My machine keeps stall on me


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    Default My machine keeps stall on me

    Hi there
    I have put together a MDF / Wood Cutting CNC Machine. But I have some problem with it, which is really bugging me for the last week or so.
    Problem that I have is during a simple 2D Profiling Cut, After few Minutes my machine stalls on me, and as you know I keep missing some line of codes, and machine starts to cut Profile wronglyyyyy. (Should Mention I am using ArtCam in order To generate G codes, and the Profiling I was doing Had a Total of 6mm depth, which I was trying to cut with 2 mm Step down Only.
    I cannot figure out what is or are the cause of this problem.
    My machine is made of the followings:
    · Two 4.5 N.m (637 OZ-In) NEMA 34 Step Motor for my Y Axis. (To be Exact the Leadshine Model No. 86HS45 Step Motor)
    · One Of The same Motor for X and another for Z Axis.
    · Y and X axis are rack and pinion with a 13 Pitch Pinion each @ 7 mm apart.
    · The drivers are also LeadShine M880A
    · My Board is the Typical Chinese made. The so called 5 axis Board.
    · Spindle is a 3 Hp Single phase which I run it using a single to three Phase LS Inverter.
    · The Structure is a Light 4”*4” (10 cm * 10 cm) Square Tube
    · The Dimension of the Table is 2m*4m, So it is sort of Big but not so heavy since the thickness of Tube is only 2 or 3 mm.
    · The Controller is Mach3 Version R3.041

    I wonder what could be the problem, and what is it that I can do in order to fix the problem.
    Should I
    1. Increase the size and Power of my Motors? Or
    2. Increase The Power of My Spindle or
    3. Is it an Electro Magnetic Noise From my Drivers or my Bob …, and if it is How can I fix it?
    4. Also about the spindles, What is more Powerful? Running with my Highest RPM which is 18000 or running with lower RPM?
    5. Should I use some kind of Gear Box or pulley System? Which one is better or less expensive or most importantly requires Overall less Design Change
    Any Recommendation is highly appreciated.
    Regards
    JohnAnsaro

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    Default Re: My machine keeps stall on me

    It may simply be you don't have enough torque . It may be you have noise. It may be you don't have the correct current setting on your drivers .

    Direct Drive Pinion setups (Pinion on the motor shaft) offers high speed rapids but lower torque. A better match is to use a belt reduction unit between the motor and pinion of from 3:1 up to 5:1 .
    While pure weight affects acceleration its probably more the cutting forces that are causing the issue. Belts and pulleys can get you those ratios. CNCRouterParts sells some lower cost belt reduction units for rack & pinion. You may need to change out the rack pitch because the pinion of the belt reduction units is a 20 TPI 20 deg pressure angle gear.


    You should start out by making an "Air cut" above the material (or rig a pin up on the end of the router spindle) and have it trace out the cut at normal cutting speeds but not cutting . That will tell you if its something in the electronics or a lack of torque.

    Another issue may be noise from the spindle. If it uses a VFD converter/speed control the VFD noise is high and may be getting into the drivers. If you do not see devation in the "dry cut" test , try it with the spindle on but still not cutting..
    Keep the VFD and the power wires to and from it as far away from the control electronics as you can.



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    Member awerby's Avatar
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    Default Re: My machine keeps stall on me

    That's good advice from Torchhead. Just to give a little more detail, the "air cut" he recommends, without the spindle running, will let you know if it's RF noise from the spindle that's interfering with the step and direction pulses. If that's the case - if it runs fine without the spindle on, but poorly when it's going - then you probably need to provide a braided wire sleeve over the leads, connected to the spindle motor but not to the VFD. This provides a Farraday cage that contains the interference without creating a ground loop, that makes things worse.

    You don't say how you're connecting your motors. but as you can see from this chart: http://www.leadshine.com/UploadFile/Down/86HSxxd.pdf , those motors have a lot less inductance when run bipolar parallel or unipolar than bipolar series. Excess inductance can kill your motors' performance. Those motors will run best if given 59v DC. Your drives can take up to 80v, so if your power supply puts out much less than 59v, that's something you could change out and get better performance. Of course, you could also try reducing the acceleration of the motors that are faulting, and see if that helps.

