Usage of limit switches is rather ridiculous as they are never accurate

Continuing the discussion from Smashed Z limit switch:

As long as your machine has its Soft Limits set. The use of Limit Switches is Ridiculous. You don’t Zero out your machine to the machine itself, but rather to the material your cutting. Besides, due to Humidity, Temperature and Age of your your Machine and its General Environment your Zero will constantly Move. Jigs and Offsets are the may to go. Namely G55, 56, 57 aso on and so forth.
For most projects, Limit Switches are a waste of time and energy.

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I’m not trying to sound derogatory, its just that there has been way to much misinformation about the necessity of both Limit and Homing Switches.

That’s great, That you’ve got a Bump Stop.
But your Zero is here today at .00000 and tomorrow its off by .00003 mm . We have a problem, because it generally isn’t considered to be ACCURATE. Though it maybe fine for sign creation, you won’t be able to do any Micro-Machining for Profit. Because you’ll have quality of fitment issues as nothing will be exactly the same and that is the whole premise for having a CNC Work Center.

My machine was off by .0003 mm yesterday. But I gave it the mad dog stare and the made you flinch lunge. It’s back to .0000 now.


I dare you to show me a topic on this board that features a project in need of that level of accuracy.
95% is signs and the like, not super tight tolerance machine parts…

the most accurate measuring dial I own is accurate up to 0.001mm. And that is way more than I will ever need


I can’t think of anything requiring that kind of tolerance control. That’s .0000012 inches. That’s so many zeros I don’t even know what it is.


Please be more accurate.
It’s 0.000001181 inches.
Excuse me, it is actually: 0.00000118110236220472 inches. :slight_smile:


What???!! No wonder my carves are turning out bad. Time to recalibrate.

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I can agree the are unnecessary. But are quite nice to have.

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The point I am trying to make is that accuracy dependent upon a mechanical switch or limiter is useless, Furthermore, why do people continue to use these mechanical switches which are prone to failure. Stop worrying about whether or not your machine is configured with Machine Coordinates and start using your Soft Limits. If a particular corner of your machine is defined as 0,0 well so be it. Now go ahead and and align your material at that point and start your milling.

What’s that, you can’t. Well why not, you stated that that is your Zero Point. So you should be able to start your processes from there Correct?

People the whole point in my discussion was to A: stop worrying about these darned switches, B: Use Jigs along with a Fixture Table using the G55 Command available to everybody in G-Code, thus allowing the operator to set their limits according to your material at hand using SOFT LIMITS.

Why can’t you?

I have in the past made Carbon Fibre Chassis’ and the like for the electric Car and Airplane Market. And if I’m paying $175 plus shipping for material. I’m certainly not going to waste it. Therefore, I have to optimize how many parts I can get out of a sheet of material to minimize wastage. This means that a lot of my cut lines were within ten thousand’s of an inch of each other. If my accuracy was off by ten thousand’s of an inch on every piece. I couldn’t guarantee that I could end up with the required number of pieces from a sheet of material.

The whole point of this entire discussion originally was to stress to people to use their Soft Limits and to Stop using or worrying about their Machine Coordinates. Also to use Fixtures along with the G55 Command that is part of the GCode Language.

You made these parts with an xcarve? They only promise .003 accuracy, and that’s a perfectly calibrated machine. You say don’t do this. But do this. With out any real explanation of what this is or how to do it. Drop some hints at least. What’s the process, what are fixtures or a fixture table. Is G55 the only code or can I use say G54 or G59. And if your machine doesn’t know where home is how do you use Soft limits?

The easiest way I have of explaining it is to have viewers watch the following video available on YouTube by one of their better presenters. By the way, I’m not using Easel but rather UCCNC to control my machine.

The video is: Homing In Mach3 To Your Raw Material Using The Fixtures Option

Corvetteguy? I’ll check it out. Watch a lot of his videos. Are you him?

The use of fixturing is a great idea for repeatable parts. But as soon as you turn your machine off, you have to find machine zero again in order for G55 to be accurate. Maybe it’s a Mach3 or UCCNC (this is not a Stepcraft forum) thing. I’m having a hard time understanding why if you start your toolpath in the bottom left corner of your workpiece, you can’t put your fixture (sounds like a bump stop to me) at machine zero and take off.

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The purpose of homing the machine is to establish Machine Zero at a repeatable and known location of the mechanical portion of the machine.

The mechanical switches on the X-carve can easily position a tuned machine to within 0.001 inches of the same location all day long.

If I remember correctly Phil’s bump stop is aligned with the homing position, so his bump stop is at Machine Zero whenever he homes his machine (could be off a little, but it’s less than 0.001 inches).

Thanks for clearing that up Larry. Lol. I guess my text didn’t come across the way I meant it. I understand and have or thought I had full knowledge of that. I was talking to Ronald who seems to believe you don’t need “these darned switches”. I’m still waiting for him to explain how to use G55 without finding machine zero first. Thought he had some knowledge to drop.


No, but I’ve learned through him what has taken me forever to understand and to alleviate a lot of my questions. I rely upon him for some of the most mundane questions.

Once again, watch the videos posted by CorvetteGuy on YouTube and everything will become clear.
Remember this a subject that his business depends upon him knowing what he’s talking about.

I hadn’t watched this. You seem to base your statements on the material presented in this video, so I thought, what the heck, go watch it I might learn something.

What I learned and what became abundantly clear is that this guy should limit his activities to his CNC work as he has very little skill in the art of communication. He is very inconsistent with his terminology to the point where when he says “home” you don’t have clue as to which of the multitude of definitions he is using for the term.

He does have some idea of what he is trying to say, he just can’t communicate very well and he is confusing the issue with his video.

The bottom line is that if you have a method that works for you then by all means use it.