VCP Feedrate override problem (stepmotor lossing steps) <don't run jobs above 100% override>

[helicop]

Hello all,

I am new with Centroid Acorn CNC with CNC12 software. I am very happy with stability and user friendly interface, and the posibility to change the VCP.

I have build my own DIY CNC router for cutting aluminium and wood, and almost everything works fine. I have one problem and that is the feedrate override button in the VCP. When I click a few times on the + button, the stepmotors are lossing steps.
When I am cutting aluminium on 1000 mm/sec, and I press a few times on the + button until 110% override, the stepmotors getting a very high step frequently, more then they can have. My DIY CNC router can handle 3000mm/sec without any problems. It looks that the 10% override is much more then 10% (may be 100%).

I am using nema23 stepmotors with high torque, and WANTAI DQ542MA step drivers.
In the attachment you can find my CNC12 report with pictures from my machine. I also attached 2 video's, one video working OK and one video with the problem when I press on de + button until 110%.

Are there more CNC12 users with the same problem?

Regards,

Thom

[CNCMaryland]

I'm interested in the answer as well.

I have experienced the similar, and I think that most will chime in and say what I have learned, and its not to use the override to go past 100%, its basically only to be used to go below 100%.

[Gary Campbell]

Probably not the answers you desire, but some questions that may lead you there.

1) How many amps are the motors you are using? Those LeadShine clone drives may only put out 3A RMS and your motors may require more than that to operate properly.
2) What voltage is the power supply running the drives? How many? What wattage?
3) What microstep setting are you using?

Are you sure that you're feedrate is 1000mm/sec? Looks more like 100

[IPGregory]

Watching with interest as I have similar problems with increasing the federate using the VCP. On mine it starts to bang and thud if I bump it with the federate and doesn't if it's a 'programmed' rate. I'm also running leadshine clones (Stepperonline CL57Ts and Nema23 4A motors on 36v/350w PSUs, 2 motors per PSU on 110v supply at 3200 steps).

I can run a 'programmed' 4000mm with no issues but if I bump the federate on say a 1000mm program using the VCP it will start to bang around at anything above say 110% or so.

[tblough]

Centroid's motion planner accounts for accel and decel at the programmed feedrate. By increasing the feedrate above 100% you are interfering with this optimization. It is better to program a feedrate that is faster than needed and slow the feedrate down than to try and increase it.

[IPGregory]

Good to know, thx Tom. I'm still in the 'learning/experimenting' with speeds and feeds place so using the override is something I am doing in the hunt for the 'sweet spot'.

[IPGregory]

To the OP, is it possible you have a similar problem to me? I am thinking my motors are not properly 'tuned' either in the Drivers or in the CNC12 SW and sometimes they will bang or thump during direction changes either in acceleration or deceleration. I am thinking that my setup is close to the edge in regard to normal operation and this causes the above. If we take Tom's point on the Federate override not using or messing up the Centroid motion planner, then this would push the motors harder on direction changes and in my case cause it to bang around and in yours to lose steps?

[cnckeith]

losing steps is caused by undersized axis motors, binding mechanicals, stepper motors not wires properly, stepper motors not being feed proper voltage and/or amps. Gary was pointing you the right direction.

[cnckeith]

and tom is correct. always run a G code program at 100% or LOWER on the feedrate override, if you want to go faster change the F command value in the G code. (simple search and replace with notpad ++ or go back to the cad/cam system and change the values)

[helicop]

I see this not as a solution to set the feedrate high and only use the feedrate override to lower the cutting speed. When CNC12 software has a problem with the + button, why didn’t remove the developers this button, or fix this problem?