Hey all-
Question for you- I'm working on a linear carriage for my cutter head. I'm debating on the control for the carrier between stepper & servo/DC Motor. The stepper could be easier to use, but I'm wondering if the 'steps' are a bit too extreme vs a slow steady movement as provided by a DC setup. Even then I'm concerned about how much noise gearing would introduce.
Any thoughts?
Stepper vs Servo vs Geared DC
Moderators: piaptk, tragwag, Steve E., Aussie0zborn
Re: Stepper vs Servo vs Geared DC
Hi,
The answer will depend on several factors:
1. How are you planning to run the stepper? (e.g. micro step, sync AC motor sine drive, etc). What controller or chip set will you use?
2. Do you plan to direct drive the feed screw or will you use a belt? Any plans to mechanically isolate the stepper from the linear actuator?
3. Are you looking to do the 100:1 or more speed range directly or are you planning to have some sort of gear shifting or two motor system to cover the large speed range?
4. What performance level are you trying to meet? Can you tolerate a bit of stepper or motor noise getting cut to your disc during lead in and lead outs?
Mark
The answer will depend on several factors:
1. How are you planning to run the stepper? (e.g. micro step, sync AC motor sine drive, etc). What controller or chip set will you use?
2. Do you plan to direct drive the feed screw or will you use a belt? Any plans to mechanically isolate the stepper from the linear actuator?
3. Are you looking to do the 100:1 or more speed range directly or are you planning to have some sort of gear shifting or two motor system to cover the large speed range?
4. What performance level are you trying to meet? Can you tolerate a bit of stepper or motor noise getting cut to your disc during lead in and lead outs?
Mark
Re: Stepper vs Servo vs Geared DC
Thanks Mark-
1:Was thinking micro-steps would be the 'quietest' that steppers could be. Controller would be open really so far. Looking at using the Arduino as a system controller all in all, but this could be connected t any number of controllers dependent on the motor.
2: I've been thinking a belt drive for some isolation, although I bet that any slippage at all would mess things up & too tight would somewhat diminish the isolation of it.
3: Ideally, a single motor that could be reversed & ran at variable speeds. I'm not too concerned if it takes a bit of time to get back to a 'home' position, but certainly faster than the pitch it would be doing during cutting.
4: Less noise the better. While I doubt I can attain the quality of commercial operations, I'd like to eventually get closer to that than the quality you'd get doing impressions.
I'm looking for a solution that would best do the job with a minimum of noise added. I've been looking mostly at steppers/DC speed controlled motors, but am very open to suggestions. I'm looking at this from the perspective that what would effect a playback setup would ultimately share those issues with recorders.
I also may be looking at things too 'big' - How much torque is even needed to pull the cutting head across?
1:Was thinking micro-steps would be the 'quietest' that steppers could be. Controller would be open really so far. Looking at using the Arduino as a system controller all in all, but this could be connected t any number of controllers dependent on the motor.
2: I've been thinking a belt drive for some isolation, although I bet that any slippage at all would mess things up & too tight would somewhat diminish the isolation of it.
3: Ideally, a single motor that could be reversed & ran at variable speeds. I'm not too concerned if it takes a bit of time to get back to a 'home' position, but certainly faster than the pitch it would be doing during cutting.
4: Less noise the better. While I doubt I can attain the quality of commercial operations, I'd like to eventually get closer to that than the quality you'd get doing impressions.
I'm looking for a solution that would best do the job with a minimum of noise added. I've been looking mostly at steppers/DC speed controlled motors, but am very open to suggestions. I'm looking at this from the perspective that what would effect a playback setup would ultimately share those issues with recorders.
I also may be looking at things too 'big' - How much torque is even needed to pull the cutting head across?
Re: Stepper vs Servo vs Geared DC
Hi,
I've used the Stealth Chop mode of the Trinamic TMC2100 with good results. Check out the datasheet for more info. The SilentStepStick
https://shop.watterott.com/SilentStepStick-TMC2100-5V-V2_1
uses this chip mounted on a breakout board that will drop into a Pololu A4988 socket that you find on the typical RAMPS Arduino shield.
