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  1. #61
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    It's probably the software reading the pulses in a different way. The counts may be reading on the rising/falling edges of the encoder square waves. you could multiply the counts by four (quadrature).



  2. #62

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    Quote Originally Posted by bloke View Post
    It's probably the software reading the pulses in a different way. The counts may be reading on the rising/falling edges of the encoder square waves. you could multiply the counts by four (quadrature).
    Yes, it is a quadrature encoder. 4 * 5 * 1000 = 20,000.

    Not sure if I really have 1/20,000 (0.00005) resolution though. I'm not 100% sure how that works. I guess I need to start watchig Fleabay for a good deal on an oscilliscope. And see if I can really associate all 4 pulses with actual movement. How do you measure 0.00005 anyway?

    I would have been happy 1/5,000 (.0002) resolution. Its better than the claimed original repeatability of the machine. I guess I will have to buy some quality measuring stuff, find my backlash, make some cuts, and do some measurements to really know.

    Bob La Londe
    http://www.YumaBassMan.com


  3. #63
    Community Moderator Al_The_Man's Avatar
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    Quote Originally Posted by bloke View Post
    you could multiply the counts by four (quadrature).
    Or more accurately basic Quadrature pulse count X4

    Quote Originally Posted by Bob La Londe View Post
    Yes, it is a quadrature encoder. 4 * 5 * 1000 = 20,000.

    .
    I am not sure how you arrived at 20,000?
    Unless the rev/inch is 5, then this is correct.
    The resolution or Least input increment, is simple to calculate.
    If your encoder is 1000 line resolution, then this is usually multiplied X4 in the controller or drive, in this case a resolution of 4000p/rev, calculate how many revolutions of the encoder occur for 1 inch of movement, divide 1 inch by the the total value of pulses, this equals your resolution or least input increment.
    You don't need a 'scope.
    Al.

    Last edited by Al_The_Man; 08-24-2012 at 07:39 PM.
    CNC, Mechatronics Integration and Custom Machine Design

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  4. #64

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    Quote Originally Posted by Al
    I am not sure how you arrived at 20,000?
    Unless the rev/inch is 5, then this is correct.
    Quote Originally Posted by Bob
    Correction. The ballscrews are 1.25" x 5 TPI.
    Quote Originally Posted by Al
    The resolution or Least input increment, is simple to calculate.
    If your encoder is 1000 line resolution, then this is usually multiplied X4 in the controller or drive, in this case a resolution of 4000p/rev, calculate how many revolutions of the encoder occur for 1 inch of movement, divide 1 inch by the the total value of pulses, this equals your resolution or least input increment.
    Quote Originally Posted by Bob
    1/20,000 (0.00005)
    Quote Originally Posted by Al
    You don't need a 'scope.
    Well, there are two things there.

    One
    I want to know if the pulse are occuring equally spaced over time and/or travel or if they may be concurrent since they come in on two different channels. If they are concurrent it may be possible that I only have half the perceived resolution. Since I don't know, the easiest way I could figure to check is with a scope, and ...

    Two
    ... a scope would also help with servo driver tuning for best performance with minimal oscillation. The motor hums or vibrates perceptabley while idling. Gecko says that the out of the box settings on the G320X drivers are probably "ok." They are probably right because I left the motor idling for half an hour and it did not get into any destructive oscillation cycle, and the motor barely got warm. Still, if you know a way to fine tune the servo drivers without a scope I would be glad to hear it.

    So, while you are probably correct that I don't "need" one, I can perceive a practical use for one.

    Bob La Londe
    http://www.YumaBassMan.com


  5. #65
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    Quote Originally Posted by Bob La Londe View Post
    I want to know if the pulse are occuring equally spaced over time and/or travel or if they may be concurrent since they come in on two different channels. If they are concurrent it may be possible that I only have half the perceived resolution. Since I don't know, the easiest way I could figure to check is with a scope, and ...
    .
    If you are talking about the quadrature pulses they are each spaced at 90°, hence quadrature.
    if you page 3/4 down in this link it shows the A&B channel pulses and the four edges where the x4 detection is obtained from to increase the resolution.
    Rotary encoder - Wikipedia, the free encyclopedia.
    You may see an encoder described as differential, this has 4 channels instead of 2 and inverts each A&B, to provide a NOT A and NOT B or complement, for noise rejection.
    Al.
    .

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  6. #66

    Default X-Arcade (DOH!)

    Ok... I was doing some wiring last night. After testing the servo motor I disconnected it and started doing my "permanent" wiring. While I was standing there admiring my work I was thinking about the various inputs. A smoothstepper has the functionality of all the pins of two parallel ports, but it also has a set of inputs normally used for encoders that can be addressed like any other input as PORT 3. That gives me 15 inputs.

    Since Mach doesn't tell you which limit was hit when you hit a limit switch I figured I would wire them all up to the same input. I will also use my limits for homing atleast to start.