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    Default Re: My machine keeps stall on me

    One thing to consider is writing a set of diagnostic routines or programs to slew individual axises around. This is sort of like the air cut suggestion above but instead you have a selection of custom coded apps to move your axises around.

    Why go this route, for one it helps to isolate an issue to one axis. Second you have a reference program (actually several) to go back to if you have other problems down the road. As suggested above one variant if each should cycle the spindle. Cycling things on and off is important because you can chase things do to individual mechanisms.

    I once had a problem with a CNC lathe losing position, but only in the sub micron range. You couldn't even see the loss of position until you had cycled the axis about a half dozen times. Come to find out a relay in the spindle drive was the ultimate root cause.

    In your case it sounds like you are giving up position at a much larger scale. Unfortunately this could be lots of things. You could have overloaded motors, binding in the linear bearings, crude or binding in the racks or a bunch of other possibilities. This is where running diagnostic programs may help greatly.

    It also pays to do a little inspection work. Make sure for example that the axis saddles move freely. Make sure electrical connections are secure, grounding is correct and so forth. Also listen to the machine when it is operating, if you lose steps during operation often it causes some nasty noise to issue from the steppers. You might be able to hear which axis causes the grief.



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    Default Re: My machine keeps stall on me

    Typically the VFD produces constant motor torque, so the faster you go, the more HP you have. So if it's a 3HP spindle, that's at 18krpm, and you'll have 1.5HP at 9krpm, etc...

    From what you mention, you're direct-driving the pinions? If so, you're reducing the torque on your drive system by a factor of pi * the pitch diameter of the pinion. Which is why most all r&p systems use gear reduction of some sort. The easiest (though not so) mod would be to get NEMA34 10:1 planetary gearheads. The down side is the output shaft will be a lot larger than the ones on your steppers now, so you'll need to get new pinions.



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    Default Re: My machine keeps stall on me

    Hi ALL
    Thanks a million for all your helps and recommendations.
    I tested the “air Cut” Test with spindle not running, that Torchhead had mentioned. And It appears That It is running Just Fine. But I will run the (air cut) Test with running Spindle tomorrow, Which Could answer a lot of my questions.
    But as far as VFD Noise goes, I should mention that I am using a Shielded Four wire Cable.
    But the point is that I treated it like a regular cable and it is not grounded to anything at all.
    I am not very good with electrical wiring, so please provide details or pictures of Grounding My VFD to Spindle Cable.
    I think I should use the Fourth wire in my Cable as the Earth wire, and I connect the Braided Wires to this wire and pin(Or screw) both wires to the Body of my Spindle. But I just do know what to do with braided wire of my cable at the other end of it, Or at VFD Part of it.

    Regards
    Jhonansaro



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    Default Re: My machine keeps stall on me

    Hi There
    Whole of last week I have been busy implementing all your different recommendations and so on.
    Followings are what I have done.
    1. I tried to eliminate the noise problem by Grounding the braided wire of my Spindle at Spindle end, and left the other end of braided wire unattached to anything.(Please verify that this is correct) Also not to mention the difficulty I had for digging the Earth well (Pit).
    2. Also I have designed and fabricated a Motor and pulley Holding Box using aluminum Sheets, which I will install tomorrow. With reduction ratio of 3:1
    3. Finally through my readings, I noticed that my Microstep Resolution settings are not that Great, If I am looking for Power or torque. What I had before was using 8 microstep for my Drivers, which as you know will reduce the torque by about 80%. So I decided to use only 2 microstep, and I will try all these tomorrow. Can you tell me, if my logic is all right or not. (Also on this issue, How can I set the full Micrstep of 200 step per revolution, as you know the settings in my Leadshine M880a driver starts with 2, and I need a 1 in order to get only 200 steps., Just for curiosity.)
    4. Finally what are your recommended setting in general config. Tab or sheet of mach3 itself.

    Again any recommendation is greatly appreciated.

    Regards
    johnansaro



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    Default Re: My machine keeps stall on me

    Hi There
    One other thing that I forgot to ask for in my previous post is,
    How abbot the smothsteppers? Do I need one? What would be your recommendations on this issue? Issues such as Budget and performance.

    Regards
    johnansaro



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    Default Re: My machine keeps stall on me

    I don't think that using microstepping really reduces torque by 80%, or anywhere near that. Nobody would use it if it did. It smooths out the motion by reducing resonance, which you might notice more when half-stepping.

