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We're recovering from a major server loss and are restoring backups as we gain access to them. Don't mind the odd time warp. Warn us in the future.

Chinesium by Basil Suddlewell - Thu, 22 Sep 2016 04:22:38 EST ID:+tz+iBph No.6991 Ignore Report Reply Quick Reply
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So, what is this magical, and presumably very cheap substance that Chinese $2 shop crap is made out of? Is it metal or plastic, or some combination of the two?
Has anyone tried analysing this crud, or how they make things out of it? It seems too brittle to be machined, maybe it's moulded and sets like that play-dough stuff you bake in an oven. But put it under mechanical stress and it deforms, tears and crumbles like cake. Sometimes it has sparkles!
1 posts omitted. Click Reply to view.
Cyril Dimmleford - Sat, 24 Sep 2016 00:25:46 EST ID:F9kDEmRB No.6996 Ignore Report Quick Reply
Be careful with the sparkles, they're toxic.
Eliza Driffingfield - Sat, 24 Sep 2016 03:27:18 EST ID:F2XRo4mh No.6997 Ignore Report Quick Reply

These locks are amazing. Are they made of candy?
Samuel Bubbertadge - Tue, 27 Sep 2016 22:50:53 EST ID:LMSWX1C6 No.7002 Ignore Report Quick Reply
They're just made from pop steel you'd use for bottom barrel part fabrication. They're not even case hardened for the full length, as far as I'm aware.

Yeah, don't fuck around with garbage cutting tools. They'll bite you more than the material. If the manufacture isn't willing to provide you a name of the material it's tool is made from, I'd be hesitant. You know something telling you it's a M42, M2, C2, C12, etc.
Isabella Dregglestone - Wed, 28 Sep 2016 05:55:39 EST ID:2R1lBWwz No.7003 Ignore Report Quick Reply
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I love the drill-bit where the threads have straightened out like spaghetti.
You Google image search for Chinesium and it's like a mechanical hall of shame.
George Nuckleworth - Wed, 05 Oct 2016 23:23:52 EST ID:ZMpXliD1 No.7007 Ignore Report Quick Reply
industrial supply places are the best for stuff like this. The bits I get at my shop are pretty solid.

WHAT HAS SCIENCE DONE by Basil Suddlewell - Thu, 22 Sep 2016 05:02:20 EST ID:+tz+iBph No.6992 Ignore Report Reply Quick Reply
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Edward Brobblewill - Fri, 23 Sep 2016 02:05:48 EST ID:gO+6q97s No.6994 Ignore Report Quick Reply
test post please ignore

Pulley ratio calculation by Cornelius Blackcocke - Thu, 04 Aug 2016 13:53:21 EST ID:0ltnlAdQ No.6978 Ignore Report Reply Quick Reply
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Hi, I hope this is the right board for this. After a few hours of looking online..I just don't have the math skills to sort this out.

I have this electric motor that spins at 1725 rpm. I need to reduce that to 25-30 rpm. I have an old 74 1/4" bicycle wheel that I hope to be able to use but need to know the size of pulley to attach to the motor, or even if it is possible with what I have. I want to use this motor because it is designed for extended use and has a sufficient amount of torque for my project.
3 posts omitted. Click Reply to view.
John Blovingcocke - Fri, 12 Aug 2016 11:17:04 EST ID:0ltnlAdQ No.6983 Ignore Report Quick Reply

I am trying to build a rock tumbler that uses a couple of 6 foot rods in order to accommodate a series of small drums. I want to experiment with a few methods I have devised without committing my big tumbler to the task.

I was going to trim a belt myself.

The drill idea is a very good one. I am pretty sure I can find one for much less than that at garage sales or pawn shops. I am trying to keep this build user $100...mainly because I like to brag about my resourcefulness.

I do have an old 10 speed kicking around .....but yeah. I really don't have the math for that.
Jack Baffingshit - Fri, 12 Aug 2016 23:22:49 EST ID:LMSWX1C6 No.6984 Ignore Report Quick Reply

No guarantee that you'll find one with that level of reduction. You're looking for a ~70:1 to ~57:1 reduction at 100% load. And I know the old Makita I picked up for a couple bucks recently is only something like 11:1. It's a really nice solid helical gear with decent bearing. Though if you wind up with an 11:1 then you would only need to reduce it about 5:1 more to get about ~31RPM, either with another gear box, or just a small cast aluminum pulley straight to the drive shaft. Plus you only need a small cheap belt from a regional industrial supplier(best if you can pickup to avoid the freight cost).
And btw, casting aluminum is pretty damn, easy. Obviously it's not certified free machining 7075 or anything. But this guy made some real nice large rounds.
After you drill the center of your puck out and chamfer it, you can pop it on a mandrel and place it in a drill chuck and spin it(slap that drill into a vise if you got to), then clean it up with a rasp file, and then spin a flat groove into it for the belt to sit in. All the angles don't got to be perfect, just make sure you keep a even flat surface for the belt to sit on, any steps in it will wear the belt unevenly.
If you locktighted your mandrel on, just melt it out with a small torch.

