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IndustryArena Forum > MetalWorking Machines > Okuma > Resonance w/no apparent fix other than S.L.O.W...
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  1. #1
    Join Date
    Jul 2017
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    4

    Resonance w/no apparent fix other than S.L.O.W...

    Hello to all. This is my first CNC Router build and I have already learned more than I ever dreamed I would.

    I do have a fully operational machine, but seems to e that I should be able to get faster speeds from her. Pictures are attached for clarity of my build and some specs.

    Currently, I can only obtain 15 in/min feed rate. The machine will operate on manual input command of higher speeds in one direction or the other (X by itself, Y by itself). Couple different directions together during full on G Code operation and the Y axis is the only axis shuddering from resonance at any speed above 18 in/min.

    I have changed the initial speed and acceleration on the axis in question as well to find that no setting I change has any positive effect.

    So I dig into the internet, deep, and find harmonic dampers to be the solution for many. I find a build and machine it (picture) and the shudder happens more often now. Seems to me this should be impossible??

    Everything (gantry rails/rollers, carriage rails/rollers, lead screws manually turn easily) seems to be right as rain. What confuses me is that the X axis (heaviest load) and Z axis (lightest load) operate flawlessly. The Y axis is the only problem, which does seem to be the case across the internet as well.

    While I am happy to have found a speed that works, there are concerns I have with such a slow speed. One, the sheer amount of time it takes for more detailed operations. Two, burning of the end mill bit because of such slow speeds (still playing with the spindle speed itself to help with this).

    The only thing (aside from this forum) I haven't tried is to purchase a new stepper motor in the off chance I have a flawed motor installed.

    Any and all help is much appreciated.

    Good day to all and thank you in advance.

  2. #2
    Join Date
    Dec 2013
    Posts
    5717

    Re: Resonance w/no apparent fix other than S.L.O.W...

    It sounds like you may have a stepper power supply problem. What power supply(s) are you using for the steppers?

  3. #3
    Join Date
    Jul 2017
    Posts
    4

    Re: Resonance w/no apparent fix other than S.L.O.W...

    Quote Originally Posted by Jim Dawson View Post
    It sounds like you may have a stepper power supply problem. What power supply(s) are you using for the steppers?
    China's finest...The only thing resembling a name brand I can find on the supply is "Weho"

    The Steppers, Drivers and controller came as a kit. The power supply outputs 36V DC. Would this still be the case seeing as all three drivers are powered from the same supply with this only occurring in only one of the drivers?

    Here are the specs from the Amazon website order page:

    3 x 23HS2430B Nema stepper motor 425oz-in 112mm (Dual Shaft)
    3 x FMD2740C stepper motor driver
    1 x 400W 36V/9.7A switching power supply
    1 x 4 Axis USBCNC breakout board
    1 x Hand controller

  4. #4
    Join Date
    Dec 2013
    Posts
    5717

    Re: Resonance w/no apparent fix other than S.L.O.W...

    The Y driver could be a little ''weak'' thus the problem. Since the drives are limited to 40 volts max, the best option might be to buy two more power supplies and power each drive from it's own supply.

  5. #5
    Join Date
    Jul 2017
    Posts
    4
    Quote Originally Posted by Jim Dawson View Post
    The Y driver could be a little ''weak'' thus the problem. Since the drives are limited to 40 volts max, the best option might be to buy two more power supplies and power each drive from it's own supply.
    There is an adjustment knob to up the voltage. Seems like I may try that first. As of now, it is at its lowest allowable setting.

    If this fails, then I shall try separate PSU.

    Thanks a bunch!

  6. #6
    Join Date
    Jul 2017
    Posts
    4

    Re: Resonance w/no apparent fix other than S.L.O.W...

    Quote Originally Posted by Jim Dawson View Post
    The Y driver could be a little ''weak'' thus the problem. Since the drives are limited to 40 volts max, the best option might be to buy two more power supplies and power each drive from it's own supply.
    ***UPDATE***

    I took your advice and and look into the weak power, so I upped the power setting on my PSU. It didn't seem to have any effect. So I decided to start eliminating any "weak" components before purchasing new items. The driver being the easiest (swapping quick connectors without cutting any wires), I swapped my Y and Z axes putting the suspected weak driver with the axis that moves the least amount (both time and distance). This seems to have worked.

    Where my top speed was 15 in/min, I have increased that speed in increments of 5 until I reached 50 in/min. I could probably go faster, just don't want to press my luck. Maybe in the future, as I get used to this speed and have proven it can handle it after a few projects under my belt I will venture into faster speeds.

    Thank you so much for your advice. It truly is appreciated!!!

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