Cupcake Endstop Installation

This page is part of the Cupcake CNC build sequence.

Summary

Endstops are optical switches that are installed at either end of each axis of motion. Endstop triggers which protrude from the stages fit into the slots in the switches when a stage moves all the way to one end of its travel. The endstop serve two purposes:

  • to allow Cupcake CNC to calibrate itself when it first starts working, to make sure it has moved the build stages to the correct locations, and
  • to shut off a motor if for some reason the firmware goes haywire and a stage tries to move too far in one direction.

A brief note on going too far

It's actually possible to run the Cupcake CNC with no endstops at all! You can manually move the stages to the correct position before starting a job— in fact, when you're getting started, we recommend trying this technique. But, you may ask, what if my Cupcake CNC tries to move a stage further than it's supposed to go? Fear not! The steppers and belt couplings on Cupcake aren't powerful enough to cause permanent damage to your machine. At worst, you'll most likely hear a groaning or shuddering noise as either the stepper loses steps or the belt slips. We don't recommend letting Cupcake CNC run wild like this, of course, but if it happens once or twice, don't freak out! Just shut off the power to the Cupcake CNC as soon as you can. After repositioning the stages, turn it back on again and it should be just fine.

If you have your endstops installed and working, but Cupcake CNC doesn't try to stop a stage at the end of its expected travel, it could be because you have the endstop connections reversed (the 'maximum' endstop plugged into the 'minimum' connection and vice versa), or into the motor controller of the wrong stage (X endstops connected to the Y controller, for instance). Double check your connections!

Time

Estimated build time: half an hour.

Build the endstops

If you haven't built the endstop kits yet— do it now! Be sure to read the endstop documentation carefully before putting the kits together.

Build the Y endstop cables

Because the Y endstops use 3-pin headers instead of RJ45 connectors, you'll have to modify two of your RJ45 patch cables to use 3-pin connectors on one end. (You'll need to keep the RJ45 connector on the other end; that's the connection we use on the motor control boards.)

Take a cable and cut off one of the connectors. Use a wire stripper or a craft knife to cut off the outer insulation about one inch from the end.

Trim all the interior wires level with the outer insulation except for the blue, green, and brown wires. Do not strip these wires!

Take one of the three-pin connectors from an endstop kit. On one side, you'll notice very small numbers embossed in the plastic. These label the pins on the connector— 1, 2, and 3. You'll be connecting the blue (VCC) wire to pin 1, the green (signal) wire to pin 2, and the brown (ground) wire to pin 3.

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Take the tip of the blue wire, locate pin 1, and place the tip in the connector. The image shows the blue wire already done and the green wire getting arranged into position. Note that all wires besides the blue, green, and brown have been clipped clean and flush with the ethernet cable insulation.

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With a small screwdriver or hex wrench, push the wire firmly down into the connector. The small metal edges in the connector will cut through the insulation in the wire and make contact with the conductor in the center. You need to get the metal edges to pierce the wire insulation and also get a tight enough grip that they won't pop off later.

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Continue until all three wires are done.

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You can then snap on the small white endcap if desired.

Install the Y endstops

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Run two M3x16 bolts through the holes in the endstop mount on the X front piece. The heads of the bolts should face the X stage.

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Put one of the endstops with a 3-pin header on the bolts as shown. Because the alignment is not perfect between the board and switch, you may need to screw the bolts in a bit to get the board on the bolts. Be careful not to break the wooden mount!

Use M3 nuts to fasten the endstop in place. Turn the nut to a position that doesn't short the contacts on the back of the board.

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Run two M3x16 bolts through the holes in the endstop mount on the X back piece. The heads of the bolts should face the X stage.

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Put one of the endstops with a 3-pin header on the bolts as shown. Use M3 nuts to fasten the endstop in place, as above.

Install the X endstops

Find the two M3 endstop mounting holes on the left side of the machine. They will be almost at the front of the machine, about halfway up.

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Use two M3 bolts to mount an endstop on the inside of the Cupcake CNC, as shown. Use M3 nuts to fasten.

Find the two M3 endstop mounting holes on the right side of the machine. They will be almost at the front of the machine, about halfway up.

Use two M3 bolts to mount an endstop on the inside of the Cupcake CNC, as shown. Use M3 nuts to fasten.

Install the Z endstops

The Z endstops are both installed on the right side of the machine. The mounting holes are indicated in the picture.

Mount the top endstop on the inside of the machine, in the position shown.

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Mount the bottom endstop on the inside of the machine, in the position shown.

This picture shows all the endstops on the right side of the makerbot.

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Install the endstop triggers

The endstops are triggered by thin bits of wood: popsicle sticks. These are not in the kits since they are widely available and one of the more pleasurable parts to source. (you get to eat ice cream!)They work better when they are painted black.

To install an endstop trigger, first move a stage almost all the way to one end of its travel. Then place the stick in the slot in such a way that it protrudes all the way into the appropriate endstop. Once it is in place, use a drop of hot glue or rubber cement to keep it there.

Install the Y stage endstop triggers

The Y endstop triggers sit in slots in the Y stage, as shown.

Install the X stage endstop triggers

The X endstop triggers sit in slots in the X stage, as shown.

Install the Z stage endstop triggers

The Z endstop triggers sit in slots in the Z stage platform, as shown.

Conclusion

That's it! You'll hook up the endstops in the next step, when we mount and hook up the electronics.

Next step: Plastruder MK4

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