"Limit" Switches Finally!

Is there an ideal configuration in terms of doing everything you’d want to do? I would think that wiring the machine for limit switches (i.e. switches at each end of each axis) would be the ideal given that it should be possible to use them as homing switches in addition to getting hardwired stops, but given that so many implementations use the single switch (homing) that I’m wondering if there’s a reason beyond cost/complexity.

If hardwired as limit switches they work as homing switches as well, one doesn’t cancel out the other.

You can use them as homing switches only.
You can use them as homing switches with soft limits.
You can use them as limit switches only.
You can use them as homing switches and limit switches.
You can use them as homing switches, soft limits, and hard limits, all at the same time.

The best compromise is to use them as homing switches with soft limits.


You forgot to add, “Do I make myself clear Soldiers.”
That’s awesome explanation Larry, as always.

This is my limit switch, there are many like it, but this one is mine …

So is there a downside (other than the cost of the switches) to setting the machine up with limit switches (2 switches per axis) and using them for homing and limits? (assuming here that the extra cost and hassle of wiring them is negligible)

I think the issue is that you don’t get a fast enough response from the switches in order to have them prevent crashes. The downside is that they give a false sense of security.

Soft limits are better.

Completely disagree with that statement. First and foremost soft limits is software reliant meaning if you neglect to home your machine by chance, your limits will not work and you will be susceptible to a crash. Hard limits on the other hand work no matter if your machine knows it’s location, making soft limits a false sense of security. While many use soft limits and i’m not knocking them (to each there own), but making a statement like yours is at best an uneducated response. As for response it stops the machine on a dime when a switch is triggered. I posted a video somewhere years ago showing how fast it stops the machine, not sure which thread it’s in. As for which is better, it all comes down to personal preference (then again I think I just pointed out soft limits major flaw :joy:)

I tried limit switches on my homegrown machine but eventually pulled them. they just kept going off in error. I had shielded them with a metal mesh sleeve, but I had them sharing a D connector with the steppers, so there could have been some field leakage there. I’m rebuilding my controller with fully separate stepper connectors and may try the limits on my X-Carve, but to be honest, the pieces that I cut are mostly 3"x3", with a few that are 6.5"x3.5", so I’m miles from the limit on my 500mm

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