How close to the end of your travel do you have your limit switches?

[dmgdesigns]

How close to the end of your travel do you have your limit switches?

[widgitmaster]

All my limit switches are 0.1" from the solid stop!
This number was a shot in the dark, i see now that it could be .05!
The micro switch and software (Mack3) communicate very well!
Eric

[Bubba]

On my mill/drill, I am about the same as noted by widgitmaster. I set them up by "eyeball" and then did several checks using G01 at various feed rates until I got up to G00 rate and made sure that I did not hit the hard stops.
You want to avoid the hard stops at all costs if possible as it can surely mess up your mechanics especially if you do it often.

[loves80z]

I would make it adjustable. slot either the switch dog or switch mounting bracket and U can get it where U want in the end.

[dmgdesigns]

Thanks Bubba -Why didn't I think of that?

Luves80z -That was the intent, I was not sure how much room I would need to stop safely.

[wizard]

Hey guys been away for awhile!

In any event this is another one of those items that clearly depends on the hardware and how the software operates. As has alread been described above you need to find out how far the axis overtravels the limit when it is hit. On many CNC systems the switch will inhibit the amp along with signalling the NC control. Systems with alot of inertia in the drive and low friction can overdrive signifcantly.

One thing to note is that when checking out how you system behaves make sure that you have the switch positioned so that the axis is in the middle of its move when it is tripped. The idea being to be at 100% velocity. You could otherwise be setting the switch based on an axis that is ramping down already due to ending of the comannded stroke of a softlimit. You want to be sure you can handle run away conditions as these can really damage a machine badly.

Dave

[CJL5585]

Originally Posted by dmgdesigns How close to the end of your travel do you have your limit switches?

1/2 inch from stops. Set by experience. Ever seen a machine crash?
My experience is with servo drive CNC's, but my personal machine uses stepping motors.

Jerry

[itsme]

What limit switches?

My Micro Mill doesn't have any and if it does hit the 'limit', then it just stops! So, I guess you could say I have mechanical limits...

Regards
Warren

[Bubba]

I put limit (and later incorporated them as home switches) simply because when I hit hard limits things started to break

As an example, I had an edge finder in the collet and told it to G0 without realizing a clamp was in the path. In less than two inches, there was enough force to bend the finder at right angles! I have also had problems with the lead screws and nuts.
I believe in limits!

[Lionclaw]

I don't have limit switches on my current machine, but my next one will have them.

Using Mach3, do the steppers stop immediately when the switch is triggered? Or do they decellerate and then stop?