If you need to trim a belt to width, don't just eye ball it with a razor and free hand it. Put a rod in a vise(or press fit into a block, and clamp it to a bench), and attach a blade to the end(braze, weld, bolt). Then the end of the vise will act as a depth stop so you have a constant width as you pull it through the blade.
Jack Baffingshit - Fri, 12 Aug 2016 23:36:36 EST ID:LMSWX1C6 No.6985 Ignore Report Quick Reply

Oh yeah, you really don't have to clean up the faces of the pulley either, an uneven cast surface is fine. As long as the surface the belt sits on isn't severely out of round(not enough even, constant pressure on the cut, or not not cutting far enough past the rough cast surface).
If you decide to clean the faces up, and want to do it with some speed. I know a lot of people often have something like an angle grinder laying around, so if you put the drill with the pulley to a low RPM, you can hit it with light passes of the angle grinder to speed up cleaning the faces up. If it's glued in, don't go to hard, or you could heat it up and melt it out.

Alternatively to a glue on mandrel is to take a rod, drill and tap the face. This goes in the chuck and the part is bolted to it, with a little touch of locktight. Just make sure the part spins in a direction that pushes the bolt tighter, rather than looser as you put pressure on it.
Sophie Clayspear - Sun, 21 Aug 2016 03:51:28 EST ID:7YnJeYuF No.6986 Ignore Report Quick Reply
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Not sure why you are building a directly driven rock tumbler. Most are a 1:1 drive to one support rod that the drum rotates on. Usually with something rubber to prevent slippage. Pic related.

By Direct Drive I assume your design is a gang of linked 5 gallon buckets with one attached to a bicycle wheel as a driven gear?

This may be necessary given you are talking 6 feet long and 5 gallon buckets. Not sure what loads you will have. If you are turning 5-6 5 Gallon buckets with rocks, internal blades/mixer shelves and water, you could be moving a good bit of weight.

This is what I would do if you are attaching the wheel to one of the drums with all the other drums connected to the driven one. I assume by 74.25 you are talking about the circumference. So the diameter is 23.5 inches? This is going to make the design pretty... shitty. To gear it right. You'd need a .5" pulley. You'd also be going through belts fast with such a sharp angle unless you put the motor very close to make the belt's tangency less sharp. If you want to use the wheel and the motor you'd do best with a VFD device but those are about 110 dollars for a tiny one.

The math behind this is:

>5/8" Drive
>23.5" Driven
>1725 input.
>15" between centers and a ~3" gap between pulleys. A little over 3"
>Belt length should be roughly 75.5 inches. Of course you should be able to tension it by moving the motor. Or an idle I guess.
>55 RPMs at the driven. Still kinda fast. .5 inch would be optimal.
Sophie Clayspear - Sun, 21 Aug 2016 04:38:59 EST ID:7YnJeYuF No.6987 Ignore Report Quick Reply
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This is the optimal way of doing it unless you expect to be turning 60-100 lbs or more.

>Green is Drum. It rides on the two 6 foot bars. Wrap these in electrical Tape or something rubber. This won't work if these are tiny as shit. If they are over .5" in diameter, it should work.
>Black rectangle is the mounting for the bearings and shit.
>Red crossed circles are your pulleys.
>Yellow Cross circle is your motor pulley.
>Light blue around the circles is the belt.
>The blue lines in the black long rectangles is your 6ft pipe.
>Motor is self explanatory. Mount it in a way you can tension the belt. Threaded rod could work. You could put nuts on the threaded rod and tighten the nuts til the belt is tight. Then run a second nut under it and tighten them against each other so it doesn't vibrate down.

This is where things get complicated. This design is far superior, cheaper, durable and easier. But the math is more involved.

