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Last night I was running my Practicalcnc router(steppers)

I was routing plastic, the roughing went o.k, (all linear paths) but when I was running the finish program the x axis was definitely losing steps after a bit.
The finish path was for a u-shaped part so the x would completely stop as the z fed vertical on both ends. I noticed that when the x would stat again there was a definite jerk into motion.
I dropped my accel way down to 50 to see if it was an accel problem. No difference?!

I tried the smothing (G09 S5, G09 S3) again no difference.

I check mechanical and didn't find anything.

I originally was running the file from a USB drive. I copied the file to the hard disc. re-booted and tried running from the HD. Still no Joy.

HELP please.

Regards,
Cutmore

[postalgbv]

what's your A setting on axisspec line of your X axis in your wincnc.ini? That is your acceleration for rapid and feed. If it's, say, a800, that means if your feed speed was 100ipm, it would take 1/8 sec to reach 100ipm speed. If it was a100, it would take 1 sec to reach full speed. Adjust that setting and see if it helps. I see no reason why your G09 should be lower than 5, as it can make it choppy going around curves. The higher G09, the smoother going through curves.

Also, you can add an F number in the axisspec if you don't have it. That give your feed speeds a different acceleration than rapids. Like you could have a400 and f200. For simple rapids it would take .25 seconds to reach 100ipm, and when running the actual feed cut, it would take .5 seconds.

it may help you. (ps, I have different router, but have had to tweak these settings for my router)

the accel setting at the top, I believe sets the velocity jump increment when accelerating. It doesn't set the actual acceleration. However, if you set it super low, like 2, you will force it to take so many velocity steps that it may trump your acceleration setting. It should be fine on 50 or whatever.

eric

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Thanks for the quick reply!
My A setting on X was 350. i set it to 50 last night and noticed no dif.+

Thanks for the tip on the F acel, I will look to see if that is set on my machine.
i will also have to look at the top accel.

Having a Practical machine means that I have needed to learn to tweak most settings!

What should have been an easy job turned into a 1a.m. project!

Thanks for the tips,
Cutmore

[postalgbv]

oh ok, you might not even have the 'accel' listed on you wincnc.ini file. I think it's default is 50, which I've found to be fine.

50 on axisspec a setting does seem pretty conservative. Mine F is 250 I think right now.. but from the factory they just had the A setting and it was like 1000, which was just too much for feeds to make accurate cuts. Only other thing I can think is maybe your accel is on these and it's high, like 200.. if it is, you can try lowering it very low and see how it changes. But I've found I didn't need to mess with the default on that one. Your mileage may vary.

[CNChelper]

Sounds to me either backlash or you have noise on the signal end of the drive. sometimes putting the computer on the same power source as the machine works real well and isolates ground issues.

thanks,

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Thanks for the replies,
I am heading home to test / make more junk!

Hopefully I will be back in action with you're help.

Thanks, Cutmore