Motor settings

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djreiswig
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Motor settings

Post by djreiswig »

Bulltear 4x8 table. C&CNC ethercut. Mach3.
I'm building a 4th axis rotary. I have the 5th motor expansion kit with the larger motor. I'm using a 10" 4 jaw chuck. Chain drive with 7.2:1 ratio.
I'm trying to figure out what to use for motor settings on the B axis. I have the steps set correctly at 14400, as I get 1 revolution when I ask for it. From my testing it seems like I have to set my acceleration really low to keep the motor from stalling or growling. Not sure how to determine the velocity to use.
My X & Y are V 600 A 35. Z is V 88.02 A 15.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
tcaudle
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Re: Motor settings

Post by tcaudle »

velocity is tricky because its the SURFACE velocity of t changes the bigger it gets. Depending on what rotary method you are using the calibration of the number of steps for one rotation
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Re: Motor settings

Post by tcaudle »

could be the issue . The MACH3 method was to recalibrate the steps per inch tot he circumference of the pipe not for one rotation. It requires you to recalibrate the Step per unit each time you change the pipe diameter. If you are using the SheetCAM Rotary Plasma plugin it handles things diffreently. It uses the steps for one rotation and in the POST you put in a scaling factor.
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djreiswig
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Re: Motor settings

Post by djreiswig »

Guess I forgot to mention I'm using SheetCam. Does there need to be some correlation between the Y and the B to make it cut correctly?
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
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acourtjester
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Re: Motor settings

Post by acourtjester »

that is handled by Mach 3 you slave one to the other.
slave.JPG

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djreiswig
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Re: Motor settings

Post by djreiswig »

B is my rotary axis. A & X are my gantry motors that are slaved.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
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Re: Motor settings

Post by BTA Plasma »

In mach it is about keeping your acceleration the same number with rotary. Depending on the weight of your assembly you may be at 10 for accel.
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djreiswig
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Re: Motor settings

Post by djreiswig »

So X,Y & the rotary should all have the same acceleration? I think with my chuck being so heavy it will have to be pretty low. What do I do for the velocity numbers?
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
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Re: Motor settings

Post by tcaudle »

You need to work backwards. You can only spin a stepper to about 600 RPM under a moderate load before it stalls. If you have a 7.2:1 stp down that equates to a max of 83.3 RPM before the motor stalls. The acceleration needs to be in the lower range on a heavy chuck with lots of inertia.

So if your velocity results in an RPM of over about 80 you will lose steps. You also are limited as to the number of steps you can produce on a parallel port systems (kernel speed) 80 RPM = 1152000 steps per minut = 19200 steps per second.
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djreiswig
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Re: Motor settings

Post by djreiswig »

Thanks Tom.
I tried spinning the chuck manually and it seem like an acc of about 6 makes the motor sound good when I speed it up quickly. So what should that make my velocity setting? I tried 50, but that was just a guess. I'm not sure how these settings relate to actual cutting.

I get the limits of the motor RPM, but I don't follow how the acc and vel numbers are determined. My table came preset from Matt at Bulltear and I haven't tuned on it any.

I have the ethercut, so assume the port limits are different.

I'm guessing on the rotary profile I will need to sync the x and y settings to match the limits of the B to get correct cuts. It's all so confusing. I've seen these questions asked before on the forum, but haven't found a simple explanation.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
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djreiswig
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Re: Motor settings

Post by djreiswig »

Still trying to figure this out.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
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Re: Motor settings

Post by BTA Plasma »

If acceleration is different your motors will be out of tune with each other...circles will be ovals...ect. In the Mach 3 plug in go to the settings tab and input your ratio and motor RPM (Try 800) this will set steps per, then go back to program run and test but then jump out on the last question when it asks you to home because it will look for a home switch which you do not have. Go to config/motor tuning and tune X, Y and B to the same acceleration....try 10. And your done. You CAN substitute B for Y if you use it to cut the material the long way and simply use it as Y axis substitution and use your regular sheetcam post. If you want to pipefit for sheetcam is available and it is SUPERB software. You will need to buy the rotary plug in for sheetcam, get a demo license for pipe fit, buy the pipe fit license and use the pipefit post for your tube cutting. You can also save the machine profile in options/machine/load-save. There are 2 ways to go. We used to support axis substitution but the pipefit software is so good it is included on new Rotacut add ons for Star Labs.
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djreiswig
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Re: Motor settings

Post by djreiswig »

Thanks for the explanation, Matt. I believe I have the steps per correct since I get one full rotation if I enter g0 b1 in the direct gcode input box. In the motor settings screens I can input the acceleration and velocity. If I set the acceleration too high on my rotary the motor sounds noisy. I'm just entering random numbers for the velocity. How is the velocity determined? Do both the acceleration and velocity need to match for all 3 axes? I have purchased the rotary plug-in from Les.
BTW: I do have a home switch on my rotary to enable alignment for square tubing.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
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