I made a series of container boxes for a ham radio buddy. He needed them for his “go-kit”. A rapid deployment case containing a portable radio and everything needed to put a short wave station on the air from remote locations.
He enjoys operating radio from federal and state parks. I assume almost any established park qualifies for POTA (Parks On The Air) Its a good reason to pack up ones radio gear and go operate from a remote location.
Everything needed packed into one case makes certain nothing is missing or forgotten. It’s why the case is called the “go-kit”.
What I designed and 3D printed are organizer boxes and special brackets to hold radio gear for travel and help position gear when operating.
Black was the color of choice and I had several spools of that color PLA (PolyLactic Acid) on hand.
I created three container boxes with removable lids and several mounting brackets and adapters for holding radios and video screens in operating position.
It all worked well for a couple of weeks but then I received a report that the plastic boxes were all warping out of shape. The Go-Kit is stored in the trunk of the car and evidently the Texas heat has encouraged the container boxes to take on strange new shapes.
The boxes are fairly large and I originally designed them with 3mm thick bottoms, tops and side walls to save space and weight. I didn’t consider storage in a hot automobile trunk.
Walls that thin should have been designed with ribs and gussets to resist warping. But that would have greatly reduced internal space. The equipment brackets are designed much heavier and ARE well ribbed and braced. No problems at all with the supports warping. Just the warping with the thin walled boxes.
I experimented with ASA and ABS plastic for the replacement boxes. Both materials warp excessively during test printing. I discovered I can not print the size boxes needed with either ASA or ABS.
I made another test print with PLA+ which is a new higher temperature PLA with much less tendency to warp. 225C print on a 70C build plate. I am now reprinting all the boxes with 5mm walls and double print +45/-45 degree infill pattern. Twice the previous infill and very high rigidity. A real strong and true honey-comb infill. More than double the amount of PLA+ for the same size boxes. They are also twice the weight. Can’t escape that when warp-free results are required.
Print time is also nearly doubled as well. But that is not an issue. It is what it is.
There is a very small loss of useable storage space with the thicker walls and that too is of little concern. I had to be very careful in the re-design where I could “steal space” for the added wall thickness. The packing case did not get any bigger, so the container boxes had to lose some internal volume.
Only one container box had a critical inside dimension. The one labeled "KEY" that holds the paddle key for morse-code sending. There was space to expand that case on the exterior dimension.
Lesson learned here. Sometimes one cannot think of all the factors when creating a new design. It was a learning experience that will not be lost in future designs and revisions.
I have discovered what I think many 3D print people call a “plugged nozzle” may not be that problem at all. At least not plugged by debris.
The heat transfer within an FDM extruder is critical to good performance. The faster the feed (more filament volume) the more critical the heat flow within the extruder becomes.
The problem is any air gap in the flow path from the heating element to the extruder nozzle. Conductive heat cannot jump gaps such as screw threads. It converts to radiated heat to span the gap then back to conductive. The gap does not have to be large, The effect is like a huge resistor in electrical flow. Perhaps more like a spark gap.
If one has ever assembled a heat sink onto a CPU or any other critical heat transfer requirement, you know a “thermal paste” is required to ensure an absolute intimate connection and flow path for conductive heat.
Yet, this is never factory applied in our critical heat flow extruder connections. Probably because off the high temperatures of 250C and higher
I have been applying high heat anti-seize compound to the threaded barrel, between the heating element, thermal mass block, and the threaded feed barrel. I have not applied any to the nozzle threads for fear of introducing foreign material into the nozzle.
Electronic CPU heat sink compound is only good to 200C., Not suitable for this use. I bought Locktite LB8009 anti-seize. Used on automotive exhaust threaded components. Not really a thermal paste but permits extremely tight no-gap screw-in assembly without seizing. Use sparingly as there is some volatile off-gassing (smoke/odor) of the low-temp base carrier material on first heat. Good to 1350C so the high-temp material is not affected by extruder heat.
The improvement to extruder performance with tight threading has cured 99% of the flow issues with my extruders. Nozzles now never “plug-up”. They actually wear down the tips after many months of continuous fault-free performance. It works for me.
For many operators (people), poor nozzle flow appears to be a plugged nozzle. So the nozzle is changed. In changing the nozzle the threaded connections are disturbed and everything “tightened up” a bit solving the heat transfer problem (for a while). Thus, it appears it was a plugged nozzle issue.
