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Thread: SBL Magnaturn Retrofit

  1. #61
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    Default Re: SBL Magnaturn Retrofit

    Hi Tom,
    So in the SimpleHomeIndexFunctionTest.c example it uses Opto in bit 138 for Z axis. So i dont use the Differential Encoder inputs? And instead use the Opto in?
    Troy

    http://www.homecncstuff.elementfx.com/


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    Default Re: SBL Magnaturn Retrofit

    Quote Originally Posted by Need TECH Help! View Post
    Hi Tom,
    So in the SimpleHomeIndexFunctionTest.c example it uses Opto in bit 138 for Z axis. So i dont use the Differential Encoder inputs? And instead use the Opto in?
    Troy
    You use the differential input. In terms of the C program, just think of it as a standard input, that just so happens to take a differential input.
    So if you're using the inputs of JP2, they connect the KFlop JP5 (8 pin RJ connector), which are bits 36-43 (KFLOP Connectors - scroll to the very bottom).

    Opto in 138 is just an example, which you can change it to whatever input bit you are using.
    However, just checking those examples, they're relying on using the limit switches for homing, then backing up until the index pulse is seen.

    Are you using the limit switches, or separate homing switches?



  3. #63
    Gold Member TomKerekes's Avatar
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    You are confusing me a bit with terms 'Z axis' and 'Z index'. Most encoders that support an index pulse often refer to the AB quadrature signals and the Index pulse as A B Z. This Z doesn't necessarily have anything to do with Z motor Axis.

    Also you seem to be confusing 'Home Switch Inputs' with 'Index Pulse Inputs'. Index pulses can provide a very accurate means of determining absolute machine position, but they occur every encoder revolution and therefore are likely to occur at multiple machine positions without a means of knowing which one it is. So the normal method is to first move to a limit or home switch to know an approximate position and then move to find the first Index pulse. So 2 inputs are required one for the Limit/Home switch and one for the index pulse.

    The IO 138 as parameter #4 in the SimpleHomeIndexFunctionTest.c example is for the Limit Bit. The #7 parameter in the example is set to -1 to indicate there is not any Index pulse available. Change this to your Differential Input. The 8 differential inputs on Kanalog J2 end up driving KFLOP Inputs 36-43

    Code:
    result = SimpleHomeIndexFunction(2,  // axis number to home
                   1000.0,  // speed to move toward home
                   -1,      // direction to move toward home (+1 or -1)
                   138, 	// limit bit number to watch for
                   0,	// limit polarity to wait for (1 or 0)
                   100.0,	// speed to move while searching for index
                   -1,	// index bit number to watch for (use -1 for none)
                   1, 	// index polarity to wait for (1 or 0)
                   5000);	// amount to move inside limits
    HTH



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    Default Re: SBL Magnaturn Retrofit

    Quote Originally Posted by m_c View Post

    Are you using the limit switches, or separate homing switches?
    I was thinking of using a visual mark to get close then use the Z index pulse of encoder to home machine.Similar to the old Fadals. There will be a limit switch on tail stock to stop Z axis when it is commanded to move past current position of tail stock.


    Quote Originally Posted by TomKerekes View Post
    Hi Troy,

    You are confusing me a bit with terms 'Z axis' and 'Z index'. Most encoders that support an index pulse often refer to the AB quadrature signals and the Index pulse as A B Z. This Z doesn't necessarily have anything to do with Z motor Axis.

    HTH
    I wasnt referring to the Z index as if it was related to Z axis, i was referring to what you explained about the once per revolution mark on encoder. Sorry if i didnt make it clear. But you still interpreted what i was talking about.

    If i am remembering correctly, a few years ago you said that a Z index mark of an encoder could be used with a physical mark on axis table to accurately home axis. Is this correct? This would be much easier if i could do this with lathe, as tail stock might be in the way from where a dog would be mounted for Ref/Limit switch of Z axis. Would also simplify wiring.

