January 29

DIY CNC Part 6: Wiring the Power Supply

driverboards1

In this part of the build I used a computer power supply to provide the necessary power to the stepper motor drivers and motors.  Finding a computer power supply wasn’t a hard task as I had three old computers in the attic.  I removed a power supply from one of the computers and made a few modifications to the power supply so I could use it to provide power to the stepper motors and drive the stepper motor driver modules.

tangouniformGenerally, an ATX power supply is usually turned on and off by the computer, but for my operation I need the power on and off when I flick on the power strip.  To achieve this, a minor modification is required to the main group of wires.  To make the power supply useful in this application, I took the green wire and connected to a black wire.  It isn’t like defusing a bomb but it is easy as eating pie.  This mod and I have done several times to use the power supply for powering up my lipo battery chargers.

powersupply1Once the power supply was modified I took all the yellow, red, and black wires out of the wire bundle and hooked them up to the stepper motor driver boards.  The boards will provide the signal pulses to the stepper motors.  From the power supply, I used some twisted pair I had to make the connections to the parallel port.  Twisted pair is generally used for telephone/data so it should do just fine for this application.

driverboards1

On the other end of the twisted pair was a 25 pin connecter which will plug into the parallel port of the computer.  The pin out was wired according to the build plans.

parallelconnector

With all the wiring just about done it was time to figure out the computer part of the equation.  Although having to purchase a PCI card was not in the game plan, I had no choice but to purchase the card or this project would be dead in the water.  The computer I chose to use for this build did not have a parallel port so it was a necessity. Most computers today have USB ports and it can be challenging to find a computer with a parallel port.   Parallel ports are old school, but I managed to find a compatible card at Frys.

PCIcardWith the card installed, I completed the final assembly of the CNC machine by installing the anti-backlash mechanisms on all three axis.  The anti-backlash provides the driving mechanism for the stepper motors to transport the carriages.

antibacklashinstall
Anti-backlash installed on all three axis.

With the table built, wired, and a computer ready for the CNC machining software it was time to bring it inside and begin the computer adventure.  In the next post, I will go over the software I chose to use on this build.

Until then,

Happy Building!

 

 

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January 28

DIY CNC Part 5: NEMA Motors

nemamotors

For this build I am using NEMA 17 motors to transport the X, Y, and Z.   The NEMA motors have the same specs in the build plans and I was able to save quite a few bucks purchasing them through FoxyTronics.  Each NEMA motor cost me $14.00 dollars plus $6.00 dollars for priority mail shipping.

nemamotors
NEMA motors purchased from FoxyTronics

I initially had the impression the NEMA motors were big in order to transport the X,Y, and Z carriages, but as you can see in the photo below, they are actually quite small.

nemasize
NEMA 17 motor

The NEMA motors will be used to transport the X, Y, and Z axis.

nemamountwithmotor
NEMA 17 motor for the Z axis

It took several trips to Ace Hardware to find the proper length of screws in order to mount the NEMA motors.  I ended up using 15mm screws for the Y axis, and 10mm screws for the X and Z axis.  Each screw will be installed with with 2 washers to avoid stripping out the aluminum.  If the screws are too long they will push the screw which holds the motor together.  I noticed a little jiggle on one of the screws when I was tightening the NEMA motor mount bolt down.  Fortunately, I did not strip the screw out of the motor.

NEMAmountY
NEMA 17 motor for the Y axis

Prior to attaching the NEMA motors to the CNC machine with the threaded rod, I will be performing a simple test of the motors.  This is one reason why I haven’t mounted the X NEMA motor to the CNC machine.  I used the X motor for a mock up of how all the wires connect to the stepper motor drivers.  Once the test is completed, I will connect the Y/Z motors to the carriages and construct the X motor mount.  For the stepper motor specs please visit the FoxyTronics website.  A link has been provided below.

Onto the wiring of the power supply, the stepper motor drivers, and finding an old computer to run the software.

Until next time,

Happy Building!

 

Bill of Materials

3 – Small Stepper Motors from FoxyTronics

4 – M3 metric machine screws 15mm for Y axis

8 – M3 metric machine screws 10mm for X and Z axis

12 – M3 washers

Recommended Stepper Motor Drivers:

3 – MyDIYCNC Universal BiPolar Stepper Motor Driver Modules

 

 

 

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January 27

DIY CNC Part 4: X Table and Gantry

Xtable2a

Being exiled to the garage for five days has given me the time to make some good progress on my DIY CNC. What started out as what I thought would be a simple build of the X table turned into somewhat of a project in itself.  Remember that “quality” plywood I had purchased for the table?   Well it turned out it had a bow in one of the corners and I was not able to use it.  I had to replace the “quality plywood” with some MDF from Home Depot.  A bill of materials is located at the bottom of the page.

xTable1
X table and rods

I had originally thought if the X table was smaller then I wouldn’t have to worry about the bow in the table or the little “wobble.”  There was a minor wobble in the X table when applying pressure to the Y axis.    I decided having a slight bow in the X table and a little wobble will cause problems later when cutting, so I replaced the plywood with the MDF.

Xtable
X Table and Gantry

Once again I had Home Depot cut me a piece of MDF and I was ready to install the X Table.    To give the X table a little support, I decided to install some supports as the MDF was quite a bit heavier than the plywood and I don’t want the rods to bend or the table to bind.  I installed four small coaster wheels I had purchased from Home Depot when I got the MDF.  After the installation I noticed the wheels were oblong and creating the X table to bind up along the axis.    This would make it hard for the stepper motors to move the table  so I removed the coaster wheels and just put a nice piece of pine underneath the X table.  I countersunk a few holes and screwed my newly created X table supports into position, tested for binding and proceeded to square up the X table and Y axis.

Xtablesupport
X Table support made from pine

Once the X table was complete and without any binding, the final assembly of the gantry was next.  I needed to make sure the Y axis was exactly square to the X table along the full length of the Y axis.  I used a speed square to check and make the adjustments.  Once I was satisfied with the Y axis being square to the X table all along it’s axis, I screwed the Gantry down on both sides of the frame and checked it again to make sure the Y carriage would transport across the Y axis without binding.

XY
Y axis square to the X table

At this point I thought I’m basically making a printer!  It’s looking like a printer anyway…  With the X and Y square to each other, the Z will also be square to the X table.  I had squared Z to Y when I constructed the Y/Z backplate.

GantryTopView
A look down the Z axis

Checking the X, Y, and Z axis I noticed the X table was slightly touching the clamps I had purchased to secure the 3/8 steel rods.  I trimmed the little rubber off the top so it was flush with the metal clamp and this provided enough clearance for the X table to move freely without touching anything other than the X table supports.  Was it time for a beer?

Xtable2a
X rod clamps from McMaster

With the machine pretty much constructed, I moved onto getting the stepper motors prepped for installation.  The stepper motors will be attached to the 1/4 20 threaded rod and transport each axis.

NEMAmountY
NEMA motor mounted on the Y axis

On the next post, I will go over the NEMA motors, the NEMA motor driver modules, and where I sourced those materials.  Yeah, it’s time for a beer or cough syrup.  Until next time,

Happy Building!

 

Bill of Materials to mount the steel rod on the X Table:

4 each – Vibration-Damping Clamp with SBR Rubber Insert, Zinc-Plated Steel, for 3/8″ OD, 3/8″ Tube Size  McMaster Part # 8981T62

 

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