Jeff Stobbe is the Maintenance Manager of a large Canadian fabrication lab, and he’s usually fixing 3D printers.
We caught up with Stobbe during his daily maintenance routines to ask him a few questions.
Fabbaloo: As the Maintenance Manager at North Forge Fabrication Lab, what 3D Printers do you proactively provide maintenance for, and can you briefly explain what you do?
Jeff Stobbe: We operate a variety of 3D printers at North Forge – FDM, SLA and Binder Jetting, each of which uses different materials and methods to produce prints, so the maintenance required for each machine varies.
Our busiest printers are the entry level FDM machines, like the Prusa MK2.5S’s and Ultimaker 2+ Extended. These units require very little maintenance other than lubrication, cleaning, making sure the print bed is level, and ensuring the filament is squishing into the bed sufficiently for a good first layer.
For high-end dimensionally accurate FDM printing, we have a Stratasys uPrint Plus and a Fortus 400mc. These units both require much more lubrication and cleaning than the entry level units, and both have laborious filament change procedures.
The uPrint requires tip shields & wipes be changed as required and purge basket emptied often. The Fortus needs its build plate regularly cleaned, purge basket emptied, and inline air filter cleaned. Tips are switched with each material change with their “mileage” meticulously tracked, and nozzle wipes are changed as required.
Our Formlabs Form 2 SLA 3D printers mostly just require surface cleaning, as the uncured resin has a way of getting onto everything. There is little to do in the way of lubrication, as there is just the z-axis visible, with the rest of the mechanics hidden inside the enclosure, away from prying fingers. Some additional work is required to keep the Wash and Cure stations clean and the IPA in the Wash station at the appropriate saturation level.
The binder jetting printer we operate is a zPrinter 650 and requires the most maintenance. Some of the typical items are: keeping the fast axis & slow axis bearings lubricated, piston screw lubricated, empty debris basket, replacing the carbon filter and purge container, flushing the clean station, cleaning alignment window & and spreader roller, replacing print heads, and topping up the amount of powder in the machine. Both the printer and processing station must be vacuumed often to remove dust build-up. The associated Zbench and Waxer units also require additional cleaning.
Fabbaloo: Providing reactive maintenance on broken parts on the 3D printers is also part of your role. What normally breaks that requires fixing?
Jeff Stobbe: For our Prusa’s & Ultimaker, it is not unusual to replace nozzles & heat bed coatings. Additional maintenance might be replacing failed fans, heater elements, belts, thermistors & cables. There have been occasions to replace power supplies, circuit boards & displays, but that doesn’t happen often. The Prusa’s have the ability to print out replacement printer chassis parts!
The most common maintenance is caused by print failure and/or user error. For example, an unattended print that failed to stick to the bed would result in a massive blob of extruded filament encasing the nozzle, heat block, air duct, heater & thermistor, that would take hours to remove & repair/replace any damaged components.
A properly working Form 2 printer relies entirely on clean mirrors & glass and an undamaged tank. If the two small internal mirrors that rotate & aim the laser get dirty, then the resulting print will be massively distorted. If the angled main mirror or optical window are dirty, they will also cause distortion. In that case, a good cleaning with Zeiss cleaning wipes will remedy the problem.
Our zPrinter 650 doesn’t see as much use as the other printers, so repairs to it have been minor. That said it does have several costly cables that are consumables, of which we’ve only had to replace the POGO flex cable so far. The parking spittoon and service station can sometimes leak or overflow, causing a mess to clean up. And the process of lubricating the fast axis bearing can sometimes cause oil to contaminate the pogo sensor & window, causing a few hours worth of disassembly and cleaning.
Fabbaloo: What was the most challenging maintenance you diagnosed and fixed on a 3D Printer?
Jeff Stobbe: I can’t say for certain, as I started maintaining 3D printers just a few years ago with zero 3D printer knowledge and have had many, many challenges to date. Now that I have a decent library of knowledge in my head, it is much easier to troubleshoot and diagnose problematic machines.
That said, some of the most challenging repairs happen when the expense required for repair parts are too high, due to being forced to purchase an entire module instead of a small part.
For example, I am currently sorting out a problem in our off-warranty Fortus 400mc, where two out of the four filament bays are not accepting or feeding filament. Stratasys does not supply much information for end user repairs, so it is just a matter of breaking down and working out the problem.
After some swapping of parts, troubleshooting & deduction, it would appear that the filament bay’s small 3″ planetary gear drive motor was damaged during a filament load — where the retaining pin was not removed from the filament canister prior to installation, causing the motor to be held in place during the whole load sequence and burn out. I’ve sourced a replacement motor with the same voltage and planetary gear spec from the original manufacturer, which we will eventually get around to purchasing. When we do, I’m sure it will be much better priced than the cost of an entire replacement filament bay from Stratasys – which starts around US$5,000.
Fabbaloo: Do you enjoy fixing 3D printers? Why?
Jeff Stobbe: I love fixing 3D printers because you can fix one 3D printer with another 3D printer. That’s just plain fun!
Fabbaloo: If a vendor of a 3D printer could redesign any part to make your job easier what would that be?
Jeff Stobbe: We all know that harness cables fatigue over time. Having connectors at each end of a harness cable would make troubleshooting and replacement so much easier. Also, protecting the heater and thermistor wires from being engulfed in an extruder blob and damaged would be a nice thing.