My daughter got a kitten, Jewel, about a year ago. She's now a teenage rambunctious maniac running around the house constantly knocking everything off the counter - the cat, that is, not my daughter. Well, I guess that too, but that's a different story.
Anyhow, what I noticed was Jewel was rubbing her cheeks on everything. She'd rub up against vases, glassware, picture frames, pencil cups, lamps. Get the hint here? Suffice it to say, we have a lot of repaired stuff in the house.
In the past with our other cats, we would just go out and buy one of those corner cat combs. They're cheap and very effective. But as I was trying to tell my daughter, who at the time was heads down distracted with musical.lys from her friends, that we needed to go out and buy one these, after which she just kept saying "what? what?", I blurted out "a cat comb!" And if you say that fast enough with enough fervor in your voice, it sounds just like "catacomb".
Of course, the first place I went to was Instructables to look for a cat-a-comb, not a cat comb, but a cat-a-comb. Nothing. I searched the web. Nothing. That's how this project came to be. If it doesn't exist, build it. One of the side benefits of this project was that I learned a bit more about catacombs and was able to share that with my kids, who thought this was just too weird and too creepy.
At first I had very high ambition. The Cat-a-Comb was going to be a tunnel-like cavern where Jewel would explore, hang out, etc., and she would rub her cheeks on the skulls and bones. After a few initial test prints of very large designs it became apparent that it would take months to print not to mention I was completing only about 10% of the print jobs. After many iterations, the final design just ended up being a simple archway with the comb teeth inside the arch for cheek rubbing and the skull and bones on the outside for decoration.
One important piece of advice upfront: buy a lot of filament. Buy 2x more than you think you need. I ran out twice and it looks too patchwork'y.
The Cat-a-Comb is primarily a 3D print project. So a 3D printer is needed, and a good one at that. I used an Ultimaker 2 (not 2+). Ultimaker no longer sells the 2 in favor of the 2+ which is supposed to be better. I wish I had the 2+ because I had tremendous amount of trouble with the 2. I'll explain below.
In addition to a 3D printer, I heavily used these tools:
The only material that's really needed for this project is the 3D filament. I used 3mm ABS because that's the size the printer uses and I wanted ABS so that the Cat-a-Comb could take a beating. In the course of this project, I had run out of black so I bought more from a different manufacturer. And then I had run out of that. The color and finish is noticeably different. I also tried a "coffee" just to see. Eh. If the entire Cat-a-Comb were to be just one color of one manufacturer, at least 2kg are needed, more if there are many print failures.
For this project, Tinkercad was just not powerful enough. I had to use the next level up: 123D Design and MeshMixer. I'm very grateful for the existence of these FREE tools and the amount of tutorials out there for these tools. Thanks Autodesk.
For slicing, I used Cura because Utlimaker provides it and it is intimately aware of the Ultmaker 2 printer.
Almost from the beginning it was apparent that the Ultimaker 2 was having problems with the intricate design of the skull and bones. After many, many experiments and filament changes, parameter tweaking, and design changes and many, many hours and meters of failed print jobs, I found that 98% of the problems seem to be directly related to the retraction feature. For those who don't know what this is, the printer can retract (or pull back) the filament just before moving the print head to a location that's not nearby thus preventing stringing from occurring. When the head gets to its new location, it then pushes the filament forward and resumes printing.
It turns out that this back and forth motion along with the knurled feeder which bites into the filament to move it and the Bowden tube which guides the filament but is not friction free causes the knurled feeder to chew into the filament. This is easily remedied by disabling all retractions both in the slicing settings and on the printer. Stringing will happen but at least the 12-hour print job will complete and I have something that I can clean up versus having nothing.
Disabling retractions had a side effect of creating too much back pressure in the nozzle area. The Ultimaker 2 has a spring that sits atop of a plastic coupler guide (PTFE) which goes into the brass nozzle. The build up of the filament in the nozzle pushed the PTFE upwards. The spring, though strong, was not strong enough from keeping the PTFE from moving and it resulted in clogging nearly every print after some number of hours. The solution was to replace the spring with a fixed cylindrical part.
The final issue I had was that the print bed is not completely equidistant from the print head guide rods everywhere in the x- and y-axis print plane. That is, the distance from the bed to the guide rods in the upper left quadrant (back left) is less than the distance in the lower right quadrant (front right). Ultimaker 2 has the ability to separately level the left and right sides of the bed but that only levels the front of the bed, not the back. The result of this misalignment is that the filament does not get laid down in the upper left quadrant because the bed is too close to the print head. Fortunately, the discrepancy between the distances seems to only be about 0.5mm. This can be fixed by squeezing together the top and bottom plates of the print bed (Ultimaker 2 has a 2-plate print bed with adjustment springs in between) in the upper left quadrant and holding it there with Kapton tape.
All of these many, many hours of discovery and wasted material. 3D printing is still very finicky.