Messages

1621

General Mach Discussion / Re: Home and/or limit switch

« on: September 06, 2008, 04:32:52 PM »

If you have Home in a place other than lower left fully up (tool in relation to table) then you will need to set up a Home Off distance for that axis so that the Machine Coordinates are zeroed to lower left fully up.

As Ray says if you use home positions other than axis extremes then you will need seperate Hom and Limit switches for each axis. If you have the switches at the extremes you can use the same switch for each axis.
 Depends on your switches whether you can connect all in series, I have 3 inputs to Mach on the machine I use optos on, not tried connecting in series.
On my other machines I have good quality HoneyWell plunger switches and my homing looks for the switch then looks for the index from my motors encoder then backs off a preset amount of encoder counts. This is only possible with either drives that can do this or Eds BOB (No longer made I believe ) but may also be a feature in the SmoothStepper in the future.

Hood

Many stepper drivers also have a "Phase 0" output that can be used the same way, switch resolution permitting.

Regards,
Ray L.

1622

General Mach Discussion / Re: Bug, or Feature?

« on: September 06, 2008, 04:30:13 PM »

Hood,

    In the immortal words of the Firesign Theater - "We're all Bozos on this bus!"  :-)

Regards,
Ray L.

1623

General Mach Discussion / Re: Home and/or limit switch

« on: September 06, 2008, 04:17:15 PM »

Kristin,

    Home position is with the table full right and out, which I believe is the most common place.  But, you can put it anywhere you like, even in the middle of the table if you like (but then you can't use the same switches for home and limits).  It really makes no difference where home is, as long as *you* know where it is.

Regards,
Ray L.

1624

General Mach Discussion / Re: Bug, or Feature?

« on: September 06, 2008, 04:14:21 PM »

Hood,

    Never mind.  I'm an idiot.  I forgot I had reverted to v2.63 when I was having trouble with brains.  I just re-installed v3.041, and all is well.  Thanks!

Regards,
Ray L.

1625

General Mach Discussion / Re: Bug, or Feature?

« on: September 06, 2008, 03:56:31 PM »

Hood,

    I'm running v3.041.  So I should get the latest development release?

Regards,
Ray L.

1626

General Mach Discussion / Re: Home and/or limit switch

« on: September 06, 2008, 03:49:41 PM »

Kristin,

    I think you've got it pretty well figured out, and pretty much the way my knee mill is setup.  I agree there seems little use to a Z "down" limit.  I used microswitches, and feel that was a good choice.  I seem to get pefect repeatability, to within well under 0.001", and they'll be less susceptible to damage from coolant/oil.  If they do ever fail, replacements are as close as the nearest Radio Shack, for about $2 each.

Regards,
Ray L.

1627

General Mach Discussion / Re: Bug, or Feature?

« on: September 06, 2008, 03:45:40 PM »

under general unlock the feed rates from the jog rates check box

OK, I can't find any such checkbox under Config->General, or even anything close.  Where exactly is it, and how exactly is it labelled?

Regards,
Ray L.

1628

General Mach Discussion / Bug, or Feature?

« on: September 05, 2008, 01:13:36 PM »

I was testing some G-code today, and cutting hardboard instead of metal.  I cranked the feedrate over-ride all the way up.  But, it appears the over-ride affects rapid rates as well as cutting rates, which makes no sense at all to me, as rapid rates are normally set to the max capability of the machine.  Needless to say, this made the machine go nuts on every rapid.  Is this really the way it's supposed to work?  If so, it sure seems really wrong to me....

Regards,
Ray L.

1629

General Mach Discussion / Re: After using the “Steps Per Unit” in “Axis Calibration” my CNC wont run properly

« on: September 04, 2008, 02:44:03 PM »

Here are the test procedure and results from measuring the X and Y axis. As you can see all the results from moving 1” came out to be 0.996” on all three tests that were ran on each axis. I am using ½” 10 TPI 1 start Acme rod. All three axis were cut from one piece of rod. This is not a high precision piece of iron.
After setup I did not have to touch the indicator, it came back to zero every time.

I will try and attach the spreadsheet with test details.

What do you think of the test results?
What would be my next step?

Regards

Hager

I would be suspicious of the accuracy of whatever indicator you're measuring.  Either that, or your screws are not reall exactly 10TPI.  Do the measurements again, using a different indicator.  If you get the same result, then you're screws are off, and the solution is to simply re-calculate steps/inch based on 10 turns = 0.996 inches.  If you get a different result, (hopefully 1.000"), then you know you have at least one lousy indicator.

Regards,
Ray L.

1630

General Mach Discussion / Re: After using the “Steps Per Unit” in “Axis Calibration” my CNC wont run properly

« on: September 04, 2008, 01:50:30 AM »

"When it is time to set the steps I will do it by trial and error until I find the magic number for my machine" - That is a horrible idea!  There is one, and only one, correct number, and it is determiend by the hardware, and should be precisely known.  If it isn't, then *something* is wrong, and just finding a number that seems to work will not give you a reliable, properly operating machine.  The proper setting for your machine should be 16,000.  If that doesn't work right, then figure out why!

Regards,
Ray L.