steve cooley presents

If you’re like me, you probably want to know what the modern device fluxamasynth arduino shield sounds like. I decided I would take a risk and pick one up without having … almost any idea of what it sounded like. It’s relatively affordable and runs right on top of an arduino… theoretically speaking, a lot to like about this kind of product. There are some issues that I’m waiting to hear back on (software serial) before I can really dig deeply into it as something I’d use in my live act, but… here’s what it sounds like:

so, do yourself a favor so you can follow along. Open this page up in a new tab:
http://wiki.moderndevice.com/pmwiki.php?n=MD.ListVoices

then hit the play button below to listen to 64 notes of the first bank of 128 different voices of the fluxamasynth shield. I just realized that I hit the record button while I was uploading a new firmware… so when you hear the “piano” start playing… that’s when you start reading down the list of voices on the other web page:
fluxamasynth_audio_samples_bank0.mp3

I got an arduino ethernet shield for xmas, so I wanted to check out if I could get it talking to quartz composer… and… I did! woot.

Welp, I decided on which CNC rig to go with. I wanted to keep my options open for the future, so I decided to go with a bigger rig than I had originally planned on committing to. I decided that I could commit several continuous days in a row to assembly, setting up a major section of my garage, and purchasing a couple-few extra things to accommodate the buildyourcnc.com Blacktoe 2×4.

Here’s the timelapse of the build:

Here’s the first run:

And here’s the first real job I ran with it:

Woohoo! Very happy!

After inquiring around about prices for lasers, I’m coming to the realization that maybe what I need isn’t a laser but a CNC rig.  I’m lucky to live near enough to Techshop that making the occasional drive up there is doable, but not a sustainable ongoing possibility with my family time needs.  So take a look at the research I’ve done into who the top contenders for desktop CNC could be for an almost total n00b to the sport.

Alright, so I know the G-code exists and that most every interesting machine that I want to work with understands how to work with that, so now it’s up to me to complete the equation. This list isn’t meant to be exhaustive, and by no means am I an expert on the topic, but based on what I could digest from their websites, this is what I took away from it all.   When I priced things to be as ready to run as possible starting with no previous equipment, here’s the ballpark figures:

machine	x	y	z	priced ready to run	notes	link
DIY!	?	?	?	$100 to $1,000	while the price may be right, the time and skill involved just don’t make this an attractive option for me right now. Don’t let my schedule and skill stop YOU though.	click here
Lumenlab MicRo	10″	12″	2.75″	~$2,143 + software	I’ve known this company since I made my LCD projector, so it was interesting to see them move into this arena. Honestly, though, details are sparse. Their blog about the build is just weird. Make a formal demo video, guys.	click here
Probotix FireBall V90	12″	18″	3″	$1,174 + router + software	This inexpensive unit won an award at the Maker Faire Austin, so that seems to bode well. There seem to be a lot of parts that you can add on, which seems to indicate that it’s not as turnkey as I’m looking for. If you already have steppers and are looking for a solid new gantry bed, maybe this would work well for you. That’s just not me yet.	click here
Buildyourcnc.com’s bluechick cnc	12″	24″	?	$1,465 + router + software	If you have more time than money, this unit seems like a *stellar* system to check out. The fit and finish isn’t the point here, it’s inexpensive and customizable.	click here
Buildyourcnc.com’s blacktoe cnc	24″	48″ (!)	5 7/8″ (!!)	$2,300 + tools + software	Holy crap, look at that. Bad. Ass. I don’t know where else you’ll find that big of a CNC rig for that price. Now, it requires a lot of assembly, but their extensive library of videos on that topic should help. I’ve been studying this machine all week and I’m drooling over how nice it seems. It can accommodate a real router, not just a trim router. It’s huge. And cheap.	click here
Next Wave Automation’s Shark cnc	13″	24″	4.5″	$2,800 all inclusive	This unit comes in a bit more expensive than the others, but three things I like about it. 1. it ships ready to run with software, 2. assembly apparently consists of 12 bolts, period. 3. Rockler sells it, so that probably means it’s a high quality tool.	click here
Next Wave Automation’s Shark Pro cnc	24″	24″	4.25″	$3,800 all inclusive	This unit is the bigger version of the above unit. the extra $1,000 gets you almost twice the width and apparently “more power”. It also ships with software and presumably is the same 12 bolt assembly. The reviews I read for the smaller unit were all positive with one person saying “I just wish I’d gotten the bigger one” which makes me just wonder if I’d end up there too. If you’re in for $2,800 … I dunno. maybe.	click here
Craftsman Compucarve Woodcraft CarveWright	12 feet!	14.5″	5″	$1,500 to $1,900	These are somewhat intriguing. I’m a little skeptical of the feed table, but maybe it’s ok. I dunno. I just… don’t know. These do have some built-in functions like cross cut, rip, and jointing. And a proprietary, but nice, quick tool change technology. Reviews seem mixed. Update: No G-Code import of any kind, and no plans to add that. So it’s a closed system with their own bits and software. Definitely a carving-centric hobby machine.	click here

