Messages

421

General Mach Discussion / Re: what is Mach3 sending to the controller over the USB connection?

« on: April 09, 2015, 08:45:33 PM »

I have the same board, and was wondering the same thing.  If you find out please let me know.  It actually works quite well too.

422

General Mach Discussion / Re: Still lost on tool height setup

« on: April 08, 2015, 08:27:19 PM »

Just so you know, it really does not matter which tool you use to set the Z height to the top of the part as long as it has a tool length value and the correct tool number.  As for a master tool I prefer that to be the edge finder.  If I have to pick up edges I might as well pick up the Z too!  I like to use a 1/2" ground pin instead of a gauge block.  Roll it back and forth with the tip of your finger, easier than holding the gauge block.

I am currently setting up a CNC mill where I have acquired about 50 tool holders.  I am machining an 1-1/2" thick 12" x 48" Poly shelf to hold all the holders with the holder number engraved next to the pocket.  A second board holds all the taper drill from 3/8" to 1-1/4" by 64ths and end mills, wrenches etc.  So shortly we will have the bulk of our tools preset in holders that are numbered, sitting in holes that numbered and length and diameter stored in the CNC that match.  I plan on touching the holder and tool with nail polish when it is installed so you can tell if it moved, or someone changed it, before you crash it in the spindle.  We are not a production shop and doing mostly one offs so this should save a lot of setup time.

423

General Mach Discussion / Re: Need some help understanding ZERO!

« on: April 06, 2015, 06:02:02 PM »

The safest thing to do if your machine has dials is make a mark roughly where each axis is or if it has scales right down the scale value. Then record the dial values to. That way you can move back there even after a power off.  I've done it this way for years.  You do of course have an edge finder and a dial indicator right?  Because they are the basic tools of picking up part locations, aligning things, checking your machine etc. So if don't have them it's something you really ought to get. They save a ton of time too.  LittleMachineShop has a fairly decent dial indicator for relatively little money.  For an edge finder I use a Starrett, and I've tried some imports to save maybe $10 but they just don't seem to work as well.

424

General Mach Discussion / Re: Seperate tool path files

« on: April 04, 2015, 07:36:20 PM »

I have limit switches for safety only. Crashing into the endstops at full speed due to program error or just running out of travels is really bad for any machine.  So mine are just there to prevent that.  To get accuracy with limit switches you must take into account how you actuate them not just the basic switch accuracy, which can be surprising difficult.

425

General Mach Discussion / Re: Seperate tool path files

« on: April 03, 2015, 09:17:42 PM »

I often load, reload, and change files without the XYZ reference changing in Mach 3. After a power off though you will loose it. What I used to do on an old CNC knee mill was use a post-it. The machine had a scale stuck on each axis and dials on the screws. So I would zero all axis with no tool in the spindle then move to X0,Y0,Z0 and write on the post-it the value on the scales and dials down to the fraction of a thousanth of an inch. Move back there in the morning hit zero on axis and go to work.

426

General Mach Discussion / Re: Zero touch off

« on: April 02, 2015, 07:23:33 PM »

Since Z0 is ussually the top of the stock you'd better have some Z negative values or you won't cut anything!  That said, park the Z up high zero it then run a program in single block mode. Watch every line and see what every G and M code does one line at a time. If the tool is supposed to be above the part there should be a Z move that gets it there and you should see it go there and the display value should match.  I always start in single block the first time I run a program. I step through watching where the tool goes next and I have feed speed way down. If the tool goes to the right place and next move looks correct then I switch off single block and continue.

427

Tangent Corner / Re: TURKEYS TAKING UP RESIDENCE

« on: March 31, 2015, 10:39:08 PM »

My wife stopped for some wild turkeys crossing the street. When she started moving again the big old guy attacked her car, breaking out the taillight and leaving blood on the rear window!  Scared my grandson strapped in the back seat.

428

General Mach Discussion / Re: Stepper Motor Maximum Voltage

« on: March 30, 2015, 06:32:35 PM »

A stepper motor is a constant power device. The current the drive provides is what limits the power it produces. As the motor speed increases the back EMF also increases, which reduces the current unless you increase the voltage. So if you don't want the torque to fall off drastically at higher speeds you need a higher voltage drive.

429

G-Code, CAD, and CAM discussions / Re: tool library Mach3 vs CAM

« on: March 20, 2015, 06:44:39 PM »

The offset that gets saved in Mach 3 is only the tool length unless you are using tool radius compensation G41 G42, in which case Mach 3 needs that. Now if you are letting the Cam program offset the tool then the Cam program needs the tool radius, but it never needs tool length compensation because that is relative to the spindle. Tool length gets measured by and stored in Mach 3.  Hope this helps.

430

General Mach Discussion / Re: Ballnose Bits

« on: March 18, 2015, 07:32:12 PM »

A few years ago I ran into a buddy that worked for Fadal and he was demonstrating a machine at a show cutting a 3D aluminum part held in a 4th axis with 4 parts in four vices.  As I watched it run I told him I could cut it faster and and get a better finish too.  What I told him to do was to take advantage of the 4th axis and the cam program and set up cutting the 3D surfaces with the part tilted so that the ball mill never cuts right on center if possible. That way you don't do any rubbing and always have a good chip load.