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Author Topic: How to set rebound distance after homing?  (Read 2456 times)

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How to set rebound distance after homing?
« on: March 15, 2010, 01:35:01 PM »
Hi all,

I'm struggling to get my stock MaxNC T2 lathe to home to a consistent position.  My current effort is to slow down the homing speed, but that doesn't seem to give it enough bounce off of the switch to consistently clear and I often end up with the limit switch still triggering.  Is there any way to set the rebound distance so that that my axis stops well clear of the switch?
Re: How to set rebound distance after homing?
« Reply #1 on: March 15, 2010, 03:24:45 PM »
Provided you are using a "snap action" limit switch, the axis will be well clear of making the switch again after the homing routine is done.
What you are most likely seeing is switch bounce which can be overcome by setting the Debounce Interval in Gen. Config up a bit.
Try 500 or so, then reduce until it goes bad, then increase slightly.
There is no way to set the Rebound Distance as you call it.
It just reverses until the switch opens. From that point, you will notice that it takes a substantial move to make the switch again.
Re: How to set rebound distance after homing?
« Reply #2 on: April 05, 2010, 07:44:25 PM »
A belated thanks for your reply Overloaded.

In truth I don't have a clue what kind of switch is being used.  They are simply the ones that came stock on the MaxNC lathe.  I suspect that they are not the snap action type as they don't make an audible click when operated manually as well as not behaving as you describe - i.e., they are very sensitive near home and can yield a home location that vaires a couple of hundreths :o.  It seems to me they are likely simple push switches.

As for the debounce, the XML file provided by MaxNC has the debounce set to 2000.  Since there is no obvious shielding on any of the stepper, encoder or switch wiring, I suspect that noise is a general problem.

As is certainly readily apparent, I am a rank novice at all of this and have my hands full just figuring out the mechanical and software aspects of this art.  If anyone has any recommendations for replacement switches, I'd be grateful.  The machine is set up to accept 1/4" diameter axial switches.