Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jimthefish on January 02, 2011, 09:03:31 AM
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Hi, I woder if anyone can help me set Mach 3 screen to show my actual spindle speed. I have set the spindle up using the config boxes and have estimated the speed, It seems about right as I haven't burnt out any cutters yet. When I converted the Denford Triac there was a Hall proximity sensor that detected the spindle position for the tool changer. I have got rid of the toolchanger so this sensor is redundant. I have checked this sensor and when I rotate the spindle pass the sensor I get a 5v on and off signal. Can I use this to tell mach 3 the actual spindle revs only I havent got a clue what to connect to what. I have spare input/outputs on my breakout board but not sure how the signal is then interpreted by Mach 3.
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Just connect that 5v to a free input on your BOB and then go to Config menu then Ports and Pins then Inputs and under the Index entry put the port and pin number you are connected to. Go To General Config and set the Index Debounce to zero if its not already.
Thats you done :)
Hood
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Cheers Hood, again you have come up with the answer, Thanks mate will try later today. Jim
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How are you powering the sensor?
You may need to tie the 0V side of it to your BOBs 0v if you are not powering from it.
Hood
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Ok I will make sure the 0v goes via the BOB. I did notice a %v and 0V port. I have a couple of machine parts to finish off then I will try it. Think I'm Ok with that side of it, it was how the signal got to the screen display, only it dont seem to tell you in the manual any thing about how to do it via index. Cheers Hood. Jim
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Hi Hood does this make sense. Connect the Hall sensor powered through the 5v on breakout board then second wire to pin input 16. then set config pins and ports to pin 16 port 1. The debounce is set to 0. Hope I've attched the BOB drawing unless this will not make sense. :-\
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According to the drawing you have pin 17 but whatever you use you set that for the Index in Ports and Pins and you should be fine.
Hood
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Hi Hood this is where i'm confused. I'm using pin 17 for the voltage variations to instruct the spindle drive speed, so pin 16 is spare so though if I connected it to the sensor then assigned index port and pins that would do it?
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Oh sorry misunderstood and also I have forgotten about the parallel port in which are inputs and which are outputs as it has been so long since I have used it. Pin 16 is actually an output so you cant use it, you need to use 10 to 13 or 15, so if you already use them then the only option is to get a second PP and use that. There may be other options depending on the way your limit switches are wired, if they are normally closed switches then you could wire them all in series and only have to use one input, that would possibly free up some inputs for you.
Hood
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OK Hood will have a think. Cheers mate.
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Hi Hood good news you got me thinking, been down the workshop and had a look, I did wire up a couple of the limits in series so I have input5 spare which is linked to pin 15 so I should be able to use it. Once again thanks for you help mate. Jim
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Yes, should work fine for you :)
Hood
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Just connect that 5v to a free input on your BOB and then go to Config menu then Ports and Pins then Inputs and under the Index entry put the port and pin number you are connected to. Go To General Config and set the Index Debounce to zero if its not already.
Thats you done :)
Hood
Going to attempt this myself. But I have a question or two.
How does Mach know that this is an input to read the spindle speed? Also, if Mach understands this is the actual spindle speed, does Mach intelligently use this to control the spindle speed or is this simply a feedback for visually checking.
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The Index input is where Mach looks to see what the spindle speed is, ie 1 pulse per rev so it can work out what the RPM is.
There is a setting which can affect that, it is the ratio in Pulley Setp page, if you have a ratio of 1 then each pulse is one rev, if however you had the sensor on the motor and there was gearing between the spindle and motor then you would set a ratio so Mach can work out the amount of pulses it sees before it calls it a rev.
The index is used for readout and if you are in Feed Per Rev mode (G95)
It is not used to correct spindle speed unless you have closed loop spindle control selected but not sure how well that works, have heard reports from some people have said it doesnt. I have never used it as my spindles are step/dir servos.
Hood
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As always, thanks for the quick response.
I have a Belt Drive Conversion kit installed, so I'd planned to mount the rare earth magnet under/on the pulley that's set on the spindle shaft itself.
Since the feedback doesn't reliably control the spindle speed, I'm not sure now whether I need to bother with all this since I have a handheld tachometer. (other than for "Coolness" sake). :D
I would be nice though to have it right there on the screen.