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Loches Z Axis Upgrade for Prusa i2
- Increase the Z Axis Build Range.
- Modify Plastic Parts only and re-use the current Vitamins.
- So many plastic parts have been modified, I'm not sure if I should consider this an upgrade or a full blown new printer version.
- It's possible that this change isn't limited to the MakerGear Prusa, but I will leave that to you.
- I had a few issues with the X and Z endstops and had to jury-rig my own solutions. Perhaps I will design some new mounts for these.
My original build area was about 80mm, I came across a print that required more height so I decided to try and design my own modification that would give it to me. Looking at my printer, I noticed a few areas that could possibly be improved, so I went to work! My new and improved build height is now 150mm!
Problems and Solutions:
- Problem 01: The rear mounted X axis belt collided with the threaded rod on the triangle frame vertex assembly. This resulted in a clearance issue when raising the nozzle.
To fix this, I had to consider a new location to mount the belt. I chose to utilize the space just underneath the X track rods as that space is already used by the extruder nozzle.
- Problem 02: A good amount of rod space on the Z axis ends up being un-used. The motor mount blocks the Z axis from going beyond the two threaded rods on the top of the printer.
To fix this, I extended the upper frame vertex piece so that it raised the two top rods a good distance. This in turn also raised the Z axis rods so I also extended to lower Z bar clamps to compensate. This worked because the space taken up by the lower clamps was previously un-used rod space anyway.
- Problem 03: My current extruder mount caused a clearance issue because the side mounted motor would go underneath the upper frame vertex. Since my new vertex still blocks this, a new extruder mount was required.
To fix this, I designed a derivitive extruder mount that was essentially the same as the one I was using except the motor protrudes from the rear instead. Since I previously moved the X axis belt, there was no issue with the motor colliding with it. You can find this derivitive here: https://www.youmagine.com/designs/makergear-simplified-extruder-block-with-quick-release-and-rear-motor-mount
- Problem 04: I found it difficult to tighten the X track rods in place without causing the X carriage to bind.
To fix this, I changed it from using the tension screws (on the bottom of each X-end) to just having some clamps on the rods themselves. The clamps prevent the rods from sliding out, but it's still ok if they slide a little bit, they don't need to be tightly locked. One of the rods is in a hole that does not give it room to 'wiggle', this gives it the stability it needs so the nozzle doesn't move around in the Y direction. The other rod is in a slightly elongated hole which provides the track with the 'play' needed to keep the carriage from binding. I've found that this modification works well and causes no noticable change in print quality.
Here is a video of me printing the Pink Panther Woman http://www.thingiverse.com/thing:1216 at full size (147.535mm tall).
- Print out the above parts. 50% infil should be enough.
- Remove your current Z axis rods and assembly. This includes the Z smooth rods on either side, the threaded rods attached to the Z motors, the Z motor mounts on top, and the Z rod clamps on the bottom.
- Take out all the bearings, nuts, screws, brass bushings, motors, pullies, belt, rods, and etc from the the removed parts.
- Take off the two upper frame vertex pieces and replace them with the new versions.
- Re-mount the Z motor mount plates on top.
- Mount the new lower Z bar clamps on the bottom, don't forget to attach the bearings to them. Note that the new version has the lower rod hole in the center and is not offset from the Z axis bar clamps like the original part, so you will have to adjust accordingly.
- Assemble the brass bushings and Z axis nuts into their respective places on the new X-ends and X-carriage.
- Thread the Z axis threaded rods into the X-ends so they protrude about 1/3 of their length from the bottom of each end.
- Place the bottom of each Z axis threaded rod into their respective locations on the lower Z bar clamps (where the bearing goes) and attach the tops to the motor Z couplings. The motor mount should be on the left side of this assembly.
- Slide and clamp the Z axis smooth rods through the top motor mount, X-ends, Z endstop, and lower Z bar clamps. The smooth rods should be almost exactly the length to clamp in.
- Level both X-ends with eachother and slide both X smooth rods through their respective tracks on the X-ends and the X-carriage. The X-carriage belt mount should be in the back and facing down.
- Place 4 X-track bar clamps on the X-track smooth rods. They should be on either side of each rod in between the X-ends. You will need a M3 nut and bolt for these clamps. Alternatively, you could also just use some tape to clamp them. Note, these clamps should be snug, but not too tight, we want them to 'wiggle' a little to provide optimal track clearance for the X-carriage. It's possible that a modified X endstop mount is necessary, but so far I haven't had a problem with my mount rotating with the rod, since the rod is only snug and could essentially free-rotate.
- Attach the X axis belt motor and idler pullies on each side. These mounts are slightly adjustable, when you attach the belt you need to adjust them so you can freely slide the X-carriage from min to max without the belt rubbing against the Z axis rods.
- The new X carriage endstop is design to clamp onto a single track rod on the X axis while rest on the other rod. This is because the new method of clamping the X rods allows them to free rotate to some degree, so we don't rely on them to keep a single clamp stable. The second function for the new endstop is to allow clearance when the Z axis is at the very top while still triggering early enough that the X carriage doesn't bump into the triangle frame.
- The Z endstop is now mostly blocked by the belt now, so I had to aim it at the motor pully instead (image provided). This works and I haven't had any problems with it so far, but a possible new mount can be designed if you're not comfortable with this.
- Run your machine and make sure all axes move in the proper direction and without binding. I had to reverse my X axis motor since the belt goes in the other direction now. You shouldn't have to re-calibrate your steps per unit settings if you did not change the belt or pullies that you were using before, but it's always a good idea to double check your calibrations :)
If you have any questions, please let me know. If you decide to build this upgrade, please share your thoughts! Any improvements on this will be much appreciated as well! Thank you!