Peachy Printer - The world's first $100 3D Printer • Hacker News Board

Re: Peachy Printer - The world's first $100 3D Printer

#21

Post by anigbrowl » Sat, Sep 21, 2013, 8:34 PM UTC

kevingadd wrote: post #7

I wonder how much error is introduced by the use of the headphone jack to drive the printer - you've gotta deal with line noise from the computer's sound card, mixing latency/glitches from the OS, and the device sampling rate, along with any noise introduced on the audio cable. Does a 3D printer like this not actually require high-precision data to work correctly?

Line noise is a bit of an issue, but that's usually quite high frequency which means it can either be filtered or that the errors will be correspondingly small. Latency and glitches are not likely to be an issue at all, even the crappiest computer nowadays can handle multitrack audio and delays of a few milliseconds that would interfere with music performance are not going to have any impact here. Likewise sampling rate shouldn't be a problem, anything above 8Khz or so should be adequate for purpose here and most cheap uCs could handle that. Cable noise is generally negligible over short runs. A bigger problem would be ground hum from poorly isolated transformers/power supplies, but that is on a fixed frequency and can be eliminated with a HPF. Certainly the output is a little crude but it will be 'good enough' for many purposes.

Note also that the audio input allows playback from an mp3 player or other sources, suggesting the audio can be wholly precomputed. Imagine how useful that could be in places like Africa so that you could print thing without necessarily needing a high-power device like a laptop.

Re: Peachy Printer - The world's first $100 3D Printer

#22

Post by simias » Sat, Sep 21, 2013, 8:35 PM UTC

WestCoastJustin wrote: post #8

Kickstarter link @ http://www.kickstarter.com/projects/117421627/the-peachy-pri... This is such a cool concept -- I backed it! I do not want to highjack the conversation, but I think it is worth mentioning, that this is kind of a "grinds my gears" [1, 2] moment when someone links to a summery, which borrows the video and images of a Kickstarter campaign, you are essentially diverting the campaigns traffic, why not ju…

Man, I got used to the kickstarter campains that try to sell me hot water and make it sound like it's the greatest thing on earth.

This is refreshing, it's simple, clever. A true hack in the best meaning of the word.

Re: Peachy Printer - The world's first $100 3D Printer

#23

Post by [deleted] » Sat, Sep 21, 2013, 8:36 PM UTC

simias wrote: post #22

WestCoastJustin wrote: post #8

Kickstarter link @ http://www.kickstarter.com/projects/117421627/the-peachy-pri... This is such a cool concept -- I backed it! I do not want to highjack the conversation, but I think it is worth mentioning, that this is kind of a "grinds my gears" [1, 2] moment when someone links to a summery, which borrows the video and images of a Kickstarter campaign, you are essentially diverting the campaigns traffic, why not ju…

Man, I got used to the kickstarter campains that try to sell me hot water and make it sound like it's the greatest thing on earth. This is refreshing, it's simple, clever. A true hack in the best meaning of the word.

[deleted]

Re: Peachy Printer - The world's first $100 3D Printer

#24

Post by jevanish » Sat, Sep 21, 2013, 8:37 PM UTC

ibrahima wrote: post #5

Hmm, this is pretty much getting into impulse buy territory (for a 3D printer), and it even helps with my #1 problem justifying getting one which was that I haven't really learned any 3D modeling, by being capable of scanning (though I guess you could also do something similar with a Kinect). Could anyone with more insight into these things explain further why this is unique and whether there might be drawbacks? This…

If you watch the videos in the kickstarter and on his site, you'll see he removed a ton of parts every other printer has to have. For example, the Z axis is now water...that's a lot cheaper than all the parts you need for a bed and the precision motors to normally raise/lower a platform. He did this in quite a few areas, which quickly plummets the price.

Re: Peachy Printer - The world's first $100 3D Printer

#25

Post by anigbrowl » Sat, Sep 21, 2013, 8:40 PM UTC

kevingadd wrote: post #13

SwellJoe wrote: post #12

Earlier quoted context omitted.

Audio output of modern computers is high precision. 16 bit resolution is pretty damned precise...even once converted to analog. I'm certain the mechanical parts being driven by it is a much, much, larger source of errors than any decent computer output would be. That said, there is measurable and audible differences between a stock audio output and a high end (or even prosumer) audio output. A nice 24 bit audio box c…

I'm not referring to 16 bit precision per sample, more to 44khz and the potential for multi-millisecond audio glitches on most modern PC configurations. Glitch-free audio is pretty tough, still.

