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Tom | 5 Dec 08:10
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servo chatter at rest is going to drive me nuts...

I have all 3 axes of the Kasuga converted to EMC2 control using 500 line
encoders (2000ppr)on brush servos and Advanced Motion PWM amps. 
The ballscrews are 5mm pitch. I have the ini set for 10160 encoder counts 
per inch.
While pid tuning I noticed that in order to get my ferror down to below 
.002" during the accel/decel ramps, I had to reduce the deadband. This was 
after optimizing p,i,d,ff0,ff1,ff2. This causes the servos to continually 
hunt about +/- .0002"(two tenths)while at rest which makes a godawful chatter. 
The symphony of clicks, moans, pops and chatter is going to drive me nuts
eventually. Of course, I can always turn the machine off in Axis to stop the
noise - but I want to leave the machine on while fixturing, setting tool & 
work offsets, etc.
Is there some secret to tuning this chatter out while keeping following 
error down?
Tom

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Eric H. Johnson | 5 Dec 04:56

Re: Write error with hostmot2 and 7i43 board

Peter,

>> What EPP mode are you using and what type and length of cable do you have
between the 7I43 and Parallel port? <<

The available parallel port modes in the BIOS are Output only,
Bi-directional, EPP and ECP. It is set to EPP, but I do not see a further
selection for mode of EPP. I think we determined previously that it was
version 1.9. 

The cable was fairly hard to find, I got it here:
http://www.sealevel.com/product_detail.asp?product_id=732&26%2DPin%5FIDC%5Ft
o%5FDB25%5FCable%5F

It is 8" long and I previously rang it out.

>> What type of paralle port do you have (motherboard/PCI add-in) <<

The parallel port is straight from the mother board. This is the motherboard
I am using:
http://www.mini-box.com/Intel-D945GCLF2-Mini-ITX-Motherboard?sc=8&category=1
00

>> Is the iteration count always the same? <<

No. Running it again I got an iteration count of 30865.

>> I dont know if it would be caught by software checking but ISTR the 7I43
cannot use a base thread (EPP operations need to be atomic) so a 7I43 HAL
should only normally only use a Servo thread <<
(Continue reading)

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Andre B. | 5 Dec 02:41

Re: 2nd Tool Offset

At 06:56 PM 12/4/2008, you wrote:
>On Thu, Dec 04, 2008 at 06:45:47PM -0600, Jeff Epler wrote:
> > emc has an X tool offset for lathes, but doesn't presently have a Y tool
> > offset.
>
>Jeff is exactly right.  If you could align them in Y, so you can get
>by with just X/Z or X/W offsets, you'd be set.

U,V,W

How much would it take to make a machine that had X,Y,Z as physical 
axies and U,V as axies only within the control the position values of 
which get added to X and Y at some easy point in the software.

Then when you wanted to switch to the second spindle you have a block 
with the words (U10.058 V2.031) in it, and to switch back to the main 
spindle (U0.0 V0.0).

______________
Andre' B.

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Richard Acosta | 5 Dec 03:12
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EMC 2.2.7 + 7i43 + Ted's sample, and same error than using EMC 2.2.6 + 7i43 + Ted's sample.... What now?

http://pastebin.com/m38308b00

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Marc Bodmer | 4 Dec 23:34

2nd Tool Offset

Dear List

I have an XY plasma cutter (gantry) with an externally height
controlled (Dynatorch THC) W Axis for the plasma torch.
This is my primary tool.

Now I would like to add a secondary tool on a Z axis mounted right
beside the W Axis on the gantry. This tool would be used for
engraving or drilling or the like.

This mechanical setup however gives an offset in X and Y between
primary and secondary tool.

I know I could compensate for this "tool offset" by setting G54 for
the primary and G55 for the secondary tool in the g-code. But I
would prefer a "cleaner" solution than that. Because with G54/G55
these 2 toolpaths are shown in axis with the respective offset.

I would prefer a somewhat "transparent" solution: select the
tool in the g-code and have the offset implicitly set.

Are there any solutions better suited than G54/G55 ?

Thanks

Marc

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(Continue reading)

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Roland Jollivet | 4 Dec 10:06

Re: Pluto-P

Hi
I presume that the network card will be dedicated, as the parport is, and
only use a simple packet structure.. If one wants to connect to the
internet, then you'd use a seperate USB link or a second network card if
possible. That way there'll be no surprise jamming.

Regards
Roland Jollivet

2008/12/4 Chris Radek <chris@...>

> On Wed, Dec 03, 2008 at 09:48:18PM -0600, Jon Elson wrote:
> > Peter C. Wallace wrote:
> > >
> > > As I said before maybe the way to ease into this is just support 1 or a
> few
> > > Ethernet chips, and require the user to have a add-in PCI/PCIe Ethernet
> card
> > > with the required chip.
> > >
> > Having fought this problem to some extent with the par port, I can't
> > IMAGINE the headache when a potential customer shows up and you tell him
> > "Oh, it only works on computers with a DEC Tulip ethernet chip."  Add,
> > he says, "How do I tell, sight unseen, whether any particular computer
> > has that specific chip?"
> > No, it has to have a bit wider hardware support to be viable.
>
>
> I think the answer is explicitly in what Peter said above.  You don't
> care what comes in the computer.  You point them to a particular
(Continue reading)