Most of the torque needed will be to move linear actuator. There is not much extra torque needed to do the cutting.
The noise problems will be most noticeable during high speed moves rather than cutting. The step rate gets up into the audible range during these times and you are typically cutting a silent groove during lead ins and lead outs. So the noise is more noticeable. On my direct drive setup, the stepper runs from .35 RPM when doing 300 LPI while cutting at 33.333 RPM platter speed all the way up to 83 RPM during homing (over a 200:1 speed range). That would take some doing using a DC motor.
I would try the stepper approach first and see if you can get the performance you desire. The cost of a good DC servo will be much higher.
Mark
I've used the Stealth Chop mode of the Trinamic TMC2100 with good results. Check out the datasheet for more info. The SilentStepStick
https://shop.watterott.com/SilentStepStick-TMC2100-5V-V2_1
uses this chip mounted on a breakout board that will drop into a Pololu A4988 socket that you find on the typical RAMPS Arduino shield.
Most of the torque needed will be to move linear actuator. There is not much extra torque needed to do the cutting.
The noise problems will be most noticeable during high speed moves rather than cutting. The step rate gets up into the audible range during these times and you are typically cutting a silent groove during lead ins and lead outs. So the noise is more noticeable. On my direct drive setup, the stepper runs from .35 RPM when doing 300 LPI while cutting at 33.333 RPM platter speed all the way up to 83 RPM during homing (over a 200:1 speed range). That would take some doing using a DC motor.
I would try the stepper approach first and see if you can get the performance you desire. The cost of a good DC servo will be much higher.
Mark
Re: Stepper vs Servo vs Geared DC
Brilliant info, thanks! I might go the stepper route then. I do have a servo that may be suitable, an old TV antenna rotator. Loads of torque, but as mentioned not very flexible in terms of speed. A ribbed belt could take care of any belt tension issues as well i guess. Lots to be done still.
What servo are you using? One of the NEMA-17's (I think) or something else?
What servo are you using? One of the NEMA-17's (I think) or something else?
Re: Stepper vs Servo vs Geared DC
I'm also using a steppermotor, right now a NEMA17 with 1.8° Steps.
There is also a NEMA17 with 0.9° Steps which would be even better and quieter.
I also run a shaft coupling filled with silicone to further lower the vibration caused by the stepper.
I also began with an arduino mega but soon found out that it's having troubles with running higher rates (lots of steps/mm when running 1/16 step mode).
I changed to a teensy 3.2 microcontroller which works perfectly and suppports much higher rates, you can program it in the arduino IDE and most libraries work as well.
The other great thing (possibly) would be 5-phase stepper motors - but it's getting more costly there and less people using it (not sure about arduino integration):
https://www.orientalmotor.com/stepper-motors/5-phase-stepper-motors.html
vinyl rock!
-Markus
There is also a NEMA17 with 0.9° Steps which would be even better and quieter.
I also run a shaft coupling filled with silicone to further lower the vibration caused by the stepper.
I also began with an arduino mega but soon found out that it's having troubles with running higher rates (lots of steps/mm when running 1/16 step mode).
I changed to a teensy 3.2 microcontroller which works perfectly and suppports much higher rates, you can program it in the arduino IDE and most libraries work as well.
The other great thing (possibly) would be 5-phase stepper motors - but it's getting more costly there and less people using it (not sure about arduino integration):
https://www.orientalmotor.com/stepper-motors/5-phase-stepper-motors.html
vinyl rock!
-Markus
Re: Stepper vs Servo vs Geared DC
I am using smc LXf/LC6D p.1 (LX-LC6D) stroke 100mm with Microstep Driver DM556, minimum currents, minimum step resolution 1/256, stepper motor almost inaudible. I also use a rubber vibration isolation before attaching the head. Arduino GRBL cnc control, GCODE from a computer, full control of any movements, the ability to realize not only the movement of the head with all spirals, but also the raising / lowering of the head