How to Make Anything (Using Acrylic and Machine Screws)

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Introduction: How to Make Anything (Using Acrylic and Machine Screws)

Well maybe not anything, but what follows is an Instructable about how we at oomlout.com build everything we produce.

It is a technique we call Interlocking T-Bolt Construction. It consists of a T-cutout in one piece of acrylic (or any 3 mm stock) and a receptacle in another piece. These pieces can then be bolted together making a very secure 90 degree joint. A deceptively simple technique that has unlimited possibilities.

All that is required is an idea, some drawing software, and access to a laser cutter.

Lets get started.

(shameless plug)
to check out our delightfully fun open source products try visiting oomlout.com

a note on metric units
it should be noted that throughout we refer to 3mm thick acrylic. This is often sold as 1/8" acrylic and is not a big issue as the difference is less than 0.007".

Step 1: Software

Before we start a simple drawing programme is required. Something like Corel Draw, or Adobe Illustrator will work. But we recommend an open source equivalent, Inkscape.

To Get Inkscape:
  • Goto Inkscape.org and download the appropriate version for your operating system.
  • Install it.
  • If you are new to Inkscape perhaps going through a tutorial or two before hand may also be helpful, but not required.

Step 2: The T-Bolt (design Considerations)

When designing anything its important to take into account the properties of your chosen production method. Here are a few things to keep in mind when designing with Interlocking T-Bolt.

Scale
  • We think a good size window to consider using this method for ranges from about computer mouse on the small end to a loaf of bread on the larger. Of course other sizes are possible, but much larger you get into prohibitively expensive laser cutting costs, and much smaller you start having issues with bolt clearances.

Angles:
  • This method thrives on 90 degree angles. If you would like lovely flowing curves or a bevy of acute or obtuse angles another method is advisable.

Corners:
  • Acrylic is quite a hard plastic and as such sharp corners can lead to an object that feels quite rough and angular. To combat this we like to round all corners.

Strength:
  • Here are a few rules of thumb we use when designing our products to keep them from being brittle. They have been arrived at through trial and error and are just guidelines.
  • Minimum distance for a hole from the edge (5mm)
  • Minimum holding run (ie. amount of acrylic to leave either side of a cutout (5mm)
  • Bolt repeat distance. (ie. if you have a run longer than this an additional bolt should be added) (100mm)

Step 3: The Component Pieces & Nuts & Bolts

There are only 2 shapes required.

The T-Cutout
  • This is the piece the machine screw extends into, a nut catching in the large cutout portion.

The RCR Slot (Rectangle-Circle-Rectangle)
  • The cutout the T-Cutout slots into.

To use, simply download the template attached to this step (03-TBOL-T-Slot Template.cdr for Corel Draw or 03-TBOL-T-Slot Template.svg for InkScape)

The Nuts & Bolts
Putting everything together is as simple as a single machine screw and matching nut. McMaster Carr is a great source for these.

Step 4: Making Your Design

Finally the layout.

To illustrate the process I'm going to use a simple little box I made to hold a little Nixie tube kit i have (pictured below).

Conceptulization:
  • Moving from a 2 dimensional drawing to a 3d object is something that can take a while to get your head around. To experiment I recommend printing out the example below on paper and cutting it out with an exacto to get a feeling for how it all fits together.

The Process:

1. Import Template
  • Import the template from the previous step which has the T-Cutout and RCR-Slot in it.

2. Draw the Base
  • Draw the bottom of your object before positioning RCR-Slots. In appropriate places. Something that makes things much easier down the line is if you keep your object as symetrical as possible.

3. Draw the Sides
  • Using loads of guidelines pulled down from the rulers position the T-Cutouts so they pair up with the RCR Slots.

4. Add Corner Cutouts
  • You can see in the design below that half the height is removed from the end of each side. These are to allow the sides to nicely interlock.

5. Make the Cap
  • Draw the cap. If your piece is symmetrical at this point the cap will have the same hole pattern as the base. Just add an appropriate cutout to it.

6. Laser Cutting
  • This is something that only a couple of years ago would have been very difficult. However a bevy of cut on demand services are now available.

