Re: Suggestions for mounting stepper Z
#MODS
This was my approach.? I bought a surplus South Bend 10L lead screw holder and milled some of it away so I could fit an extension to hold the pulley. 
Then cast a couple of brackets and set them at right angles to hold the motor nicely out of the way. ? 
? The belt takes care of any alignment issues.? I'm going to try the 400W Bergerda AC servo and I'll just have to change the one bracket and maybe get or make a pulley with the correct bore size.? With the AC servo that has a max RPM of 3000 I think I'll stay with 2:1 reduction.? I'll still end up with 4x the current speed. ? John Dammeyer ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Ralph Hulslander
Sent: February-01-20 1:01 PM
To: [email protected]
Subject: [digitalhobbyist] Suggestions for mounting stepper Z #MODS? Craftsman 12x36 lathe.
The motors fit an angle NEMA 23 stand or I could make up something.
Any ideas?
Appreciate any help.
Ralph
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Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Suggestions for mounting stepper Z
#MODS
Craftsman 12x36 lathe.    The motors fit an angle NEMA 23 stand or I could make up something. Any ideas? Appreciate any help. Ralph -- Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Hi, Barry, Yes, that is an interesting setup, and it does lend itself to the addition of a simple CSS system. But you originally said you wanted to avoid using an Arduino. It should be possible to implement some form of CSS using the Arduino and some additional sensors. But implementing the Arduino speed control requires some electronic design and assembly. Whether someone would consider it a major or minor project depends on the degree of expertise and available components, etc. Do you want to go down that path? If so, do you have someone down there is Oz who can help with assembling the electronics needed?? -- Regards, Charlie New Jersey, USA
LAW OF ANNOYANCE: When working on a project, if you put away a tool that you¡¯re certain you¡¯re finished with, you will need it instantly.
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Re: Step #1 Encoder
#RELS
Ant, do you have a link for "
Variable step rates controlled on the fly by SPI are a common feature on drivers currently available."? What drivers? Everything I am seeing are only set by switches when the motor is not turning or powered. I need 3 - 5 amp drivers and would love dynamic? step control.
Ralph
If I've understood correctly you can beat the 700rpm speed limit by changing from microsteps to full steps? Does it take full steps or could you get away with a low microstep rate such as two or four? Variable step rates controlled on the fly by SPI are a common feature on drivers currently available.
Seems as though gearing for increased tourque is also gearing for increased precision. Obviating the need for microsteps? Obviating the 700rpm limit?
What I find interesting about these new closed loop drivers is that they use a simple diametric disk magnet (North and South are diametrically opposite sides of the disk, not the flat faces of the disk) with a clever sensor chip that measures multiple magnetic field properties to create the equivelant of a 32k line per rev encoder.
Seems like that should be transferable tech. You can buy the driver without the motor now.
The only issue can be getting the diametric disk precisely centred on the end of the motor shaft. Prolly trivial for the skill sets you have.
There is debate how essential this is. The calibration procedure sets things up after all. People claim that when used for 3d printing, the cheaper MKS motor sets, selling for $20, produce a moir¨¦ surface artifact known as salmon skin.
Speculation varies from thinking centering the magnet, PID tuning,? or skimping with a different magnetic sensor chip and? less well filtered circuit are the cause.
The $50 ones from originators, MisfitTech don't appear to have the problem.
They use this sensor chip:
The TLE5012B is a 360¡ã angle sensor that detects the orientation of a magnetic field. This is achieved by measuring sine and cosine angle components with monolithic integrated Giant Magneto Resistance (iGMR) elements. These raw signals (sine and cosine) are digitally processed internally to calculate the angle orientation of the magnetic field (magnet).
I'm not sure it matters in this application anyways but...
Further research while writing this provided a possible cheap fix for the cheaper motors. Eight diodes per motor avoid the moir¨¦ effect. Was for same effect on different driver though.
There are a couple of alternative explanations of why it works in the comments. I'd be interested in any opinions anyone here has on which is the better explanation.
This method appears to provide? high resolution? encoder feedback at trivial cost. Eliminating the need for expensive optical encoder disks and replacing them with a more robust solution.
Looks like the future of servo feedback to me.
Ant?
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Re: Step #1 Encoder
#RELS
If I've understood correctly you can beat the 700rpm speed limit by changing from microsteps to full steps? Does it take full steps or could you get away with a low microstep rate such as two or four? Variable step rates controlled on the fly by SPI are a common feature on drivers currently available.