    A Smoothstepper can help if you have a lot of small motion commands, common in 3D work, and your computer is bogging down with them. It will also allow you to use a computer without a parallel port. But I would advise you to get your machine working better as it is first, before introducing another variable.

    [FONT=Verdana]Andrew Werby[/FONT]
    [URL="http://www.computersculpture.com/"]Website[/URL]


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    Default Re: My machine keeps stall on me

    Quote Originally Posted by awerby View Post
    I don't think that using microstepping really reduces torque by 80%, or anywhere near that. Nobody would use it if it did. It smooths out the motion by reducing resonance, which you might notice more when half-stepping.

    A Smoothstepper can help if you have a lot of small motion commands, common in 3D work, and your computer is bogging down with them. It will also allow you to use a computer without a parallel port. But I would advise you to get your machine working better as it is first, before introducing another variable.
    Each microstep will have a reduced torque, this is because each microstep is actually an "in between" position so to speak. If you're position "falls" at a particular microstep, and a force on the machine is stronger than that of the microstep torque, the machine can potentially move to the next microstep in the direction of that force till there is enough torque to stop said force. With a 5mm ballscrew pitch and 8x microstep that's a move of .00012" per microstep. Same thing when moving - just because the controller sends out a step does not necessarily mean the axis will move. The axis will move when the torque at the particular step exceeds that which is needed to move the axis. This is why I believe in having a good balance between mechanical resolution and speed. With the OP's former setup, the mechanical resolution is very coarse, which requires microstepping to "gain" resolution at the expense of what I've described above. So yes, microstepping will give smoothness, especially at lower speeds where the number of steps per unit time is rather coarse. It's also a reason why drives like GeckoDrives are great, as they microstep below 240rpm and morph to full step above, giving the benefit of smooth motion at low speeds and tight curves, while offering more torque at full speed.

    From my very unscientific tests, if you have a computer fast enough, which is basically a P4 that was made at least 15 years ago, you don't really need a SmoothStepper. Especially this setup, where there is not a lot of resolution requiring a higher pulse frequency. Mach3 has a LookAhead setting that is set default at an abysmal 10 lines, and adjusting that number to 100 or 200 will greatly smooth out the motion, SmoothStepper or not.



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    Default Re: My machine keeps stall on me

    Hi awerby and louieatienza
    Thanks for the reply.
    regarding the microstepping, please take a look at the following:

    To calculate the resolution information, we need two values:

    – Steps per revolution: Most steppers use 200 steps per revolution, but you should see what your manufacturer says. For servos, it is a function of how many steps per revolution the encoder has.

    – Microsteps: While your stepper drive may accomodate very fine degrees of microstepping, it’s wise to remember that you lose a lot of torque the more microsteps you use. Consider the following when you select how many microsteps you can actually count on:

    Microsteps/full step Holding Torque/Microstep
    1 100.00%
    2 70.71%
    4 38.27%
    8 19.51%
    16 9.80%
    32 4.91%
    64 2.45%
    128 1.23%
    256 0.61%
    As you can see, that 256 microstep resolution is an illusion–there’s only 0.61% of holding torque available at that resolution.

    I can show you many more supporting Documents on the issue. Also the site micromo.com explains all this.

    Regards
    johnansaro

    Last edited by johnansaro; 06-08-2017 at 12:02 AM.


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    Default Re: My machine keeps stall on me

    Quote Originally Posted by johnansaro View Post
    Hi awerby and louieatienza
    Thanks for the reply.
    regarding the microstepping, please take a look at the following:

    To calculate the resolution information, we need two values:

    – Steps per revolution: Most steppers use 200 steps per revolution, but you should see what your manufacturer says. For servos, it is a function of how many steps per revolution the encoder has.

    – Microsteps: While your stepper drive may accomodate very fine degrees of microstepping, it’s wise to remember that you lose a lot of torque the more microsteps you use. Consider the following when you select how many microsteps you can actually count on:

    Microsteps/full step Holding Torque/Microstep
    1 100.00%
    2 70.71%
    4 38.27%
    8 19.51%
    16 9.80%
    32 4.91%
    64 2.45%
    128 1.23%
    256 0.61%
    As you can see, that 256 microstep resolution is an illusion–there’s only 0.61% of holding torque available at that resolution.