    Thanks again,
    Troy

    http://www.homecncstuff.elementfx.com/


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    Gold Member TomKerekes's Avatar
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    If i am remembering correctly, a few years ago you said that a Z index mark of an encoder could be used with a physical mark on axis table to accurately home axis. Is this correct?
    I assume you mean a mark that you could Jog to manually by eye? Is so then yes. You might just call the SimpleHomeIndexFunction() and specify the Index bit as the limitbit and specify none for the index bit. In this case it will simply move to the first Index, stop, and zero. Note the visual mark should position the encoder not very close to any index pulse. In this way the starting position will always be on the same side of a particular index pulse and the routine will always find the same index pulse and not sometimes one and sometimes the next.

    HTH



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    Default Re: SBL Magnaturn Retrofit

    So, had to take a little detour from the electronics and do some more mechanical. After i started tuning the VFD i realized that the spindle was in rough shape. Was kind of expecting it tho. Ended up replacing all bearings. And found out that someone else had been in there before and used the wrong bearings and other incorrect practices. Here is some pics of the mess....

    Attached Thumbnails Attached Thumbnails SBL Magnaturn Retrofit-backofspindle-jpg   SBL Magnaturn Retrofit-frontofspindle-jpg   SBL Magnaturn Retrofit-rearassy2-jpg   SBL Magnaturn Retrofit-spindle1-jpg  

    SBL Magnaturn Retrofit-spindlehousing1-jpg   SBL Magnaturn Retrofit-spindlehousing2-jpg  
    http://www.homecncstuff.elementfx.com/


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    Default Re: SBL Magnaturn Retrofit

    But as of tonight its all back together and running nice. Spindle housing just gets warm,VFD amps are where they should be and DB level no longer sounds like a rabid dog biting itself.

    Next on the list is locating an encoder for the spindle and start building my C codes for KMCNC. Which reminds me, any suggestions on type and resolution of encoder being used for spindle feedback on a lathe?

    Thanks
    Troy

    Attached Thumbnails Attached Thumbnails SBL Magnaturn Retrofit-partscleanup1-jpg   SBL Magnaturn Retrofit-partscleanup2-jpg   SBL Magnaturn Retrofit-claenhousing1-jpg   SBL Magnaturn Retrofit-cleanhousing2-jpg  

    SBL Magnaturn Retrofit-greasedbearing1-jpg   SBL Magnaturn Retrofit-spindlerebuild1-jpg   SBL Magnaturn Retrofit-spindlerebuild2-jpg   SBL Magnaturn Retrofit-alldone2-jpg  

    http://www.homecncstuff.elementfx.com/


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    Default Re: SBL Magnaturn Retrofit

    Quote Originally Posted by Need TECH Help! View Post
    And found out that someone else had been in there before and used the wrong bearings and other incorrect practices. Here is some pics of the mess....
    Out of curiosity, how did you know that the bearings were the wrong ones? If I'm working on something like that I would have just blindly replaced what was in there with the same equivalent bearing. Nice job.



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    Default Re: SBL Magnaturn Retrofit

    First indicator was the sealed China bearings. Sealed bearings that size typically have a much lower rpm do to heat of seal.
    Then I used the number on bearing and checked with a good manufacturer on specs for same bearing number is.
    And the bearings in front where mounted back to face instead of back to back or face to face. The blueprint I have on machine shows how they should be mounted also.
    Troy

    http://www.homecncstuff.elementfx.com/


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    Default Re: SBL Magnaturn Retrofit

    Hay Tom,
    Iam looking at a US Digital encoder for spindle feedback on my lathe. The max RPM of spindle will be 4000.And encoder is connected to spindle by a 1:1 ratio timing belt setup.
    This is the encoder iam looking at....
    https://www.usdigital.com/products/e...llow-bore/HB5M

    The configuration of encoder would be ...
    CPR: 2048 (or 2500,4000,4096,5000)
    Index
    Differential

    Would there be any advantage with a higher CPR and if so which one do you recommend?
    Thanks,
    Troy

    http://www.homecncstuff.elementfx.com/


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