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tomp | 4 Dec 10:06
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Re: How can I calculate the INPUT_SCALE value?

john,

i wasnt aware that emc used floats ther
it is unusual in cnc to do so, but thats an observation

the 'nice number' refers to the numerator and denomimator
which are outside if emc
which are inside the driver

unless these 2 are nice numbers ( ints divisible by 4 )
then the home pulse delivered to control is longer than the real home pulse
this can lead to trouble in homes that do not coincide always.
when both are ints divisble by 4, then the home pulse is same size as 
mfctr intended

floating point has to do with emc
nice numbers have to do with driver

integer counts per user unit of measure might be an advantage to emc
because most cnc manufacturers use integers there (Fanuc Heidenhain )
and there are some that use floats (PMAC EMC )

the general public (non-emc?) would think ints when thinking counts per 
unit of measure

fwiw
tomp

John Kasunich wrote:
> tomp wrote:
(Continue reading)

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Ray Henry | 4 Dec 00:45
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Ethernet, rtai, and rtnet


http://www.ce.utwente.nl/rtweb/publications/MSc2004/pdf-files/011CE2004_Buit.pdf

An interesting study of RTnet.  In it they say; 

        "RTnet communication times are mostly determined by the
        hardware. Not only processor speed but also architecture and
        type of network interface card (NIC) are of great importance.

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John Kasunich | 3 Dec 17:16
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Re: How can I calculate the INPUT_SCALE value?

Howard Chan wrote:
> Dear all,
> At first, I used latency-test to check my computer and I set the
> BASE_PERIOD to 25000. I used Integrator manual to calculate the
> INPUT_SCALE but it is not correct.
> My machine requirements:
> Unit using mm.
> I hope the max rpm of motor is 1200.
> I use SANYO DENKI servo motor which has an 2000 ppr internal encoder and
> max rpm is 3000. The motor mounts a 16T pulley and connects a 36T pulley.
> http://myweb.polyu.edu.hk/~icwfchan/p2.png
> 36T pulley mounts a lead screw which is 4 turns per inch
> http://myweb.polyu.edu.hk/~icwfchan/p3.jpg
> 
> According to Integrator manual, my calculation is:
> INPUT_SCALE=2000 * (36/16) * (4 /25.4)=709
> but the computer displays x-axis value is not the real-distance value.
> I try and error to find the value round 1250
> 
> Would you mind telling me which part is wrong?
> Thank you
> 
> Howard

Your calculations appear to be correct.  But obviously something is not 
working.  The screw pitch and pulley ratios are easy to verify, but the 
encoder counts might not be what they should be.

Here is an experiment:
(Continue reading)

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Stephen Wille Padnos | 3 Dec 17:16

Re: How can I calculate the INPUT_SCALE value?

Howard Chan wrote:

>[snip]
>I use SANYO DENKI servo motor which has an 2000 ppr internal encoder and
>max rpm is 3000. The motor mounts a 16T pulley and connects a 36T pulley.
>http://myweb.polyu.edu.hk/~icwfchan/p2.png
>36T pulley mounts a lead screw which is 4 turns per inch
>http://myweb.polyu.edu.hk/~icwfchan/p3.jpg
>
>According to Integrator manual, my calculation is:
>INPUT_SCALE=2000 * (36/16) * (4 /25.4)=709
>but the computer displays x-axis value is not the real-distance value.
>I try and error to find the value round 1250
>
>Would you mind telling me which part is wrong?
>  
>
It sounds like you have 3600 count encoders, not 2000.  The rest of your 
math is correct as far as I can see.

Try this:
set the INPUT_SCALE to 1000
Leave the motor disconnected from the screw and put a mark on the pulley
Jog far enough to make the pulley move 1 turn (by eye at least, more 
accurately if you can)

This will tell you whether the motor is moving as far as you think it is.

If it is, you should check the table movement by measuring how far it 
moves when you turn the screw 1 (or 10) turns.
(Continue reading)

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Wayne Parks | 3 Dec 17:02
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Re: Surface Finsishing

These sites deal with the finishing and polishing of Aluminum
http://www.car-accessories-magazine.com/aluminum-polishing.html
http://www.irinfo.com/polish/html/polish.html
A Scotch-Brite™ Cut and Polish Flap Brush in a hand held drill would work.
I could also see using a small round abrasive pad with a foam backer in 
the spindle of your mill
and run a small G code program that moves the work piece approximately 
3/4 the diameter of
the pad and then lowering the head to just contact the work surface and 
repeat this the full length
of the part resulting in the traditional circle polishing affect common 
on aluminum.
Wayne

>> You can get special belts for a sander that polish aluminum... the finish depends on the 
>> grade... they look like 3-m polishing pads but on a belt...
>>
>> John
>>
>> On 2 Dec 2008 at 22:51, admin@... wrote:
>>
>>   
>>     
>>> What do you guys use as the quickest and best cost effective and
>>> time-effective way to finish flat surfaces before the parts are
>>> Anodized?
>>> The parts are 8"x6"x3" Al boxes made from square tube with a few
>>> slots
>>> and holes CNC'd in so the surfaces are still the raw surfaces.
>>> I can CNC the boxes with a flat-face-mill , but wonder if there
(Continue reading)

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Gmane