to a VFD. Since ferrites are more lossy at high
frequencies I'm curious about it.
Thanks,
Javid
- Original Message -
From: Kirk Wallace [EMAIL PROTECTED]
To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
Sent: Sunday, October 28, 2007 6:24 PM
Subject: Re: [Emc-users
Javid Butler wrote:
If you do use the ferrites in the outputs let us know how much heat they
produce. I would guess it will be a function of the quality of the VFD's
output stage, but have never tried power ferrites.
The filters used in theatrical dimmers can get pretty hot, and those
Kirk Wallace wrote:
Jon gets a gold star. I believe his is line filter suggestion solved my
noisy spindle encoder index problem. I got a couple of PREO filters:
http://www.eastek-intl.com/images/PreoSeriesER.pdf
One for the spindle VFD input (30 A) and another for the coolant VFD
input
If anyone is interested, I posted a few new pictures here:
http://www.wallacecompany.com/cnc_lathe/HNC/
--
Kirk Wallace (California, USA
http://www.wallacecompany.com/machine_shop/
Hardinge HNC lathe
Bridgeport mill conversion pending
Zubal lathe conversion pending)
On Sun, 2007-10-21 at 09:56 -0400, Gene Heskett wrote:
On Sunday 21 October 2007, [EMAIL PROTECTED] wrote:
John Kasunich wrote:
Even better, if you can get some, is a braid that can be expanded enough
... snip
Regarding motor cables: I am using a Belden microphone cable called
Star-Quad,
John Kasunich wrote:
Even better, if you can get some, is a braid that can be expanded enough
to run the three motor leads through it, then stretched lengthwise so it
snugs down around the motor wires. Again, connect one end directly to
the motor frame, and the other directly to the VFD
On Sunday 21 October 2007, [EMAIL PROTECTED] wrote:
John Kasunich wrote:
Even better, if you can get some, is a braid that can be expanded enough
to run the three motor leads through it, then stretched lengthwise so it
snugs down around the motor wires. Again, connect one end directly to
the
John Kasunich wrote:
Kirk Wallace wrote:
Thanks for the e-mail Einar. There is a cabinet on each side of the
lathe. The VFD is in the right cabinet and is grounded to the cabinet. A
flex conduit with a plastic outer and a metal spiral inner carries three
conductors to the motor connection box
SNIP--
Using an oscilloscope, when I probed the power supplies with the spindle
running, I got about .5 Volts of ripple that had a three stair step up
and down appearance. Probing the +5 Volt differential signals I got a
very
: [Emc-users] Threading Hickups
SNIP--
Using an oscilloscope, when I probed the power supplies with the spindle
running, I got about .5 Volts of ripple that had a three stair step up
and down appearance. Probing the +5 Volt
On Sat, 2007-10-20 at 09:56 -0700, Peter C. Wallace wrote:
On Sat, 20 Oct 2007, Kirk Wallace wrote:
... snip
drain. I don't know its impedance, but I suppose I could start with 200
Ohms and work my way up. The data-sheet indicates that anything lower
that 90 Ohms should not be used. I'll
Kirk Wallace wrote:
The whole idea of the differential boards where to reduce the
susceptibility of the system to noise, but the boards themselves seem to
make the effect of the noise worse.
What are you using for the differential driver chip? Is it
totem-pole output or open-collector?
I
Kirk Wallace wrote:
My encoder disk problem cropped up again too. I am using a one inch U.
S. Digital disk with a .466 inch hole and .500 inch shaft. There doesn't
seem to be enough clamping area to keep the disk flat, so I have run the
disk up towards the receiver end of the slot, so it
On Sat, 2007-10-20 at 13:01 -0500, Jon Elson wrote:
Kirk Wallace wrote:
The whole idea of the differential boards where to reduce the
susceptibility of the system to noise, but the boards themselves seem to
make the effect of the noise worse.
What are you using for the differential
Kirk Wallace wrote:
On Sat, 2007-10-20 at 13:01 -0500, Jon Elson wrote:
What are you using for the differential driver chip? Is it
totem-pole output or open-collector?
I am using the DS26C31 http://www.national.com/ds/DS/DS26C31M.pdf
Oh, my, a blast from the dark ages! I've used a 75172
Thanks for the e-mail Einar. There is a cabinet on each side of the
lathe. The VFD is in the right cabinet and is grounded to the cabinet. A
flex conduit with a plastic outer and a metal spiral inner carries three
conductors to the motor connection box which is screwed to the motor
housing. So,
Kirk Wallace wrote:
Thanks for the e-mail Einar. There is a cabinet on each side of the
lathe. The VFD is in the right cabinet and is grounded to the cabinet. A
flex conduit with a plastic outer and a metal spiral inner carries three
conductors to the motor connection box which is screwed to
I may not have seen all the posts regarding this, but none that I saw mentions
using shielded
cable from the VFD to the motor?
If not already done, change to shielded cable for the motor leads too!
The braid needs to be grounded at the VFD and the motor.
