Messages

371

General Mach Discussion / Re: Recommended Encoders

« on: December 01, 2015, 01:22:56 PM »

An encoder on an axis that has a problem will just provide you with a new way for the machine to tell you it can't do what you want. Is that your goal?

372

G-Code, CAD, and CAM discussions / Re: Need help converting .png to gcode

« on: December 01, 2015, 01:19:08 PM »

Sometimes you need to use something other than your favorite hammer. This is one of those times. Get yourself a copy of CamBam with 40 uses for free. Draw your part, create a G-code file, machine your part, done!

373

General Mach Discussion / Re: Constant Velocity vs Exact Stop

« on: November 28, 2015, 10:15:16 PM »

Exact stop means every move will come to a complete stop before executing the next move so the path will be exact. When there are lots of short moves the machine will sometimes appear to stutter. Continuous will attempt to keep the machine in motion so there may be corner rounding or overshoot depending on the speed. Both have their place.

374

General Mach Discussion / Re: CNC4PC C52 board and C32 Board PLC

« on: November 27, 2015, 11:03:10 PM »

The c52 board gives you digital outputs, the plc has digital inputs. So if you got the correct plc the connections are simple. A signal back to mach 3 is a digital output to a digital input on the c52. The real question is how many tools you want have. You can code tool numbers as binary.  Four inputs to the plc and read as binary can give you fifteen tool positions. Similarly you could use 4 switches to identify which of 15 tools are in position. Hope this helps.

375

General Mach Discussion / Re: best intro software for very basic lettering to be cut on a 20x14cm machine.

« on: November 26, 2015, 04:29:09 PM »

One of the things I've always believed is that the P in PC means 'personal' and with software you may love one and hate another just because of the way you work.  I know there are a number of jewelry designers working in Rhino 3D and I used it for mechanical design for a long time. Truly excellent support through their user forum too, a lot like Mach 3.  There is Cam software that runs inside of Rhino available too.  I use CamBam for the cam side of things right now, quite a good value.  Also there is Meshcam that works with STL files to produce cutting files.  An inexpensive program like any of these can teach you enough to know what you really need for what you are trying to do, before spending big bucks.

376

Video P*r*o*b*i*n*g / Re: Best setup for probing a trumpet mouthpiece

« on: November 18, 2015, 06:54:18 PM »

Your lathe may be able to make a cut that accurately, but one minute later holding the part in you hand where it warms up all bets are off. I'd spend my time finding out the limits of accuracy required, in other words what the customer could detect, then work from there.  In the real world accuracy is seldom the issue, and repeatability is much more important.

377

Modbus / Re: MODBUS vs PWM control of spindle performance

« on: November 18, 2015, 06:43:28 PM »

Unless your VFD has an encoder on the motor shaft or is a sensorless vector control type that can determine shaft position using back EMF then you won't get a really steady speed in any event.  Unloaded the spindle will be nearly synchronous with the Hz output. When the tool touches the work or the depth of cut changes the speed will go up and down by 60 rpm or so.  So I'd not be too worried about it.

378

Mach3 under Vista / Re: Stumped on how to code iterations

« on: November 18, 2015, 06:37:03 PM »

Does your sig imply a Jersey guy?

Programming by hand is what we used to do. Get CamBam and use it free for 40 sessions.  Even if you don't buy it you'll learn a whole lot and my bet is you will buy it for $150.  The user forum there is great too, everyone will help.  Your slot task gets programmed in about the same time that it took me to write this! Once you start looking at code that works you'll learn G-code real fast.

379

General Mach Discussion / Re: safe z

« on: November 18, 2015, 06:27:48 PM »

Safe Z can keep you from crashing but it can also be a huge time waster. Especially on a hobby machine that does not move terribly fast.  So I sometimes have it at 0.050" above the part, and sometimes several inches above the part. My machine has an 18" Z, moving to the maximum Z every time for safety would take forever!

380

General Mach Discussion / Re: Fixed Gantry Table

« on: November 03, 2015, 06:20:50 PM »

I hate moving tables. They always spill my coffee during rapids.