Prototype day and other misc things

Starting on a prototype build of the CNC. Well really this build will be more of a plotter then a CNC but in all it does the same thing.

The prototype will be built from junk I have collected. As a test bed I’ll use a couple of old floppy drive stepper motors to drive the X and Y axis. The Z axis will be a DC motor with a H-Bridge circuit that will pulse hi and low to act kinda like a servo. If anything I can skip it until I can locate a servo or another floppy drive to rob the controller and stepper.

To use a floppy drive stepper I will use the floppy drive’s controller board. All it takes is putting a couple of signals to ground and you can control it directly from a parallel port or with a Arduino. Reason why I’m going on this route for now is to show some progress on the project and to keep myself motivated


The other day I had to toss out a old metal frame youth bed and when I was taking it apart I realized I can use the metal rods as glide posts for the CNC. There are quite a bit of rods and I can easily connect them to make them longer. Made me started to thing about the final build that maybe, just maybe I can make it modular. I want to make the system to use a direct drive system so I don’t have to use belts and gears let alone a threaded rod.


Upgraded the tinker computer. Tossed in a old SoundBlaster Live 5.1 card and a I/O card for more serial and parallel. For some odd reason the motherboard already has two serial ports but only COM1 is accessible in the BIOS. Even though there is a header on the motherboard for COM2. To use the I/O card I had to disable COM1 on the motherboard.


I bought a small 9inch B&W TV from Goodwill for $5.00. I plan to build a small oscilloscope with it. I know they work great for audio use but I wonder if I can use it to test electronics.

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Found some nifty software

I recently found a couple of programs that I think are nifty for hobbyist electronic testing use.

The first one is called Visual Analyser. It does everything from voltmeter to LCR. Just The website also a a couple of schematics for building the probes. The software is free to use and can run on Win9x to Win8.

The second program is called ScopeOnPC. This is another simple PC oscilloscope. Instead of using a soundcard it uses the Parallel port on the PC. Uses a simple ADC converter built from a ADC0820 or a TLC0820 with some 74 logic love. The software has a DOS version and Windows version.

Newish computer

Still working on it. Got the PS3 fan mounted and fits perfectly. Sadly the motherboard doesn’t have PWM so I’ll just use the typical setup for power, ground and tach signal. Instead of having all three fans running on a single fan host on the motherboard i’ll just use the floppy drive power connector and run a single wire to the tach signal to the motherboard.

I wanted to use a old floppy drive bezel to hide the front USB ports but sadly it won’t work because the USB port would sit too far back making a USB jump drive or cable unreachable so for now I have a single USB port glued where the eject button on the floppy drive bezel. I might just go ahead and make a whole new bezel and load it up with all of the USB ports and front audio ports. Dunno really, if I had it my way I would do all kinds of nifty things like a remote LCD for time, date, music info.

I still need to make a hard drive caddy for all of the extra drives I want to toss in since all of the drives except the primary are 2.5 inches.

Putting together a newish computer

Last week my brother had me upgrade his PC. It was more of a total rebuild that only the case, CD-ROM and hard drive was reused. I got to keep the old parts and they’re much better then the main system in my household. The case I am using is a older A-Open desktop case.

Isn’t the most hansom case but very functional and has plenty of room.

The top even has a vent that is over the CPU that I plan to add a blower fan from a old Sony PS3. The rear will have dual exhaust fans.

The specs isn’t much but it will have 8GB of ram and a nVidia GT220 video card. That is twice more then what my main system has. My current main system has 4GB of ram and a nVidia 7600 GS. The CPU is a very low end AMD Phenom 9100e. The replacement has I think a AMD as well but more suited for gaming. I want to leave out the CD-ROM but since the case is second hand I don’t have all of the bay covers. However I have a couple of old floppy drive face plates that I could use and modify them to hide USB ports since the case doesn’t natively have front USB. I like how older computers look compared to new ones due to ultra thin aluminum construction and look like toys. I like my systems to look bulky and built like a tank. Not to mention I hate the new case designs that have the power supply on the bottom of the case. A power supply is the second or third hottest part in a PC, heat rises so you don’t want all of that heat to go through the PC. Well enough of ranting on thermal dynamics.

I plan to dual boot Windows 7 and Debian Linux. For giggles I might triple boot with SteamOS. It will be a nice system until I can go build my dream PC, hopefully before tablets and smart phones completely take over the market.

