As I mentioned in my previous blog post, I volunteered to assess, repair as needed and make functional again a 3D printer that belongs to our local library, in exchange for the use of it to experiment printing some parts for my airplane. The primary issue reported by the library staff was that it wouldn't print and they suspected it was a plugged extruder nozzle. They don't have the knowledge or salary dollars to assign a staff member to investigate further, so the printer sits idle and unused.
The brand of printer appears to be HICTOP which is one of many widely reproduced, made in Asia copies of a Prusa 3D printer. This is more common than one might think - there are literally hundreds of knock-off models on the market and this practice was commonplace at the time the unit was purchased by the library a few years ago. The market now has several different manufacturers competing for dollars.
No manual in the box, but I found one online to give me some hints for what to look for. Here is how I received it and what I found.
First up, an unlabled box of what appears to be left over/spare parts, typical of knock-off manufacturing, but this was likely where someone just dumped anything extra left over:
There appears to be a bunch of stuff in the box, leading me to wonder what's missing on the printer!
Some of the bags are labled, some aren't....
Initially I thought why would someone would keep (what appears to be) a broken cog-drive belt. Further looking at the HICTOP assembly manual I downloaded from the interwebs shows that the belt is left open ended for adjustment purposes (ties off on the chasis slides at each end). Learned something new.
Some extra split tube wiring conduit/loom that didn't get used.
The box has a tonne of filiment in it, however anything in a bag appears to be labled 3D "pen". I know the library was touting they had a 3D crafting pen, so I'll have to research if this also works in the 3D printer. It doesn't seem to be the same stuff - different diameter and texture, but I also know filaments comes in many different material types and diameters (you can switch nozzles on the printer), but for now I'll run on the assumption they are not compatible.
The printer itself looks well used (or well abused?) and typical of home built hobbyist kits. Everything seems to be in place and secure on first glance.
It looks like some attempts were amde to tidy up the wiring, either at the original build stage or later on - however it needs some attention. Probably what the spare wiring conduit loom was for:
Power cord seems intact. The other grey cable is an older style USB cable common in early versions of 3D printers, but nice and long.
Also typical are simple filament spool holders, in this case the model has a threaded rod with nuts on the end uprights:
The print bed is damaged but still flat. It's somewhat common practice to use glue sticks to spread a thin layer on the print bed for the printed item to stick to as the bed moves back and forth. I think the proper procedure is to clean the glue off between prints though. This glue is very thick and likely baked on over several heat/cool cycles of the bed.
Early users of 3D printers struggled sometimes to remove completed prints from the bed and I imagine the evolution to heated print beds (like this model) might have made hard adhesion of the extruded plastics even more prevalent. Looks like someone used a hard tool of some sort to remove prints and left some fairly deep gouge marks.
After cleaning up the glue residue a little, it looks like a previous user also dragged the print head nozzle across the bed when trying to print something, leaving a permanent hash shaped mark in the soft aluminum. In this picture you can also see the nozzle and heater is covered in old plastic debris. It also appears loose and freely turns on it's mounting pipe.
This printer has a small display screen and single control knob to both prepare and operate the printer.
With a bunch of initial tidy up, everything looked good for power up. There doesn't appear to be any master switch to control power on/off, so I plugged it in hoping to not see any blue smoke! The power supply groaned a bit then the LCD display lit up. The menu selection knob seems to be functioning correctly and I can navigate through the menus easily:
After a couple of minutes, the extruder began to spit out melted filament which I caught in a tissue. Seemed more of a drip than a push by the extruder, but maybe the clog managed to clear itself?
Using a socket on a drive handle, I removed the nozzle once it cooled down after power off:
The nozzle is most definitely blocked and this confirms the string that appeared was just melting debris. So the nozzle will need some serious attention.
A few more attempts to clean the bed while on the printer proved difficult, removing four anchor bolts and unplugging the electrical connector is easy. I'll take both to the shop where I have access to lacquer thinner which should make short work of the glue that appears to be baked on over a long time. Acetone will melt the blockage in the nozzle.
Looking down from the top, everything looks good externally, maybe a bit dusty from sitting. Looking left to right at the extruder assembly is the extruder cooling fan, heat sink fins, filament loading latch (hole) and the extruder driver motor). On the front of everything is another fan which is ducted towards the nozzle tip.
Remove a few screws and the drive parts of the extruder assembly comes off the carrier. This revealed a partly melted pieced of filament which looked like it had jammed in the feed tube. It came out easy with a small tug on the exposed end. I removed the set screw that holds the feed pipe and heating element (called the "hot end").
I had some other supplies to drop off at the shop, so I took the nozzle and print bed with me to clean them up.
Previously, I had purchased a ultrasonic jewelry cleaner at a thrift store. Turns out it's perfect for cleaning small parts like the printer nozzle. I placed it in the tray and added just enough pure acetone to submerge it.
The cleaner has a bright blue LED light that makes it hard to see anything due to the reflective stainless bin bottom, but I'm not complaining, the cleaner was less than $7.
A short video of the cleaner when on.
While the nozzle soaked and buzzed away in the cleaner, I used lacquer thinner and a paper towel to remove the mess of glue buildup. It worked well when let to soak a bit and "encouraged" with a plastic scraping tool.
Removal of the glue reveals even more deep scratches. I originally thought about sanding them out with some fine sand paper, but I'm concerned about damaging it further or worse taking out the flatness. I'll have to research options.
The long acetone soak in the ultrasonic cleaner worked very well. Little bits floating in the acetone were a good sign. A small piece of wire in the tip of the nozzle pushed the rest of the debris out along with some high pressure air from the compressor. All good again!
Next up, reassembly of the printer including improving/replacing the print bed. Stay tuned.
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Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.