Speaking of Mach 3 offsets and limits

JC

Coos Cues
I have watched every how to video I can find and still have trouble with this concept.

I set up soft limits to prevent my gantry and spindle from crashing in g54 and it works fine as long as you don't zero an axis. For instance if I center my x axis for ring billets by clicking on the zero x button it changes the default g54 x from the lower left corner to the center of my fourth axis permanently. Or if I touch off my router bit and click zero z the zero position for z in g 54 changes permanently and the machine position also then says zero instead of what it's supposed to tell you which is how far from home you are. Then when I hit go to zero the router slams into my table. Therefore I'm scared to death to push that button as I am never sure what's going to happen even though I know it's supposed to go back to the original home. It's supposed to be the slickest thing since sliced bread but I am not sure what to do different to stop this from occurring.


Then I tried setting up an offset in g55 mainly just for remembering the center of my ring billet rounds in the x axis which is a pain to find every time I want to cut a billet and when I clicked on reference all home and zeroed the axis' it worked perfectly. Until I went back to g54 to find every setting there was identical to what i had just set up in g55. So If I set zeros back on g54 to the lower left corner of my table and then click on g55 it's also now zeroing there. I do click save settings after every change. And then when I close Mach and come back it's just a hot mess.

On the videos I watch it works like a dream but on my machine it's a damned nightmare.

Can anyone relate to these issues in their past and found out what they were doing wrong?

Thanks,
 

iusedtoberich

AzB Silver Member
Silver Member
It doesn’t sound like you are homing your machine to me on each power up. If you don’t have home switches, you can do it with a mechanical reference (like a hole in the tackle, etc). You can test where home is with g53 x0 y0 z0.

Zeroing an axis is zeroing the work offset (G54-G59). Homing is the “ref axis button”.

Sorry if you already know all this. I took me a while to get a handle on it myself.
 
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kgoods

Consistently Inconsistent
This drove me crazy when I was using mach3. If you don't have home switches and you press ref all home mach3 will set the machine coords to zero where ever the tool happens to be regardless of what work offset you're in. I crashed my machine a few times trying to figure this out.

A couple things to keep in mind, G53 is actually machine coords, G54 is your first work offset. But since mach3 always comes up in G54 I tended to treat that as my machine coords, so G53 and G54 were always the same. I started my work offsets with G55.

I have since switched over to UCCNC and I can't tell you how much easier everything is. I think a lot of my problem with mach3 was also that it was a "funny version" if you know what I mean. :)

Try this (and I'm going from memory so keep your finger on the e-stop just in case), turn on your machine, set your machine coords as you usually do (I assume you move the machine to a known position and "ref all home" there). This will set G53 to 0,0,0, G54 will normally also be 0,0,0 at this point in time.

Now do not ever touch the ref all home again as this will change your machine coords since you don't have home switches (assuming again). Now click on the G55 work offset and move the machine to your billet start position. Now makng sure you're in G55 zero all the axis. Now save offsets. Now on your work offsets tab the G54 offset should be different than the G55. G55 should be 0,0,0 and G54 should be the distances between the machine's 0,0,0 and G55's 0,0,0.

Now this is where I always had problems with mach3, in a perfect world if you press goto zero nothing should move since you're in G55 and the coords are 0,0,0. Do it with your finger on the e-stop. If that worked, then switch to G54 and press goto zero and the machine should move to machine coords 0,0,0. If that also works then you should be able to switch back and forth at will and add more work offsets as necessary.

Having home switches makes this a lot easier but once a "ref all home" is done it should work without them. The ref all home is the only way the machine knows how far it can go before it hits the soft limits regardless whether you have home switches or not.

Like I said though, it drove me crazy for a long time as it still didn't seem to be consistant, or maybe it was just operator error on my part. It could be a lot more intuitive. UCCNC is a no brainer in comparison when it comes to work offsets.

Let me know how you get on.

Also... I know exactly what you're going through. The above is how it is supposed to work. I don't think my chinese version ever worked correctly, I got to the point of not trusting the "goto zero" button at all. Very scary when the z hits the top and starts grinding and skipping steps! It seemed like it would never act the same from one press to the next. I just got in the habit of insuring I was in the correct work offset and then typing G0X0Y0Z0 into the MDI since even though it was more than a button press at least it always worked.