    Add in probing inputs and a few other misc stuff for various trouble conditions spindel speed etc, and I would normally have only a couple inputs left over. With those port 3 inputs however I have enough to hook simple switches up as jog switches for manual control other than the keypad.

    At first I was thinking of some cheap Radio Shack momentary push buttons, but then I started thinking of other things I might be able to adapt. Maybe an old Atari joystick or something else. Then I started looking on Ebay for arcade buttons. I was almost ready to order some. One outfit has 2 HAPP joysticks and 14 buttons for about $40.

    This morning I remember something I already had. Years ago we bought an arcade style interface to use with a PS2. I was never a serious gamer and my son didn't like the way it played so it got put in storage.

    Its perfect. No its not a pendant, but I can make a little box shelf, mount it on the head of the mill, or hang it off one side of my keyboard tray. The exact location can be determined later. I suppose I can even make up a pendant style box I can hang on a hook out of the way when not in use.

    Initial cost for testing the idea. Nothing.

    Maybe I can add a pinball table and a tilt swinger to the machine. LOL.

    P.S. The buttons and the joysticks all use the same form C micro switches. Since these were intended to take a pounding in a game environment they should last forever when used occasionally as manual machine controls.

    Attached Thumbnails Attached Thumbnails KMB1 Conversion-new-pendant-controls-jpg   KMB1 Conversion-micro-switches-jpg   KMB1 Conversion-like-one-jpg  
    Last edited by Bob La Londe; 08-27-2012 at 12:29 PM.
    Bob La Londe
    http://www.YumaBassMan.com


  7. #67
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    Hi Bob, am I right in saying you ended up with a total of 3 turns off the secondary windings in the transformer, and that gave you around 57 volts ? I am about to do mine, it runs on 415v (2 phases off a uk 3 phase supply)

    what voltage did you end up with on the DC side ?



  8. #68
    Community Moderator Al_The_Man's Avatar
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    You know if you want to get the turns ratio right and have the room on the TXFR winding, Use some small gauge wire and put on say 10 turns.
    Measure the AC and extrapolate the turns/volt.
    You then know exactly how many you need to take off to reduce it to the level you want.
    DC out is x 1.414 of the secondary AC.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  9. #69

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    Quote Originally Posted by GT390 View Post
    Hi Bob, am I right in saying you ended up with a total of 3 turns off the secondary windings in the transformer, and that gave you around 57 volts ? I am about to do mine, it runs on 415v (2 phases off a uk 3 phase supply)

    what voltage did you end up with on the DC side ?
    I got a rock solid 78VDC. Since my servo controllers are rated for 80 I figured that was close enough. I took my time I pulled one wrap and measured. Then pulled another wrap and measured.

    I posted a link to an on-line calculator for this stuff earlier in this thread.

    Here:
    Martin E. Meserve - K7MEM - Un-Regulated Power Supply Design

    Don't guess about what you will get. Use your volt meter.

    Bob La Londe
    http://www.YumaBassMan.com


  10. #70
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    Thanks Bob, will give it a go, and thanks Al, I get the 1.414 thing okay, thanks for that, it will be useful, but I have no idea what "TXFR" or "extrapolate" mean,
    I am gonna have to google those !!

    On a big learning curve here, dont think I would stand a chance at completing this without help from you guys

    thanks again !



  11. #71
    Community Moderator Al_The_Man's Avatar
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    TXFMR is and old acronym for Transformer and extrapolate, say you get 5vac for 10 turns, then this is equal to 2 turns/volt.
    Every two turns removed = 1v reduction.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  12. #72
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    Thanks Al, I get it now, boy I had some trouble trying to get a few turns off, the windings are real tight to the metal frame, could not even get the paper cover off at the sides, the whole thing has lashings of varnish all over it, tried to wedge a thin plastic rule between the paper and frame, impossible !

    Finally had to snip the wire close to the frame, and tap the ends with a small hammer to drive them through, then grip with snips and cam walk the wire through, was really worried about damaging the varnish on neighbouring wire, so once I got it moving, had to chamfer the ends before pulling all the way through, almost gave up at one point, thought I had pretty much ruined the thing, eventually got two turns off

    I had 59.8 vac at the start, minus two turns gave me 56.9 vac, so x 1.414 should give me 80.5

    I hope this will be okay for the gecko`s, I was reading on another drive manufactures website that the over voltage protection circuit kicked in at
    just 0.5 over voltage, I am wondering should I take off one more turn ????



  13. #73

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    Quote Originally Posted by GT390 View Post
    Thanks Al, I get it now, boy I had some trouble trying to get a few turns off, the windings are real tight to the metal frame, could not even get the paper cover off at the sides, the whole thing has lashings of varnish all over it, tried to wedge a thin plastic rule between the paper and frame, impossible !

