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Stepper motors for MK1.5?

Discussion in 'MOTORS - Stepper Motors' started by nunny, Apr 4, 2009.

  1. nunny

    nunny New Member

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    Hello all,

    I've just purchased the MKI premium kit at the Toledo show and did an all-nighter researching multiple mods and adds to the design. From the start of the build, I'm looking to do the MK1.5 belt drive upgrade on the Y-axis, bronze bushings or linear bearings on the Y/Z-axis and possibly using an ACME rod for the Z-axis.

    I'm getting a grasp on how the steppers work and the whole torque to speed relationship, etc. However, after reading through many posts I'm confused on what steppers to buy with the above mods in mind, especially the MK1.5 belt drive upgrade.

    I see people with all-thread and/or ACME threaded rods seem to be upping the torque on the Y-axis to get better speeds. I realize that the belt drive method requires less effort to move, and a higher torque is probably not necessary. However, I sense that even with that in mind, a higher than stock torque (90 oz/in with the Easy-CNC recommended kit) is still preferred?

    I'm looking at the steppers from web-tronics.com. Either the 57BYGH207 at 111 oz/in. (http://www.web-tronics.com/stmo5.html) or the 57BYGH303 at 208 oz/in. (http://www.web-tronics.com/stmone235.html). Which size motors should I use for the above setup? And/or should different torques be used for different axes?

    Also, I see that some other motors out there are dual shaft. It looks like if dual shaft were to be used for the Z-axis, that one of the back-side shaft needs to trimmed to fit in the gantry? Out of curiosity, what tools have people used to trim/cut the shafts without damaging the shaft?

    Any input would be greatly appreciated!

    Thanks,
    Nunny
     
  2. 3DMON

    3DMON Moderator Staff Member

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    The 2nd choice(208 oz) is the better on the steppers.
    As for as cutting the shaft of I used my dremel with the reinforced disk to cut the shaft off on my Z motor. I just did a little at a time as to not heat the shaft up too much.
    Make note that if you go with the bigger steppers they will stick out the side and you have to raise the pp up because of the Z axis.
     
  3. rjarois

    rjarois Moderator Staff Member

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    nunny, personally i would stay away from the stock steppers...if you dont you will be buying a second time. i think you can get the control board and the power supply seperate now. if so i would recomend that you get the steppers from a different vendor. 3-dmon is right about the bigger stepper. before you start your build, go to the mod section, and read everything you can before you start your printer, it will be worth it trust me....and one other thing, take your time on your build...and enjoy it like i did. also post away any questions...you will get plenty of help and support from the fellas....welcome to the phlatboyz.
     
  4. rjarois

    rjarois Moderator Staff Member

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    nunny, just for quick reference, i use 260in oz steppers on my y and z axis, with a 185in oz on the x-axis. i am running a 3/8-8 four start acme screw on the y and z. the stepper power will depend on the acme screw pitch you pick. randy.
     
  5. Anonymous

    Anonymous New Member

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    My machine, with the MK1.5 mod, is running the STOCK steppers from the Easy-CNC kit. My V-ref voltages are all set at 1.4 volts. It's running at 300ipm on X and Y, which seems to be the functional limit on how fast you can push the Dremel cutter through 1/4" foam, anyway. I modified Z to run with a 3/8-12 single-start Acme thread, running around 25 or 30ipm, as I recall.
    So, if you want to spend more money to get something that's "bigger, better, faster, more", your checkbook is your limit. I won't bother changing my steppers unless something breaks or burns out, which is very unlikely. :geek:
     
  6. kyyu

    kyyu Active Member

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    But that's the thing. Nunny doesn't have any steppers, yet. So if you can get a better stepper, why not. The problem is which one to get.

    I don't think you want this one, 57BYGH207 at 111 oz/in., if you are going to use a threaded rod. Check this forum. A few people have already used it and it is really slow. I guess velocity wise. Maybe it is high torque, which would be ok for a belt, but I don't know. If you check it's spec. It's kind of strange, also, 30ohms and 0.4A. The stock motor ,we use, is 10 ohm.

    The bigger motor would be an inch too long. Not too big of a deal with the X and Y. You would just have to cut a hole and let them stick out. But for the Z, you would have to make a base to raise your case off of the table.

    -Kwok
     
  7. 3DMON

    3DMON Moderator Staff Member

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    When looking at the phase resistance specs, basically it is the lower the better.
     
  8. nunny

    nunny New Member

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    You guys are great, thanks all your responses... I'm absorbing it like a sponge! :geek:

    Thanks Randy, that's pretty much what I've gleaned from my mod research so far and I'm planning to do just as you suggest. The only confusing part for me at the moment is the question of which steppers to use. Can you expand more on stepper power vs. thread pitch for me?

    Thanks Kyyu and 3DMON for the ohms/resistance explanation. Would less resistance on the stepper also relate to less heat on the relevant axis in the controller board?