Ken
 
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kgoods

Consistently Inconsistent
Wow, I wrote that late last night... should have waited until this morning. :)

I tend to use "limit switch" and "home switch" interchangably and I shouldn't, it only adds to the confusion. I only have three home switches on my machine and no limit switches, relying on soft limits from there. I'll fix that post to avoid any confusion.

But the most important thing to remember is if you don't have HOME switches the machine is relying on you to set the machine home (0,0,0) every time you start the program. Then the soft limits and work offsets are always referenced to that position. Home switches makes this a lot easier because you can simply fire up mach3 and press ref all home and the machine will then home itself. Then your saved soft limits and work offsets all "just work".

Hopefully I didn't add to the confusion. :)
 

JC

Coos Cues
This drove me crazy when I was using mach3. If you don't have home switches and you press ref all home mach3 will set the machine coords to zero where ever the tool happens to be regardless of what work offset you're in. I crashed my machine a few times trying to figure this out.

A couple things to keep in mind, G53 is actually machine coords, G54 is your first work offset. But since mach3 always comes up in G54 I tended to treat that as my machine coords, so G53 and G54 were always the same. I started my work offsets with G55.

I have since switched over to UCCNC and I can't tell you how much easier everything is. I think a lot of my problem with mach3 was also that it was a "funny version" if you know what I mean. :)

Try this (and I'm going from memory so keep your finger on the e-stop just in case), turn on your machine, set your machine coords as you usually do (I assume you move the machine to a known position and "ref all home" there). This will set G53 to 0,0,0, G54 will normally also be 0,0,0 at this point in time.

Now do not ever touch the ref all home again as this will change your machine coords since you don't have limit switches (assuming again). Now click on the G55 work offset and move the machine to your billet start position. Now makng sure your in G55 zero all the axis. Now save offsets. Now on your work offsets tab the G54 offset should be different than the G55. G55 should be 0,0,0 and G54 should be the distances between the machine's 0,0,0 and G55's 0,0,0.

Now this is where I always had problems with mach3, in a perfect world if you press goto zero nothing should move since you're in G55 and the coords are 0,0,0. Do it with your finger on the e-stop. If that worked, then switch to G54 and press goto zero and the machine should move to machine coords 0,0,0. If that also works then you should be able to switch back and forth at will.

Having home switches makes this a lot easier but once a "ref all home" is done it should work without them. The ref all home is the only way the machine knows how far it can go before it hits the soft limits regardless whether you have limit switches or not.

Like I said though, it drove me crazy for a long time as it still didn't seem to be consistant, or maybe it was just operator error on my part. It could be a lot more intuitive. UCCNC is a no brainer in comparison when it comes to work offsets.

Let me know how you get on.

Also... I know exactly what you're going through. The above is how it is supposed to work. I don't think my chinese version ever worked correctly, I got to the point of not trusting the "goto zero" button at all. Very scary when the z hits the top and starts grinding and skipping steps! It seemed like it would never act the same from one press to the next. I just got in the habit of insuring I was in the correct work offset and then typing G0X0Y0Z0 into the MDI since even though it was more than a button press at least it always worked.

Ken

Ken you understand my dilemma exactly and have given me some things to look at and and a better understanding. Thanks for taking your time to explain it.

I have a Chinese e bay 60 40 router table that came with it's own version of Mach (pirated). I am thinking of formatting the hard drive, reinstalling XP and Mach with a legit version and starting from scratch on setup. It was handy that they sent a mill file with the motors more or less tuned already but I can copy all the settings and use them for a starting spot on a fresh install.

This thing also has another glitch where you are set on a stepped jog and then you hold shift to jog faster and let go and the gantry or worse yet the Z axis just keeps on trucking until it crashes or you hit the stop button. The first time it did this it drove a .030 end mill about a 1/8th inch into a butt sleeve I was inlaying before breaking it off and driving the cue off the centers gouging the end. Am hoping this behavior may be cured with a legit mach version as my other machines have never done anything like this. At least I know when this happens and prepare for it. Most of the time it doesn't do it and then suddenly it's off to the races. Very disconcerting.

Have a great day!
 