These prices assume you already have a computer… duh. And they don’t really take the cost of software into consideration, which is probably ok because there are a lot of software packages out there so I’ve heard. They do different things and cost different amounts of money… so it’s hard to factor it in easily. The other thing I haven’t factored in here is speed. And because I’m inexperienced, I don’t really know how to gauge that, other than to see that the Blacktoe is fast as hell. Ok, so I get that these machines all have an “inch per minute” speed rating… I would suspect it would also depend on 1. your router, 2. your gcode, and 3. the material you’re milling… so given those parameters, what does “high speed traverse” mean? Just how fast the machine does what it needs to do when it’s not doing a cutting maneuver? That’s my best guess.

So, those are the current contenders. Did I miss anything substantial? Leave a comment and let’s get it on the chart.

There’s been an awful lot of hand wringing from some extraordinary minds about the “direction” of software because of the iPad. I’ve also been thinking a lot about the iPad, but in the other direction than most of the hand wringers.

1. They want all the highest technology, design elegance, thoughtful attention to detail, tried and true connectivity and sync ability of Apple designed hardware, but keep your filthy hands off their code! Hey, remember when Apple didn’t let you develop for the iPhone OS at all? Go try developing for the Playstation and see how cheap and easy that is for you. Developing for the iPhone OS is really inexpensive relative to other “nearly closed” platforms.

2. They want access to the largest possible audience, promotion, effortless infrastructure, simple credit card transactions, and user reviews. But not any kind of code review to make sure they’re not hiding functionality or exposing their users to risk. I believe Apple would call this “protecting the Brand” It’s probably good to remember that as a developer, you’re an invited guest piggy-backing onto their hard work. If you want to be associated with the Apple brand, you have to enhance the user’s experience, period.

3. They say absolutely nothing about what keeping the villains out costs. Or what the benefit is. Because apple’s done a good job of locking down the iphone to widespread hacking by black hats, they seem to view banishment of stupid apps as some kind of crime against humanity. Remember this fake banking android app? Yikes. Adhering to contractual obligations may not be something they’ll really take into consideration while complaining about developing for the iPhone OS, but Apple must take steps to ensure that some stupidhead (or malicious) 3rd party doesn’t screw everything up for everyone. Secondarily, keeping stupid apps out helps increase the discoverability of your app. Reducing the noise from the signal is *good*.

4. They complain about the app store being the only way to install software. Having an app store significantly reduces developer support time for installation and configuration to the end user. If you’ve never had to do that, you’re lucky. Having a zero-configuration installation process frees you up to spend your time building your next great app instead of having to help your mom get your app installed on her iPod Touch. No matter how simple a manual installation process would be, time spent helping your users install is time away from you making your next revenue stream.

5. They complain about all of these things like the rest of the world is going to instantly adopt this methodology of software development and deployment. That’s simply not the truth. Developing for the iPhone OS is *optional*, folks. Some people seem to give off the impression that Apple is forcing them to develop for the platform. It sounds silly to even have to point it out. We will never live in a world where you will be denied access to development tools for a tinkering platform. Honestly, it’s preposterous.

