Messages

1491

General Mach Discussion / Re: Peck Drilling

« on: November 03, 2008, 09:25:32 PM »

Sam,

    Thanks for the quick response.  Not sure I fully understand all of it though.  The machine is, for all practical purposes, a Bridgeport (it's a very literal Taiwanese clone - if I painted it gray, nobody would know it wasn't a real BP).  I guess I did OK on RPM - around 1500.

    "If your hole is deep, it would be a good idea to set a retract depth" - I thought the idea of peck drilling (I'm probably wrong....) was plunge, pull back, plunge, pull back, etc.  Should I instead plunge, stop, plunge, stop, etc. and only on deep holes actually retract periodically?

    Sounds like I need to crank the feed up a lot higher....

Regards,
Ray L.

1492

General Mach Discussion / Re: Rapids change spindle speed

« on: November 03, 2008, 08:01:52 PM »

Roy,

    It won't ever be perfect.  The response of the analog output on the CNC4PC board is not perfectly linear, and neither is the response of the VFD.  If you can manage to be within 10-15% worst case, you're probably doing pretty good.  Mine varies 5-10% from day to day.  But it really doesn't matter.  If getting precise RPM is important, then you have to go to some kind of closed-loop control.

Regards,
Ray L.

1493

General Mach Discussion / Peck Drilling

« on: November 03, 2008, 07:58:19 PM »

When peck drilling, say a 3/8" hole, in 6061, what feed rate, peck depth and retract depth would be appropriate?  I've been using about 5IPM, 1/8" peck, 0.05" retract.  That still results in some pretty good "strings", and drilling holes takes quite a while.
What would you guys use?

Regards,
Ray L.

1494

General Mach Discussion / Re: Motor Lock Up with New G201's

« on: November 01, 2008, 04:47:27 PM »

Check the voltage levels at the Gecko STEP/DIR pins.  They should be swinging from very close to 0V to very close to 5V.  If either is not get close to its ideal level, then you've found your problem.

Regards,
Ray L.

1495

General Mach Discussion / Re: Motor Lock Up with New G201's

« on: November 01, 2008, 03:59:17 PM »

That is not necessarily a valid assumption.  They may both have opto-coupled inputs, but they are not necessarily biased the same, and the Gecko may require more current from the PP to activate the opto than your old drives.

Regards,
Ray L.

1496

General Mach Discussion / Re: crazy circles from an ARC PP on one machine, OK on another!

« on: October 31, 2008, 04:34:27 PM »

Jim,

   Have you looked in the G-code to see what in there is causing Z to creep like that?  Kinda smells like perhaps a post-processor bug.

Regards,
Ray L.

1497

General Mach Discussion / Re: new spindle drive not working

« on: October 30, 2008, 04:06:07 PM »

i installed a new analog spindle drive on my saw and it works but it wont let me vary my rpms. any ideas? if you need more info just tell me what and ill do what i can.

thanks....
dave

Maybe I'm dense, but....  Isn't the whole point of a spindle drive to be able to vary RPMS under software control?  So what does it mean if it's "working", but it can't do that?  Sounds to me like it's not working?

We do need to know what drive you're using, what digital/analog converter, how it's configured, etc.  Ya gotta give us something to go on....

Regards,
Ray L.

1498

General Mach Discussion / Re: Another (bug) issue for the list

« on: October 29, 2008, 09:42:01 PM »

I have yet to see the elapsed timer make it past about one minute, even on a two-hour program.

Regards,
Ray L.

1499

General Mach Discussion / Re: Mach3 Spindle Speed Problem

« on: October 29, 2008, 09:40:31 PM »

Greg,

   On mine, it's really not a problem, since it always settles to the right speed before any movement takes place (I have a 5-second dwell on spindle start) and I've done nothing to determine if it's the SS or the CNC4PC analog output that causes that initial "surge".  The spindle has been behaving well lately, after the problems a couple of weeks ago, so I'm afraid to touch it!  :-)

Regards,
Ray L.

1500

General Mach Discussion / Re: Mach3 Spindle Speed Problem

« on: October 28, 2008, 08:33:47 PM »

Chris,

    Your spindle is open-loop, right?  i.e. - you do not have a spindle speed encoder?  I believe the "RPM" DRO will only be active if you have a spindle encoder, and it will show the actual spindle RPM, which is not necessarily exactly the same as the commanded RPM.
    I have a sort-of similar problem with mine, and I also have a SmoothStepper.  At low spindle speeds, when I turn the spindle on, it comes on too fast (sometimes 2X), then over a period of several seconds settles down to the correct speed.  Mine is open-loop - no encoder (yet).

Regards,
Ray L.