JoeyInCali

Maker of Joey Bautista Cues
Silver Member
Ken you understand my dilemma exactly and have given me some things to look at and and a better understanding. Thanks for taking your time to explain it.

I have a Chinese e bay 60 40 router table that came with it's own version of Mach (pirated). I am thinking of formatting the hard drive, reinstalling XP and Mach with a legit version and starting from scratch on setup. It was handy that they sent a mill file with the motors more or less tuned already but I can copy all the settings and use them for a starting spot on a fresh install.

This thing also has another glitch where you are set on a stepped jog and then you hold shift to jog faster and let go and the gantry or worse yet the Z axis just keeps on trucking until it crashes or you hit the stop button. The first time it did this it drove a .030 end mill about a 1/8th inch into a butt sleeve I was inlaying before breaking it off and driving the cue off the centers gouging the end. Am hoping this behavior may be cured with a legit mach version as my other machines have never done anything like this. At least I know when this happens and prepare for it. Most of the time it doesn't do it and then suddenly it's off to the races. Very disconcerting.

Have a great day!
That's a crash waiting to happen.
Buy a cheap old PC with XP loaded.
Clean out the programs and just leave a fresh Mach 3 in there.
 

kgoods

Consistently Inconsistent
Ken you understand my dilemma exactly and have given me some things to look at and and a better understanding. Thanks for taking your time to explain it.

I have a Chinese e bay 60 40 router table that came with it's own version of Mach (pirated). I am thinking of formatting the hard drive, reinstalling XP and Mach with a legit version and starting from scratch on setup. It was handy that they sent a mill file with the motors more or less tuned already but I can copy all the settings and use them for a starting spot on a fresh install.

This thing also has another glitch where you are set on a stepped jog and then you hold shift to jog faster and let go and the gantry or worse yet the Z axis just keeps on trucking until it crashes or you hit the stop button. The first time it did this it drove a .030 end mill about a 1/8th inch into a butt sleeve I was inlaying before breaking it off and driving the cue off the centers gouging the end. Am hoping this behavior may be cured with a legit mach version as my other machines have never done anything like this. At least I know when this happens and prepare for it. Most of the time it doesn't do it and then suddenly it's off to the races. Very disconcerting.

Have a great day!

I hate to be the bearer of bad news John but yes I know exactly what you're going through. Sad to hear that it messed up that cue, I can't tell you how many work pieces I lost due to the crappy electronics these things ship with. I fought mine for about 6 months, sometimes it would go weeks without a glitch then all of the sudden with no warning to would just do something crazy. I just couldn't trust it.

Late last year I decided I had enough and replaced everything except the VFD in the control box. I shopped around and priced everything needed and the least expensive route I could find was going with UCCNC. Spent about $500 but now I have a machine that I can walk away from during 8-10 hour carving jobs without giving it a second thought. Far cry from making sure my finger was on the e-stop continously while running any job using the old electronics and pirated mach3.

I was lucky that the machine was mechanically sound and very mechanically accurate otherwise I may have just wrote the whole thing off. I'm super happy with the way it turned out.

Some people have had better luck with the existing electronics using a full blown version of mach3 but some have not since the controller is suspect. If you have the red (flying eagle) USB controller board and the cheap stepper drivers you may want to consider an upgrade. A lot of people on the CNC Zone board suggested the upgrade to me but being stubborn I kept thinking I could get it squared away on my own without having to do it. Now I wish I would have just bit the bullet and did it sooner. On the other hand, if you have a parallel port there are some other less expensive options for you that have worked well for some.

Let me know when you're tired of fighting it and I'd be happy to share my journey and maybe save you some time in research. :)

Be safe and stay well,
Ken
 

JC

Coos Cues
That's a crash waiting to happen.
Buy a cheap old PC with XP loaded.
Clean out the programs and just leave a fresh Mach 3 in there.

That's what this is a cheap old pc that I wiped clean and installed xp fresh. Nothing installed but mach 3, cue billet and adobe reader.

It's the jinky mach 3 I would guess. Leonard Bludworth left me a registered copy in his will :wink: The only part of my saw machine worth salvaging was the mach license.
 
