Cupcake CNC Body Assembly

This page is part of the Cupcake CNC build sequence.


In this step, we'll be building the outer frame of the Cupcake CNC.

Estimated build time: 3 hours.

Tools You'll Need:

  • Allen keys in various sizes
  • 2 13mm crescent wrenches (pliers will work in a pinch)
  • Metric Hex Keys
  • Metric ruler

Parts You'll Need


So here are the parts that you'll get to make the MakerBot body:

  • Top
  • Bottom
  • Middle
  • Front
  • Back
  • Left side
  • Right side
  • Power Plate for power supply
  • A lot of M3x16 bolts
  • A lot of M3 nuts
  • An ATX power supply
  • 4 plastic M8 pulleys.
  • 1 pulley to go on the stepper motor.
  • Toothed belt to go on the pulleys.
  • 2 printed ABS idler pulleys.
  • M8 bolts for the belt tensioners
  • M8 nuts for the belt tensioners

NOTE: Some of the pictures on this page are of older Cupcakes which have a slightly different assembly order. You're not going to put the clear acrylic Z-stage in until later on, so don't worry about it showing up in some of these pictures.

Prep Work


If you're going to customize it, now is the time. You could paint it, stain it, or wax it like a surfboard or whatever you want to do with it.

You don't have to do this, you can just put it together as is, but in theory, if you're planning on making it last long enough for your grandchildren to use it, you should eventually protect it somehow and it's easiest to do before you put it together.

You can see in this picture that all the lasercut pieces are labeled for easy identification. We do this with a special setting on the lasercutter that lets us do different kinds of cuts. One to go just a little into the wood for the labels and the words "MakerBot Industries" and another, more powerful cut to cut all the way through the 5mm thick birch plywood.

I had a few choices when we decided what to make the body out of and after a number of tests we chose this birch plywood for its strength, ease of modification, and beauty. We had an option to buy cheaper plywood, but it looked ugly and had lots of structural imperfections and our philosophy is to make our machines strong and good looking at the cheapest price possible.

For our first machine, we were so excited to put it together that we didn't do any prep work. Looking back, we wish we'd taken a little time to sand down the edges and coat the wood with a layer of varnish or paint. If you can stand to wait for your paint or varnish to dry, it wouldn't be a bad idea to do that now before you get started putting it together. We have found that one can of black spraypaint will paint one MakerBot. Your results may vary.

You may notice that there are some charcoal smudges on your parts and some "flame" marks. That's because the laser incinerates the wood and leaves a bit of charcoal behind and the flame leaves a bit of an amber stain. You can wipe the smudges off with a clean rag but if you you sand it, don't sand too much, the top veneer of the plywood isn't very thick and you'll go through it if you use more than more than a few back-and-forths with sandpaper.

We daydream of MakerBot operators customizing their MakerBots in all sorts of ways. Personally, I hope someone makes a MakerBot that looks like a machine version of Darth Vader with super shiny black paint. UPDATE: Done!

As you're going through this tutorial, take note when you do something special and take a picture. We've set up a flickr group for you to document your machine and your process of putting it together so that others can learn from your innovations and have their mouths drop to the floor when they see your robot building ninja skills. If you put anything in this flickr group, we'll see it. Again, we're waiting in serious anticipation for your pictures to show up in that group on flickr. The url is []

Ok, so at this point you may or may not have painted or otherwise protected the finish of your MakerBot. If you know about staining and wood finishing, please take pictures and document the process so that we can all benefit and have more beautiful MakerBots. Some of us are serious software geeks and not woodworkers and can use guidance.

Put the bearing brackets on the middle layer.


Use the M3 nuts and bolts to put the 4 brackets on. The brackets go underneath the middle layer on the bottom which is the side without text on it.

Here's what it looks like from the bottom!

Front, Back and Middle Together


Use M3 nuts and bolts to attach the front and back to the middle. Make sure the middle has the writing side up and the bearing brackets are mounted firmly to the bottom.

NOTE: Consider mounting the back with the writing side INSIDE the makerbot, not outside like the other pieces. See the picture, where the up arrow can be seen inside the box and the graduations on the inner rim of the back opening can be seen also on the inside. This will allow you to look through and easily see the height of the z-stage by matching it up with these graduations.

See that Allen key? It's your new best friend!

Assemble the Z stage rods


Note: The z-stage doesn't look like this anymore. Bonus points for you if you take a picture of yours and put it here!

Check Your Components.

Here are the components of the Z stage rods. Make sure you've got all these!

  • 4 Threaded rods - Approximately 330mm long
  • 8 608-style Skate Bearings
  • 20 8mm nuts.

