Inaccurate feedrate

[alfalfa]

Setting up a gantry planer mill using Camsoft Pro 15.9. GEAR/RATIO is adjusted to get the correct amount of phyiscal travel for a given commanded distance. Each axis is different as there are different gear boxes/pulleys on each. The problem is that when I make a move G1X10F10 it moves at approx 1/3 commanded feedrate. Camsoft has given me their explanation, but I am too dense to understand why the feedrate isn't accurate when making a simple, 1-axis move. (I haven't really tested multi-axis yet.) Am I that unusual that I have the only machine where not every encoder is reading the same pulses per inch? Any suggestions would be great. I have Camsoft looking at my .cbk, but I would like to hear from any of you front line guys that may have a practical, here's-what-to do, suggestion. I have looked at Q114 and tried to follow it - to no avail.

Thanks,
AL

[HuFlungDung]

All you really need to do is check that the calculated move ends when your stopwatch says it should.

For example, make a 1, 2 or 3 axis move that has a total length of 10 inches at a feedrate of 10 inches per minute. The motion should stop exactly after 60 seconds.

If you are using the standard Camsoft variable \73 for feedrate, you can adjust this variable in your STARTUP.fil
\73 =333

This sets the initial boost of Camsoft's normal feedrate to 333% of normal. Trouble is, you have to take pains in the rest of your logic to return any feedrate override to this factor so that at normal feedrate, the \73 = 333

What I did was kept my feedrate override boost values in a new seperate variable, and set up logic to call in that new variable. Here is sample code from my INPUTIO.FIL that might help you with feedrate override, or it might confuse the heck out of you

IF#18=1THEN\318={\318+1} :GOTO :HOLD 'input18 is called "feedhold momentary pushbutton"
IF#17=1THEN\273={\273+.1} 'feedrate increase pushbutton located on right side of feedhold button
IF#19=1THEN\273={\273-.1} 'feedrate decrease pushbutton located on left side of feedhold button
IF\273<0THEN\273=0 'minimum feedrate override is zero, or equivalent to feedhold
IF\273>2THEN\273=2 'maximum feedrate override is 200%
\73={33.5*\273} : DISPLAY4 {\273*f} : DISPLAY2 {\273*100} 'when feedrate variable \73=33.5, actual commanded feedrate is at 100% by external clock.

One thing you might want to check first, is the servo update rate of your Galil card. Factory default is fairly slow at 1 millisecond, and it may be possible to get it down to .375 millisecond without loosing any features of the card. It is possible to decrease this setting, and I did and would recommend it as it improves system response. However, you will have to retune the motors.

In my case, I have to slow my feedrate variable \73 down by almost 66% by initializing it this way in the STARTUP.FIL:
\73 = 33.5

If your system is running 1/3 of normal speed, then maybe changing the servo update rate on your Galil card would make the system about right. You would still have to retune the motor PID filter though.

[alfalfa]

Thanks Hu,
For the sake of not only me but others on here - how does one adjust the servo update rate on a Galil card? Or is it better to talk to Galil directly?

[HuFlungDung]

You should have a manual that came with the Galil hardware.

Check for the TM command ( for the update rate) and the BN command (to burn the change into the memory on the card so it will start up at the new desired rate everytime you start up the PC).

There should be a simple Galil terminal interface that you can run independently of Camsoft to do this.

[Karl_T]

Here's a link to the command reference:
http://www.galilmc.com/support/manuals/optcom.pdf

A heads up on installing Galil software. It can hijack your system and Camsoft won't work anymore. Camsoft's first warning is to make sure you have up to date software.

If you already have Camsoft on your computer, installing Galil WILL kill it. This trick worked for me.

1. Install the Galil software after the Camsoft already on the computer.
2. Rename the AS3000 directroy to something else, I like AS3000 old <yymmdd>
3. Reinstall Camsoft.
4. Move anything you need out of the old Camsoft directory.

FWIW, I personnally wouldn't speed up the Galil board sample rate here. You don't have a need. Just change the \73 value in startup.ini. Good programming practice is make changes to another variable (Hu's approach) in the body of your .cbk

Karl

[alfalfa]

I have had no problems with running WSDK on top of Camsoft (not simultaneously though). That said, I do have the most current versions/drivers from Camsoft. I will take a look at /73, it just seems strange to me that a given machine, set up to move the correct distance as commanded, won't run at the right feedrate w/o a bunch of extra coding. Isn't this basic CNC control operation?

[HuFlungDung]

Yes, it is strange. I take it that you have double checked that a commanded movement of 10" actually gives you a movement of 10" in each axis that you test? I don't see why the gear ratios, if set up correctly should have any effect.

Did you purchase your Galil hardware in new condition? I'm wondering if for some reason, it may have had some parameters "burned in" to eprom by a previous user.

It might be a thought to do a master reset of the card. Again, this would be done within the Galil terminal program.

[HuFlungDung]

Karl,

I don't really know why Galil sends the cards out running in slow mode. It makes no sense to me. Compare it to buying a 3 ghz cpu and then running it at 1 ghz. I've been running mine for several years now at the max speed that card allows with all features still allowed, and it works fine.

[alfalfa]

Yes 10" = 10".

The card was not new, but I have done several Master Resets and even had it in for repair on a different issue (maybe?). Having talked to Camsoft, it seems that they acknowledge the issue, but implementing a fix is a little bit cumbersome at best.

[HuFlungDung]

Al,
Master reset should have put everything back to defaults, no question.

You can also use the command
TM ?
to find out what the current sample time is set at, just in case there is some funky value set in ROM on that card.

[Karl_T]

Originally Posted by HuFlungDung Al, Master reset should have put everything back to defaults, no question.

I just worked through an issue with a used Galil card where a couple Camsoft commands didn't work correctly. The master reset didn't correct things, this just sets default speed, accerations, etc.

An update firmware, downloaded for the Galil website, corrected the trouble. It only takes a minute, might be worth a shot.

Karl

[fseger]

have you found resolution to your problem - I seem to ran into the same thing you described?