aceeleration in .nc code

[cnckeith]

you need to do two things to get this machine running fast and smooth.

1.) steps per rev for the drive should be 1600 or higher, follow the drive instructions to set them up properly. and then set the Acorn wizard to match.

2.) as a good rule of thumb... overall turns ratio on a rack and pinion CNC machine should not exceed 25mm of linear movement per one revolution of the axis motor shaft (using any cnc control, not just Acorn) for good all around performance. (there are exceptions to this but they are special cases)

most rack and pinion systems should have at least a 3:1 belt reduction or better yet a double belt reduction yielding 6:1. there are also some nice zero lash 5:1 gear boxes which work for this application as well.

what make, model , size motors and drives are being used?
post photos and specs of the machine and its components

[cnckeith]

I have lied to the program because I can not add the value of 125 mm (what is the real progress in my transmission, for each revolution of the engine), but that brings me the problems. How do I enter a value greater than 39 in the overall turn radio?

follow my instructions and set the steps per rev correctly.. that has to be done first.

[claudio]

Dear, modify the values and the operation improved a lot, but as expected, travel 4 times more distance than it should,
To put a reduction on my machine is to redesign it again and it is not viable, if you tell me that I can not put 126.5 or another larger value in overal turn ratio, I should get this control out.
previously I used this equipment with mach3 and it worked perfectly
it's a shame not being able to fix this parameter without having to redesign the machine
I attached the current report
best regards

[claudio]

there are also some nice zero lash 5:1 gear boxes which work for this application as well.

to take into account in future designs of my machines, what brand can you recommend me of planetary gearboxes without back lash?

[Centroid_Tech]

To put a reduction on my machine is to redesign it again and it is not viable, if you tell me that I can not put 126.5 or another larger value in overal turn ratio, I should get this control out.
previously I used this equipment with mach3 and it worked perfectly
it's a shame not being able to fix this parameter without having to redesign the machine

The issue isn't with the control. It's with the setup of the control.

Looking at your report, you increased the Encoder Counts/Rev from 200 to 800 but yet your Motor MM/Rev field only changed from 29.97 to 27.8758 which doesn't make sense. If commanded a move of 100mm previously and the machine physically moved 100mm then that means that the combination of the axis pitch and encoder counts per revolution were somewhat set correctly for positioning purposes. As far as having any kind of smooth motion, however, wasn't achievable as you only have 200 encoder counter per revolution of the motor, which was causing the issue that you were seeing. That is why cnckeith suggested an Encoder Counts/Rev field of at least 1600. Is that not possible with the drives that you are using?

It appears that you may have overlooked the section of that post that talks about setting the pitch or the overall turns ratio of an axis . Once the Encoder Counts/Rev field is correctly set then you have to correctly set the pitch of that axis. As far as the positioning is concerned, you essentially multiplied the Encoder Counts/Rev field by a factor of 4. In order to be able to get to the same physical location on the machine, you have to divide the existing pitch, Motor MM/Rev field, by a factor of 4. That means that the pitch of your axes would be 29.9 / 4 = 7.475mm/rev.

[cnckeith]

Dear, modify the values and the operation improved a lot, but as expected, travel 4 times more distance than it should,
To put a reduction on my machine is to redesign it again and it is not viable, if you tell me that I can not put 126.5 or another larger value in overal turn ratio, I should get this control out.
previously I used this equipment with mach3 and it worked perfectly
it's a shame not being able to fix this parameter without having to redesign the machine
I attached the current report
best regards

you can not put the larger turns ratio value in since the steps per rev is still too low.. 800 is not
in your case you'll probably need to be at least 3200 , and then you can put in larger overall turns ratio.
also increasing the step frequency to 400khz (if your drives can handle it) will allow a larger turns ratio number.

what make model of axis motors and drives are you using?

[cnckeith]

What is the pitch of the rack?

And how many teeth are on the pinion?

[claudio]

The pitch rack is 1mm and the pinion have 40 teeth,
the result is an advance 126,5 mm per revolution

Yesterday put in 5000 step in my driver and acorn, butbut still I do not let me put in overall turn ratio a value higher to 39.4, this value should replace it by 126.5mm which is the real mechanical advance that I have. now the machine works smooth and silent, but it is not serrated correctly, as it can not change the overall turn ratio
how can I not add mechanical reducers, the only thing I need is that they allow me to add the value of 126.5 mm, and that will be the end of my problems. Or tell me if this value is not possible to change it for one greater than 39 ??

[cnckeith]

yes it is possible.
post a fresh report.zip file please

what make model of axis motors and drives are you using?

please post photos as well.

is the pinion 40 teeth? or 40mm pitch diameter?

[claudio]

yes it is possible

it would make me very happy !!!!


piñon external diameter :42mm
number of teeth :40
pich : 1 mm

driver model 2hss86h Hybrid Step Servo ( set 5000 step per revolution)

motor model : 86j18156EC-1000-ls-14-HBL ( 12 Nm each one)