Firstly, I need to know the diameter or the circumference of the outside diameter of the pipe the drum will rest on. Then I will need to know the diameter or the circumference of the drums. Nothing too precise but I'll show you so you can work it yourself.
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Ground Needed\Stray Voltage? by James Pillyhood - Wed, 13 Jul 2016 23:38:51 EST ID:LMSWX1C6 No.6975 Ignore Report Reply Quick Reply
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So I got a new attic fan and lighting wired up and there is no ground available on the circuit coming from the breaker. Option one I'm seeing is to run a wire out the wall, tucked under the siding all the way to the ground rod, bloating this "simple" project even more; or just say fuck it and not run a true ground to it, even though I spent the time tying all the ground wires together; third option bite the bullet and buy a GFCI breaker.

Problem 2, when I put the voltmeter to the case of the fan, after flipping the breaker on, I get 1 volt on the case. Should I be concerned with this, is this excessive stray current?
Cedric Cunkinferk - Thu, 14 Jul 2016 21:15:26 EST ID:3ODb0gls No.6976 Ignore Report Quick Reply
I would probably just install a fuse on the power wire to the fan.
Lillian Brookbanks - Thu, 14 Jul 2016 23:37:17 EST ID:LMSWX1C6 No.6977 Ignore Report Quick Reply
Suppose that could work. Haven't seen a fuse outside of a car circuit in a long time. Don't think any stores even carry holders around here. Have to order one.

Instrument cable instead of speaker cable? by Alice Clayridge - Wed, 29 Jun 2016 19:07:44 EST ID:wpTfjl5n No.6972 Ignore Report Reply Quick Reply
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I let friends use my fucking sound system and I found out they ran instrument cable instead of speaker cable from the powered mixer to the speakers for their dance music show and now a.) there was popping for like 3 seconds mid sound-check the next day but hasn't happened since and b.) the power amp limiter LEDs come on for two seconds right when you start it up but has yet to come on any time after that. Should I be worried? This system is brand new and I'm really upset about this.

Pictured is the power amp used. The manual doesn't say anything about what the limiter lights are supposed to do at startup so I don't know if that's normal.
Simon Hummlenot - Wed, 29 Jun 2016 23:44:42 EST ID:LMSWX1C6 No.6973 Ignore Report Quick Reply
/m/ Might be the proper board.

How many amps does it dump out the powered end, and how long was the line? If itt was a small 18ga instrument patch, under several amps, and wasn't remotely pushed to peak, it was probably not an issue.
Was the pop like when you plug in a line? That might be a loose jack issue.

Thing two. Don't lend gear unless it's a beater, or you know the individual will buy you a new one it they damage it(this works with coworkers, because you know they have actual income).

Electrical Sharegineering by Polly Dartville - Sat, 27 Feb 2016 03:24:15 EST ID:EGgJzstS No.6919 Ignore Report Reply Quick Reply
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I'm a millionaire drunk stoner with a pretty complete knowledge of everything concerning electrical engineering. Ask me anything!
14 posts and 4 images omitted. Click Reply to view.
Alice Buddlestat - Thu, 05 May 2016 16:25:00 EST ID:Mammg+Yw No.6957 Ignore Report Quick Reply
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I've got a chemistry degree but I really like EE stuff as a hobby. I make effect pedals and amps and shit, but I try to gear myself more towards doing something "new" than making a bunch of clones of pedals from various established manufacturers. I try to stick to analog-ish designs, not because I think analog has some kind of magical "sound", but it's just not as fun to throw an expensive digital chip at every problem you encounter.

Currently I'm trying to build a circuit that uses a CD4046 PLL to determine the fundamental frequency of the input, then subtracts it with a differential amplifier, leaving only the harmonics on the output. I'm trying to use a JFET-based VCA circuit to vary the level of the cancellation signal so that it exactly cancels out the fundamental frequency of the input, but I'm having trouble figuring out how to get the control voltage to work right. Too little cancellation just feeds the original signal through the output, and too much cancellation just recreates the original signal with the fundamental out of phase, so I need to figure out some way to detect when the output is at its minimum signal level and keep it there with some kind of feedback loop. I tried rectifying the output to pulsed DC and feeding it through a differentiator; based on the assumption that the DC output level from the rectifier is approximately parabolic as the signal from the PLL is swept through "too little" and "too much," I'd assumed that the signal out of the differentiator would be approximately linear, with the approximately parabolic minimum from the previous stage corresponding to 0 VDC on the output.