Some folks raise print temperatures trying to improve flow. Sometimes to the point when the filament breaks down, gasses (cooks) off (thought to be proof of water) and actually burns on the nozzle, Result is an actual debris plug.
Improve the thermal conductive path of the extruder. Every assembled component needs to have high temperature compound to eliminate every possible air gap, no matter how small.
I greatly improved the performance of my extruders. Conductive thread compound should be an industry standard with 3D print extruders the same as heat sinks on CPU’s.
Search “High Temperature Heat Transfer Compound” for other brands. There may be something other than the high temp anti-seize I use, Must be suitable for temperatures 300C and above.
I have a heated bed on Cetus with a glass surface placed on top. Hair spray is my adhesive. It generally works very well. But there are some “tricks” in getting a good print without using a raft.
The big issue with Cetus is there is no manual leveling of the print surface. A thick raft is used to build a level surface before starting the intended print.
This takes considerable time and some wasted material. The material consumption is no big issue unless one is close to the end of the spool.
PETG is particularly sensitive to everything being “right” with initial layers.
I use G-code produced with Simplify3D. It has much better control of variables than offered with the stock UPStudio slicer/print software. There is a new Beta for UPStudio which shows promise but stopped working on my WIN10 PC.
UPStudio is still required - to load 3rd party G-code to Cetus. Simplify3D cannot communicate directly with Cetus.
PETG extrusion temperature is 150C. with a 90C bed. I am presently using 0.25 layer height with +200% for the first layer (0.50 height) This is required to help compensate for the un-level bed. I am using 100% extrusion flow with a 0.4 diameter nozzle. non-solid infill is set at 150%
These figures don’t seem extreme, and what I have found as necessary to get good non-raft PETG prints on Cetus.
Sone factors when set too high tend to push the Cetus extruder close to its flow limits. Missed steps (clunking) can be heard if pushed harder. This is the feeder gear slipping on the filament and cutting a notch. This will usually stop filament feed.
Travel (print) speed is also quite low with PETG, 2100 mm/m with under-speeds of 60%. Rather slow but PETG is also speed fussy.
Note Well: These are setting that work for me. Your results will certainly vary. Use these settings as an example of where you may have to go to get satisfactory PETG prints on a heated bed Cetus.
Moving On
181 grams, 20 hour print, 0.15mm layer heightAfter the learning experience of additive manufacturing making plastic Junque designed by other people, I asked myself, “What’s in the process for me?”
I admit it was the technology and the low cost equipment that first drew me in. I am a techno-type person attracted to complex operations.
My spouse declared before I had my first piece of 3D printing hardware. “I don’t believe you haven’t started 3D printing” She knows me well after 57 years of companionship.
I was aware of the process many years earlier but hadn’t realized there was a new breed of lightweight and low cost “hobbyist” hardware available. I was hooked and permitted to engage. She lit the fuse.
Nine printers later, I pause to contemplate. One thing stands out is the amount of plastic I have processed into “stuff”. Making stuff is what it is all about. Learning how to do it was the initial motivation.
It soon became apparent, most of the stuff is what I started calling plastic “Junque”. How many plastic skulls does the average person need?
I quickly tired of printing “other peoples” designs. The real creative juices flow when I can use 3D CAD software and graphic software like ZBrush to create printed objects of my own design.
Time to move away from Junque making.
I see the 3D print process as a tool. It is not my goal to “get the machine running” to watch it perform. I pretty much have that under control. All CNC is fun to watch. Not a good use of personal time.
The hardware I own and use is not junk (normal spelling). The major weakness is rigidity and capacity. Three dimensional printers need to be rigid and stable as every professional grade CNC machine tool. The bigger the size, the more massive they must become.
I have no desire (at this time) to produce massive 1 piece plastic items. My plan is to use the smaller machines I have to their full capacity when necessary.
Larger prints require longer run times. This has become my standard method of operation. My “moving on” thoughts are to design and produce larger and higher resolution prints. Consuming more raw material. 100 and exceeding 200 gram components not unusual. 12,16, 20 hour print times.
My previous recent posts in this blog are indicative of my “larger is better” printing goals.Moving On
Printing small parts to be assembled into larger items is a very good way to make larger items. I always avoid the mind-set that a product design must be created in a single all-inclusive 3D print.
Nice when it can happen but most large items are component assemblies.
“Moving On” goal is to produce less Junque by concentrating on larger and superior quality items. Not interested in how fast I can print, but generating the highest quality for the purpose.
It’s still plastic but it should be high quality plastic…
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