EMC2 (linuxcnc) and turner's cube

[neity]

Hey guys,
I've been posting now and again, and have mostly figured stuff out, and I appreciate all the help I've been given! Sorry If I come off as needing all answers with no appreciation or receprication! I'm working on being able to answer other people's questions, but I'm not quite qualified yet!

Anyway, i switched to LinuxCNC and am having much better luck with that than I was with mach3.

It was much simpler for me (lots of linux experience) to setup. It also seems to run smoother if you will. I set up limits sort of?

I want to use 1 set of switches for I guess home and minimums, but I am confused.

When I set inputs 1, 2 and 3 to home + minimum, and then go into EMC2 and home all axis, it runs the Z axis up to the top (had to reverse this in stepconf) and then I temporarily have the home switch mounted up there with my finger and it hits the switch, bounces off, then continues travel so I hit the switch again and it gives me an error. Something like Joint 2 blah.

So I switched it to only minimum....Now I have to home by guesswork

So I switched it to just home, now it homes up against the switch and the travel limits are backwards? So I reversed the axis and same problem, different direction? Very confusing for me here.

What is the correct way to do this (what should I set my inputs to), and WHERE should I mount my home switches?

If I can get that figured out, it would be much appreciated. I just can't figure out this homing stuff! Can anybody point me in the direction of a good tutorial or explanation or even a book about this? I don't get it. I set my home switch, say home is 0 and set my travel and i still have this problem.

Maybe I need to better understand what "home" is.

So from there, I know how to use workpiece offsets (touch off in emc2), I would like to create a turners cube of maybe 1.5 by 1.5 by 1.5 cube or so. I don't know what size endmill or tooling in general to use, or how to program it.

I am able to setup my axis and get my expected travel correctly using the home switch etc. But then when I try to enter code in the MDI, it runs the first line like g0 x1. Then after that if I try like g0 x-1 it says it would exceed limits. If I repeat g0 x1 it doesn't say anything at all! WTF is that?? The visual graph clearly shows I'm in my bounds.... At least mach3 didn't do that.

BTW machine is a micromark X2. I'm using 6 inches travel on the x, 3 on the y, and 7 on the z just to be safe. and MAN that Y travel at a max of 4 inches is KILLING me. Is there any way to extend that or does that mean trashing everything I have and getting an X3? It's so short. At least with emc2 i'm not crashing my axis anymore, mach3 caused many a bad crash for me.

Thank you in advance!
-jeff

[epineh]

Lots of questions there, I will try answer a few while I have my coffee

What should happen during homing is that the axis will travel towards the homing/limit switch (in your case if you want to use the same switch) then once it activates the switch it will move off, then travel once more towards the switch slower, activate it once more then move off and stop.

The idea is that the machine then knows how far you can travel without hitting the end (mechanically)

Hitting the switch by hand is probably not the best idea as emc thinks the homing/limit has tripped while moving away and thinks something is wrong, maybe you have to set the travel from home switch distance to something smaller so it comes back sooner for the second time. My machine has a buggy limit/home switch so this happens sometimes for me as well, I just have to click it a few times to sort it out.

You can set all the speeds for this in stepconf.

Unfortunately if you don't get the homing right then running jobs will be hit and miss to say the least. You could possibly home manually for a start, I have a couple of small machines I do this with as I am too lazy to wire in the limits. Simply move each axis one at a time to its minimum travel and press the home axis button. To do this you will have to not set the switch to homing during stepconf setup, otherwise you will not have this button.

The Z axis is a little more tricky as you want Z0 to be at the top of its travel and travel in a negative (or down) direction from there, so the directions can seem back the front.

Oh yeah while you are playing around with all this make sure your estop is working properly, you will most likely need it in a hurry at some point !

I am away from my machine so I can't give you the specific settings for my machine to help just yet, but I can once I get back.

Hope this is some help, I will follow up with some of the rest later, I have to head out the door right now.

Cheers.

Russell.

[neity]

Thank you Russell!

That's a start. I would like to mount my homing/limit switches tonight if I can. Maybe I can give a better explanation here.

Where should I mount my switch? Should it be at table 0,0? That would mean that the TABLE (from operator standing in front of it standpoint) is fully towards me and to the right. (i'm just following what the markings on my CNCfusion motor mounts say...).

When I hit home all, and was able to get the x axis correct, it moved in the TABLE X positive direction (Table moved to the right). Very confusing for me.

I don't care if my X limit switch is at one end or the other, same with Y, but I would like to know what the RIGHT place is!

Here are pictures of the mounts for reference. Photo Album - Imgur

[epineh]

Yep that sounds right (correct anyway) the axis movement is in relation to the cutter so to make the cutter go to x0 the table will move to the right so the cutter is "moving" to the left if you know what I mean. Same goes for the Y, moving that to 0 will make the table move away from you towards the back of the machine.