Never ever use a pigtail to extend the
On Thursday 18 October 2007, Kirk Wallace wrote:
On Thu, 2007-10-18 at 00:17 -0400, Jim Coleman wrote:
On 10/18/07, Jon Elson [EMAIL PROTECTED] wrote:
Kirk Wallace wrote:
Thanks again Jon and Chris. What should have been obvious
turns
... snip
interference
if there is a ground loop somewhere in your setup, it won't conduct any
current unless it's ... a loop! so when you disconnect the sensor, it
breaks the circuit; no current is induced in the wires by stray magnetic
fields, and you dont see any voltage.
if the noise were 'coming from the
Gene Heskett wrote:
A possible test to see if its VFD generated noise would be to see if it
largely goes away when the motor is at full speed, and gets progressively
worse as the speed is lowered.
Basically, look for a correlation between spindle speed and the extra noise
pulses.
A
On Thu, 2007-10-18 at 09:38 -0400, John Kasunich wrote:
Gene Heskett wrote:
A possible test to see if its VFD generated noise would be to see if it
largely goes away when the motor is at full speed, and gets progressively
worse as the speed is lowered.
Basically, look for a
Another possible trouble is that your motor frame is not grounded with a low
impedance to earth ground. If this is the case, capacitance from motor
windings to the motor frame will couple switching spikes from your VFD into
your encoder via the motor shaft or encoder cover (metal covers make
Kirk Wallace wrote:
I used the existing cable which has four shielded twisted pairs. I have
one pair for each A, B, I and power.
Are the shields grounded at both ends?
also what about an inductor or capacitor at the encoder in its power
line to help smooth any noise introduced there?
John Kasunich wrote:
Gene Heskett wrote:
A possible test to see if its VFD generated noise would be to see if it
largely goes away when the motor is at full speed, and gets progressively
worse as the speed is lowered.
Basically, look for a correlation between spindle speed and the extra
Kirk Wallace wrote:
I totally underestimated and overlooked the issues involved with VFD's.
I guess they aren't a simple plug and play kind of thing. I plan on
using allot more VFD's in the future and developing experience will not
only help now but in the future.
I'll be interested to hear
Jon Elson wrote:
I did have some non-CNC interference from my mill's VFD, mostly
to my computer monitor. I put a Corcom-type line filter box on
the line in to the VFD, and it solved the problem.
Jon
I had the same thing with the fractional HP VFD on my drill press.
It was only running
Thanks again Jon and Chris. What should have been obvious turns out to
be the problem. Graphing the encoder index shows random pulses mixed in
with the regular pulses. I really did not want this to be the problem
since I had already gone through fixing another issue with this encoder.
I guess
On Wed, Oct 17, 2007 at 12:35:12PM -0700, Kirk Wallace wrote:
Previously, the dialog box would complain, but as soon as I got a valid
number entered it would stop complaining. Now, as soon as the error
message appears, it won't go away until I close the dialog box and start
over. I have
Chris Radek wrote:
On Wed, Oct 17, 2007 at 12:35:12PM -0700, Kirk Wallace wrote:
Previously, the dialog box would complain, but as soon as I got a valid
number entered it would stop complaining. Now, as soon as the error
message appears, it won't go away until I close the dialog box and start
Kirk Wallace wrote:
Thanks again Jon and Chris. What should have been obvious turns out to
be the problem. Graphing the encoder index shows random pulses mixed in
with the regular pulses. I really did not want this to be the problem
since I had already gone through fixing another issue with
On 10/18/07, Jon Elson [EMAIL PROTECTED] wrote:
Kirk Wallace wrote:
Thanks again Jon and Chris. What should have been obvious turns out to
be the problem. Graphing the encoder index shows random pulses mixed in
with the regular pulses. I really did not want this to be the problem
since I
On Thu, 2007-10-18 at 00:17 -0400, Jim Coleman wrote:
On 10/18/07, Jon Elson [EMAIL PROTECTED] wrote:
Kirk Wallace wrote:
Thanks again Jon and Chris. What should have been obvious
turns
... snip
interference sources like motor-VFD cables and any other that
On Wed, 2007-10-17 at 23:02 -0500, Jon Elson wrote:
Kirk Wallace wrote:
Thanks again Jon and Chris. What should have been obvious turns out to
... snip
trouble shooting for a while.
Check the grounding carefully. The best is to not have the
encoder grounded to the machine frame, but
After having some success with my tuning, I went back to making threads
without much success. Randomly, but close to every third or fourth pass
comes out being about a half thread off. I have Halscope graphs here:
http://www.wallacecompany.com/cnc_lathe/HNC/emc2/g76-bad.png
Kirk Wallace wrote:
After having some success with my tuning, I went back to making threads
without much success. Randomly, but close to every third or fourth pass
comes out being about a half thread off. I have Halscope graphs here:
On Tue, Oct 16, 2007 at 09:06:29PM -0500, Jon Elson wrote:
With the spindle running, you should see
regularly-spaced narrow pulses on index. If they are not
regularly spaced, you are picking up noise on the encoder index
channel.
If you are getting some threading passes in the wrong
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