Tom, 4.31s solved the problem I was having with backlash. Thanks. Jack From: DynoMotion@yahoogroups.com [mailto:DynoMotion@yahoogroups.com] On Behalf Of Tom Kerekes
Sent: Tuesday, March 04, 2014 8:37 PM
To: DynoMotion@yahoogroups.com
Subject: Re: [DynoMotion] Radius to end of arc differs from radius to start [2 Attachments] Please try the latest Test Version we have had bugs in the Backlash Compensation. Regarding BACKLASH_LINEAR: They are both the same. One just gives a symbolic name to the value of 1. PC-DSP.h has // Backlash Compensation Options
#define BACKLASH_OFF 0
#define BACKLASH_LINEAR 1
Thanks for the quick response Tom, I’m running 4.3 driving an open loop stepper system. My mistake, 1599 steps/inch. What is the difference between: ch0->BacklashMode=BACKLASH_LINEAR; What Version are you running? Did you mean to say 1599 steps/inch? What is your configuration? ch0->BacklashMode=BACKLASH_LINEAR; It is simplest to let KMotion.exe generate the C Code for you. I thought I had this figured out the other day but now it doesn’t seem to be working correctly. I’m running with 1599 steps/rev. This is working very well. I have .004 of backlash, this is very consistent. 1599 X .004 = 6.4 so that’s what I entered in the backlash amount. Using your suggestion below 6.4/.020= 320 so that’s what I loaded under rate. It doesn’t seem to make any difference. I’ve run the amount from 1 to 100. The rate from 10 to 2000 (bad things start to happen at 2000). Here’s the code I’m using: The help menu says something about usingBbacklash Mode_Linear but I get a compiler error. What is the proper syntax for this? What am I doing wrong? Hi Jack,
I'm not sure there is any exact way to calculate it. It depends on your system. KFLOP corrects backlash using a ramp function. If the backlash is taken out too fast it might shock your system and give poor results. If the backlash is taken out too slowly then then position will be wrong for a while before it is corrected. If you know the time period over which you would like the correction to take place divide the amount by the time to get the rate. So for example to have a backlash amount of 50 steps corrected in 20 milliseconds the rate would be:
50 / 0.020 = 2500 steps/sec
Good luck
Regards
TK How do you calculate Backlash Rate? Hi Jack,
Sorry KMotionCNC only supports relative I J arc centers. Most all CAM packages support that mode does yours?
Regards
TK I finally have my CNC router with a Kflop up and operational, sort of. I'm generating my G code in a CAM package and then running it through my KmotionCNC. I ran 6 programs and they all ran perfectly (none of them had a G2 command) but the 7th one stopped on line 90:
N0G90
N10(End Mill 0.25 inch)
N20M6T1
N30M3 S12000
N40G0 X0.7500 Y0.7500 Z0.2000
N50G1 Z-0.1250 F30.0
N60G1 Y3.3125 F100.0
N70 Y4.0625
N80 Y8.2500
N90G2 X0.8750 Y8.3750 I0.8750 J8.2500
N100G1 X1.8125
N110 X2.5625
N120 X5.1250
N130G2 X5.2500 Y8.2500 I5.1250 J8.2500
With an error message that says "Radius to end of arc differs from radius to start".
The math on line 90 looks ok to me. I'm using abs Coordinates. Machine Coord is unchecked. Help!!
Jack  
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