Seems as though gearing for increased tourque is also gearing for increased precision. Obviating the need for microsteps? Obviating the 700rpm limit?
What I find interesting about these new closed loop drivers is that they use a simple diametric disk magnet (North and South are diametrically opposite sides of the disk, not the flat faces of the disk) with a clever sensor chip that measures multiple magnetic field properties to create the equivelant of a 32k line per rev encoder.
Seems like that should be transferable tech. You can buy the driver without the motor now.
The only issue can be getting the diametric disk precisely centred on the end of the motor shaft. Prolly trivial for the skill sets you have.
There is debate how essential this is. The calibration procedure sets things up after all. People claim that when used for 3d printing, the cheaper MKS motor sets, selling for $20, produce a moir¨¦ surface artifact known as salmon skin.
Speculation varies from thinking centering the magnet, PID tuning,? or skimping with a different magnetic sensor chip and? less well filtered circuit are the cause.
The $50 ones from originators, MisfitTech don't appear to have the problem.
They use this sensor chip:
The TLE5012B is a 360¡ã angle sensor that detects the orientation of a magnetic field. This is achieved by measuring sine and cosine angle components with monolithic integrated Giant Magneto Resistance (iGMR) elements. These raw signals (sine and cosine) are digitally processed internally to calculate the angle orientation of the magnetic field (magnet).
I'm not sure it matters in this application anyways but...
Further research while writing this provided a possible cheap fix for the cheaper motors. Eight diodes per motor avoid the moir¨¦ effect. Was for same effect on different driver though.
There are a couple of alternative explanations of why it works in the comments. I'd be interested in any opinions anyone here has on which is the better explanation.
This method appears to provide? high resolution? encoder feedback at trivial cost. Eliminating the need for expensive optical encoder disks and replacing them with a more robust solution.
Looks like the future of servo feedback to me.
Ant?
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? Charles, ?????????????? Well Xmas done well and good? for anther year,had a few bush fires to keep us on our toes how did your celebrations go in the big smoke , came across these files from Digital machinist,are they of any use re CSS under PWM ? ? ? ? ? ? ? ?
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From: [email protected] <[email protected]> On Behalf Of CLevinski
Sent: Wednesday, 25 December 2019 7:42 PM
To: [email protected]
Subject: [digitalhobbyist] Merry Christmas! ? Best wishes to all for a Merry Christmas!
--
Regards,
Charlie
New Jersey, USA
MURPHY'S CONSTANT:?Matter will be damaged in direct proportion to its value.
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Re: Finally finished assembly...
#RELS
A very nice job.
The benefits are enormous,
Well done to you and Richard UK.
--
John
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Finally finished assembly...
#RELS
Hello, All, I haven't been on the site much, as I have been working trying to finish my RELS construction. I finally got it done, but not yet debugged. Photo below is of the "smoke test", where I powered it up for the first time. There are some issues, which I will sort out in the next few days, and then I hope to connect it to the lathe and actually make something move! Stay tuned!  -- Regards, Charlie New Jersey, USA
LAW OF SELECTIVE GRAVITY: An object will fall so as to do the most damage.
JENNING¡¯S COROLLARY: The chance of the bread falling with the buttered side down is directly proportional to the cost of the carpet.
KLIPSTEIN¡¯S COROLLARY: The most delicate component will be the one to drop.
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Re: Step #1 Encoder
#RELS
The math is pretty simple.? Assume at 700 RPM you still have enough torque to move the table against the cutting load (unlikely unless the motor is large enough). ? At 700 RPM with 0.1" per rev it's 70 inches per minute.?? ? Here's what machinist toolbox comes up with for cast aluminium. ? And comes up with Cast aluminum | Sand and permanent mold casting alloys | 165 |
? Less than 1/2 horsepower, 1260 RPM and 16.64 ipm. ?That's also been demonstrated by lots of small mills with direct coupled stepper motors having no problem milling aluminium.? And it's at a much lower RPM where the torque is much higher.? Also directly coupled 10 TPI still gives a repeatable 0.0005" positioning? (0.1"/rev divided by 200 steps/rev) ? That mill with a 5 TPI pitch screw directly coupled is now 0.001" repeatable resolution and requires twice the torque since the reduction is 1/2 of the 10 TPI. ?All things being equal you'd need a motor with twice the torque. ? 