    I can show you many more supporting Documents on the issue. Also the site micromo.com explains all this.

    Regards
    johnansaro
    Yes, I explained how this works. To try this again, these are incremental steps. So using a ruler as an analogy, using 8X microstepping as an example, 1" would be a full step, then you'd have 1-1/8" which would be an eighth-microstep, 1-1/4" would be a quarter-microstep, 1-3/8" would be an eighth-microstep, 1-1/2" would be a half-microstep, and so on. This is why having enough MECHANICAL RESOLUTION is important, that when your machine happens to fall not on a full or half step or even quarter step, the change in position to one of those steps is very small in relation to the overall accuracy of the machine. So if you are using 4X micro-stepping, if the machine happens to "land" on a quarter-step, and an outside force overcomes the torque at that step, the stepper will "spring" to the next closest half or full step. Remember the torque drop is moving INCREMENTALLY from one phase to the next.

    This was the crux of your original design. By direct driving the pinion, you "spread" the resolution (and therefore the torque) of your axis over a larger distance, which effectively reduces the torque applied to that axis. You then need to gain resolution by using microstepping. But because you have no mechanical advantage moving that axis, the microstep torques are also reduced. This is why most all stepper driven rack-and-pinion and belt drives use gear reduction.

    If you didn't use microsteps, and milled a tight radius with a lot of point to point moves, your machine would sound like at Gatling gun, and if you didn't have a drive with anti-resonance, it would stall out.



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    Default Re: My machine keeps stall on me

    Hi louieatienza
    Thanks for the comment, But I am more confused by your post. At the time I am trying to machine a vacuum table. In general My most work would be Cutting MDF.
    The vacuum table I am cutting is a 65 mm square box and the gap is only 8 mm and the depth is 6 mm, which i am doing it in 3 passes. Now if I set my machine with 4x microsteping, am I going to have problem? My logic is simple that I would have more torques in my motors or axis. as matter of fact with 4x microsteping my mach3 step per unit is about 10 for Y and X axis, Would not this means that my accuracy is about 1/10 mm (.1 mm).
    and wouldn't this be good enough for most of wood cutting Jobs?

    Regards
    Johnansaro

    Last edited by johnansaro; 06-08-2017 at 02:28 PM.


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    Default Re: My machine keeps stall on me

    Quote Originally Posted by johnansaro View Post
    Hi louieatienza
    Thanks for the comment, But I am more confused by your post. At the time I am trying to machine a vacuum table. In general My most work would be Cutting MDF.
    The vacuum table I am cutting is a 65 mm square box and the gap is only 8 mm and the depth is 6 mm, which i am doing it in 3 passes. Now if I set my machine with 4x microsteping, am I going to have problem? My logic is simple that I would have more torques in my motors or axis. as matter of fact with 4x microsteping my mach3 step per unit is about 10 for Y and X axis, Would not this means that my accuracy is about 1/10 mm (.1 mm).
    and wouldn't this be good enough for most of wood cutting Jobs?

    Regards
    Johnansaro
    You can watch my videos, or anyone else's on YouTube, and you'll see I have no problems, even at 10x microstep.

    You won't lose torque going to 8X. But you'll gain a lot of motor smoothness, which should help mitigate resonances. You'll still have .1mm accuracy. Again, your logic is incorrect, as the torque loss is INCREMENTAL, meaning, microstep to microstep.

    Last edited by louieatienza; 06-08-2017 at 07:49 PM.


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    Default Re: My machine keeps stall on me

    Hi there
    Today I had been busy doing all different kind of experiment on my machine.
    And I noticed that I could easily stop my X axis from moving or causing it to lose steps, and I am quite sure that this shouldn’t be the case, If I can cause it to lose steps so easily for sure it will happen during actual cutting. I think my X axis has a design flaw; (The way that I am attaching the pinion and the motor to the rack is not rigid enough.) I am attaching some pictures of it.
    Any Ideas on how I can make it more rigid will be greatly appreciated.
    I should mention that my Y axis is in much better shape. And the Z is ball Screw and again is in good shape. One thing that I learned from all these is that for my future machine if any I will defiantly go Ball Screw all the way and will never bother with Rack and Pinion.