But it's not working. Is this an incorrect approach or do I just need to keep fine tuning to get the right RC constants? Are there any semi-easily accessible analog computing books or sites that would help me with this kind of signal processing?
Phyllis Blytheson - Mon, 09 May 2016 18:39:54 EST ID:tT4bTGqP No.6958 Ignore Report Quick Reply
As a PC game programmer, reading MSDN documentation is pretty much my life now. At least it's leagues better documented and better organized than the stuff Apple puts out though.
Charles Chorringkag - Mon, 23 May 2016 13:06:20 EST ID:Mammg+Yw No.6960 Ignore Report Quick Reply
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If I used a simple filter it would only work for the note that the filter removes. I would have to make the filter frequency controllable by the input frequency, so it would be just as complicated as what I'm trying to do now.

The circuit I have so far actually simulates rather well. With input signals above 1kHz, I can get the oscillator level to match the input rather well from 10mV to 1V, with a response time around 1ms. The problem is that lower frequency signals cause the control voltage to oscillate, which really garbles the PLL signal and thus the output. The filter following the recitifers is well overdamped, so I'm thinking the problem has something to do with the non-linear response of the JFET VCA. I wanted to keep using JFETs for cost reasons, but I may switch to something optoelectronic, since the response is typically much smoother/slower.
Ebenezer Pummletork - Wed, 25 May 2016 13:04:02 EST ID:Mammg+Yw No.6962 Ignore Report Quick Reply
I don't think you understand what I'm trying to do. I want to remove only the fundamental frequency of a note from a guitar or other instrument and leave the harmonics untouched. It should be able to do this over the entire range of the instrument. If I use any fixed-frequency filters in the signal path, it will only work correctly for a certain range. For example, if I eliminate 500-1000 Hz with a filter, the effect will work for this range of input frequencies; but if I play a note at 250 Hz, it will filter out the first and second harmonic (500 and 1k Hz) and leave the fundamental untouched; if I feed in a note at 2000Hz it won't do fucking anything. If I make the bandwidth any larger than an octave, it won't work for ANY input frequency because the for it will start filtering out the harmonics of any note within the filter range. There is no way to get more than one octave of useful range with static filters because I specifically want to remove "one" frequency which can vary over several octaves. Something MUST track the input frequency; it cannot be done with fixed-frequency filters.

Don't be so condescending. I understand how filters work. You mixed up highpass / lowpass as well as bandpass / bandstop.
Shit Bizzleforth - Tue, 07 Jun 2016 21:48:46 EST ID:7ztzoB70 No.6970 Ignore Report Quick Reply
Calculus, asides from obvious shit like wolfram alpha and its rubbishy pay to get step by step shit can you recommend any good resources or books to learn from?

DIY underwater home by Ernest Clinkintid - Thu, 04 Feb 2016 17:45:26 EST ID:S8hxXMl5 No.6894 Ignore Report Reply Quick Reply
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possible? i know it is possible but i'm talking about the average person
6 posts omitted. Click Reply to view.
Basil Burrymurk - Mon, 15 Feb 2016 10:41:16 EST ID:a607tU9R No.6910 Ignore Report Quick Reply
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Caroline Bruckleville - Mon, 15 Feb 2016 12:03:27 EST ID:nivRxxRT No.6911 Ignore Report Quick Reply
i live in a town called bellevue..
Martha Fimmleman - Tue, 19 Apr 2016 21:41:14 EST ID:JT+zLDlO No.6947 Ignore Report Quick Reply

LMFAO this brings back memories. Thank you so much anon.
Shitting Gottingstodge - Thu, 21 Apr 2016 19:08:38 EST ID:uywTW9Q3 No.6949 Ignore Report Quick Reply
How the heck would you build that? I feel like having an air-lock and a system to keep the interior at 1 bar pressure alone would cost more than $100,000.

I feel like the most feasible, cost-effective option here would be to build a giant ventilation duct that sticks well out of the water (high enough so that it's never underwater, even in the case of extreme flooding) and to pump air in and out of the underwater area.
Samuel Bembleridge - Tue, 31 May 2016 12:37:46 EST ID:cNouZAzb No.6967 Ignore Report Quick Reply
What if instead of using a water lock you just counteract pressure mechanically?

MODEL SHIT IN A GAME BRUV by Hugh Bunshit - Tue, 03 May 2016 23:45:58 EST ID:/SWUqKch No.6955 Ignore Report Reply Quick Reply
File: 1462333558556.jpg -(26457B / 25.84KB, 657x403) Thumbnail displayed, click image for full size. 26457
I want >>>/vg/664016 to succeed so I'm shamelessly shilling it. I personally am (extremely slowly) working on a city simulator, using historical public census/weather data from various cities as input. It's a big project and I've only just begun but it feels right.

