Better 3D Prints, Courtesy Of A Simple Mass

Apr 23, 2024

Yes, I design all of my own 3d printed pieces that interface aluminum extrusion by sliding on such that they pocket the profile entirely. This creates not only more contact surface, but more contact surface in multiple directions that, depending on print orientation, can even stiffen the print by the shape it creates in the print.

Parts that don’t slide on can still take advantage of similar concepts.

The downside is that the design and printing involves tighter tolerances that usually require tweaks related to the specific printer and nozzle size, either in the design or in the slicing. It may also involve tweaks specific to a given manufacturer’s rail profile, even if it’s supposed to be “standard”. Equally, printing them without internal supports requires forethought in the design work, and sometimes requires some interesting design choices in terms of meeting the profile’s inner “T” extruded areas. It’s all doable, but it’s no longer “click, click, done, isn’t that pretty for YouTube!?”.

I see Slant3d content show up in recommended stuff a lot, and the titles and previews always look suspicious. George’s comment makes a lot of sense in that regard, that it’s about posturing to clients and not actually about serious mechanical engineering juxtaposed with serious ergonomic and wider system thinking design. If this article is a good representation, then really it seems like a fairly bogus/snake oil channel that’s more focused on flim flam hand waving for selling than on honesty.

For one thing, nothing makes what the video is promoting any more difficult to injection mold than anything else, other than requiring a multipart mold as designed. The shrinkage mentioned is… not even worth bringing up in context of doing professional part design. You take your material data sheet and can just apply it as a scalar to the design even. These are all knowns when designing and ordering from any even halfway reputable injection molding manufacturer. Other things require more specific work done during the design for better release/etc… but 3d printing is no different in requiring comparable specific design consideration to do well, versus simply passably.

For another, it’s… not that good of a design, even “just for demonstrating a point”. It looks nice (I guess? *as she shrugs*), and that’s about it. But it’s like it was designed by someone who never actually builds anything with aluminum extrusion (equally, I’d question whether the outer angles are the best choice, mechanically, especially over other options 3d printing/design makes readily available… not to mention all the simply flat outer walls 90 degrees to the loading). Those cast metal inner corner braces with screws and those side corner plate fixtures that the video is apparently trying to talk down? They provide room for cut tolerances (including less than perfectly square cuts) and the ability to easily see that you’ve securely gotten your pieces flush, and easily inspect for slippage during use. This doesn’t. Now, a pair of windows would solve part of that (and a good demonstration of how easy it is to iteratively prototype for realizing more problem space aspects). But… you’re still losing easy adjustability by comparison. Even before getting to other issues.

Personally speaking, I don’t 3d print parts for aluminum extrusion when there are off the shelf parts readily available that do the appropriate task properly: it’s a waste of time, money, printer time, effort, and often there are going to be hidden aspects in terms of usability or mechanics.

Which isn’t to say I don’t design and print for 3d extrusion interfacing. Highly custom, specific parts or interfaces designed as integral to a different component (ideally in ways that still involve bracketing for securing assembly rather than having to slide something all the way down a rail).

I try to focus on things where I need a custom designed piece because what is already out there won’t work well or fit well for a specific need, and working around that to use off the shelf parts anyway will require as much or more time and effort as designing something custom. Or, admittedly, things where I want a certain aesthetic and am willing to make trade offs to get it, and I have a 3d printer to do it with rather than other possible processes. Or small batch cost savings when spending the time is cheaper than ordering an otherwise expensive part (and often this turns out to have been a mistake if looking at it from a financial perspective on the time spent, lol, but it at least hones skills).

Survivorship of design is always a fascinating concept, because often there are far more aspects involved than immediately apparent. Designs that survive aren’t necessarily even the best design for the emblematic/prototypical person using them. They’re almost certainly not necessarily the best design for **everyone** or **every** use, even in the simplest of iron triangle concepts. There’s a network of concerns that includes frictions between supply side ones and demand side ones, and certain priorities of certain parties will win out even over the needs of others. Practicality. But often, designs that win out do so for multiple reasons, and just jumping past to “well I can make a thing, so why don’t I?” when something already exists in the same utility space isn’t necessarily smart, particularly as a use of time and especially energy. Sometimes it’s a big opportunity to a shortcut to success (or savings on something “adequate” for a lower tolerance purpose than what’s commonly available, or vice versa) when a new process lets you better meet even just niche demand that wasn’t being served well by the generic pre-existing part(s). But sometimes there are aspects you’re not considering… and if that’s the case, is whatever you’re working on something you care about enough to expend yourself that much on? Will you even achieve your goals, or have you embarked on a dead end quest that’s not going to have been worth the time if your only measure of worth would be financial or even commercial success (and let’s not get into how deeply commercial success relies in things that have nothing to do with how a product is designed or works compared to other available products)? What do you WANT to be spending time and focus on, and why?

I’m not trying to curb anyone’s enthusiasm: go forth and make things! All the things! But… as much as the video apparently claims to be about thinking, it’s kind of doing the opposite itself (at least judging by the article). So go forth and make things, but don’t be like that about it. Don’t be full of hubris: be the student of the world who admits they don’t know everything and is eager to learn more from everything already in existence around them, including from perspectives beyond solely their own, admitting fully that their own will always be limited and therefore miss things. Don’t assume you’re solving everyone’s problem by what solves your concept of your own. Be proud of what you make, but stay grounded and inquisitive and empathetic. Don’t convince yourself that just because you have a tool or process at hand, you have to posture like it’s the best tool for every job with pretzeled attempts at arguments to shoot down alternatives rather than simply affirm the pros of your own. Instead, learn about and learn from the strengths and modalities and processes of other things and other methods, even ones you don’t personally have the capacity for or desire to use: often the reason certain things work or are done certain ways can be deeply insightful to re-applying concepts in other domains (even knowing pottery can be useful for fdm 3d printing mechanical design work, for example, and for understanding why certain things often made in ceramic have certain design features commonly, and potential insight into related skeuomorphic vs actual usability carry over). You don’t have to try to talk down everything else to talk up your own work, if you actually understand what it’s good for and why-so in a wider context than just trying to p hack your way to claiming supremacy and success.

3 axis fdm 3d printing is, overall, a manufacturing process with a number of limits and caveats. But it’s so incredibly accessible for achieving refined results compared to “traditional” large scale manufacturing processes, also without requiring the depth of talent/training/practice/workspace and tool access needed to do more individual scale traditional manufacturing things like sculpt and cast mold blanks by hand (especially accurately) or smith metal, and most significantly allows for easy editing and iterative design compared to non digital processes. It’s so incredibly fast to having a prototype or even a working part in hand, especially with practice. It’s not the best for everything. But it’s an amazing place to get started making physical things, and it does shine in areas even beyond that context.