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iusedtoberich

AzB Silver Member
Silver Member
If you are not homing your machine upon each power up of the software, then you will 100% have the same offsets and soft limits problem regardless of which control software you use, and regardless if it’s pirated or paid for. That’s really the first thing to fix. You don’t need home switches. I use a hole in my table for X and Y with an indicator to sweep the hole. For my Z, I use a 1” gauge block to set the distance between the top of the Z and it’s leadscrew bearing block. Then “ref all axes”. Then everything will work.
 

iusedtoberich

AzB Silver Member
Silver Member
You don’t home the machine to the work. You home it to the physical parts of the machine itself. That’s all under G53.

Then you use any of G54-G59 offsets to zero to your actual stock.

If you don’t do it this way, you will always have problems.
 

JC

Coos Cues
You don’t home the machine to the work. You home it to the physical parts of the machine itself. That’s all under G53.

Then you use any of G54-G59 offsets to zero to your actual stock.

If you don’t do it this way, you will always have problems.

How to you get into g53 to ref all home there? Every thing I've seen shows setting up home in g54 and referencing other offsets from there.

Thanks
 

iusedtoberich

AzB Silver Member
Silver Member
Quick answer is when the machine coord button is active, the DRO is displaying G53 coordinates.

And if you are in g54-g59, and you want to let’s say move to “machine zero”, you can type g53 g0 x0 y0 z0 in the mdi input. The g53 is special it only applies to the line it’s on. So if your next line you type in mdi is x0, the table will rapid transverse to x0 in the work offset (g54-g59), and not in g53 machine coordinates.
 

JC

Coos Cues
Quick answer is when the machine coord button is active, the DRO is displaying G53 coordinates.

And if you are in g54-g59, and you want to let’s say move to “machine zero”, you can type g53 g0 x0 y0 z0 in the mdi input. The g53 is special it only applies to the line it’s on. So if your next line you type in mdi is x0, the table will rapid transverse to x0 in the work offset (g54-g59), and not in g53 machine coordinates.

That makes more sense thank you.
 

iusedtoberich

AzB Silver Member
Silver Member
I made a video on how to home a cnc without home switches, and how to use that in conjunction with the work offsets, safe Z, Z28 home, and more. This was very confusing to me when I started in cnc world, and probably confusing to most of us when we started. I hope it helps!

Link:
https://youtu.be/Wg8I5eFKgz0
 

whammo57

Kim Walker
Silver Member
I have been trying to follow this thread but....... I am missing something/....

when I draw a part or inlay... it is drawn in BobCad on a coordinate system........ I know where zero is........... on the part or the material.............

when I run it ... I set my zero at that position ....... and press cycle start

Kim
 

iusedtoberich

AzB Silver Member
Silver Member
<=== Not a cue maker....


What if you have a cnc router with a big table. And you set up 4 identical stations with rotating axes on it, so you can inlay 4 cues while you do something else in the shop. Each of those cues would be on its own work offset.

Or, you have 4 different stations on that table. One for turning shafts, one for pocketing inlays, one for cutting out inlays from a sheet, and one for cutting grooves for trim rings. Each station would have its own offset. So if you select a new zero for the station for cutting inlays from a sheet, it won't affect your zero for the station that turns shafts.

You need a home position, and offsets for each station, to do that. Otherwise, you'd be using the same offset for each station, and would have to ruin your 0,0 anytime you change stations.
 

JC

Coos Cues
I have been trying to follow this thread but....... I am missing something/....

when I draw a part or inlay... it is drawn in BobCad on a coordinate system........ I know where zero is........... on the part or the material.............

when I run it ... I set my zero at that position ....... and press cycle start

Kim

The reason I want a repeatable zero in an offset is to be able to go back to the exact center of round stock mounted between centers on the fourth axis. Really it's only the X axis I care much about. Jogging to exact center ends up taking more time than I want to use over and over again each time after I do something else on the table and zero there. I want to establish the center line of my dovetail and keep it.

That's my motive anyway. Lots of ways to skin a cat I like to do it fast.
 

conetip

AzB Silver Member
Silver Member
I made a video on how to home a cnc without home switches, and how to use that in conjunction with the work offsets, safe Z, Z28 home, and more. This was very confusing to me when I started in cnc world, and probably confusing to most of us when we started. I hope it helps!

Link:
https://youtu.be/Wg8I5eFKgz0

Thank you for the informative video. I will bookmark this for future reference.

Neil
 
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