The end result is that Apple doesn’t have to justify the costs to join the developer program, or the procedures. You either grow up and realize that the marketplace revolves around rules — not trust, or you can go play in your own sand box. If you hate the rules, just wait a few years while the rest of the industry slowly does their inevitable imitation act, and then you can deploy your cool idea onto a platform for like minded people. I’m choosing the biggest market and the rules that come with it. It’s just not that hard to deal with.

So this “war against tinkerers” rings completely hollow for me. The iPhone OS is for when you’re *not* at your desktop or laptop. Not *instead* of your desktop or laptop. If you can use the iPad instead of a desktop/laptop, you probably don’t care about this debate anyway. You’re not a tinkerer. You’re a consumer. If you’re a self-identified-tinkerer, you’re going to use producer tools, not consumer access devices.

While making my Beatseqr project, I’ve been trying to find a reliable source for some faders / sliders / slide pots / slide action potentiometers, and I’ve been having a challenging time finding exactly what I want. So I thought I’d share what I’ve learned. Click on through to get a crazy large dose of science.

Here are some of the parameters I’m working with:

• I’m a hobbyist. I’m trying to make a project with a user interface, but I’m not trying (at this time) to make a hundred copies of my project. So I can’t order 1000 pieces of anything.
• I can’t (won’t!) finalize on sending my PCB out until I have parts that I know I like, and that will work well for my project, and that I can go back and reorder if I do need to make more copies of my project.
• Because I’m just getting started, I want to keep the total cost of parts as low as possible while maintaining the user experience I’m looking for.

Specific things i’ve learned:

• You have to learn how to read datasheets. There’s just no getting around it if you’re thinking of making a repeatable project. If you don’t read the metric system, get ready to start doing that. And also get ready to start estimating or calculating how to go between imperial and metric, because not all manufacturers describe their parts one way, so when you’re comparing parts, you’ll see some talk about their parts in decimal inches, and others in millimeters.
• Don’t always trust datasheets unless they’re drawn specifically by the manufacturer. I’ve ordered parts from a distributor (mouser!) only to discover that they weren’t at all like the datasheet provided by the distributor’s website. Notice the difference? The data sheet was provided by the distributor in an attempt to give more information about the slider, but they gave me the *wrong information*. Comforting, isn’t it?
• There are only a handful of companies that make slide potentiometers — that are readily available in the USA — so consider learning who they are and how their part numbering systems work. Here are the usual suspects:
• • Bourns
  • Alpha
  • ALPS
  • Panasonic

  Also, don’t expect faders to be what these companies consider to be their sexiest products. They’re not. At best they’ll have some datasheets available for you to look at. At worst, you won’t be able to find sliders on their website… at all. It’s a little perplexing to me how companies can make stuff and not seem to even realize it as far as their website knows.

• Linear movement potentiometers are not sliders/slide potentiometers/slide action potentiometers. Linear movement potentiometers appear to be made to track the movement of kinetic/robotic things in a factory. Probably used in conjunction with stepper or other kinds of motors or actuators. If you’re looking for a thing that goes on a user interface, these ain’t those.
• Motorized faders sure look nice, don’t they? Crazy expensive!

There are several kinds of companies that will sell you parts, and they require different levels of commitment and experience.

