What stepper motor should I use thread


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Thread: What stepper motor should I use thread

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    Default What stepper motor should I use thread

    Please post the specs and application for the stepper motor you are using. Please give as much in you can to help people who can't decide on what to buy.

    Similar Threads:
    Thank You,
    Paul G

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    Default What ever happened to this thread???

    Seems with all the new blood, mine included, that this thread and others of similar nature in the other Zone forums, would be welcomed with open hands!

    For instance:

    I am trying to understand the issue of Volts, Amps, Power Supply specifications, etc. and what to look for when trying to match some steppers to my router mill.

    Then you add to that, the RPM. resolution, ratio reduction, etc. and how that changes the stepper performance, speed, accuracy, etc, compared to straight out of the box performance... Why some are coupled to the ballscrew and others are connected to pulleys and running a reduction….

    Then you get into the Controller compatibility and compensation issues and how all this inter-relates to the total package performance and us novice's end up asking all the same individual questions... over, and over, and over again... I can imagine you vet's get tired of seeing the same questions but to us, it is being asked for the first time!

    Let me give you an example:

    I have spent the past three months researching and trying to acquire ballscrews and linear slides on Ebay, around which I will configure my final mill design.

    The frustration relative to what to bid on and what to pass on was insane. I even resorted to posting pictures to people and asking for opinions... actually bought one and asked if I "done good" only to get chuckled at for my purchase. I ended up paying the seller a small fee to keep the screw and resell it.

    Now the good stuff... Enter SWEDE's absolutely beautiful dissertation on Ballscrews! I read the entire post and also visited his web site and read even more about linear slides. I can say, that without a doubt, I can look and read about almost any ballscrew and linear slide on the market and feel comfortable about making a decision... all because a knowledgeable veteran took the time to create a concise explanation.

    This is sorely needed on Steppers ( and Servos for that matter ). If anyone wants to understand what I am describing, read SWEDE's post on ballscrews.

    So, what about it... anyone willing to pick up the challenge and follow in SWEDE's footsteps and bring some of us beginners along so we can one day do the same?

    ... waiting in the Stepper Twilight Zone......



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    Registered Dave's_Not_Here's Avatar
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    Default Okay... so where are...

    ... all the Pro Stepper people that go into melt down when people ask about Servos?

    Guess you either don't have any configurations you REALLY like or you just don't like Servos... ..

    Or maybe you are spending too much time looking for "missed steps" to reply...



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    Hi all,
    how do you calculate the power of a stepper?
    I have some stepper motors with following specs 1.4 amps/phase 5.6 v 1.8 deg/step
    so its 7.8 W/phase now what does it mean will they be any good for a hobby type CNC router or foam cutter?

    Thanks & regards
    Ajmal



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    Registered Dave's_Not_Here's Avatar
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    Default ...no one...

    ... home here anymore...



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    I was convinced servos were the way to go at one time- but I've become somewhat disappointed with my purchases so far. After talking with the folks at Geckodrive, the nature of steppers seems to make more sense for gantry type milling/routing machines. I set out to build a poor man's version of the Daytron mini Raptor, which uses servo motors, and acheives rates up to 400 inches per minute. I cannot recall if those are feed or transit rates, but I'd like to see an endmill that can handle 400 IPM of feed rate in the matrials i work with...

    The problem with servos is that they seem to possess exactly the wrong qualities for simple machines. Steppers have high torque at low speed, and that drops off as speed is increased beyond a certain threshold. We don't require much torque when transiting, but need more when actually doing the machining. Brushed servos have pretty much the same torque at low speed as they do at high speed, which is to say- not much. Yes, there are some VERY large servo motors out there, but they are typically for very large machines, not what I'm building. Smaller servo motors need reduction mechanisms attached, to run them in their "sweet spot". Steppers don't typically need gear reduction, unless power requirements are such that high current steppers are out of the question.

    Steppers have disadvantages, to be sure, but they are related to power consumption more than anything else. Huge steppers are simply too inefficient to run huge machines, as they (can) consume the same amount of current whether or not they are moving. Steppers run HOT. Servos consume current and voltage at a variable rate, proportional to their rotational speed, step drivers supply more or less constant current, the motor asking for more VOLTAGE as the step speed increases.

    A stepping motor rated at 5.6 volts at 1.4A, will typically run on a supply exceeding that voltage by 20 times when using a controller. In the example above, that means your supply voltage can be as high as 112 volts. this means the maximum output would theoretically be 156.8 Watts. The maximum output of the motor may be lower, due to insulation ratings and losses, but 20 times voltage is the rating most use when running a Geckodrive controller. In this case, the Geckodrive will be a limiting factor, with a maximum rating- if memory serves- of 80V supply. Depending upon such factors as coil inductance, supply impedance, and thermal losses, we can expect output figures to be somewhat inflated, but after considering their limitaions, steppers are still favorable for smaller machines.