Thrift Store shopping

I need more parts for the CNC so I have been going to thrift stores trying to find old printers and scanners. Reason for this is for Stepper Motors and hardware. So far I have only found newish bubble jet printers that use typical DC motors and hall-effect sensors. In all it looks like I might have to buy the motors and find some rods.

However I found a CRT 9 inch TV for $5.00 and bought it. I’m planning to turn it into a oscilloscope.

CNC power supply R&D

A simple ATX computer switching power supply isn’t going to cut it for this machine unless I buy new 12 volt Stepper motors. So my idea is simple. The circuit will have two LM317 to control the 12volt and 24volt outputs. Also it will have a LM7805 to power the Arduino. A 30volt Transformer rated at 3 amps with nothing other then a rectifier from Diodes and a couple of caps.

The Arduino should handle the rest for PWM and speed control for the spindle that is running on the 12volt rail. The 24 volt rail will be used for the steppers. I’m trying my best not to Heath Robinson this project.

Cheap prototype PCB

My wife has the desk littered with paper thumb tacks / push pins.

They’re copper or copper plated. Anyway a nifty idea for when you’re in a pinch and want to prototype a small low voltage circuit you can just use a bunch of these copper push pins and card board. However I wouldn’t use it for long-term. I myself if I can’t get a PCB I’ll leave it on the bread board or do a point-to-point setup for a long-term solution.

Another route for the CNC

Late last night I found a nifty Arduino CNC shield. Toss on some motor controllers such as EasyDriver and you’re good to go. Thing is I hate emulating a serial port through USB, sooner or later it always bites me in the butt. However I can build a simple clone that uses a real serial port. I can use a old school 74 logic chip to convert the serial to normal RS-232 standard or I can buy a MAX232 chip. Reason why I am switching to the Arduino is because the simplicity of it. I can always update/upgrade the unit. I can use any Arduino that uses a 328 or higher. Not to mention I can use ChiliPeppr so I don’t have to use a dedicated machine. I also found a website that looks like from China that sales the stuff I need real cheap.

I only came across this when I was trying to find a better pinout for a parallel port and while looking in Google Images I came across a article about the GRBL shield. Then I looked into that and found Elecrow.com then found out ChiliPeppr is supported. I’m still working on the CNC’s frame so I can easily convert to the Arduino.

CNC Machine R&D

Spindle motor
In the last post I said that I am going to use a brush-less DC motor from an old Airsoft rifle. Here is the reason why. I’m trying to use stuff I already have for one. It is also a very powerful high torque motor that is almost as powerful as a Dremel. Now how will I attach a chuck? Easy, a while back I bought a cheap-o rotary tool from harbor freight. to finish a job since my Dremel decided to die after ten years. It was dirt cheap and the construction isn’t bad but the motor is a small hobby motor. Anyway the chuck on it will fit Dremel bits and small drill bits just fine.
Another thing had come across my mind. The motor can wear out quickly with constant current. To fix this I need a PWM solution. I found a nifty circuit that will use a 556 timer or two 555 timers. This will give me a speed control and even an option to reverse the motor that could come in handy.

Some cool addons
I have an old two megapixel web cam. It would be neat to use it on the machine so I can be in front of the computer monitor watching the CNC software do it’s thing and still keep an eye on the machine cutting the object.

Power Supply
I’m thinking to use an old laptop charger that is rated at 19 volts and 3.16 amps. I can step down the voltage if needed but I might end up building a power supply that can produce 24 volts and 3 amps for the sake of the Stepper motors. Just need a transformer, diodes, couple of mosfets and a LM358N opamp.

Controller case
The case is simple. A box with switches, lights and plugs. What comes to mind is keeping the controller away from the CNC machine. If I build a power supply it will be in the case as well.

Wiring

Wiring up something is an art per-say. You want it to run the least amount, keep it tidy, well documented if you have to troubleshoot. I plan to put the cabling from the CNC to the controller in some old school fabric wrap. I’m still deciding to use limit switches or not. I just might skip the limit switches. Dunno if I can even add limit switches to my controller board, however I have a schematic.

If I do I can add a spindle control.

There are so many ways to do this but I want it simple as possible so anyone with simple knowledge can build one.