Installation Notes

This is not a detailed how-to guide for installing the mod but rather a collection of notes to help someone else who is attempting to decide the best way to assemble everything such that it is all square runs freely. The available instructions at this time seem to be pretty non-existent...

Obviously, the first step is to disassemble the existing bed (and if doing the extended z all the hardware and extra extrusions for the stock z). Once you are down to the bare parts, you need to start assembling the new z axis.

I started by mounting all of the following parts for the rear sub-assembly:

• the 2 linear bearings to the read end plate (the one without the notch, they are not exactly the same!)

• the 2 lower rail mounts (the pieces that attach the linear guides to the extrusion)

• the 2 linear rods to the rail mounts

This gives a rigid assembly that you can slide up and down the rod. Since I was going the extended z, I used the existing holes to try to mount this sub-assembly in approximately the same place as the stock sub-assembly. Attach the two rail mounts to the extrusion with the end plate at the bottom of the rails to keep the bottom square. Once that was attached, I slid the end plate to the top and used that to position the two top rail mounts. Make sure that the end plate slides up and down easily along the entire range.

Next assemble the front sub-assembly (2 linear bearings, 2 lower rail mounts, 2 linear rods). Attach the bed mounting plate (the large piece of aluminum) to the rear assembly flush against the linear bearings to get it roughly square to the frame and loosely attach the other end to the front mount. End the full assembly to position the lower rail mounts on the front extrusion. Once attached, attach the top rail mounts just like you did with the back.

At this point you should have a dual z that you can manually move up and down freely over the entire range of motion. Make sure that's true.

Next, loosen the screws attaching the bed mounting plate to the two end plates to give it all a little freedom to move. Attach the the bottom half of the anti-backlash nut to the lead screw and the top half of the anti-backlash nut to the end plate. Thread the two halves of the backlash nut together until they are full engaged. You can turn the lead screw to give you some room to work with the stepper motor. Attach the stepper to the motor plate. Attach the shaft coupler to the lead screw and then to the stepper.

I couldn't find any mechanical way to exactly center the stepper on the end plate and I opted to measure the distance and use the measurement to get it centered-enough and when I was happy attached it to the bottom extrusion.

Repeat with the other end measuring the distance from the extrusion to the top of the end plate to get both sides to an even height.

Finally tighten the screws holding the bed mounting plate to the end plates and verify that it moves easily over the entire range by turning both steppers in unison.

And last, but not least, put the print bed back on there and you are ready to go. When you're done, it should look something like this for the front:

Lead Screw and Stepper Choice

I went with this lead screw and anti-backlash nut:

• 400mm T8 Tr8x2 Lead Screw and Brass Nut (Acme Thread, 2mm Pitch, 1 Start, 2mm Lead)

• T8 POM Anti Backlash Nuts Tr8x2 for Lead 2mm Pitch 2mm

The cost was low enough and the gain in resolution was significant enough that I thought it was an obvious addition to the upgrade. Furthermore, I wanted to make sure I had exactly the same lead screw and stepper on both ends to avoid any slight differences from one source to another.

Earlier in the year I accidentally killed my z stepper while upgrading to a duet board. I have been using a full height stepper pulled from my Tevo Little Monster and some feet that raise the printer high enough to use a full size stepper (thingiverse: 3965689). I just used the same stepper. If I were adding a new stepper, I would personally replace both with the same stepper and not reuse the existing one.

Duet3d Configuration Changes

For the majority of you that aren't running a Duet3d board, this is a pretty useless section. My understanding for a stock installation is that you'll need to buy a "y cable" for the steppers to drive both off the same stepper driver and then use a screw driver to adjust the reference voltage to be high enough to provide sufficient power to both steppers.

For a Duet3d board though, I added the stepper to the E1 connector and setup the drive:

• M569 P4 S0 ; physical drive 4 goes backwards

• M584 X0 Y1 E3 Z2:4 ; set drive mapping: Z motors 2 (z) and 4 (e1)

setting the drive direction to match how you ended up wiring the motor. The only other change I made was to set the new steps/mm for z to match the lead screw. If you are using the same leadscrew and have a 1.8 degree per step motor:

• M92 X80.00 Y80.00 Z1600.00 Exxx ; set steps per mm

where the extrusion steps should be kept the same as what you have now.

I was originally planning on using the true bed leveling functionality in the firmware to level the two motors to the bed mounting plate. I never bothered because it was more than close enough already and the bed leveling is so much easier that I can get a very level bed very easily so I didn't need the hardware assist.

Using the bltouch to Level the Bed

Without the dual z axis, I couldn't use my bltouch to help assist with bed leveling because the bed flexes when you try to probe it. However, now that all 4 corners are rigidly supported, you can now get an accurate reading. I'm not going to explain in detail how to do the leveling here. You can read the writeup for my 3 point leveling and then you just need to repeat with the 4th corner.

It is going to be more tedious to do the 4 point leveling because each adjustment changes the other corners, but if you keep repeating the adjustments you'll get to a level bed.

Or just bite the bullet and go with 3 point leveling...

Conclusions

Overall, the upgrade cost around $200 and the printer costs around $300. Does that make sense? For some people it does. When combined with the 3 point leveling the ease of leveling was worth every penny given that it used to take me hours to get a bed that was actually less level than I can achieve in minutes.

Personally, I purchased the ender 5 because I needed a printer quickly to complete work that was being delayed due to a printer failure that was going to take a fair bit of time to repair. It filled in the gap nicely. But after filing the gap, I wanted a printer that rivaled the quality of my other printers and I have been gradually improving it to the point where it is a more reliable and accurate printer than my Lulzbot Taz 6!

You would have to decide for yourself whether or not it makes sense for you.