    The nice thing about steppers is they are stupid easy to use, and the failure modes are benign. When a servo loses its mind, it can result in spectacular crashes, many times resuting in the destruction of the tool, the work, the machine, or all three. The old Hurco at work has gone crazy several times, usually due to a lost encoder, and every time, it resulted in some serious downtime. Steppers usually just stop. They are perfectly happy at a dead stall, because they are drawing the same amount of power as when they are sitting still. Steppers are pretty much plug and play- no tuning required. Servos ARE ultimately more powerful, because they can be scaled up almost infinitely, into the 100s of Kilowatts. Steppers are limited to about 500W or so, and thats pushing pretty hard. But in the 50-200W range, where most of us build, they are a very good choice. Lost steps are a bit of a fallacy, because if the mechanical system is functioning properly, and the stepper is sized correctly, they will not lose steps. If you are losing steps, you need a larger stepper, higher supply voltage, or you need to slow down your cutting and/or transit speed.

    As I'm going to be asking for rapid transits in the 400 inches per minute range, and cutting speeds around 60, I'm going to try about 3.2V 600oz./in steppers running at 52V. They'll draw 4.5A a piece, for about 702 Watts between the three. If the Geckodrive engineer properly conveyed the mode of operation to me, they will idle at something less, but I'm new to the Geckodrives...



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    I want to build a cnc plasma table. Table will be able to cut 4x2 foot pieces of steel. I will actually leave one end of the table open so I can slide a 4x8 sheet in and just cut that last 2 feet of it, when I am done, slide it forward...

    I am trying to figure out what size motors I need and what controller to use...



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    It really depends on how well set up your X/Y/Z mechanism is. Is it runs smoothly with little effort, which it should if you are just carrying a plasma torch, then you don't need much power in your steppers. There is no cutting force to speak of, so you are really just working against the losses of your mechanical system. If you keep the mechanism lightweight, and well aligned, you could probably get away with 200 oz./in. motors, and be very happy. The Z axis is the only one that will see any constant load, in the form of the weight of the clamp and torch body. With steppers, the smaller you can get away with, the better. Generally speaking, the smaller the stepper, the broader its torque curve. Large steppers are limited in top speed dramatically- they drop off a lot faster than the smaller, faster responding motors, and the higher speed can be an advantage, provided you have the need for it. Smaller steppers also have smaller power supply requirements.



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    I have a LARGE machine I built, it's all steel and will handle 4'X4'.
    The machine is built poor man style and intended for play.
    How would I check to find my inch pound needs?

    Place a set load against the tool bit and use a inch pound torque wrench to see what it takes? (I'm a auto mechanic by trade)
    I considered using some motors that I have saved from crashed cars (the fan motors for the radiator) then make my own encoders and home grown step a direction circut, but after thinking about it the thing would act just like a stepper if I don't have some sort of buffer or error handling. I started this whole thing by making some small wood ones and driving them with small printer steppers and single chip drivers, but after several times of seeing the wood flex and not having quality slides the wobble of the tool was too dramatic. The heaver I built the weaker those little steppers where. The current one out of steel has little or no movement at the bit and should do what I'm looking for.

    I need to get some pics up so you can understand more.



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    Many newbie questions are (re)answered in the FAQ section.

    Or, some interesting reading about servos/steppers and wiring thereof are found here (if not in FAQ section already, it would be nice it these links were posted there):

    What gage wire: http://www.cnczone.com/forums/showthread.php?t=17350

    Servo vs Stepper:
    http://www.cnczone.com/forums/showthread.php?t=17419

    Simply stepper:
    http://www.parkermotion.com/catalog/catalogA/A12.pdf

    Do you have a link to Swede's dissertation on ball screws???



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    Default Unsure on how much torque I need...

    Well I have started planning to build a CNC router, I am planning to use it with woodworking and hopefully also to make PCB and to mill soft aluminium. This is a pretty new area for me. Well I am planning to build a gantry style CNC, I have been reading a lot on the forum and looking at different types of cnc machines. I am going to build it out of aluminium (but I migt build the frame in steel...). But I womder how much torque do I need my stepper motor to have, to drive the different axis at an acceptable speed? My y axis ballscrew is 25,4 T.P.I., while my X and Y axis ballscrew is 5 T.P.I.
    Well I have found some 286 oz inch stepper (driven in bipolar mode) to an acceptable price, but I wonder if this will have enough torque?

    Edit: I might add that every axis runs on 1 ballscrew and 2 linear slides, and I am a bit unsure how heavy the gantry will be but I guess around 30 lb.



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    Quote Originally Posted by NC Cams
    Many newbie questions are (re)answered in the FAQ section.

    Or, some interesting reading about servos/steppers and wiring thereof are found here (if not in FAQ section already, it would be nice it these links were posted there):

    What gage wire: http://www.cnczone.com/forums/showthread.php?t=17350

    Servo vs Stepper:
    http://www.cnczone.com/forums/showthread.php?t=17419

    Simply stepper:
    http://www.parkermotion.com/catalog/catalogA/A12.pdf

    Do you have a link to Swede's dissertation on ball screws???



    No I sure don't but if you have one any info is good



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What stepper motor should I use thread

What stepper motor should I use thread