--[ x14km2d

| Cup Holder

--[ 0 - Intro --[ 1 - Problem --[ 2 - Building --[ 3 - Finish --[ 4 - Wrong Scaling --[ A - Comments --[ B - Changelog

17/09/2021

--[ 0 - Intro

Actually, I'm always the first to buy new technology. Especially with Maker products that you can use for your own projects. So I have all Raspberry Pi models, some even several times. From the first one to the Raspberry Pi 400 I always signed up for the pre-order lists. The price also played a role, because the single board computers are very cheap, just like the Arduino Uno for example. However, when it came to 3D printing technology, I held back for a very long time. Most products were just way too expensive for me and I didn't want to spend 2000€ for a printer at that time. So I waited. Last month I finally ordered the Ender-3 3D printer and immediately started my first projects. Until now I had always built my prototypes the old school way and that took a lot of time and material. With a 3D printer, I finally wanted to improve my workflow when creating prototypes and products.

--[ 1 - The Problem

Like so many other makers, I love plastic cups. However, I do not buy them separately but use some from Korean sweets. These cups are a little more stable than the European products and are very good to sort pens, small screwdrivers, brushes, wooden spatulas, rulers or other tools. So then the disposable product does not have to be thrown in the trash and extends the runtime significantly. In total, I had four cups that were filled with all sorts of things and I always put them somewhere where I found a place or just worked. Unfortunately, over the last few months, they started getting in the way and taking up space. In a shop, that's deadly if you clutter up your own workspace. So I had a really good problem to deal with. Up to this point, I had only printed out a few modifications to improve the 3D printer. I had not yet created and produced anything of my own. After a few sketches with ideas, I came up with a cup holder in which the cup could be inserted. This ring could then be fixed somewhere with two screws. Preferably near the desk. This way I would have all tools within arm's reach, which should improve my workflow considerably.

--[ 2 - Building

But before I could implement my idea, I had to learn new software. Among them FreeCad with which I created the model as an stl file and also PrusaSlicer with which I then converted this model for my 3D printer. This sounds easy at first, but if you have never created technical models before, there is a lot to learn. The software is very different from, for example, Godot game engine, which allows you to create 3D level for computer games. With FreeCad you can work to the millimeter and until I understood it all very well, I printed out some proofs that I couldn't use. I also learned how to properly measure a plastic cup to get the dimensions right. There was a lot to learn, but with each day I became more confident and after a few failures I was finally able to print a proper model. The prototype is minimalistic in design and has no additional elements or shapes, because I'm still too unprofessional for that. But it serves its purpose and I can put the cups somewhere where they won't interfere. I uploaded the cup holder model under the public domain license to the Archive, because I think that such projects should be developed for the general public. Not everyone has the time to build it themselves and it is ok if they can then simply print out the model with their own 3D printer or create a new version.

--[ 3 - Finish

Actually, it is not important, but I think that everything can always look a little better. So I painted the cups with a black spray paint. I didn't use a primer because that would cost too much. I just wanted it to look neater and more uniform. Since I use a heavy kitchen countertop as a desk, I was able to pre-drill the holes quite well with a drill and screw the cup holder on. Now I have all the tools close at hand and don't have to get up when I'm at my desk working on my projects. The good thing about my system is that I can swap the cups or take them with me. This gives me a modular system that I can adapt to my projects. For example, if I have a modeling project, I take the cup with the brushes and bring it closer to me so I can get to it quickly. I don't need the pins and screwdrivers that often at the moment, so they can be pushed to the back of the cup. Finally, I put my Elektrocat stickers on the cups so that it looks really professional.

--[ 4 - Wrong Scaling

When you start working with 3D printing, you can expect the troubleshooting process to drag on and on. Most of the time you don't see the error because the part has to be stressed first. That's why everyone tests their designs either in a test environment or, as in my case, under real conditions. Due to a careless movement I pushed my office chair too far backwards and broke a printed construction. This happened at an unusual place, because actually constructions break rather at a connection point, where e.g. two objects are connected with each other. I took a closer look at my printout and the printed material seems to be thinner in the area of the drill holes.

In order to examine the component more closely, I broke off the area in question and scanned it. You can see the result on the left side of the photo. To see it even better, I imported the image into Gimp and applied a filter [1] on the right side for better clarity. Now I could see it really well. The pattern in the middle should not be like that and clearly shows that the material was printed thinner, respectively that the upper/lower area is very different from the middle area. I then took a closer look at the drill holes and these were apparently incorrectly scaled. These now had the dimensions of 5.6 x 3.6 mm, which was not planned by me. As I have already described with the lid, there is the problem in Freecad that the size of the object is not taken over in PrusaSlicer. Apparently I have inserted a size value incorrectly during the scaling (which I then did manually). So only x and y was scaled, but not z. I then created a new gcode file and printed it again.

In this photo, you can see the massive differences quite clearly. On the right is the old version. The one with the wrongly scaled z axis. This also made the ring stronger and thicker, but I didn't see that because I thought it was correct. On the left side is the new version, where you can clearly see the correct drill holes. All in all the construction is now much more fragile and thinner and I have to check the stability of the construction in further tests. Nothing changes in the actual stl file that I uploaded to the archive, because it is only a transfer error between two software products. But here you can see that just like in the creation of big software projects or PCBs, everything must be tested very carefully. But for this you need experience and the foreknowledge, where you have to look exactly to avoid these errors. Since I'm just learning all this, I have yet to understand it. There will be such manufacturing errors certainly more often, which I will document here exactly, so that you can learn from my mistakes and do not have to repeat them.

--[ A - Comments

[1] Colors > Brightness-Contrast > Contrast > 127

--[ B - Changelog
--[ 3D-Print