    Dorsal, thanks for the specs on your stock setup with MK1.5. That will give me something to compare against once I'm up and running. It looks like stock is working good for you, but let's put it this way... if all of your steppers DID burn up and you HAD to replace them ;) , what non-stock steppers would YOU use for your setup?

    In the end, if anyone has better or more optimal steppers to suggest for my setup, please... I'm all ears! Otherwise, I'll probably just go for the 57BYGH303 on all three axes and mod/lift the case to fit.

    Thanks again fellas,
    Nunny
     
  9. Anonymous

    Anonymous New Member

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  10. Flashsolutions

    Flashsolutions Active Member

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    Stay away from the 57BYGH207. It will be no better than the easy-cnc 90oz stepper, maybe worse.

    The coil resistance is 30 ohms and it will not drive the all thread sufficiently.

    The other stepper, while powerful enough (2.5 ohm coil resistance), will require a case mod in order to use in Z gantry because it is longer than the standard stepper we use there.

    I'm still trying to locate a suitable stepper for the Z axis that does not require modification to the cabinet.

    My Z axis is pathetic! This evening it decided it wanted to miss steps at 16 ipm and I had to lower it to 13ipm. Gotta find a good replacement myself but I just don't want to have to raise the cabinet especially now that my belt drive mod is slaming it around as is.




     
  11. rjarois

    rjarois Moderator Staff Member

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    flash, i also did not want to mod my phaltprinter for my bigger z-axis mod. i made a "sub plate" table for mine. i took two pieces of 3/4 mdf and cut a relief square in one, wood glued it togather. i have some photos posted in the mod section. also if you dont want to go with the super high pitch acme, you wont even need a longer motor. the 185in oz i got is exactly the same length as the stock. even a single start acme will give that z-axis some kick. randy.
     
  12. rjarois

    rjarois Moderator Staff Member

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    nunny, , here is a link to some info. also before i installed my set-up i e-mailed tim over at dumpster cnc, and inquired about what size stepper to use. all i can tell you is my 260in oz stepper drives the 3/8-8 four start acme very well. so you can get a good idea of lets say a 185in oz would drive. to be honest, i really dont know enough about it, i just got what tim at dumpster cnc recomended. randy.
    http://www.nookindustries.com/acme/AcmeGlossary.cfm
     
  13. Thewz

    Thewz Moderator

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    I had to lower mine as well....it missed a few steps about 2/3 of the way through.....since it didn't pull back it ended up cutting through most of the parts when it returned to 0,0,0..... :x Man.....I don't have time to baby sit while it cuts......

    It's pretty funny when it's cutting full speed and then has to make a V-Tab.....talk about hitting the brakes..... :shock:

    I'm in the market for a drop in replacement as well but if I have to hack at it I will.....

     
  14. nunny

    nunny New Member

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    Excellent link Randy. Everything you wanted to know about ACME threading but were afraid to ask! I'll definitely be reading up on that.

    At the moment, I'm feeling pretty safe with the 208 oz/in steppers for the z-axis w/ 3/8-8, 4-start ACME. And, since they're not horribly expensive, I won't feel too bad if I decide to swap out the Z for something else in the future if need be. Also, I'm definitely going to do something like you did with a platform on the bottom to accommodate the extra length.
     
  15. Flashsolutions

    Flashsolutions Active Member

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    Well, I must and idiot. I can't seem to find the photos in the mod section. Any chance you can post a direct link to them?

    Knowing nothing about acme threads other than everyone here seems to rave about them, any chance you can post specifics as to what to buy, where to buy it, links to help the dummy folks like me?

    Where did you get your 185in oz stepper? links again would be helpful.

    I am ready to bite the bullet and do something about this but need some hand holding. Dance with me :mrgreen: .


     
  16. 3DMON

    3DMON Moderator Staff Member

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  17. Flashsolutions

    Flashsolutions Active Member

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    Yep, I saw all of those. I was trying to find pics he mentions about the sub plate mod where he raised his cabinet.

    Thanks for the Acme rod info, however... There seems to hundreds of choices. I'm looking for specifics. There are 3/8 - 10, 3/8 12, 3/8 16.... list goes on and on.


     
  18. kyyu

    kyyu Active Member

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    Here is Randy's base mod:
    viewtopic.php?f=12&t=145&start=225#p4402
     
  19. kyyu

    kyyu Active Member

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    You know, I asked Mark today on the chat; and he is still using the stock easy-cnc steppers on the MK2.
     
  20. Flashsolutions

    Flashsolutions Active Member

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    The MK2 does not have the weight to horse around that the MK1 does... The gantry is lighter because the dremel is not planted on it so he can get away with needing less torque and holding power from the magnets.

    The X and Y axis are both belt driven which means you don't need as much power as well.

    But, whatever speeds he can now achieve with 90 oz/in steppers, think what it can do if you add some horsepower under the hood! Not that you need it though. I think the MK2 is plenty fast enough without souping it up.



     

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