A Few Cutting Services:
Spikenzie Labs Mini Cuts - http://www.spikenzielabs.com/Store/Mini_Cuts.html - Montreal based and his prices include shipping (to USA or Canada) which is always a nice touch.
Ponoko - http://www.ponoko.com - A great group.
Big Blue Saw - http://www.bigbluesaw.com - Offers laser cutting as well as waterjetting more rugged materials. Which means any design can be rendered in 1/8" stainless steel if you so desire.

Complete:
  • Well a bit of an over simplified process, but it is something that is best experimented with. If you have any pressing questions drop a comment below or send us an e-mail at info@oomlout.com

Step 5: Adding More Pieces

Sadly you can only build so much using just T-Cutouts and RCR-Slots. However one of the best things about laser cutting is if you have anything with mounting holes, and a pair of calipers, you can quickly draw up a mounting hole for it.

I've Compiled a file with the main cutouts we use in our products.

The Cutouts:
  • RC Servo
  • Mini RC Servo
  • LED
  • NEMA 23 Motor
  • Skate Bearing
  • MicroSwitch
  • Arduino Diecimiela
  • Pololu Servo Controller

(cutout templates available below)

Step 6: The Possibilities

... Endless.

I won't leave it at that. Attached are a few examples of things we have made at oomlout.com .

We'd love to see anything you make. If you make something leave us a comment below or send us an e-mail at info@oomlout.com. We'd love to share what you've done here.

Stuff Made By Others

Doug Eastman made a lovely little box for his still in development Arduino project. I think it looks great (photo below)

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    user

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    265 Comments

    i doubt you would even want to try. acrylic is brittle and the cuts are small. it's "possible" to do it by hand, but the amount of time you'd have to pour into it would be a waste. i'm sure if you were to go to this guy (it's me actually) on craigslist, he'd be happy to set something up...

    sfbay(dot)craigslist(dot)org/eby/cps/5156461262(dot)html

    I made a couple of these example enclosures and of course along the way nothing is ever perfect. So I have attached my "modified" file and a few pics. At home depot or lowes, I forget which, they have sheets of acrylic, but it's .08 inches. I modified the file to this new dimension. Also, I discovered if you make the vector lines slightly bigger in the rectangle of the RCR portion so the tabs simply slide right in. What I did still makes it a pretty tight fit. These are surprisingly sturdy little boxes! The raw material may be flimsy and flexible and you think to yourself, is this gonna work? But it's awesome! Thanks for posting this, It's a fun little project :-)

    001.jpg002.jpg003.jpg

    Sorry, by hand saw, I meant knife or something like that...

    1 reply

    I'd say no. You do not need to own a laser-cutter. I just upload the plans and order from a laser-cutting service (I use Ponoko).

    For my box, it is important that the entire inside space be available. As I understand it, with 3 mm acrylic the nuts will stick into the inside by a few mm. In order to fix this using this hardware, I calculate that I would need to use acrylic at least 6.4 mm thick. Do you agree?

    Thanks for this great information. I know this is from a few years ago, but are the templates still available somewhere? When I try to download the .sgv file, it just takes me to a .tmp page.

    1 reply

    If you right-click and "Save Link As..", just make sure you save it as .svg instead of .tmp. I just tried it and it opens in Inkscape without problems.

    user

    how about gimp, sketchup or blender?

    10 replies

    How about Ubuntu??? There you get Gimp AND inkscape (gimp rules!!!) AND it's FREEer than windows, cos windows sucks ubuntu's emm, orangness!

    Yes. i am running ubuntu. DEATH TO WINDOWS. although i cant get the sound in audacity to work.... D:

    Oh well. still worth using linux. and its Windoze btw :P

    you mean winblows?

    windoze winblows CrapOS what other ones are there?

    BSOD-os

    nice one. anything else? actually, can anyone think of any good linux sayings?

    Linus has great ones, "Software is like sex, it is better when it's free."

    Followed closely by his other famous quote, "Only wimps use tape backup: real men just upload their important stuff on ftp, and let the rest of the world mirror it ."

    I rather like this one myself, "Really, I'm not out to destroy Microsoft. That will just be a completely unintentional side effect. "

    This one is good too, "A computer is like air conditioning: it becomes useless when you open Windows."