps its some flashing left over from the press cutting of the nut plates. When dealing with multiple corners, it can be REALLY hard to maneuver the assembly to get the nut plate to line up right. This is especially pronounced when dealing with something like a box. You only have so much freedom of movement and its nearly impossible to get all the plates slotted up before pushing it together.

So the alternative is to put the nut plate into the slot first and then line up and screw the joining plate onto it. Pretty easy.

Joining two rails, inserting nut plate first, then screwing together.

I decided to try building up a quick box using a few of the parts in the kit. It didnt take very long and brought back memories of playing with Erector Sets. One trick is noting the direction the L-Joining plates will go, and being sure you are putting the nut plate on to match properly. I had to flip over one to learn this. There is another video showing how to make a linear slider with just the basic parts, so I added one to the box to give it a try. Pretty easy if not elegant.

Completed box with slider

It should be fairly easy to put MDF or Acrylic sides on a box like this. It wont be water proof but it is a nice quick way to make a small frame. For larger projects I would definitely use 80/20. The MicroRAX folks recommend it for projects over 18 inches.

Here’s a flickr set from my first night building….

[slickr-flickr tag=”microRAX” descriptions=”on” flickr_link=”on” sort=”title” use_key=”y” ]

4 replies
  1. Eric Johnson
    Eric Johnson says:

    Thanks for the write-up on this Jerry!
    Given the questionable fit between components, I’m wondering if you’d recommend the kit overall or not? Is it a worthwhile investment for repeated uses and quick enough to work with for everyday rapid prototyping projects?
    Thanks again!

  2. Jerry
    Jerry says:

    I definitely like the kit. The issue with fit seems to be a tiny bit of metal left on the edges of nut plates from the stamping process. That or simple operator failure. Its gotten a lot easier to work with as I go on. I am going to re-use the parts from initial build for a project box I need for TEDxMaui this weekend. Then the parts can be re-used again and again. I look forward to trying out acrylic/wood side boards. This will be hopefully be superior to chopping up a metal/plastic box permanently for a temporary project.

  3. Michael
    Michael says:

    Thanks for this great article. I didn’t know about this product before. I have seen a lot of people work with 80/20, Item and so on. Looking at the box you made just gave me an idea on making a kitchen cabinet drip tray.

    Is this product available locally so you don’t get hit with such a big shipping cost. I know that Grainger has some 80/20 in stock and can get order in by ocean freight if you don’t need it in a hurry.

  4. Jerry
    Jerry says:

    Michael – I very much doubt there is a local source for this product. I bought my pack from and took the hit on shipping — I was already over the USPS limit, so I loaded up my cart with larger items that didnt kick the price up much. We have the option of pooled buying as a group from SparkFun (and other similar sites) as a makerspace. This saves us like 10% on cost – which can make shipping much less painful.


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