That's not true at all and hasn't been for a long time. Maybe if you're mixing more than 8 tracks on a low-power CPU, but even a chromebook can do that sort of thing. Even my phone (several years old) can do that. Playing back stereo audio (which all that's required here) is something that can be done from a device that fits on your keyring. What you're arguing hasn't been true since the 90s.

Certainly, it would be bad if this thing relied on every last available bit of audio bandwidth all the way up to 22.05 Khz, but there's no particular reason to do that.

Re: Peachy Printer - The world's first $100 3D Printer

#26

Post by MrBuddyCasino » Sat, Sep 21, 2013, 8:43 PM UTC

andrewcooke wrote: post #4

this may be obvious to everyone else, but took me a while... stereo! [there are two mirrors to drive (or, equivalently, a point in 2D to target with the laser) and i couldn't see how to do that with a single audio signal.]

Ha, glad I wasn't the only one. I feel less stupid now.

Re: Peachy Printer - The world's first $100 3D Printer

#27

Post by oakwhiz » Sat, Sep 21, 2013, 8:43 PM UTC

kevingadd wrote: post #7

I wonder how much error is introduced by the use of the headphone jack to drive the printer - you've gotta deal with line noise from the computer's sound card, mixing latency/glitches from the OS, and the device sampling rate, along with any noise introduced on the audio cable. Does a 3D printer like this not actually require high-precision data to work correctly?

The resin takes a certain amount of light exposure to fully cure. I doubt that noise or buffer glitches would seriously cause a noticeable effect on the print. More likely, soundcards with improper equalization, and galvanometer impedance and group delay would be the cause of shape distortion.

Re: Peachy Printer - The world's first $100 3D Printer

#28

Post by jlgreco » Sat, Sep 21, 2013, 8:45 PM UTC

scoofy wrote: post #10

This is a bit too good to believe, but at $100 i'll bite. I've been into 3d printing for years now, and my main concern is material. If this resin is durable, and doesn't get soft in the car on a warm day, this design could be really groundbreaking. If not, it'll be a waste of everyone's time. The quality looks pretty decent given how awful low end 3d printers can be without a ton of tinkering. My current printer cos…

It looks like the resin they are using is "Makerjuice" (http://makerjuice.com/). I don't know anything about that resin though.

Re: Peachy Printer - The world's first $100 3D Printer

#29

Post by scotty79 » Sat, Sep 21, 2013, 8:46 PM UTC

Awesome idea. But isn't mirror inertia a problem?

Also constant velocity of z-axis movement might pose some inefficiencies because if you want to print a box you have to set the rate of ascend low enough for the laser to create full bottom and you can't speed up when you are building sides of the box.

Re: Peachy Printer - The world's first $100 3D Printer

#30

Post by kevingadd » Sat, Sep 21, 2013, 8:47 PM UTC

anigbrowl wrote: post #25

kevingadd wrote: post #13

Earlier quoted context omitted.

I'm not referring to 16 bit precision per sample, more to 44khz and the potential for multi-millisecond audio glitches on most modern PC configurations. Glitch-free audio is pretty tough, still.

That's not true at all and hasn't been for a long time. Maybe if you're mixing more than 8 tracks on a low-power CPU, but even a chromebook can do that sort of thing. Even my phone (several years old) can do that. Playing back stereo audio (which all that's required here) is something that can be done from a device that fits on your keyring. What you're arguing hasn't been true since the 90s. Certainly, it would be b…

I'm not talking about 'can you play back audio', I'm talking about 'can you play back audio with zero glitches'. This becomes a problem of scheduling precision, whether or not scheduling will 'stall' if a driver hangs while processing an IRQ, whether or not the graphics driver has a potential to hang due to a rendering operation, etc, etc. These are all a reality on modern desktops even if they're fairly rare (I don't think I see audio glitches on my desktop more than maybe once a month).

The people I talk to who do professional audio recording and mixing insist that it is still a difficult problem; it was back when I did mixing (early to mid 2000s, not 'the 90s'). The prevalence of custom APIs for glitch-free low-latency audio playback like JACK and ASIO suggests to me that you still can't rely on just feeding samples to the OS and having them come out of the sound card at the appropriate rate 100% of the time.

FWIW, Windows introduced an entirely new audio stack in Vista that was tuned specifically to address these problems. Their first iteration managed to cripple ethernet bandwidth because of the scheduling requirements imposed for glitch-free audio.