Messages

1421

General Mach Discussion / Re: 2 Questions

« on: December 25, 2008, 09:13:00 PM »

Bob,

    If your machine does not have home switches, you don't need to concern yourself with the whole concept of home - It's of no value to you.  Decide where you want zero to be for the job you're running, put the machine there, and zero the user coordinates.  Don't worry about what the machine coordinates are, they're not important.
   Home is only useful if you have home switches, and it's primarily useful for quickly re-zeroing the machine after power-loss, a tool-breaking, etc.  Without home switches, you just have to manually re-zero to whatever you chose as your user coordinate zero point if something goes wrong.

Regards,
Ray L.

1422

General Mach Discussion / Re: cat 5

« on: December 21, 2008, 03:04:59 PM »

I have used solid Cat 5 cable for a couple of years with no problems.  Make sure you run your channel A and B in different pairs of the cable.

Vince

I have used solid Cat 5 cable for a couple of years with no problems.  Make sure you run your channel A and B in different pairs of the cable.

Vince

Solid core wire is not a good choice for an application where it will be repeatedly flexed.  It will eventually fatigue and fail, and when it does your servo will run away on you, possibly damaging the machine, or hurting someone.  You'll get away with it for a while, but it's a poor choice for long-term reliability.

Regards,
Ray L.

1423

General Mach Discussion / Re: ports and pins

« on: December 19, 2008, 06:45:36 PM »

There is an LED on the BOB for each input and output.  Does the LED change state when you activate the limits?  If it does, then you know the switches are working, and the optos on the BOB are working.  If you're not seeing the "LEDs" in Mach change state, then the problem is the PP drivers on the BOB, or the PP itself.  If the LEDs on the BOB do not change state when you activate the limits, then either the switches are not working, or are incorrectly wired, or the optos on the BOB are likely blown.  You can order replacement opto chips from CNC4PC, or try swapping two of the opto chips on your board, to see if that gets the limits going.  The opto chips are the LTV847s at positions IC5, IC6, and the chip between IC6 and the PP connector (which does not seem to have an IC designator....).  I would guess IC6 is probably the one that is used for all the input signals.

Regards,
Ray L.

1424

General Mach Discussion / Re: Opinions on use of ancient computers to run Mach3

« on: December 19, 2008, 11:21:47 AM »

The only way to know how well it works is to try it and see.  Every machine is different.  Some slow machines work fine, and some screamers are flaky.  I'm running my knee mill on a 540MHz pig, but it works fine.  You'll have to get used to some people immediately blaming CPU speed for every problem you have, but in my case, I've always found other causes, and never once had a problem that could be definitively blamed on CPU speed.  If you have any concrens about speed, you can also add a SmoothStepper, which off-loads all the real-time work of creating the pulse trains to dedicated hardware, making the PCs life far easier.  I did this several months ago, and it gave me far better performance, due to the much more precise timing.  My rapids went from a shaky 150 IPM to at least 400 IPM, with no changes in configuration other than motor tuning.  Installation was a total no-brainer, and the machine has worked much better ever since.

Regards,
Ray L.

1425

General Mach Discussion / Re: l297/l298 with mach3

« on: December 19, 2008, 11:14:07 AM »

this problem was occured previously.but no one explained HOW solved it .
plz help me solve it.

I would suggest simply wiring the drives so they are always enabled.  With steppers, I see no real benefit to having Mach control the enables.  Servos are a different matter.

Regards,
Ray L.

1426

General Mach Discussion / Re: l297/l298 with mach3

« on: December 18, 2008, 11:06:54 AM »

If enable turns off, the motors will be completely un-powered, and will be able to be pushed off position by cutting forces.  You NEED enable to remain active, unless the system is in E-stop.   Buzzing and hissing are facts of life with steppers.  You'll have to either get used to it, or turn up the radio.

Regards,
Ray L.

1427

SmoothStepper USB / Re: SS DISCONNECT SAFETY CONCERNS

« on: December 09, 2008, 03:26:58 PM »

Ooh!  That is BAD!  The SS should be getting some kind of "heartbeat" from the PC that acts as a deadman to protect against exactly that situation.  A trivial thing to implement, since it's using USB communications, it's got the perfect timebase for this functionality.  I find it hard to believe Greg would've designed it that way.   More likely it's just not working in the release you're using.  Was this with the latest plugin?

Regards,
Ray L.

1428

General Mach Discussion / Re: RPM Display

« on: December 06, 2008, 10:41:06 AM »

You can use the timing input instead but you will need one slot widerthan the other.
Hood

Hood,

    I'm no macro weenie, but couldn't he overlay the RPM display with another DRO, and have a macro, or perhaps even a brain, that reads the "real" RPM DRO, divides by two, and uses that value to update the new DRO?

Regards,
Ray L.

1429

General Mach Discussion / Re: Mapping output #6 to another pin?

« on: December 05, 2008, 12:01:01 PM »

You can map any signal to any pin.  Just go to Config->Ports & Pins.

Regards,
Ray L.

1430

General Mach Discussion / Re: mach runs away

« on: November 30, 2008, 05:12:38 PM »

i think the problem is that mach is homing in the wrong direction i think i dont know if you have a mill or not .But Should not the mill table home towards you and to your left would this not be the negative direction am i correct in this or am i wrong? thanks again

Your commenta suggests you may be confused about how axis directions are defined.  Axis directions are always defined by the direction of movement of the tool relative to the work, *not* by the direction of movement of the table.  So, an X move in the minus direction will move the tool to the left, or the table to the right.  A Y move in the minus direction will move the tool towards the front of the machine, or the table towards the rear of the machine.  A Z move in the minus direction will move the tool down, or the table up.

Regards,
Ray L.