As many I already know, I am a big fan of cable carriers.

This is also a thing that has annoyed me so much with my current prusa, because I haven’t been able to find a good way to put any cable carriers on it, but with this MendelMax2 build I am aiming in that direction from the beginning!

The first axis I am going to do this on is the Y axis. (Notice, my rail is not the one from the complete kit, so yours might look different)

To attach one end of the cable carrier to the axis I simply found a good place to drill the holes. The place you want to find is somewhere where the axis can move from minimum to maximum, with the shortest cable carrier possible, and without it getting in the way for anything. To do that you want to do it like this.

With the first end mounted like this, it will be able to go out over one edge of the printer without hitting anything. At the same time it can also go to the opposite extreme end without hitting anything, because the cable carrier is so short it will just curl up and get out of the way.

The next step is to get the wires through, this is done by simply drilling a hole and pulling the wires through, after that it gets more difficult because now it’s time to get the wires through the cable carrier itself.

If you look closely at mine you will notice mine is the completely closed type. This type is a lot harder to get the wires through because you can’t just put them in from one side which you can from the half closed type.

Now with the wires through we are ready to find the position where the opposite end should be fastened. To find this position you simply move the axis from one extreme end to the other a few times where you just hold the lose end with your fingers, then mark the spot where it looks right.

My printer is going to have a bottom where both the power supply, controller, step-down and so on will be securely mounted, so this end of the cable carrier will be mounted to that too.

At last you might be thinking why going through all this trouble, just for some wires… Well, there are a few reasons. Not only does it look much more clean than wires just hanging off, it also makes sure the wires only go where you want them to go. They will never get caught on anything, or get too close to some eventual hot parts you want them to avoid. But there is an even bigger advantage of these, and that is the wear on the cable. When you got a cable hanging free between two points, the wear is most often a lot higher near the two ends of the wire, that is where it will wiggle back and forth with the rest of the cable just hanging in the same arc. With a cable carrier you will spread the wear out to more of the cable and you will also be sure the radius it is bent in is never too small and could damage the cable.

Update, just to give an idea of how picky I am with this build.

In the earlier photo you can see the two wires for the heater is crossing on the way through the hole, that annoyed me so much I took it apart again just to straighten them, and to do that I also had to twist the two wires all the way through the cable carrier, just so they would lay parallel there too without twisting around each other.

First post about my MM2 build, and here is one of the first things I am going to make different.

I am upgrading my MM1.5 to an MM2, so I have the plate set only, some of this will not be the same on a full kit, so some things might need changing because of that, other things I just want to change because that is what I do…

The first thing I am going to change is the Z lead screws, I got some with lower friction between the nut and screw and at the same time more straight than the ones I could salvage from the MM1.5 too. There are however also a downside to this, the downside is that the flanges on the ones I am going to use instead isn’t the exact same type, so they will not fit directly onto the ends of the X axis, but more about this in another post when I get to that.

But here is the problem, the MM2 got a bearing at the bottom to guide the lead screws (notice, if your lead screws aren’t straight, or if you can’t align them properly, then constraining them in both ends is a bad idea), and also to help lift the X assembly so the motor doesn’t do all the lifting. Another advantage of this is also the coupling connecting the lead screw to the motor can be stretched so Z could vary a bit depending on how much they stretch, this bearing will eliminate that potential stretching.

My problem was now the lead screws I got, they are turned down to a diameter of 7.9mm 10mm in, on the opposite end than the motor, where a 608 bearing (which is the one the MM2 use) is only 7mm wide. This makes the end of the lead screw rest on the extrusion instead of the bearing. This might work just fine, but I don’t like it.

Instead I am going to make this little device to replace the 608 bearing at the bottom of the Z lead screw.

This contraption consist of a top and bottom part, with a thrust bearing (51101) in between. The thrust bearing is made to handle this kind of pressure, and at the same time this also lifts the end of the lead screw up so it will rest on the top piece instead of on the extrusion.

If you have no idea what a thrust bearing is, here is a little description.

A thrust bearing is pretty much like a normal ball bearing, just instead with the sides cut open. This allows the top and bottom half to rotate freely even with a lot of pressure on them. If a normal ball bearing was used for this the balls would press against one side in the inner and outer ring instead of the grove it was designed to ride in. But even when normal ball bearings are not made to be used as they are in the MM2 it is no problem because the forces involved are so small compared to the load they can handle.

And here we are, ready to assemble!

The bottom part fits tight into the hole in the black aluminium part.

The thrust bearing then fits lose into the bottom part, and same goes for the top part.

When the bearing is put in and the top is put on, there will be a 0.5mm gap between the two parts with the thrust bearing lifting the load from the X assembly.