• Retail shops like Radio Shack (aka “The Shack”) or even Fry’s don’t even sell them at all. Probably because it’s so friggen’ complicated that there’s no mass market in it like there is with radial potentmeters.
• Ebay – there may be some available, but the sheer number of parameters you should know before you buy anything makes this a really horrible idea unless the seller has taken great pains to make it clear what they’re selling. Most times you’ll see something like “slider for DJ mixer, $20″… totally inadequate information.
• Hobbyist online shops or pro audio shops that sell music/speaker parts. These places will sell a few, but they’ll be extremely limited in their selection. They’ll at least tell you “slide potentiometer, 10k, $3 each” and list out some dimensions. Much better, but maybe still inadequate if you’re looking for repeatable purchases. (And/or may be overpriced if you need a quantity of 10 or more for your project)
• Surplus stores (halted supply, electronics surplus) These places may well have what you need, may well be priced at or below (or sometimes extremely below) new retail prices. The only problem here is that they may not have what you need. Sometimes they’ll have frustratingly close to what you need, but not quite right. Or worse yet, they’ll have what you want today, and when you need more down the road, never again. Surplus stores are a mixed blessing. I wouldn’t trade my Halted Supply store for anything… except maybe a (fictitious) Mouser retail store. I’ve purchased some of the most important components of my life at a surplus store… some of the very components that ignited the fire of my understanding of how this world works, so if you have one of these places near you, don’t hesitate to look. They may have something from a manufacturer you’ve never heard of and it may provide a lead for your online searching.
• General parts suppliers that have multiple hundreds of thousands of parts. (mouser, digikey) These places may have what you want, but you’ll need to understand how their websites work and how to search for what you’re looking for. This is closer to rocket science, but it’s doable. This is where I live now. They’ll show you a list of the parts they sell by you navigating to their “resistors” or “resistive products” section, then on to “potentiometers/rheostats”, and then if you’re lucky you can select “slide potentiometers” or search for “slide pot”. Alternately search for “slide” and then if they have any, they’ll list the number of parts under resistors.
• Vertical market resellers/distributors. I’ll list out my experience of their websites below. If you’re a hobbyist, they’re probably not for you. They’re for large companies and the government/military. Sometimes you’ll see that they specialize in “milspec” parts or specific value-added manufacturing processes like cable-knitting or other services that are probably needed by large scale manufacturers. In most cases you’ll need to order multiple hundreds of your part in order for this to make sense. So far as I can tell, hobbyists like myself need not apply.
• Manufacturers from overseas. Drool all you like at their nice components. Unless you need 10,000 pieces, it’s unlikely you’ll get to use what they make. I sorely wish someone would start a specialty components store for things like this: (potentiometer with led ring). Drool.

There are several parameters you should bre of before ordering a bunch of sliders. Here are the top ings to look for:

• Mounting method. The most common ways are “PC mount”, where it’s soldered directly onto a circuit board, or “solder lug” where it’s intended to be mounted onto the control panel with screws and connected with wires. I’m guessing that the rule of thumb is that if you don’t see a “mounting holes diagram” on the datasheet, it’s not supposed to go to a circuit board. Some sliders also have additional curved or bent pins to help snap the slider into the circuit board. Make sure the datasheet is easy to read for what the hole pattern should be on your circuit board.
• Recommended soldering technique. “Wave” soldering is not something you’ll be doing, so make sure they list out what temperature (ex: “manual soldering: 300° C for 3 seconds”) … some sliders I’ve seen datasheets for *don’t* recommend you manually solder them at all. Usually those are “open frame” sliders, but double check before you buy.
• Control lever height. It *will totally matter* if you’re making a project with 1/4″ thick laser cut acrylic and the slider is mounted onto a circuit board. The tallest control levers I saw were 19mm tall… which is what (guesstimating using my newly activated metric to imperial translation skills), almost 3/4″ tall. If your slider isn’t tall enough, it may not give you much to grab onto once it’s poking over the control panel surface. There are a couple of other parameters here that may be important to you. How hard is it to move the lever, and how much “play” will the lever have if you push on it from the side? these are usually listed on the datheet, sometimes not.
• Pins. Check the datasheet to make sure it explains how many pins there are and what pin does what. Which is the ground pin? which is the pin you measure the data value from? If I were you, I’d put a bit more trust in manufacturers that spend the time to document this in the datasheet. If the slider has an LED embedded in the lever, does the datasheet outline how to mount it on the PCB, and which pin does what?
• Data curve. Be careful! If you’re doing a microprocessor-based project (PIC, Arduino, etc) you *probably* want a “Linear” curve (sometimes also known as “B” curve, sometimes called another letter). Linear curve pots, which are versus an “Audio curve” or “log curve” or “A curve” pot. This whole parameter will affect the rate in which the slider will read data values… this is definitely easier to show with a chart, so pardon my ham-handed guesstimate at the data points, and take a look here:
  
