P3Steel Build Log (#11) – Endstops / Limit Switches

X, Y and Z Endstops / Limit Switches

Now that all the axis are complete, we can install the endstop/limit switches. These are simply a switch which is triggered mechanically by one of the printers moving parts hitting it, be it the hotend, print bed etc. You can set up virtual endstops in your printer software, but there are here to physically stop your printer from crashing into something it shouldn’t! For the P3Steel there are three endstop switches, which mark out the minimum travel the printer is allowed. You can add maximum ones too, but this isn’t required and a little overkill for a Prusa i3 design.

I am using some endstop switches which can be purchased from AliExpress, or on Amazon if you like. Best getting them in a pack of at least three, and they should come with some signal wire too to hook up to your RAMPS board. The AliExpress ones tend to be discounted if you buy them in 5, 10 etc, and they are very handy for future projects.

You could wire up your own switches and use only two wires, but the ones I have gone for have three wires and an LED which lights up when triggered. I will go over the wiring later, this post is just the installation of the switches and where they go. It is pretty quick – so I will rattle through it!

Print out the endstop parts and secure them with some small M3 bolts and nuts – simple!

X-Axis Endstop / Limit Switch

The x-axis endstop is attached to the two 8mm smooth rods. It should just clamp on with a little force. For now you can just butt it up against the stepper part of the x-axis. But when configuring your printer you may well need to move it towards the bed a little. And if it is loose – secure it by adding a zip tie to the 8mm smooth rod just behind the endstop. The endstop should then be able to be triggered by sliding the x-axis carriage into it. Make sure you can hit the endstop switch.

Y-Axis Endstop / Limit Switch

The z-axis endstop is located at the back of the printer. It can be at the front, but it depends on how you want to configure the firmware later. For consistency across other builds. and Toolson’s design – I have kept the y-stop at the back. It can be secured to the frame either side of the stepper motor in the available screw holes in the frame. For ease of use and to reduce cable lengths, I have opted to keep it close to the RAMPS board, which is to the left of the printer as you look at it.

Secure it in with some more M3 bolts and nuts which install into the plastic and it’s done! The switch is triggered by one of the bed bushing clamps. Slide the bed back until it triggers it to make sure everything is hitting as it should.

Z-Axis Endstop / Limit Switch

The z-axis endstop is probably the most important endstop and stops the printer from crashing into your print bed and possibly ruining your hotend and print bed surface. Take care with this part! It is installed on the side of the left z-axis motor mount as per the image below. You will need to remove one of the M3 bolts in the frame, line up the part and screw in a slightly longer bolt.

The endstop is then triggered by the x-axis stepper assembly. And due to numerous hotend configurations and setups – this length needs to be adjustable and manageable. For the P3Steel Toolson Edition Lars added in a small plastic part which bolts into the stepper part of the x-axis with an M3 bolt and nut. This can be re-designed, adjusted, replaced etc without affecting your whole x-axis assembly. The little part also needs a small m3 nut inserted into the gap which allows you to screw in an adjuster bolt through it. You can see it in the below image inside the little orange part:

With that part now secured to the z-axis, screw in an M3 bolt down so it sticks out the bottom. You are just going to roughly set this up as you won’t have the hotend on yet! You can get away with just a bolt, but over time this will vibrate and may well thread up or down. To secure this the bolt needs a small spring. Using a spring and a couple of washers gives tension on the bolt to stay still and make a more solid “poking device” to the trigger. I have used a standard spring which are commonly used for bed levelling. In fact that is where I go it from – but I have also purchased a pack of springs too. The AliExpress listing I got them from can be found from seller ‘All Electronics Mall‘ here – 3D Printer Bed Springs. I got the 10 pack.

You may/will need to adjust the tension depending on your bed and hotend configuration, which can be done by adding and removing extra washers. The spring and bolt will eventually want to be solid with no movement or rattle.

Once all is setup as per the image above – lower the x-axis by turning your shiny knurled knobs to drop the z-axis. The screw seen below should line up with the trigger switch and eventually come in contact. When you have your print bed and hotend installed, it would be at this point when the endstop is triggered that the nozzle is just microns above your print bed. This is why this part is very critical and needs to be done carefully. I have found that my z-axis endstop switch is a little away from its PCB (printed circuit board) and as such the M3 bolt only just triggers it. I will swap this out with one of the x or y stops as they do not need to be as accurate or secure.

Related posts:

P3Steel Build Log (#10) – Z-Axis P3Steel Build Log (#09) – X-Axis P3Steel Build Log (#05) – Frame Feet P3Steel Build Log (#07) – Y-Axis Carriage and Belt