? ? I'm running the X axis on my mill (5 TPI) with 3:1 pulley reduction and a 250 line encoder on a DC servo. ?That's 3000 lines per 0.2" or a resolution of 0.00006667" and could run as high as 200 ipm.? The motor torque rating is 226 oz-in (678 at the lead screw) with a peak torque of 3375 oz-in.? I've also run it with a Bergerda AC Servo 1.27N.m? (180oz and 538 oz-in at the lead screw) with again peak torque values way above that. ? Nicest thing about the AC and DC servos is they are so quiet and can move the table so fast for rapid position for say tool changes etc. John ? ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of BuffaloJohn
Sent: January-10-20 4:00 PM
To: [email protected]
Subject: Re: [digitalhobbyist] Step #1 Encoder? Need to do the math - 700 rpm with a 10:1 pitch lead screw means the lead screw is turning at 70 rpm, close to 1 rps - do the math to see if there is enough speed to do what you want, or enough torque to do what you need... ? That's interesting information, thank you. I mean the whole post but didn't want to quote it all for brevity.
I kinda understand as I'm familiar with some of the concepts already but I'll have to re-read it a few times and maybe read around as well.
My question is still what speeds do you really need at what torque? How fast would you want to move a cutting tool???
On Tue, Jan 7, 2020 at 02:10 PM, John Dammeyer wrote: Micro-steppers tend to run out of torque at around 700 RPM in general.? It's the physics of the design.?
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Re: Step #1 Encoder
#RELS
Need to do the math - 700 rpm with a 10:1 pitch lead screw means the lead screw is turning at 70 rpm, close to 1 rps - do the math to see if there is enough speed to do what you want, or enough torque to do what you need...
Buffalo John
That's interesting information, thank you. I mean the whole post but didn't want to quote it all for brevity.
I kinda understand as I'm familiar with some of the concepts already but I'll have to re-read it a few times and maybe read around as well.
My question is still what speeds do you really need at what torque? How fast would you want to move a cutting tool???
On Tue, Jan 7, 2020 at 02:10 PM, John Dammeyer wrote:
Micro-steppers tend to run out of torque at around 700 RPM in general.? It's the physics of the design.?
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Re: Step #1 Encoder
#RELS
That's interesting information, thank you. I mean the whole post but didn't want to quote it all for brevity.
I kinda understand as I'm familiar with some of the concepts already but I'll have to re-read it a few times and maybe read around as well.
My question is still what speeds do you really need at what torque? How fast would you want to move a cutting tool???
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On Tue, Jan 7, 2020 at 02:10 PM, John Dammeyer wrote:
Micro-steppers tend to run out of torque at around 700 RPM in general.? It's the physics of the design.?
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Re: Step #1 Encoder
#RELS
Sorry.? Meant to type Size 17.? ? My router uses size 23 micro-stepped to 1600 steps per rev onto 10TPI lead screws.? Even with full steps that's still 0.0005" position accuracy. ? The Mill has a ?Size 34 1200 oz-in on the knee and Size 34 Brushed DC Servos on XY ?motors good to 3000 RPM and 225 oz-in constant torque but peak torque to 1125 oz-in. ? The mill can do 200 ipm on the X axis and 150 ipm on the Y but that's scary fast for all that metal. ?I have it throttled back to 150 and 120 ipm. ? Oh and the encoders are set for 250 lines or 1000 pulses per rev of the motor. ?With the 3:1 toothed belt reduction that's 3000 per 0.2" on the X and 4000 per 0.2 on the Y. ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Ralph Hulslander
Sent: January-07-20 5:26 PM
To: [email protected]
Subject: Re: [digitalhobbyist] Step #1 Encoder? What is a "size 15" motor?? ? On Tue, Jan 7, 2020 at 8:19 PM John Dammeyer <johnd@...> wrote: My first 3D printer was built in summer of 2014.? An extruder fastened in place of the router on a JGRO self built CNC router.? I used MACH3 to interpret the Repetier sliced G-Code. ? The results were by no means attractive.? I learned a few things from that experiment.? My CNC router wasn't quite fast enough.? A heated bed was essential. And finally, the more mass has to start and stop the more shaking.? A CNC router, and this is a flimsy implementation, isn't designed for the rapid movement of a 3D printer.? ? The printer would have to be a belt drive and some of the frame wobbliness would have to be changed.? But in either case, the more mass, the bigger the motors and then again more mass to keep the vibration down.? The current crop of 3D printers use size 15 motors and small hardware for a very good reason. John Dammeyer ? ? ? ? Of course for 3D printing movement is more important than torque.
