Dynomotion

Group: DynoMotion Message: 4306 From: tig415 Date: 3/25/2012
Subject: Crusader 2 conversion
Hi

I have an Alliant mill with a Crusader 2 system that I did a conversion on. This was in 2004 and conversion choices were somewhat limited. I used Rutex 0/10v drives and initially used the existing glass scales. The drives would hunt between the counts on the scale so the axis were always pulsing back and forth when at idle. The X axis had a scratch in it which obviously caused position issues. I ended up installing rotary encoders and have been pretty much making decent parts since then.
As fate would have it I just ended up with a Bridgeport series 2 with the same exact Crusader system. At $500.00 I just couldn't say no :) I got it from one of my customers and it worked when they removed it from service.

I use Mach3 as my control software.

My plan for this conversion is to use the Kflop and the Kanalog boards. I'm hoping for a conversion that yields better accuracy.

My questions are:
Will I have the same problem with the axis hunting between counts?
Has anyone ever done a Crusader conversion with Kflop and the Kanalog boards.
If I wanted to add a separate step and direction drive as a 4th axis would this be possible.

Thanks
Derek
Group: DynoMotion Message: 4307 From: tmday7 Date: 3/25/2012
Subject: Re: Crusader 2 conversion
Hello Derek,
I have not done a Crusader conversion, but have used the Kflop board on two mills. Both with awesome results. These 2 mills have stepper motors and use the Glass scales to close the loop. Neither machine has done the "dithering" that your talking about. I once had this same issue with the 1st mill's old control,VERY irritating to say the least.

Control software is also Mach3 on both machines.

Tom from Dynomotion would be able to answer better than i. He will more than likely chime in soon. Also excellent support from Dynomotion.

HTH
Troy

--- In DynoMotion@yahoogroups.com, "tig415" <tig416@...> wrote:
>
> Hi
>
> I have an Alliant mill with a Crusader 2 system that I did a conversion on. This was in 2004 and conversion choices were somewhat limited. I used Rutex 0/10v drives and initially used the existing glass scales. The drives would hunt between the counts on the scale so the axis were always pulsing back and forth when at idle. The X axis had a scratch in it which obviously caused position issues. I ended up installing rotary encoders and have been pretty much making decent parts since then.
> As fate would have it I just ended up with a Bridgeport series 2 with the same exact Crusader system. At $500.00 I just couldn't say no :) I got it from one of my customers and it worked when they removed it from service.
>
> I use Mach3 as my control software.
>
> My plan for this conversion is to use the Kflop and the Kanalog boards. I'm hoping for a conversion that yields better accuracy.
>
> My questions are:
> Will I have the same problem with the axis hunting between counts?
> Has anyone ever done a Crusader conversion with Kflop and the Kanalog boards.
> If I wanted to add a separate step and direction drive as a 4th axis would this be possible.
>
> Thanks
> Derek
>
Group: DynoMotion Message: 4308 From: Tom Kerekes Date: 3/25/2012
Subject: Re: Crusader 2 conversion
Hi Derek,
 
I don't know of anyone specifically who has made that conversion.  Limit cycle hunting is always a problem with servos.    It is actually a very complex nonlinear problem that depends on the mechanics of your system - stiction, friction, compliance, resonances, etc.  The best defense is to have really high resolution encoders.  I think we have some of the best tools for observing and minimizing the effect (Filters, deadband) but it can still be a problem.
 
Servo hunting and servo stability is most difficult where there are lots of components in the control loop such as with glass scale feedback.  A second feedback device at the motor such as a tachometer or encoder can help a lot.  You should be able to get your glass scale feedback working.
 
Yes you can have a 4th Step/Direction drive.
 
Regards
TK

Group: DynoMotion Message: 4309 From: Brad Murry Date: 3/25/2012
Subject: Re: Crusader 2 conversion
Hello Troy,

I am having trouble remembering where your testing wound up on the HTML
controller. Does it work on your machine?

Thanks,
-Brad Murry

Group: DynoMotion Message: 4310 From: tmday7 Date: 3/25/2012
Subject: Re: Crusader 2 conversion
Hay Brad,
I posted it on the CNC forum, actually just asked you about it the other day. :)
http://www.cnczone.com/forums/dynomotion_kflop_kanalog/146320-kmotion_cnc_net-2.html

Thanks,
Troy

--- In DynoMotion@yahoogroups.com, Brad Murry <bradodarb@...> wrote:
>
> Hello Troy,
>
> I am having trouble remembering where your testing wound up on the HTML
> controller. Does it work on your machine?
>
> Thanks,
> -Brad Murry
>
Group: DynoMotion Message: 4315 From: tig415 Date: 3/25/2012
Subject: Re: Crusader 2 conversion
Thanks for the replies everyone.
I guess step one is to see if I can get motion with the existing system so I can see where I'm at. The Crusader system uses glass scales and tachometers so hopefully it should be a nice conversion. Fortunately this is a second machine so I don't have the pressure to get it going that I had on the first conversion.

Derek