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Pwdr / Pwdr-Model-0.1

A powder substrate rapid prototyping machine
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Any Idea behind the 1500W Power Supply? #2

Open SungwonJ opened 12 years ago

SungwonJ commented 12 years ago

Congratulations to the release of Pwdr 0.1!

While I am purchasing all the electronics, I noticed that Pwdr is using a power supply of 1500W, is it necessary to power all the motors? What's the idea behind that?

Eddie

Pwdr commented 12 years ago

Thx Eddie

On the first sight, it looks a much doesn't it. But I can quote from my graduation report:

The stepper motors require in total at least 5,05A (750mA_3+1.4A_2). To be on the safe side, a power supply with a maximum current of at least 10A is chosen. Because commercial stand-alone power supplies with these specs are very expensive, an ATX computer power supply is modified.

So, the 10A at 12V make 120W, thus a power supply of 150W is need to power all the motor (potentially) simultaneously.

SungwonJ commented 12 years ago

Got it. "Potentially" is the KEYWORD.

nothinman commented 11 years ago

You Sir must surely be out of your mind to be using that huge 1500W PSU. Let me do the math for you... P=U * I (or V * I if you prefer). P[W] = 10[A] * 12[V] P[W] = 120 No, I'm not missing a zero. You need a 100W PSU MAX

nothinman commented 11 years ago

Otherwise, a good project, I was thinking of building something similar, but using Xaar solvent print heads. One thing that worried by was powder deposition. How do you create another layer of powder so that it is smooth, thin, and even? Couldn't figure it out from the photos (transparent case does not help at all).

Pwdr commented 11 years ago

You're right, too many zeros in that calculation (updated my previous comment). The selected PSU delivers 350W, that's more than sufficient. In fact, any odd ATX PSU will work.

SungwonJ commented 11 years ago

Depositing a smooth layer of powder has been a major issue for me. The roller either knocks the printer layer away or the layer is to thick for the ink to penetrate. I am working on new schemes to deposit powder. Hopefully it will work.

nothinman commented 11 years ago

One could use a laser printer type of roller with corona wire; but if your powder can't be charged it won't work... I will be looking into doing it mechanically soon too. Let us know if you come up with something interesting!

Pwdr commented 11 years ago

I haven't encountered serious problems with powder deposition. After trying some setups, it works fine and does make a fine powder layer without disturbing the previous layer.

As a rule of thumb, the new layer height should be between 5 and 10 particle diameters high.

And to lower friction between the roller and the powder, the roller must be polished thoroughly. I've done that by first using 1600 sanding paper (wet) and then polishing using polishing paste and a polishing machine (don't know the correct English term)

On Sep 13, 2012, at 6:10, Eddie notifications@github.com wrote:

Depositing a smooth layer of powder has been a major issue for me. The roller either knocks the printer layer away or the layer is to thick for the ink to penetrate. I am working on new schemes to deposit powder. Hopefully it will work.

— Reply to this email directly or view it on GitHubhttps://github.com/Pwdr/Pwdr-Model-0.1/issues/2#issuecomment-8517803.