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Messages - garyhlucas

351
General Mach Discussion / Re: Limit switch issues
« on: December 26, 2015, 04:28:48 PM »
You know I don't trust the CNC, ANY cnc. So the limits on my machine are connected right in the E-Stop circuit which controls the main power contactor which quite literally stops everything, and puts Mach 3 in E-stop.  Now If I hit the limit and everything shuts down I have to push the reset button and hold it in while jogging away from the limit. My limits slide by too, not a physical stop that could break something. So you can see it move the wrong way still and not break anything. This is a pain to reset.  Or it was, once I learned my machine I stopped hitting the limits!

352
General Mach Discussion / Re: limit swith vibration
« on: December 26, 2015, 04:16:14 PM »
Switches that are used to establish a 0 position must open with a very small amount of travel, otherwise your 0 will be all over the place. Limit switches are often snap action so they don't vibrate open, but they won't be accurate.  So a switch that is accurate and vibration resistant is a bit tough to do.  Do you actually home your machine or just pick up coordinates for a part and go?

353
General Mach Discussion / Re: Rippled finish only when cutting arcs
« on: December 22, 2015, 07:06:36 PM »
Is the code actually actually arcs or is it a lot of short lines that make up an arc?

354
General Mach Discussion / Re: Auto Squaring Gantry
« on: December 21, 2015, 03:51:12 PM »
I have never worked with slaved axis but I would think they'd work better if when they are square that both motors are sitting on a full step and holding. Otherwise everytime you power up I would think the motors will both come to a full step and the gantry will be off by some fraction of a full step every time.

355
Screen designer tips and tutorials / Re: CNC Flame Cutting Machine
« on: December 18, 2015, 11:22:32 AM »
RDR,
I'd love to see pictures of your home built water jet.  First one I have ever heard about.

356
Screen designer tips and tutorials / Re: CNC Flame Cutting Machine
« on: December 17, 2015, 08:41:07 PM »
I think in order to do bevel cutting with 5 axis to tilt the torch you will need a 5 axis CAM program as Mach 3 and 4 are just machine controllers that can do 5 axis motion if the G-code tells it exactly what to do.  Lots of axis coordination needed to go around a corner while cutting a bevel.  A five axis Cam program though is BIG bucks.

357
Mach4 General Discussion / Re: Motor counts per in
« on: December 17, 2015, 08:35:03 PM »
I don't think this is going to work out with the pitch diameter because a chain sprocket is chordal, not round. So for one revolution the distance will be number of teeth times the pitch or 14 x 0.25 = 3.5" However chain does not run smoothly like a belt. It oscillates forward and backward. You can see this clearly on sprockets with a very small number of teeth and it can produce violent vibration.  You also can't tighten a chain up taught without causing tight and loose as the sprockets turn.

So chain is kind of a bad idea for linear motion, but if that is what you have my explanation of the math above will work.

358
General Mach Discussion / Re: Z-Axis Not Always Positioned Correctly
« on: December 11, 2015, 07:09:25 PM »
So if you move the tool to Z=0 is the tip of your tool right on the surface?  Did you use 0.010" feeler gauge to set the tool and forget to compensate for it?  I like using a 1/2" precision roll pin to set tools.  Keeps the tool away from my part far enough that an oops jog won't hit.  You roll it back and forth under the tool as you jog and it finds the lowest point on the cutter, not the lowest point where the block or feeler gauge is.

359
Once you have a motion card with USB or Ethernet the PC speed becomes a non-issue.  I am surprised no one else has chimed in here with motion card suggestions.  The cards I hear about the most seem to be the ones from Pokeys or Kflop, and Smooth Stepper.  My Xiulifeng from AutomationTechnologies has worked well but I don't know any other users.

360
General Mach Discussion / Re: limit switch set up
« on: December 09, 2015, 07:00:26 PM »
That was what I was trying to say. Once you have Mach 3 working really well you forget how exactly you got there!