    Finally had to snip the wire close to the frame, and tap the ends with a small hammer to drive them through, then grip with snips and cam walk the wire through, was really worried about damaging the varnish on neighbouring wire, so once I got it moving, had to chamfer the ends before pulling all the way through, almost gave up at one point, thought I had pretty much ruined the thing, eventually got two turns off

    I had 59.8 vac at the start, minus two turns gave me 56.9 vac, so x 1.414 should give me 80.5

    I hope this will be okay for the gecko`s, I was reading on another drive manufactures website that the over voltage protection circuit kicked in at
    just 0.5 over voltage, I am wondering should I take off one more turn ????
    80.5 would be fine, but I bet the forward voltage drop through your rectifier will drop it down under 80.

    The online calculator I pointed you to says 80.23 no load / 78.83 full load.

    Bob La Londe
    http://www.YumaBassMan.com


  14. #74

    Default Air & Oil - Spindle Brake

    Snipes44,

    Or anybody else... is this correct?

    I plan to run an electric pump and water soluble coolant so the first tap could be totally eliminated if I have this right.

    My (water seperator) / (regulator) / (air tool oiler) is pretty rough so I was thinking of replacing/rebuilding that whole assembley.

    The machine oiler looks ok. Figured once I had the correct flow figured out I would test to make sure it actually pushes oil out where its supposed to. Maybe a start/test with direct air off the main regulator and build pressure to see if anything blows out and then hook it back up the way its suppose to be.

    Since the spindle is run with a VFD that uses regenerative braking and has a HUGE braking resistor on the back of the machine, exaclty how and when would you employ the electrically operated air brakes?

    How much presure does the air brake require to operate properly?

    Attached Thumbnails Attached Thumbnails KMB1 Conversion-air-oil-jpg  
    Bob La Londe
    http://www.YumaBassMan.com


  15. #75
    Community Moderator Al_The_Man's Avatar
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    If it is anything like the pneumatic operated brake on the Excello's it is only picked up at zero rpm.
    Mainly to lock the spindle to assist in a manual tool change.
    I have the solenoid relay pick up off the At-Zero-speed output of the VFD, so once the motor is stopped the brake picks up, I have a manual overide SW in series which removes the brake at stop if required.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  16. #76

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    Quote Originally Posted by Al_The_Man View Post
    If it is anything like the pneumatic operated brake on the Excello's it is only picked up at zero rpm.
    Mainly to lock the spindle to assist in a manual tool change.
    I have the solenoid relay pick up off the At-Zero-speed output of the VFD, so once the motor is stopped the brake picks up, I have a manual overide SW in series which removes the brake at stop if required.
    Al.
    That's all I could figure. That it might be useful for changing tools. I've swapped a few of the tool holders already just to see how it works, and you have to reach in and hold the spindle even with these quick change tool holders to get it to come loose. I was thinking of maybe a manual switch to lock it up, but if I can trigger it off the enable disable on the VFD that would be ok too...

    Getting it to stop isn't really hard to figure out, I was just wondering why.

    Bob La Londe
    http://www.YumaBassMan.com


  17. #77

    Default Home Made Motor Cover

    Somewhere along its life the fiberglass cover on the X-Axis servo motor got crushed. Probably when that motor was broken. Anyway, I was just going to throw the motor on and not worry about it, but I am going to run a water soluble coolant, and I may run a high speed companion spindle so I figured it atleast needed a splash guard. Especially since the Y axis wires, and the X&Y proximity wires also go through here.

    I'm not trying to make it water proof or anything. Just a splash guard so anything that does go that way doesn't pour over the motor. I'll probably make an insert cap for the end eventually, just to make it a little more rigid and help it hold its shape. I need to go get another piece of sheet first though.

    Attached Thumbnails Attached Thumbnails KMB1 Conversion-2012-08-31_12-17-29_687-jpg  
    Bob La Londe
    http://www.YumaBassMan.com


  18. #78
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    My Gecko`s and PMDX bob arrived today, cannot believe how tiny the gecko`s are !

    gutted out the cabinet and started to do some exploring, my machine has the three wire proximity limits on x and y, but has regular mechanical 2 wire micro switches on the z

    three questions I would really appreciate help with,

    are the 3 wire (black red white) proximity switches wired as follows, red +5v, black ground, and when activated they switch white to ground ?

    my black and silver electrocraft servos have the main black and red 80v supply, but also have two smaller wires, white and blue, what are these, for tach feedback ? and what do I connect them to

    I have litton 82BZ-1000-5-3 encoders with five wires
    can someone help me with the wiring
    Red 5v
    Black ground
    green ???
    White ???
    Blue ???

    thanks



  19. #79
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    Hurco KMB1 encoder wiring now sorted

    Black- common
    Red- +5v
    White- A
    Blue- B
    Green- Marker

    From what I can see, I dont use the tach on the electrocraft, I guess I should remove the brushes, correct ??

    just need to know about the limit switches in post above

    Thanks



  20. #80

    Default

    I already posted a link to info on the proximity sensors I have. I was able to read the part number off the top one in the Z because I have all the covers off the head right now. They have two limits on each axis partially tied together. Its a good idea to physically look so you know how.

    Bob La Londe
    http://www.YumaBassMan.com


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