Clear as mud

Cheers.

Russell.

[epineh]

So to answer your question the homing switches are usually at the 0,0,0 position, you could have them anywhere but this is the most common and simplest to setup.

This means you want the machine's homing switches to operate when the table is moved fully to the right and as far to the back as it can, so the cutter is in the x0,y0 position.

As for the Z it should be where the axis is at the highest point it can travel, or at least close, otherwise since you are using limit as homing you will never be able to travel any further than this anyway.

Russell.

[jt4897]

I probably am not the best reference for this but there are a couple points I'll mention from what I remember. Hope it helps.

On my system the home switch is at one end just before the limit switch. Once it hits the switch it's set in the config to bounce back a certain distance to its home position. Put another way - it moves almost all the way to my Y + limit, hits the "home" switch and then moves back 5 inches or so to home and sets Y to 0. My X home switch is next to my - limit so it only bounces back an inch. This is set in the config.

You can actually just use one switch for both home and limit.

You can also have both + and - limit switches connected to the same signal since it knows which way its moving when it hits the switch.

My home position isn't at the physical limit of travel but that's my preference. Try to think of homing as giving the machine a reference in space to where its limits are so that it can use the soft limits rather than the hardwired switch limits. That's the machine's home. After that point you'll mount your part somewhere on the table and set a point based off the part as your user home for that part. Some machines, I've heard, don't have limit switches at all - just the home switches.

[cyclestart]

(i'm just following what the markings on my CNCfusion motor mounts say...).

CNCfusion's markings are in agreement with the 'right hand rule' for vertical milling machines fwiw. Ignore the markings, they only serve to confuse

I move the table full right and up against the column to Home but really it's all a matter of preference and convenience, even for CNC manufacturers.

btw: the previous post is dead-on -the-money.

[neity]

CNCfusion's markings are in agreement with the 'right hand rule' for vertical milling machines fwiw. Ignore the markings, they only serve to confuse

I move the table full right and up against the column to Home but really it's all a matter of preference and convenience, even for CNC manufacturers.

btw: the previous post is dead-on -the-money.

Ok Just to make sure i'm clear so I can mount my homing switches today!

Cutter 0,0,0 should be at table far right, and AWAY me, with head at the top of the column, got it. That makes sense to me.

My ONLY concern is this: http://www.youtube.com/watch?v=2v5tCda3lZE]home switches and soft limits - YouTube

Skip to 1:50 to see all three switches within 22 seconds!

That's a video by HOSS that has his limit switches at X far (Table) to the right and Z at the top, but Y is at the TOP. Or rather, away from operator. On further brain usage by me, that would put the cutter at 0,0,0 (bottom right on plan).

Also, THAT Y EXTENSION ON THE COLUMN! ANYBODY KNOW HOW TO DO THAT?

But I digress. So I think I will install the limit switches like he has them.

Now, in emc2 or LinuxCNC as it is now known, in stepconf, does anybody know what I should set the switches as for X,Y and Z?

There are three options each. Home. Home + Max, and Home + Min.

Would the Z be the opposite of the X and Y because its movement goes in the opposite direction?

[hoss2006]

That's the way mach 3 recommends for homing, that way all X and Y moves are positive and Z moves are negative.
I've seen some VMC's just the opposite but the mach way makes more sense to me, don't have to mess with - numbers going from home to the work and the z moves are negative just like in a typical program.
Hoss

[neity]

That's the way mach 3 recommends for homing, that way all X and Y moves are positive and Z moves are negative.
I've seen some VMC's just the opposite but the mach way makes more sense to me, don't have to mess with - numbers going from home to the work and the z moves are negative just like in a typical program.
Hoss

Ok so I'm a bit confused on what axis need to be reversed, etc....

I installed the Z axis switch permamnetntly on the metal gauge on the side of the column. Thought it was a really nice, non-invasive place to put it. Thing works like magic.

The X and the Y I did temporary mounts and here is what happened.

The Z went great! Then cam the X. The X Moved the table all the way to the LEFT. Which I guess puts the cutter at the right of the workpiece, but anyway, hoping for the best, I let it go, and it went and hit, backed off, and hit again on that switch. Ok cool.

Then came the Y, the Y went all the way back to the column which I was happy about, and it went hit the switch, backed off, and hit it again. Ok Awesome!

Then I went to jog the axis... The Z was fine. But both the X and the Y were more or less stuck. That is to say, they would only travel further PAST the limit switch. Now it seems like the X is backwards to begin with, So I guess I should invert that in EMC2, but that doesn't explain the Y.

What should I set my limits as? What should my soft travel limits be (in terms of min, max). And what should my home be opposite I guess?

Anybody familiar with EMC2 should be able to help. Come to think of it...one reason I threw my hands up at mach3 was the same reason.... Hmmm...