But anyhow, visualizations feel good as hell and gamedev is a hobby that works with modeling interests. I bet a whole bunch of you have played Banished or Cities: Skyline or DF or whatever else, and been like "huh" or "nah bro, what they should have done there..."

So maybe you should get into amateur gamedev. The barrier to entry is low. The tools are free. It's a good hobby.
Archie Dracklestot - Wed, 04 May 2016 01:24:31 EST ID:CUcr8ZcI No.6956 Ignore Report Quick Reply
Yep it is a good hobby, and also a ton of work. Good luck!

Electrochemistry Support by Thomas Murdcocke - Tue, 26 Apr 2016 23:40:21 EST ID:9ofAWPV8 No.6952 Ignore Report Reply Quick Reply
File: 1461728421005.jpg -(441377B / 431.03KB, 1920x1157) Thumbnail displayed, click image for full size. 441377
Well, i've got my chemical engineering degree recently and i'm in my first freelance job. Need to design a desalination process; as a pretreatment, i require an electrolysis cell to electrolyse seawater producing Cl2, H2 and NaOH, the later is the main agent of the pretreatment.
As such, i need to understand and design an electrolytic cell for the purpose, but my electrochemistry in uni was shitty to non existing, and besides RedOx understanding, i'm naked at it. Can you lend me material to read an learn? I'm facing death with "Electrochemical methods and fundamentals (Bard & Faulkner)"cause it has like 800 pages and is pretty thick.
Also, i've found some ppt's lessons, but they lack the teacher. Anything works, but i'm focusing in sizeing and evaluation by now.
Alice Follydag - Sat, 30 Apr 2016 08:55:55 EST ID:Nf9XqI8L No.6953 Ignore Report Quick Reply
You shouldn't have a job, let alone a degree, if you don't understand RedOx, nor even have the energy to read a 800 page book to help you.
Isabella Sushstone - Sun, 01 May 2016 19:03:03 EST ID:9ofAWPV8 No.6954 Ignore Report Quick Reply
what a nice reading comprehension...

S-senpai.. my piston rods are moving on their own by Alice Dackleshit - Sat, 13 Feb 2016 23:26:48 EST ID:eLQ43SxB No.6909 Ignore Report Reply Quick Reply
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You know, the Engie board was originally my idea, but it's taken me this long to find suitable porn.
Graham Grimway - Wed, 20 Apr 2016 20:29:46 EST ID:UWdc7qZ1 No.6948 Ignore Report Quick Reply
well that was fucking weird

so if you want decent engineering videos I like AvE and clickspring for sure.

fuck by Faggy Blettingfuck - Tue, 22 Mar 2016 16:28:28 EST ID:ej7dKnE7 No.6935 Ignore Report Reply Quick Reply
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So after being out of high school for 7 years now, I want to go back to school for aerospace engineering. No engineering schools worth a single fuck anywhere within driving distance. LOL, fuck me, right??
Claus Cunt - Thu, 24 Mar 2016 16:09:38 EST ID:842pDf5G No.6939 Ignore Report Quick Reply
Yo Taylor? Move to New England fag.

RGB Strip Wiring by Polly Dashwure - Wed, 09 Mar 2016 19:47:22 EST ID:0sTD210V No.6926 Ignore Report Reply Quick Reply
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Does anyone know how these RGB strips are supposed to be wired/controlled?
I was able to wire a PC fan connection (with power and ground) to the +12v on the LED strip, and the ground to either an R, G, B, or combination.
So what I don't understand is why the ground connection is what determines the color, and also how am I going to vary the colors to get all possible combinations other than the current 8 combinations I can make.

If I use the fan controller's pot to control the GROUND wire, will that even work? If so, will I be able to wire each individual R G B to a separate knob on the fan controller?
Polly Dashwure - Wed, 09 Mar 2016 20:28:41 EST ID:0sTD210V No.6927 Ignore Report Quick Reply
This is confusing. The fan controller has it's own molex power & ground. It's not as easy as just wiring the fan's positive outputs from the controller to each R G B, because I'd end up with 4 12v inputs going the LEDs.
But it's confusing because I have
+12V; R; G; B. So that means at least one of those R G B's has to be a ground connection. Are they ALL a ground connection? Will a potentiometer even work when wired on a ground wire?

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