My experience with the Taz 6 hasn't been the best, if I'm honest. One of the biggest issues I have had with this printer since Day 1 has been the very, very poor bed levelling. The bed levelling became significantly worse when I purchased and installed the Official "Modular" bed upgrade.
As we know, the Taz 6 will not level if the nozzle is dirty, and owners also know that the wiper pad has its own problems, from not wiping sufficiently, to sticking annoying fibres on the head that end up disrupting the bed levelling calibration.
What not too many people seem to know (it would seem, because I had to figure this out on my own after significant trial and error, forums offered nothing, and their email tech support was not terribly helpful in this regard) is that there are 4 other problems with the Taz 6 that tend to cause issues with bed levelling. They are:
The Y Axis Assembly Y-Ends + Y-Feet Alignment. I feel these parts should have been made as one single metal machined part that slipped over the 20x20 rails on each end as 1 large piece, to ensure that there is no play / slippage / alignment problems. But it wasn't. And there are. The Y-ends are tied together with many screws and there is a lot of play. That play leads to uneven rail placement, which the bed levelling procedure cannot compensate for. This seems to happen even if you print off and use their Bed Levelling Jigs. I think even beds that were assembled and shipped direct from lulzbot will "slip" over time with heat and cooling cycles loosening the bolts, and when a user such as myself taps parts off the bed to get them to come off after a print. This is likely further agitated by high temp printing while using an enclosure like the Taz 6 Enclosure by Printed Solid (which I use). I've done nothing to fix this with this upgrade - but I typed it up so it gives you something to look for if you're struggling with getting the levelling to work.
The flexy bed corners that ship standard with the Taz 6 are too tall to accommodate the modular bed add-on, specifically, where the glass plate mates into their corners. Using them forces you to compress them down way too much, and they deform relatively quickly over time because the corners end up deforming unevenly, leaving your bed corners sitting at shifted heights (yes, they can't go below the 10mm spacer size, but recall that I mentioned they are too high and that, by default, they keep the modular bed glass 'lifted'). IMO, Lulzbot should have redesigned the corner mounts and included them when they sold the modular bed upgrade, but they didn't, so here we are :)
When you upgrade to the modular bed, there is not enough clearance underneath the bed for the heater wiring and the Y table end-stop switch wiring. You can spend all friggin' day trying to get it to fit, but I have two separate heated bed modules, and the rubberized covering that they slop on the heater to manage the wires where they go into the heat coil are too lumpy for the clearances provided when you factor in the end-stop wiring - and this leads to a massive lump/bowing in the glass in the left hand middle side between the front and back left calibration pads. This bowing isn't even apparent until you drop a straight-edge across the glass - and then you can see it's not sitting flat! Even if you manage to spend 20 minutes and get the wires such that everything somehow "fit", it'll likely get completely screwed up the next time you go to flip the glass and bump the aluminum transfer plate, making the whole "modular" idea basically untenable and highly frustrating.
- You need to ensure that your Z offsets are even left to right, front to back. Since the Z axis is driven by two separate rods, they both have to be calibrated even. ( I recommend calibrating in the middle of the Y axis, left and right, to average front-to-back variances )
Because of #1, #2 and #3, if you have the modular bed, you likely will never succeed at #4. Front Left nozzle clearance to plate, Back Left, Front Right, Back right will just not be even, and you can't fix 4 problems with 2 Z-lead screws.
This mod aims to fix #2 and #3, enabling you to properly calibrate your bed in #4, assuming #1 is not an issue. If #1 is an issue, you need to fix that before doing anything else (by loosening the Y table bolts and adjusting each until they are even).
When Lulzbot released the Taz Pro, it seems they finally figured out that they had problems. They discovered (based on comments I read on their internal devel forums) that the Z auto-calibration was inconsistent. They figured out why - the bed corners! So they finally revised the bed corners, but seemingly did nothing to provide more clearance for the wires (which isn't as critical on the Taz Pro because they've eliminated the manual end-stops in favor of the Archim 2.0's drivers which can detect stalling), so the fundamental problem I have may still exist. They fixed #2, but they did not address #3. Worse, the corners have basically 0 tolerance to them, so the glass doesn't fit in the corners if you just print the Taz Pro corners and install them, even if you print them with the same parameters they use in their GCode.
I have taken steps to address all of these deficiencies in #2 and #3.
What parts do I need to buy?
To make use of this, you will need to order:
- 13mm Stainless Steel Spacers. These 13mm spacers are exactly the same as the 10mm spacers that the Taz 6 ships with - they're just 3mm taller. Same manufacturer, same appearance. You need to order 4 of these from Digikey; Part number: 1772-4102-ND
- 8 x M3x14mm Button Head Cap Screw (BHCS, Stainless; for the Ninjaflex Bed Corners)
- 4 x M3x18mm Flat Head Cap Screw (FHCS, Black oxide; for the Levelling Washers)
- [Optional] 1 x M3x10mm Flat Head Cap Screw (FHCS, Stainless or Black, your choice)
What parts do I need to print, and how?
Then you need to print the bed corners and bed spacer in Ninjaflex TPE with the following settings: (It's critical that you print all 4 bed corners and spacer as one batch, to ensure they come out exactly the same height/thickness even accounting for Z-offset)
- Layer Height: 0.30mm
- Infill Density: 60%
- Infill Pattern: Zigzag
Then, Switch to ABS, and print a new Z-min switch holder and a new Wiper Pad Mount (or Dual Wiper Pad mount if you have the dually)
How do I install this upgrade once I've got everything?
First - this voids your warranty. Do this at your own risk. I accept no responsibility whatsoever for damage, failures, fires, anything. No warranties are expressed or implied here. This is on you. 100%. Not comfortable with that? Than don't do it!
Take the old bed off, unscrew the bed corners, keep the black washers and the stainless "pad" washers, and replace with the new hardware (using the old washers). Then replace the Z-min switch holder and wiper pads.
At this point you also have an option to provide support for the modular heater. It tends to sag in the middle. In a perfect world, this would be installed centered under the glass, but Lulzbot elected to not further change the bed design on the Pro - all they did was drop a screw from the Y-belt tensioner and use that location instead. You can do this on the 6 - there is one screw hole that is very close to the centre of the metal plate. It's occupied by the Y-tensioner. Remove that screw from the bottom, freeing up this hole, and install the new spacer with a Flat Head Cap Screw making sure the screwhead is countersunk to the rubber surface. This step is optional, but improves heating consistency across the plate.
Reinstall glass, check fit, home your printer. Printer should home correctly.
THIS MAY CHANGE YOUR Z-OFFSET. You need to be VERY cautious on your first print to ensure the head doesn't smuck into the glass and damage something.
First, please note that this will drop your Z-build volume by 3mm. So if the vertical build volume is 280mm from factory, it'll be about 276 or 277 after this mod.
Second, I really hope this helps someone. It's too bad that when you buy a Lulzbot printer you are basically committing yourself to becoming a 3d printer designer, because it seems they don't do quite enough work either in hardware or software to test things through in real world applications. I feel like they hit 90% and say 'close enough' and ship. Now, that's just my opinion and is solely based on my unique experience. You form your own opinions and make your own decisions - just sharing my experiences. I do like certain aspects of Lulzbot printers and I do like certain areas of their business, but they have gaps that I don't believe should exist given the premium they charge.