I'm curious as to why this question was closed. So far as i can see from reading the reasons a post can be closed, there is no validity for shutting someone down for having their project be bad. His question was about a motor specification, not about his actual project so i'm wondering why it got closed anyway. I've been on stack exchange (mostly blender) for about a year now and I just recently tried out your site, and there are shocking differences. Not bad differences, I just want an explanation why this guys question was closed for just being stupid.


  • $\begingroup$ if it's any help at all, the post i read about why questions get closed can be found here $\endgroup$
    – ruckus
    Commented Nov 25, 2015 at 1:37

3 Answers 3


I'm curious as to why this question was closed. So far as i can see from reading the reasons a post can be closed, there is no validity for shutting someone down for having their project be bad.

I closed the post for a few reasons:

  1. There were at least 3 or 4 interpretations of what the OP was asking for. You saw a motor specification; Olin saw a perpetual motion machine; Jacen saw an inefficient power conversion; and I saw a poorly construed DC to AC converter.

  2. There was an existing close vote on the question.

  3. There were a number of comments requesting clarification on what the OP was trying to do.

That's a textbook example of when a question should be closed as unclear.

In some cases, the community can edit a question to put in "obvious" details and make the question meaningful. In this case, only the OP could provide those details. The risk in leaving the question open while the details are that answers will come in that are invalidated by future edits. That invalidation wastes the time of the answerers.

I just want an explanation why this guys question was closed for just being stupid.

I want to be really clear on this. The post was not closed for just being stupid. The question was closed because it was unclear and needed more detail. For all I know, the OP has a legitimate reason for attempting to convert DC to AC in that manner or whatever it is they are attempting to do.

there is no validity for shutting someone down for having their project be bad.

That's partially correct. This appeared to be a bad project where the problem wasn't clearly explained. That lack of explanation is grounds for closing a question. A bad project could also still be closed for the other reasons as laid out in the help center.

And going so far as to grant the hypothetical "bad project with a very clearly explained problem that can be reasonably answered within the SE Q&A format", then I believe that hypothetical unicorn question ought to be able to remain open.

Some tangentials...

First off, thanks for asking your question here in meta rather than creating meta comments on the question. Meta is the appropriate place for this sort of discussion.

Second, every SE site has a different culture to it. Some sites are more tolerant of loose questions, others are not. As you noted, it's not a bad thing, it's just a reflection of the community at that point in time. We're all wanting to creating a site with interesting, high quality Q&A.


When a question is put on hold, a banner is added to it explaining why it has been put on hold. In this case, the question is on hold because it is:

"unclear what you're [the OP is] asking Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking.

(my emphasis)

In this case you can read the comments under the question to get the full picture. They explain why it has been put on hold, so that the OP can edit the question and clarify it. Putting it on hold prevents answerers from wasting their time by taking guesses at what the OP might mean, and then answering completely the wrong question.

The comments say:

How to design a perpetual motion machine is off topic here.


Several community users are struggling to understand what problem is attempting to be solved, which is a sign that the question needs more details


If he wasn't trying to make a perpetual motion machine, then why use electricity to spin a motor, to spin a generator, to make electricity again? Perhaps there is a legitimate reason for wanting to do this, but since none was given, I suspect attempted perpetual motion machine. I won't even get into the impracticality of using 12 V to supply 2.6 kW. In any case, the question has been closed. Let's see if the OP comes back and explains himself properly

I'd also note that someone asking about getting "FREE energy" probably has some mistaken asssumptions, and those need to be bottomed out before a question can be sensibly formed and answered.

If and when the question is edited to remove the ambiguities, then it can be reopened.

  • 1
    $\begingroup$ you'll notice in the original post there was only one line at all that had any sort of question: "What kind of DC motor can I use to rotate that 5HP with 3,540-3,720RPM?" the rest was simply describing a nonsensical project that everyone had a problem with, but the question i think was clearly stated without discrepancy. $\endgroup$
    – ruckus
    Commented Nov 25, 2015 at 15:56

I was the first to vote to close this question, and I also downvoted it. Here is the body of the question at the time I saw it:

The purpose of that project is to produce energy from a generator head that will produce 2,600 Watts and requires 5 hp (3,540 - 3,720 RPM). To make that generator head running, I am planning to have a DC motor that can run from a 12 V battery, next I will solder the two shafts together. I don't want to use any engine that use gas to make that running. What kind of DC motor can I use to rotate that 5HP with 3,540-3,720RPM?

This is a crappy question for severel reasons:

  1. The first sentence says the purpose is to produce power. He wants to do this from a "generator head". How is that different from just a generator? Does he only mean part of the generator? If so, what is the relevance? How can you strip down a generator and still have something that generates electricity? He's making a point about this thing not being just a ordinary generator, but I'm not getting what that point is or what it's supposed to mean to me.

  2. He wants to spin this generator, whatever it really is, with a electric motor. This smells fishy. If he's starting with electrical power, and the purpose is to produce electrical power, why is a motor and a generator needed at all? There are simpler and more efficient ways to convert between different types of electrical power.

    A inverter is the obvious answer. Since these are well known and available out there, there must be something inherent to this motor-generator combination that is important. But, he said right up front the purpose is to produce power. At best this is a bad question because it's asking about a supposed solution instead asking about the real problem, which could be simply converting 12 V DC to some AC. But then no specs were given for this AC, which is odd if that's the point.

    Ah, I get it! This is another free energy crackpot idea. Betcha this is something about getting 120 V out, with only 12 needed to run the battery. Look, over 100 volts of free power!

  3. The input to the motor is a 12 V battery. Does this guy have any clue that it would take 217 A at 12 V to get 2.6 kW, and that's not even counting losses. No mention was made that he has any understanding of this. It seems he's asking about some hairbrain scheme he imagined, but with so little understanding of the physics and engineering that it's going to be very difficult to talk about, and he'll probably think we're all being idiots for not just telling him how to hook things up.

  4. He plans to solder the motor and generator shafts together. OK, so this guy has no clue about soldering, welding, or shaft couplers. It is going to be a mess trying to explain things to him. Any answer is going to end up way too broad because this guy has so little understanding of what he's trying to do.

  5. He doesn't want to use a gas engine to spin the generator. So it's not just about producing power, but what is it about?

There are too many open questions to make a reasonable answer possible. And then he has so little understanding of the basics that way too much teaching of fundamentals is required first, if he is even willing and to listen and capable of understanding them. This just isn't a good fit for this site.

The latest revision of talks about "free energy", so now it sounds even more like perpetual motion machine nonsense than before. I have now voted to delete the question.

This sort of nonsense just doesn't belong here. We do engineering here, based on real science. Free energy crackpots need not apply.


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