Clean The Z-stage Rods

We cut the rods to length and de-burr them with a grinder but there is a lot of metal bits generated in this process and that stuff can get into the threads and make the rods not turn freely.

Clean your rods by putting some electrical tape around one end and putting that end into an electric drill. Then put a bunch of 3 in 1 oil on the rods and wrap a paper towel around the end. As you run the drill push your thumbnail into the paper towel and let it groove through the threads on the rods. Most of the gunk on the rods will come off into the towel and your rods will be clean and make the nuts spin smoothly!

The Z-stage sandwich


NOTE: There is an 8mm nut behind that piece of wood. It's hiding, but it's there!!!

The goal here is to make a sandwich out of nuts and holding brackets on a threaded rod. Here's the layers you want to have.

  1. Grab the 8mm threaded rod. If the ends are a bit rough, you can smooth them out with a file or a grinder.
  2. Start with one end and add a nut, a bearing, and another nut. It's a bearing sandwich!
  3. From the other side, add a nut and then a holding bracket (looks like the face of a die that has a 5 on it). UPDATE: The bearing bracket is now "U" shaped, and will be attached later. (See "Attach the wooden Z Stage guides" below.), You still MUST put the nut on in the middle, though.
  4. Add another nut, then a bearing, and the last nut. It's a another bearing sandwich!
  5. Measure the whole thing. The measurement you are looking for is that you want to have it be 268mm from the bottom of the bottom bearing to the top of the top bearing on the other side.
  6. UPDATE: If you don't have a metric ruler, you can eyeball it. Remember the most important thing is to have the bearing be just slightly below the surface of the top panel of the machine!
  • Tip: Measure the distance before putting on the last nut for easier adjustments.

Tools: You can see that you're going to need a ruler here and in the next step you're going to use two 13mm wrenches.

Tighten it up!


Once you have everything in the right place, use two 13mm wrenches to tighten the nuts against the bearing. Don't go too tight, you will likely have to adjust it again later!

  • Tip: Find a piece of cardboard with a straight edge longer than 268mm (say 300mm) to make an adjustment template.
    1. Mark off the middle and 134mm to each side.
    2. Cut perpendicular notches inward from each end (toward the middle mark; 268mm between the outside notch edges) long and deep enough to straddle the mounted bearings
    3. Cut a notch at the middle long and deep enough to straddle the mounted holding bracket.
    4. Use this template to adjust all four sandwiches to the same height.

A closer look at the bearings on the middle layer


See how the bearings poke out of the bottom holes? That's because they are 6mm thick and the wood is 5mm thick. It's supposed to be that way. It's all good.

Right-side up?


See that writing there? That's the way it should be with the letters readable from the top. If it's upside down, then you did it wrong. Also double check that the wooden rod guides are on the top of the acrylic Z-stage.

Put the top on!


Here's the top of the makerbot. You want the bearings to sit just below the top. You may have to adjust this if they peek over the top.

Getting the height of these bearings is CRUCIAL! If there is friction here, your MakerBot will not move the Z-stage smoothly. Spend some time getting the height of the bearings right. Then bolt the top on with the M3 nuts and bolts.

UPDATE: Another gremlin that sneaks in here is if the actual space where the bearings go into is too tight. If it's too tight, the bearings might not turn as well as they should and add friction. You may need to sand the space where the bearings go in down a bit so that the bearings fit perfectly.

Put the bottom and right side on.


Make sure the labeling is on the outside. First put the bottom panel on, then fit the slots of the side over the tabs of the body. I find that it works best when I put the slots in on the top and get them to fit then get the ones on the upper sides and then the middle and then the bottom.

Then get M3 nuts and bolts on it to keep it there!

Put the left side on.


Do the same for the left side that you did for the right side and step back and just marvel at the machine. Doesn't it look good?

Twiddle the Z stage threaded rods to make sure they move smoothly and use the ruler marks around the windows on the front, left, and back sides to make sure the Z-stage is level.

Have a drink of water. Hydration is important for humans.

Check the bearings again


I fussed with these a lot to get friction minimalized. See how it looks like I'm about to jam my thumb into the wood? Ya, that kinda hurt.

Attach the Z Stage Brackets


See those squarish wooden bits on top of the bearings? Those are the Z-stage brackets. Bolt them on with M3 nuts and bolts. Twiddle the M8 threaded rods to make sure they still turn smoothly. If they don't… well go back to the last step and get your 13mm wrenches out again!

NOTE: I only put these on with two bolts because I wanted to make sure the whole thing worked properly and had to keep putting them on and off. -Bre

Update! Adjusted Z stage rods!


