It is very easy to ask questions that only tangentially involve 3D printing, such as:

  • How do I drill a hole in a 3D printed part?

  • How do I paint 3D printed parts?

  • How do I sand, smooth, etc...?

  • How do I take a picture with a 3D printed camera?

My last example is clearly not on topic, and the other examples aren't

difficult, specific questions — the kind of questions pros and experts ask each other, not the kind of questions novices ask pros.

However, the point is that it's very easy to involve 3D printing in a question that isn't about 3D printing. Drilling a hole in a 3D printed part is, for the most part, just like drilling one in wood. Such questions may be more suited for a general DIY/makers-type site.

On the other hand, there do exist 3D printing specific issues (for instance, low infill or delamination can be a problem when drilling in a (FDM) 3D printed part).

At what point does a question involving 3D printing become on-topic for our site? Should questions identify a specific issue ("I've tried drilling a hole, now my part has delaminated, what now?")?. Queries for general advice and best practice don't seem to fit the bill of being difficult and specific.

  • 1
    $\begingroup$ Decide by case. On another site, Open Source, we've seen close reasons where something involves open source, but is not specifically about open source, and were closed as off-topic. They would've made excellent, relevant questions. $\endgroup$
    – Zizouz212
    Commented Jan 13, 2016 at 13:39

2 Answers 2


The dividing line of "tangentially off topic" is typically when the actual subject of the question being asked is only coincidentally adjacent to 3D printing.

Here is a clear example illustrating the "tangential issue:"

I printed a crane mechanism in 3D. How much voltage must I apply to the motor to lift 150 grams?

I see this type of thing all the time. Users will go to the mat arguing that they are printing in 3D, so their question is on topic. It is not. The actual expertise needed to answer this question is in electronics. With a question like this, the premise that the user happens to be printing in 3D is entirely coincidental to the actual issue.

The examples you cited above are a bit more iffy. I might argue some of them could (potentially) be on topic… if the issue of the material being printed in 3D is somehow germane to the problem. I actually don't know enough about the subject to say, so I'm only considering the possibility that it is relevant to this subject space.

Let's not be too quick to start barring questions that aren't explicitly about the physical process of 3D printing literally. There are a lot of industry issues that could be interesting to include here. It's probably better to wait for actual examples before trying to create a general rule around this issue.

As a general rule for building this site, it is often better to wait for a preponderance of problems that occur in actual practice before we start seeking to create a lot of rules around hypothetical situations. Words to live by.


The problem with the questions you raised are (except for the camera one) that they are all about dealing with the materials that are used with 3D-printing and not about the mechanics of printing. But when I started 3D-printing, that's certainly where a large part of my questions lay. It's because the materials are DIFFERENT than ones we're used to dealing with, and if it weren't for 3D-printing, I wouldn't have been working with them then. It's BECAUSE I was 3D-printing that the questions arose. There are certainly similarities between the materials used for 3D-printing and other materials we might run into, but there are also vast differences. For example, ABS is the same plastic that we know from Legos. But how does working with the plastic that's been 3D-printed differ from working with a Lego? I would consider any question about that area to be valid. You mention drilling plastic, but then got the answer wrong. It is NOT like drilling wood; the way you drill plastic should be different from how you deal with wood, such as the speeds used and the use of hand drills. There are even special plastic bits that you can buy that make it easier to drill plastic. Good questions might be: for PLA, ABS and other 3dpg plastics, when is it appropriate to use such bits and when can you get away with using high speed drill bits like you would use for wood? Are higher drill speeds better than lower speeds for some 3D-printed plastics and not others, or vice versa?

In summary, I feel that questions about a technique or material that is being used in the 3D-printing process, or dealing with the materials afterward, should be valid because 3D-printing changes how the techniques are done or the materials are dealt with.


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