CNC Machinery

Check out my site on lutherie (guitar / stringed instrument building)

This a CNC mount for the Rotozip router.  I made this for the Harford Hackerspace CNC Router Project.  Hopefully we'll have this up and cutting wood within the next couple of weeks.  If you are in the Baltimore area, you can come join us for one of our making / building / hacking get togethers.

PCB Isolation Routing

First Cuts with New Desktop CNC Machine

Table is being machined flat and perpendicular to the cutting head

This machine has a cutting area that is 9in x 6in x 1.75in and can cut at 40ipm with 60ipm rapid moves.

New CNC Machine at Robotfest 2009

Here is a video of my latest machine that we showed at Robotfest 2009 and here are the solidworks drawings for this machine

Fixture for CNC machining small parts

After trying several methods to fixture a banjo bridge blank (about .625" x 3") and having several of them come loose and fly off of the machine, I found that Sears has a small vise that is very well suited to holding parts and uses a cam-locking mechanism that allows for rapid setup.  I have been using sacrificial blocks on the jaws and routing a slot into them that is slightly (.025") smaller than the piece. 

Here is a video of the setup

The idea is to use the cutter itself and a soft conductive plate as a switch that triggers the probe input on Mach3.  The touch plate is connected to a parallel port input pin that is pulled up to +5V with a 10k resistor (see part of schematic below for an example) and the ground is connected to an alligator clip.  The ground is clipped onto the cutter bit and the touch plate is held on the work surface.  Clicking the Auto Tool Zero button runs the Visual Basic code that lowers the cutter until it gets a signal from the probe input, sets the Z-axis readout to the thickness of the touch plate (.060" in my case) then raises the cutter to 1 inch above the surface.

For the touch plate, I used .060" thick PCB material.  This is inexpensive and can be gotten from many sources.  I recommend looking on ebay and searching for copper clad board.

Here is a demonstration of the setup in action.

First we set up the input pin for the probe.  We need to have it configured to the proper pin with an active low input since it is normally pulled up to 5VDC. 

Then we need to add the Visual Basic code to the button.  We go to the Operator menu then click on Edit Button Script.  The configurable buttons will now be flashing and we click on the Auto Tool Zero button.  This will bring up an editor that may have a Not Implemented message in it.  Copy the code below into this editor replacing any existing code.  You will want to modify the .060 value to match the thickness of your touch plate.  Save the file (same name) and exit the editor then restart Mach3.  You should now be able to press the Auto Tool Zero button and have the Z-axis lower until the touch plate connection is made.  I suggest that you try touching the alligator clip and plate together the first few times with the Z-axis nohwere near the table to make sure that this is working.

VB Code for Auto Tool Zero Button

Message( "Auto Zeroing..." ) If IsSuchSignal (22) Then code "G31 Z-3 F20" While IsMoving() Wend Call SetDRO( 2, .060 ) code "G1 Z1" End If

First Cuts with my DIY CNC Router

A few months ago, I ran across the http://www.buildyourcnc.com website and was inspired to build a CNC router. I have added several things to the machine and have done a few projects. I plan to publish the details of these projects here.

Video of my DIY CNC Router cutting a 52 tooth involute gear

Photos of my CNC router can be seen at my flickr site.

Additional Electronics Added to my DIY CNC Router

Here is a schematic of the additional circuitry that I added.  This started off by wanting to turn the router and vacuum on and off with Mach3.  I got that part connected but then realized that the computer puts the printer port into an unpredictable state when Mach3 isn't running.  It is quite surprising to have the router and vacuum come on after Mach3 is closed.  I then found that Mach3 could output a square wave when it is running that can be used as a safety.   The charge pump circuit only activates the relay when the square wave signal is present at the output pin and it doesn't matter what state the pin is changed to as long as it doesn't oscillate rapidly.   

Here is the parts list for the above schematic.  If you already have 12VDC available, you can eliminate U1 and C4.  If you have 5VDC, you can eliminate D4 and D5 then connect R2 and R5 to 5VDC.  If you're running a HobbyCNC Pro (like I am), I suggest getting the low-current DC power input from the 24VDC fan connection so you don't risk going over the input voltage range of the 12V regulator.

Parts list for CNC Electronics

Digikey.com
Description	Digikey PN
IRL510PBF N-Ch Mosfet	IRL510PBF-ND
.1uF Capacitor 50V	399-4264-ND
.01uF Capacitor 100V	399-4147-ND
.001uF Capacitor 100V	399-4144-ND
10k Resistor 1/4W	10KQBK-ND
1Meg Resistor 1/4W	1.0MQBK-ND
BAT41 Schottky Diode	497-2493-1-ND
12A DPDT Relay 5V coil	PB1159-ND
SL22 5R012 12A Inrush Current Lim.	570-1053-ND
Optional
Terminal Blocks .2" Spacing	ED2609-ND
(These are cheap and fit into .1" perfboard spacing)
Alligator Clip for Touch Plate Gnd	314-1034-ND
MPJA.com
Description	MPJA PN
25A @ 480VAC Solid State Relay	17155 RL
E-stop Switch	17054 SW