    Regards
    Johnansaro

    Attached Thumbnails Attached Thumbnails My machine keeps stall on me-20170609_131025-2-jpg  
    Last edited by johnansaro; 06-09-2017 at 10:08 AM.


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    Default Re: My machine keeps stall on me

    Quote Originally Posted by johnansaro View Post
    Hi there
    Today I had been busy doing all different kind of experiment on my machine.
    And I noticed that I could easily stop my X axis from moving or causing it to lose steps, and I am quite sure that this shouldn’t be the case, If I can cause it to lose steps so easily for sure it will happen during actual cutting. I think my X axis has a design flaw; (The way that I am attaching the pinion and the motor to the rack is not rigid enough.) I am attaching some pictures of it.
    Any Ideas on how I can make it more rigid will be greatly appreciated.
    I should mention that my Y axis is in much better shape. And the Z is ball Screw and again is in good shape. One thing that I learned from all these is that for my future machine if any I will defiantly go Ball Screw all the way and will never bother with Rack and Pinion.

    some how i could not attach the pictures

    Regards
    Johnansaro
    Again, you have no mechanical "advantage" designed into your system. In fact you're decreasing your torque by direct driving the pinion. If you install your pulley reduction you'll find it a lot better.



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    Default Re: My machine keeps stall on me

    Any Ideas on how I can make it more rigid will be greatly appreciated.
    You need to make some triangular side panels so that nothing can flex at all.

    You're also going to find the bearings in your steppers failing fairly quickly. They are not designed for thrust loads, and the helical pinion puts a lot of thrust loads on them.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: My machine keeps stall on me

    If you look at the numbers ( and a scope current waveform) it approximates a sine wave function so at any given step you see the reduction in torque at that instant BUT torque is not static and you measure POWER which has a time element . So you take the average torque under the curve (for a sine wave its .707 ) rather than look at any single step.

    The average torque over 256 steps is no less than over a smaller number. As you approach 10X and less, the current waveform is not a sine wave so the average goes up some. Microstepping was introduced because full or even quarter step cause ragged motion at lower speeds and that sets up resonance problems . The better drivers morph to full step at higher RPM because the rotor and load inertia cause the motion to smooth out so you are no longer at 70% torque. The interesting thing is the torque curve of the motor that deceases linearly with RPM until about 1/2 the rated RPM and then drops at a faster rate . While motion using a (true) ballscrew is somewhat smoother its more about the ratios than what type of linear drive. Its all about torque versus speed. A ballscrew trades speed for torque (and resolution) You DIVIDE the RPM at the motor by the tread count TPI. That MULTIPLES the torque and resolution. A rack and pinion does just the opposite. It MULTIPLIES the SPEED by the circumference of the gear and DIVIDES the torque and resolution. That is why to get a similar torque and speed to a ballscrew you have to reduce the speed using belt or gears. With a given stepper motor the motion with a ballscrew with 5 TPI (threads per inch) is the RPM / 5 in IPM and if you have a 1" diameter pinion gear you get a 3X speed increase and to get to the same as the ballscrew you have to have a 15:1 belt/gear reduction to get an overall 5:1 reduction. Remember we are trading speed for torque and resolution (or vice versa)

    IPM with a 5 TPI ballscrew and stepper (with about 800 RPM of total RPM) = 800/5 = 160 IPM. Torque increase > 5:1
    IPM with a 1" pinion gear and 15:1 belt or gear reduction = 160 IPM. Torque increase of > 5:1

    IPM with a 1" pinion stuck on the motor shaft is 800 * 3.1416 = 2500 IPM Torque = < 1/4 of motor torque at a given RPM

    Acceleration = F/M (force/mass)

    There are some setups you can't do with ballscrews because you have to spin them faster than they can handle. So you have to decide what your goal is: Do you need low spped with lots of torque or high speed with less torque?

    The further complicate things , with a stepper its not a straight linear trade off of speed and torque. If you have to open the motor twice as fast to get the same target speed it will have less torque even though you gain torque though a transmission. I can see how it can be frustrating because everything is dynamic based on multiple variables.



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    Default Re: My machine keeps stall on me

    Quote Originally Posted by Torchhead View Post
    If you look at the numbers ( and a scope current waveform) it approximates a sine wave function so at any given step you see the reduction in torque at that instant BUT torque is not static and you measure POWER which has a time element . So you take the average torque under the curve (for a sine wave its .707 ) rather than look at any single step.

