Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: aballworth on February 01, 2016, 01:27:21 PM
-
I placed a prox sensor on spindle to monitor rpm to cut threads. Mach 3 picks up the signal and it matches the number on the LED screen that came with the sensor. My problem is when I turn my spindle off, the RPM reading on mach3 does not return to zero. Has anyone else had this problem. It will stay around 130 or so. When I turn spindle back on it will display the correct RPM but it will never return to zero.
http://www.ebay.com/itm/121571984060?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
-
Sorry, I cannot help you as I am having the same problem. Just installed my sensor.
-
Are you using the same type sensor I am? I wonder if it has something to do with the output voltage of the sensor?
-
Magnetic sensor I would guess as I am just using a bolt head passing by the sensor, single pick up. One other thing is that the RPM reads to about 750 and then the read out in Mach drops to half the actual RPM. You experience anything like that?
-
Yes.. my low speed will work just fine 490 RPM but when I switch to high speed it should show 900rpm but mach 3 shows around 500rpm . The lcd screen shows the correct rpm but not mach 3. I know it is something simple, just cant figure it out.
-
I figured out mine.. i went to general config and reduced the "debounce interval" & "index debounce" it will now show the correct rpm. But it still wont go to zero when I turn off the spindle.
-
Well you are making progress, I am going backwards. I was getting a spindle RPM read out, but before I tried your debounce change I decided to change my motor setup into metric. I am working in metric and my ball screws are in metric. All seemed to go well and my programs run as before, BUT I no longer get a spindle RPM read out. I then did try raising and lowering debounce, moving my sensor back and forth but nothing worked. The sensor seems to be working as the light on the sensor flashes for each revolution. What a pain. Any ideas?
-
In very basic terms; Increasing the 'de-bounce' means that a signal has to be present for a longer period of time in order to be recognized.
When it comes to speed or position sensors increasing the detected time is the way forward (for an optical sensor this may be increasing the width of the slot, for a magnetic sensor it may be placing two or more magnets next to each other etc.).
Hope this helps.
Tweakie.
-
How are you starting/stopping the spindle?
What version of Mach are you using?
Hood
-
If you turn off the spindle manually Mach 3 doesn't know it's stopped.
Sent from my iPad using Tapatalk
-
Im using an older version that came with the machine. Thanks for the info. I just figured the RPM's would return to zero if the computer isnt receiving the clock signal. Also, Does anyone know the current specs for the parallel port. The sensor outputs 4.5v @ 200ma, im debating whether to put a resistor in to reduce the current.
-
The old version is likely the problem.
In Later versions Art changed things so that the RPM would only start to show if you started the spindle via Mach (G Code or button) and it would stop reading when you stopped by the same method.
In older versions Mach never really knew when the actual spindle had stopped and thus you could get a reading showing for a long time after the spindle had actually stopped, especially if you had spindle speed averaging applied.
Hood
-
Which parallel port? Actually it doesn't matter, the sensor will output up to 200 mA, depending on the impedance it's connected to. Actually a resistor is more likely to cause problems as it will reduce the voltage swing at the port input and reduce noise tolerance.
By the way I have the latest recommended version for threading and I switch the spindle on and off manually. But have to press "spindle" button to tell Mach 3 that lathe is started and rpm reading still persists when I manually stop the lathe.
Sent from my iPad using Tapatalk
-
and rpm reading still persists when I manually stop the lathe.
Sent from my iPad using Tapatalk
Yes you need to stop the spindle either by using M3 in the code or pressing the Stop on screen. Of course you don't actually have to stop the spindle by these methods but rather you are telling Mach you have stopped the spindle even though you use external (to Mach) method of starting/stopping.
Hood