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Re: Step #1 Encoder
#RELS
What is a "size 15" motor??
On Tue, Jan 7, 2020 at 8:19 PM John Dammeyer < johnd@...> wrote: My first 3D printer was built in summer of 2014.? An extruder fastened in place of the router on a JGRO self built CNC router.? I used MACH3 to interpret the Repetier sliced G-Code. ? 
? The results were by no means attractive.? I learned a few things from that experiment.? My CNC router wasn't quite fast enough.? A heated bed was essential. And finally, the more mass has to start and stop the more shaking.? A CNC router, and this is a flimsy implementation, isn't designed for the rapid movement of a 3D printer.? ? The printer would have to be a belt drive and some of the frame wobbliness would have to be changed.? But in either case, the more mass, the bigger the motors and then again more mass to keep the vibration down.? The current crop of 3D printers use size 15 motors and small hardware for a very good reason. John Dammeyer ? ? ? ? Of course for 3D printing movement is more important than torque.
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Re: Step #1 Encoder
#RELS
My first 3D printer was built in summer of 2014.? An extruder fastened in place of the router on a JGRO self built CNC router.? I used MACH3 to interpret the Repetier sliced G-Code. ? 
? The results were by no means attractive.? I learned a few things from that experiment.? My CNC router wasn't quite fast enough.? A heated bed was essential. And finally, the more mass has to start and stop the more shaking.? A CNC router, and this is a flimsy implementation, isn't designed for the rapid movement of a 3D printer.? ? The printer would have to be a belt drive and some of the frame wobbliness would have to be changed.? But in either case, the more mass, the bigger the motors and then again more mass to keep the vibration down.? The current crop of 3D printers use size 15 motors and small hardware for a very good reason. John Dammeyer ? ? ?
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Re: Step #1 Encoder
#RELS
Of course for 3D printing movement is more important than torque.
Ralph
On Tue, Jan 7, 2020 at 5:10 PM John Dammeyer < johnd@...> wrote: Micro-steppers tend to run out of torque at around 700 RPM in general.? It's the physics of the design.? Two things have to happen to make them turn.? You have to change the direction of the current through the windings.? The back emf from the RPM which is what limits standard DC motors is the second problem. ? Think of it this way.? Turn a DC motor at a specific speed and as a generator it produces a voltage.? If the applied voltage is say 12V then that generator voltage rises to 12V and that's what holds the motor speed to a given RPM. ?Increase the applied voltage to increase the speed until the back emf matches again and the speed stays steady. ? Stepper motors have very low voltage windings and use current feedback to determine when to shut off the voltage.? That's when the drive starts chopping the power to hold the current at a given value and that torque (amp x turns) is what you get to rotate the armature.? But now you have to reverse the current through the windings and if the motor is turning it's generating that back EMF.? ? Plus the current through the winding has to decay (inductance slows that) before it can reverse. The more pressure? (voltage) the faster the change in current.? That's why stepper motors with 1.5V windings have 24V power supplies.? But at a certain RPM the back EMF matches that power supply voltage and it takes too long to reverse the current in the windings before the next step.? End result no torque. Motor locks up. ? So even with an encoder, you still have speed limitations.? And, BTW, the motors with encoders come in larger than size 17.? I used one with a gearbox on the end of it as size 23 and 400oz-in with an encoder built in.? Used CANopen messaging for control. Real sweat motor.? Still not more than about 700 RPM before there were issues. ? OTOH, the Bergerda AC Servos down side is they require 220VAC so you can't run them on 110VAC or a 24VDC battery system.? But with the 2500 line encoder they run 3000 RPM.? I swapped on in place of a 90VDC DC Brushed Servo. ?Worked well for the mill X axis at 150 ipm.? (3:1 to 5 TPI lead screw).? And not nearly as mechanically noisy as steppers. ? John ? ? ? ? ? I'm surprised, what speed is that?
Smooth and quite is what the the new driver modes do well using clever microstep control. Spread, stealth, chop.
???