It turns out that I just couldn't live with having the rods stick up so high so I took the machine apart and made it so the rods are now the perfect size and don't poke up. I recommend doing this from the start!

NOTE: If you don't do this, you'll have a place to put wonderful printed decorations on your machine.


This is what it will look like when you bolt on the brackets.

Mount the power supply to the back plate


You don't have to buy a power supply from us, you might have one in that old computer you don't use. We believe in recycling old junk and keeping parts of it in use.

I will say this, the power supply we sell fits perfectly and M3 bolts hold it in. UPDATE: We now have official bolts for this that really fit perfectly. They are silver and use a phillips head. You're probably getting sick of hearing me say it, but keep the writing on the outside of the machine.

Design update!


Update: I just changed this design a little bit to add some more tabs to the bottom of this wood piece and add some more structural integrity so yours won't look exactly like this photo. It'll look better!

Cord wrangling


All the cords go through the bigger hole as shown above. There will be some cables you won't use. Don't cut them, you might someday want to put a sweet 16x16 LED display grid across the front and you're going to need to power that, right? In the meantime, if you want to be tidy, throw a few zipties on the wires and get them under control. (Zip ties not included, but if you don't have zip ties, this is a great excuse to go buy 100,000,000,000 because they are just that handy to have around.)

Bolt the back plate onto the machine


Use M3 nuts and bolts to bolt the backplate into place. Again, you'll have two more bolts to add to this that aren't seen here, thus making it stronger.

Put the pulley on the stepper


You'll notice that this stepper has a small silver colored pulley on top of it. Use one of the smaller Allen wrenches to tighten down the pulley on top of the stepper at this time.

Mount the X-Axis Stepper


The X-Axis stepper pulls the chassis left and right. You can just put it right through the side hole and bolt it to the middle layer with the shorter M3 bolts. No nuts are needed since they thread right into the stepper.

NOTE: the pulley height is important when you get the step where you install the XY stage assemblies. On Build 9 at least, my pulley was too high if installed like in the picture.

Orient the motor so the wires will exit neatly through the large slot in the side of the body.

The Z-stage stepper motor


As before, put a pulley on a stepper and bolt the stepper onto the top panel. There it is attached with 4 bolts. It's important that you tighten this down good with the Allen wrench because steppers, by nature, vibrate.

When mounting the motor, consider that the cables will eventually be routed out through the slot on the right of the 'bot.

Attach the pulleys to the M8 threaded rods


These get put on upside down in comparison to the stepper motor pulley. That's so that the pulley part can clear the M3 bolts underneath it and be at the same level as the stepper motor pulley. This pulley uses a slightly less tiny Allen key.

Getting the height right on all these pulleys is important because if you have it wrong, it adds stress and friction to the belts. I used my eyes to get them at the right level, but thinking back on it, it would have been simple to lay a ruler across them to make sure they are level with the top of the machine and at the same height as the stepper pulley.

Put the Z Stage tension pulleys on


The Z stage tension pulleys keep the belt tight so that it maintains a grip on the rest of the pulleys. They are made out of wood and you attach them to the top with an M8 bolt with an assortment of M8 nuts and washers. The goal here is to get them to be the same height as the stepper pulley. Take time to get these the right height.

When you tension the belt, you want it to be tight, but not too tight. If you make it too tight, it will cause friction and it won't be able to move smoothly. If they are too loose they will miss steps or have slack that will result in sloppy extruded objects.

Visual Check


This is how it should look. In front of the stepper pulley is a laser-etched arrow and the words "up" and "down". If you need to move the Z-stage manually, you can do it by turning the pulley.

Keep this machine out of the reach of small children. You are responsible for your own safety and the safety of those around your machine. Keep this robot out of the hands and mouths of small children!

Now that you've got your Z stage working great and you know how much M8 rod is popping out the top, you can optionally use a hacksaw or grinder to make it go away (but don't get metal filings in your bearings!) or shift the extra rod to go underneath the robot next to the power supply. Alternately, put tennis balls on of these threaded rods.

Z-stage stepper wiring


The wires for the stepper go through this hole here. You probably already have the connector on the end of the wire, but I hadn't done that at the time that this photo was taken!

Bolt on the left side rod covers


Use M3 nuts and bolts to put all four nut and bolts on each of the left hand side rod covers.

Bolt on the right side rod covers


Until you put the carriage onto the MakerBot, you're going to want to be able to put these smooth rods in and out of the bot. On this side I only put one nut and bolt on each rod cover so I can open and close them and remove the smooth M8 rod.

Next step: Cupcake Y Stage Assembly

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