• Center detent. Do you want that? A center detent is when the contol lever pops to a definite center point. This can be good in some instances, and bad in others.
• Travel length. This denotes the actual amount of distance the lever will move. I’ve seen tiny 20mm to gigantic 100mm. 30mm, 45mm, and 60mm are common. This measurement usually refers to the distance the control lever travels, not the overall dimensions of the component itself. Make sure you don’t space your sliders too close together.
• Knobs. I’ve not had great luck locating knobs specifically for sliders/faders. They’re out there, but without being able to test fit a range of contending knobs onto the specific fader you own, it’s hard to say whether a knob you see online will fit onto some random fader, even from the same website. Knobs can be really cheap, but if they don’t fit the parts you own… then they’re actually kind of expensive to order.

And lastly, and unfortunately, sometimes you need to just roll the dice and see what happens. Take your best guess, bite the bullet, order some parts and see what you get. Got any tips? Leave ‘em in the comments!

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APPENDIX: United States suppliers of slide potentiometers

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Companies that advertise in google adwords, or show up in top google search results for “slide potentiometers”:

mouser = 1600 products, datasheets have been proven to be wrong, but this really is the best resource I found for slide potentiometers.
tti = none / too hard to locate (mouser actually is tti)

digikey = 82 products, expensive, sometimes larger minimum purchase
newark = 74 products, expensive … same as
farnell/uk … 111 products, UK currency
tsan = none / large quantity sales only
allied = non-stocked, 100 minimum pieces for bourns (however, cheap)
arrow = 2 products, large quantity sales only
sager = 4 suppliers, large quantity sales only
future electronics = 1 product

And… here we go… here’s an exhaustive list of US suppliers as found on an electronics industry group’s website, and my comments. Where it says “none/too hard”, that means that they don’t deal with small-timers like me:

all american = large quantity sales only
all electronics = 1 product
avnet – non-stocked
bell industries / micro – none
bgmicro – none
capital – none
cdm – large quantity sales only
dr components – large quantity sales only
electronix express = none / easy
ericnet – large quantity sales only
fcc franklin choi = one
ibs = large quantity sales only
i systems = wtf?
icc = large quantity sales only
jaco = large quantity sales only
jdr = large quantity sales only
kentek = none
knight = large quantity sales only
tequipment / leader = none
lemos = none
mentor = large quantity sales only
mitronics = large quantity sales only
new york semi = large quantity sales only
NTI / connector people = none
north atlantic = large quantity sales only
nte = none
nuhorizons = none
powell = none
richardson electronics = none
richy cypress = arrow nac
space coast semi = large quantity sales only
4star elec = large quantity sales only

Update: I’ve written a huge post on how to buy sliders/faders/slide potentiometers

As copiously stated, I have no formal training in electronics, and I’ve reached a mature enough age that I can no longer accept an electronic component as a black box, so when I come across a device and can figure out how to use it without being able to locate instructions, i feel like it’s only right to make a drawing of it and try to explain my hypothesis for how it works.

With that being said, here’s my best guess at how the 10k slide potentiometers (sliders / slide pot) works:

The obvious control at the top sets the resistance. The voltage in (V+) and ground (V-) pins run inline with each other, and the resistance value is read from the pin adjacent to the voltage in pin. I’m using an Arduino to read the value, and in my case, i actually needed an additional resistor in front of the voltage in pin to limit the incoming current. When i hooked the slider up directly to the arduino, it didn’t work very well, acting way more like it was a logarithmic curve potentiometer than the linear curve pot I thought it was. About 2 minutes later, it was blistering hot. Too hot to touch, actually! So, I quickly disconnected it from the arduino and added a 10k resistor in front of the voltage in, and then it started behaving much more reasonably. The values I was getting from the 10k slider were not what I was expecting, so I’ll have to dial back on the current resistor from 10k to maybe 1k and see if that helps get the values from the slide pot more inline with my expectations.