On Tue, Dec 17, 2019 at 03:07 PM, John Dammeyer wrote: But then there is the problem with steppers is they just can't turn as fast as you need
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Re: Step #1 Encoder
#RELS
Micro-steppers tend to run out of torque at around 700 RPM in general.? It's the physics of the design.? Two things have to happen to make them turn.? You have to change the direction of the current through the windings.? The back emf from the RPM which is what limits standard DC motors is the second problem. ? Think of it this way.? Turn a DC motor at a specific speed and as a generator it produces a voltage.? If the applied voltage is say 12V then that generator voltage rises to 12V and that's what holds the motor speed to a given RPM. ?Increase the applied voltage to increase the speed until the back emf matches again and the speed stays steady. ? Stepper motors have very low voltage windings and use current feedback to determine when to shut off the voltage.? That's when the drive starts chopping the power to hold the current at a given value and that torque (amp x turns) is what you get to rotate the armature.? But now you have to reverse the current through the windings and if the motor is turning it's generating that back EMF.? ? Plus the current through the winding has to decay (inductance slows that) before it can reverse. The more pressure? (voltage) the faster the change in current.? That's why stepper motors with 1.5V windings have 24V power supplies.? But at a certain RPM the back EMF matches that power supply voltage and it takes too long to reverse the current in the windings before the next step.? End result no torque. Motor locks up. ? So even with an encoder, you still have speed limitations.? And, BTW, the motors with encoders come in larger than size 17.? I used one with a gearbox on the end of it as size 23 and 400oz-in with an encoder built in.? Used CANopen messaging for control. Real sweat motor.? Still not more than about 700 RPM before there were issues. ? OTOH, the Bergerda AC Servos down side is they require 220VAC so you can't run them on 110VAC or a 24VDC battery system.? But with the 2500 line encoder they run 3000 RPM.? I swapped on in place of a 90VDC DC Brushed Servo. ?Worked well for the mill X axis at 150 ipm.? (3:1 to 5 TPI lead screw).? And not nearly as mechanically noisy as steppers. ? John ? ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Ant No
Sent: January-07-20 1:18 PM
To: [email protected]
Subject: Re: [digitalhobbyist] Step #1 Encoder? I'm surprised, what speed is that?
Smooth and quite is what the the new driver modes do well using clever microstep control. Spread, stealth, chop.
???
On Tue, Dec 17, 2019 at 03:07 PM, John Dammeyer wrote: But then there is the problem with steppers is they just can't turn as fast as you need
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Re: Step #1 Encoder
#RELS
Hello Ralph
Am I correct to assume you mean torque when you say work? They are geared down to move scopes. Some hefty bits of kit with counterweights, but as well balanced as the specific mount can manage so torque can be minimised in a way you can't do when cutting steel.
These smart steppers are new and a 32k integrated encoder and driver is pretty amazing. Obviously the 17 is a popular size to launch with. I imagine other sizes will become available over time.
???
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On Tue, Jan 7, 2020 at 01:14 PM, Ralph Hulslander wrote:
You can get movement but not much work from a NEMA 17 motor.
?
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Re: Step #1 Encoder
#RELS
Whilst price performance are important, supporting a favoured bit of existing software is a compelling reason to choose one hardware base over another.
???
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On Tue, Dec 17, 2019 at 03:23 PM, John Dammeyer wrote:
Raspberry Pi or a BeagleBone Black since running LinuxCNC
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Re: Step #1 Encoder
#RELS
1. Most certainly true although, as you show, you can sand cast your prints as well. PLA prints are cheap to make but it does take awhile for some forms. Of course you only need a very light fill on a lost PLA investment cast so not as much time as for a structural component.
2. Not always. Depends on your printer and how you print. At worst it's no different in principle to a raw cast before machining. At best I've had to look closely to determine that it is a print. There are some nice raspberry pi offerings that come in miniature retro computer cases. My friend has one as an Atari ST.
???
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On Tue, Dec 17, 2019 at 03:22 PM, John Dammeyer wrote:
1.????? Often takes a long time to print something and if the casting fails that's a lot of hours lost what with foundry setup and pouring time too.
2.????? 3D prints are generally pretty ugly.
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Re: Step #1 Encoder
#RELS
I'm surprised, what speed is that?
Smooth and quite is what the the new driver modes do well using clever microstep control. Spread, stealth, chop.
???
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On Tue, Dec 17, 2019 at 03:07 PM, John Dammeyer wrote:
But then there is the problem with steppers is they just can't turn as fast as you need
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John Lindo
BuffaloJohn
