Messages

1581

General Mach Discussion / Re: Bridgeport Quill Feed Mechanism

« on: September 15, 2008, 11:58:15 PM »

RC,
Just finished going through all 15 pages in the forum Ray L isted, and find he used the knee for the Z.
also see a guy name of Hood on that forum. He just has to have a clone. Just like S--T. he's everywhere.

Attached pic of my Excello mill. The z servo drives a shaft with a miter gear to the ball screw.
The ball screw replaces the quill stop screw.

Brett use to have a link on his web page to Hoods machine pics, but not anymore.

As far as the pic with the quill handle. Got a torch?

Ed

Except that message #11 gives pictures of pretty much all the parts required to do a quill conversion in a nice, clean way.  I believe there's a whole thread somewhere there dedicated to that machine.

Regards,
Ray L.

1582

General Mach Discussion / Re: Bridgeport Quill Feed Mechanism

« on: September 15, 2008, 10:08:24 PM »

This should get you started:  http://cnczone.com/forums/showthread.php?t=18178

1583

General Mach Discussion / Re: Need advice for retrofit of millrite

« on: September 15, 2008, 07:56:46 PM »

I was under the impression that with Mach 3 the backlash does not really matter so long as it is consistent because you can compensate for the backlash with Mach3. Your input is greatly appreciated and here are the kits I am considering and 95% sure on the steppers; they have a 1 year warranty on the motors, breakoutboard, and powersupply with the standard gecko warranty for the drivers. What do you think?

Stepper http://www.kelinginc.net/CNCNEMA34Package.html

Servo http://www.kelinginc.net/CNC34ServoMotorPackage.html

Mach3 can mitigate backlash, and reduce it's impact on the quality of your work, but backlash *always* matters, and you'll never get truly good results with backlash in the system.  The cutting forces will sometimes work to push the cutter away from the desire path, regardless of Mach3's best efforts.  With such large amounts of backlash, the machine will never work particularly well, and your work will nearly always have visible artifacts of the backlash.  With as mch backlash as you have, those artifacts will be *very* visible.

Regards,
Ray L.

1584

General Mach Discussion / Re: Need advice for retrofit of millrite

« on: September 15, 2008, 06:27:42 PM »

Speed is not a huge concern for me and I intend to gear the motors down 1:2, but are the steppers less accurate than servos? If so, by how much?

Worrying about accuracy differences between servos and steppers is a little silly in a machine with such high backlash.  That backlash will be by far your biggest problem if you expect better than wood-working accuracy (if that) out of that machine.

Regards,
Ray L.

1585

General Mach Discussion / Re: First Post - need some set-up guidance

« on: September 15, 2008, 01:48:55 PM »

Hood,

    Yup, with drivers having opto inputs, active low is the way to go.   But for others....

Regards,
Ray L.

1586

General Mach Discussion / Re: First Post - need some set-up guidance

« on: September 15, 2008, 01:19:53 PM »

Hood,

    I'm curious why you're curious why I'm curious....  :-)

    Setting the step polarity wrong can cause lost steps on direction change with some controllers, depending on what the timing is, delays through the BOB, etc.

Regards,
Ray L.

1587

General Mach Discussion / Re: backlash for both direction on same axis

« on: September 15, 2008, 12:10:34 AM »

I am looking at a dial indicator showing it. I have .003 one way and i am estimating on the other amount because it doesn't read to the fourth decimal but i estimate .0001 the other way. when it goes to .007 and comes back to a fraction before zero. it takes like ten times before it clearly doesn't return to zero.

That doesn't sound like backlash to me.  I just don't see how a mechanical fault could possibly behave that way.  More like an electrical problem when you change directions.  Are you sure you're getting step/dir timing and polarity that's compatible with your stepper drivers?

Regards,
Ray L.

1588

General Mach Discussion / Re: First Post - need some set-up guidance

« on: September 14, 2008, 11:36:22 PM »

Pete,

    I'm curious why you have the step signals set to active low in the pin config?  Also, I'd disable all the limits until you have the motors working right, just to eliminate a possible are of confusion.
    When you try to move, do the Mach DROs indicate Mach believes the axes are in motion?

Regards,
Ray L.

1589

General Mach Discussion / Re: Running Mach Without Hardware

« on: September 14, 2008, 06:16:43 PM »

Hood,

    Ah!  What it calls spindle speed is not spindle speed, it's VFD frequency.  That is also set manually at the moment.  I was running around 380RPM with a 1/2" end mill, which is right around 50SFPM.  That's reasonable, no?
   The simulation is working now, just don't ask me why.  I re-started Mach a few times, and it started behaving!  Go figure!

Regards,
Ray L.

1590

General Mach Discussion / Re: Running Mach Without Hardware

« on: September 14, 2008, 06:02:09 PM »

you got the xml from your machine in there?
Hood

Hood,

    No, just using whatever was there in the install, which is reasonably close to the real thing in terms of rapid speed.

    That part was 304 SS, with HSS tools - my first ever SS project.  Came out perfect, and only ruined one tool, when the coolant stopped mid-cut.

Regards,
Ray L.