jerky movement when in the g code view.

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avp
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Re: jerky movement when in the g code view.

Post by avp »

Great, that sounds easy enough. Thank you
Bill
avp
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Re: jerky movement when in the g code view.

Post by avp »

So I figured I would update this situation here since the new PC has been up and running for quite a while now. All is working well and I have everything dialed in good. I know some of you talked about the overall turns ratio that I have setup as way too low. What I am trying to understand is if the number that I have setup in the software is well below that "sweet spot" for routers I can't see how it could be a larger number. I calibrated the axis with the gauge blocks and lever style dial gauge like in Marty's video. All measurements are pretty much spot on. I don't see where the 2-1 reduction that I an using comes into play in the calculations. If I double the number for the overall turns ratio, my commanded distance as well any my federate doubles. The machine works perfect, I'm just curious .
Bill
Gary Campbell
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Re: jerky movement when in the g code view.

Post by Gary Campbell »

Bill...
When I design a stepper system for a router from scratch I shoot for a turns/inch number between 1.5 & 2.5 for the XY and around 5 for the Z. This is accomplished by adjusting the gear or belt reduction ratio and the pinion teeth or by belting down a ball screw.

So your answer is that you must change the mechanical reduction and then reset the turns/inch to match
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avp
Posts: 124
Joined: Fri Aug 13, 2021 12:25 pm
Acorn CNC Controller: Yes
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CNC Control System Serial Number: E062346A1C67-0716214939
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Location: New York

Re: jerky movement when in the g code view.

Post by avp »

Yes, I know the belt reduction changes the overall turns ratio, What I don't understand is why the .6367 that I have set as the overall turns ratio does not have to be entered at 1.2734 which is .6367 times two for the 2:1 belt reduction that I am using. I was under the impression that this number would be actual motor revolutions before the reduction which makes sense. I am eventually going to change over to a 3.2:1 reduction so I figured that would get me to an overall turns ratio of about 2.037 revolutions per inch at the motor shaft.
Bill
Gary Campbell
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Re: jerky movement when in the g code view.

Post by Gary Campbell »

Bill...
.6137 is the correct number for 2:1 reduction and a 20t pinion gear:
2 to 1 Rez Calc.JPG
The reason is as follows:
With a 20 T 20*pa pinion it's pitch diameter is 1". Circumference is 3.14. Revs/inch would be 1 / 3.14 or .3185. Since you have 2:1 reduction, yours is double that or .637
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avp
Posts: 124
Joined: Fri Aug 13, 2021 12:25 pm
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Re: jerky movement when in the g code view.

Post by avp »

Yeah, that is what I came up with as well. Thank you for your help. I was just confused because you and keith were saying that it is very low for good performance, which may be true but the machine works great and like I said I will be going to the 3.2:1 ratio so that will get me a little higher maybe 1.019 or so.
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