    The average torque over 256 steps is no less than over a smaller number. As you approach 10X and less, the current waveform is not a sine wave so the average goes up some. Microstepping was introduced because full or even quarter step cause ragged motion at lower speeds and that sets up resonance problems . The better drivers morph to full step at higher RPM because the rotor and load inertia cause the motion to smooth out so you are no longer at 70% torque. The interesting thing is the torque curve of the motor that deceases linearly with RPM until about 1/2 the rated RPM and then drops at a faster rate . While motion using a (true) ballscrew is somewhat smoother its more about the ratios than what type of linear drive. Its all about torque versus speed. A ballscrew trades speed for torque (and resolution) You DIVIDE the RPM at the motor by the tread count TPI. That MULTIPLES the torque and resolution. A rack and pinion does just the opposite. It MULTIPLIES the SPEED by the circumference of the gear and DIVIDES the torque and resolution. That is why to get a similar torque and speed to a ballscrew you have to reduce the speed using belt or gears. With a given stepper motor the motion with a ballscrew with 5 TPI (threads per inch) is the RPM / 5 in IPM and if you have a 1" diameter pinion gear you get a 3X speed increase and to get to the same as the ballscrew you have to have a 15:1 belt/gear reduction to get an overall 5:1 reduction. Remember we are trading speed for torque and resolution (or vice versa)

    IPM with a 5 TPI ballscrew and stepper (with about 800 RPM of total RPM) = 800/5 = 160 IPM. Torque increase > 5:1
    IPM with a 1" pinion gear and 15:1 belt or gear reduction = 160 IPM. Torque increase of > 5:1

    IPM with a 1" pinion stuck on the motor shaft is 800 * 3.1416 = 2500 IPM Torque = < 1/4 of motor torque at a given RPM

    Acceleration = F/M (force/mass)

    There are some setups you can't do with ballscrews because you have to spin them faster than they can handle. So you have to decide what your goal is: Do you need low spped with lots of torque or high speed with less torque?

    The further complicate things , with a stepper its not a straight linear trade off of speed and torque. If you have to open the motor twice as fast to get the same target speed it will have less torque even though you gain torque though a transmission. I can see how it can be frustrating because everything is dynamic based on multiple variables.
    I think you explained this better than I did! Many folks doing calculations with rack-and-pinion, or belt, seemingly realize the decrease in resolution but not the decrease in torque, since the pinion factors into the overall gear reduction of the system.

    The confusing thing I believe about steppers is there is a huge focus on torque, but not as much on power. Power being a function of the work done over time. With the stepper, its maximum power output is somewhere right after the "corner speed", or where the current is limited by the resistance of the coils, and is purely voltage-driven. After that point the power output drops a bit because of losses. Alas not many people try to get an approximation of how much power is needed to move each axis, and stepper manufacturers almost never release a power/speed chart.



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    Default Re: My machine keeps stall on me

    Quote Originally Posted by johnansaro View Post
    Hi louieatienza
    Thanks for the comment, But I am more confused by your post. At the time I am trying to machine a vacuum table. In general My most work would be Cutting MDF.
    The vacuum table I am cutting is a 65 mm square box and the gap is only 8 mm and the depth is 6 mm, which i am doing it in 3 passes. Now if I set my machine with 4x microsteping, am I going to have problem?
    Most likely yes.
    My logic is simple that I would have more torques in my motors or axis. as matter of fact with 4x microsteping my mach3 step per unit is about 10 for Y and X axis, Would not this means that my accuracy is about 1/10 mm (.1 mm).
    As others have mentioned you really want to use a "gear" reduction when driving a rack. I quoted "gear" because a belt drive could do just as well if the ratio is modest.
    and wouldn't this be good enough for most of wood cutting Jobs?

    Regards
    Johnansaro
    This is the problem, what is good enough? That varies widely with the user of the machine and his goals. I liken it to the difference between building a wooden boat and a fine musical instrument. A musical instrument maker might realistically need tolerances under 0.001" while a boat builder might get away with tolerances well above 0.010". Ultimately what is good enough can only be defined by you, when you ask. us your can get answers that vary by two orders of magnitude which will be right in the minds of the person that posted them.



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My machine keeps stall on me

My machine keeps stall on me