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Mach3 Release questions and the usual CV question
« on: May 29, 2008, 09:31:34 AM »
Hello all,

I know the very rudimentary basics of how the CNC machine works. My specialty is AutoCAD and MasterCAM. Mach3 is totally new to me as well. Our CNC machine is a ShopCAM from Lindsay, ON and apparently they went bankrupt and are no longer in existence as of just this past week. So I'm on my own to troubleshoot the machine.

A little on my setup:

x150 y64 z7 router table
Colombo 7.5hp spindle
Microstep Stepper motors
 - X Vexta PK2913-F4.0A 2-Phase 1.8degree/Step
 - Y Vexta PK2913-F4.0A 2-Phase 1.8degree/Step
 - Z Vexta PK296-F4.5A 2-Phase 1.8degree/Step
Mach3 R2.0.037 running in Vista (which runs fine it seems)

My first area of confusion is this. When I first started the process of learning the machine I noticed that there was a much newer releases of Mach3, so I DLed it and installed it. The ShopCAM guy came by and was kinda upset that I had did that. He said that the newest release was no good and the machine wouldn't work right, so he reverted it back to the R2.0.0037 and ran some sort of driver tests (not sure what he did) to verify that the machine was ok.
Questions:
- Is that the case or should I be running the latest version to get the best results?
- If I do upgrade, how do I do that without losing any vital setup information like motor steps per pulse and that critical sort of info?

Me second area where I need assistance is with CV and rounded corners. I can only get the square corner cuts I want right now with Exact Stop, but I've been warned by my MasterCAM people that it is really hard on the CNC machine. They told me I needed to play with accel/decel curves to get what I want. I guess this pertains to my question about release versions as well.
- Does the latest version of Mach3 handle CV better than my older release?

Thanks for any assistance and if I need to provide anymore information to help clear my situation up just ask.

EDIT: Added the actual stepper motor specs.
« Last Edit: May 29, 2008, 11:19:56 AM by GTRacer »

Offline jimpinder

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Re: Mach3 Release questions and the usual CV question
« Reply #1 on: May 29, 2008, 01:53:02 PM »
Mach 3 is under continual developement, and at any time there are several versions available.

If you go to Downloads, you can see what is available. Tou can download an old version, download the latest lockdown version, or download the latest version under development.
If you are wanting a serious version for serious work, there is one rule - If it not broke, don't fix it - so if the versionof Mach 3 that you have does all that you want, stick with that.
If you want the latest version that is "guaranteed" as far as possible, then use the latest "Lockdown Version". This will not change - and if anything goes wrong, you can download it again and get the same program.
If you want to be up there with the boys you can have a version that is still under developement - but if you download it again, it may have changed.

I personally use the latest "Lockdown " version.

You should be able to download the latest "lockdown version" and retain all your XML file and settings. In your case you do not say whether the version you downloaded was a "lockdown" or one under developement - so I cannot comments of the ShopCAM guys remarks.

As far a CV is concerned, this is an old problem and you should understand the difference between Cv and absolute stop.
 If you are to cut a "square corner" the your axis(s) must travel to point A and then, instantaneously travel to point B, leaving (apart from problems with the diameter of the tool) a sharp corner. The only way the machine can do this is to come to an absolute stop in the direction it is travelling, then having put on any backlash required, set off in the new direction.

On my machine, with relatively slow travel, it might not be noticable (except for backlash which is terrible), but the faster your machine is, the more noticable it becomes, since the cutting head (or the table) has to accelerate to speed, then decelerate to a stop, then accelerate to speed and so on.

If you use CV, then as the machine decelerates to a stop in one direction, it also calculates and implements accerleration in the other direction - and never comes to a complete stop - but it must, by definition, leave rounded corners on your work (as well as any for the tool).

You cannot get square corners with CV - you must use absolute stop and put up with it, I'm afraid. You can alter the acceleration and deceleration parameters for CV to end up with as square a shape as possible - but you will never get to the "square corner"

Not me driving the engine - I'm better looking.

Offline Hood

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Re: Mach3 Release questions and the usual CV question
« Reply #2 on: May 29, 2008, 02:05:27 PM »
Probably best to use the latest lockdown version (2.63) but if the one you are using works fine then stick with it, the latest Dev versions seem to work fine and have bug fixes but if you dont have problems its probably not worth updating until they become lockdown.

Motor setup, pin setup etc is all stored in the xml file, it should remain intact after an upgrade, if it doesnt then you should be able to go back to a previous XML by going to the Operator menu and choosing restore. However it is always a good idea to copy your xml and keep it on another disc or computer, that way if your hard drive crashes or you get a new computer you can restore all your settings by pasting the xml into the new computers Mach3 folder.


You can set up the angle at which CV works and which it doesnt, this can help for sharp corners, you will find the settings on the General Config page from the Config menu.

Hood
Re: Mach3 Release questions and the usual CV question
« Reply #3 on: May 29, 2008, 02:17:36 PM »
Thanks, I played with the feedrates and acceleration for all 3 axis to fine tune as much as possible. I ended up with:

X
feedrate = 400 in/min
acceleration = 60 in/min/sec

Y
feedrate = 400in/min
acceleration = 60in/min/sec (I could go faster on Y, but I thought it should be equal to the best i could get out of X?)

Z
feedrate = 40in/min
acceleration = 10in/min/sec

I'm just going to go with Exact Stop and forget CV mode then. I'm cutting $1000 a sheet aircraft honeycomb panels that have to be exact, rounded corners of any sort are unacceptable.

I believe my version of Mach3 is a lockdown version.
Re: Mach3 Release questions and the usual CV question
« Reply #4 on: June 09, 2008, 09:56:50 AM »
I wanted to revive this post as I have some serious problems with Mach3 and my CNC router manufacturer is no longer in existence. I'm on my own to troubleshoot this machine. I've included a picture of the entire machine for reference.

1) First off, I'm having some axis woes. I discovered that when ShopCAM installed and setup the machine initially, they never bothered to calibrate steps per pulse for each axis, so everything was being cut half an inch too big. Using a dial indicator, I used the Axis Calibration tool on the Mach3 Settings screen to set the X, Y, and Z axis dead on, with a repeatability of +/- .0005". When I run a program, which I did one with a 1/2" diameter bit and then a different program with a 1/4" diameter bit, the Y axis adds exactly 1/16" of an inch to the part, the X axis cuts perfect. That's axis problem number one.
2) Axis problem number two is what I would call Z axis drifting. To cut my part I specify the exact Z thickness of the part, and add .050 for breakthru, which is overkill, but the part still ends up with an onion skin once I get about 18" along the X axis. See the attached picture of a pocket that was cut where the bit should have been at the same Z depth the entire time, but it drifted. The other picture is of various cuts that were all specified in the code to be the exact same depth, but notice the variance, the further ones even lifting completely above the spoiler board.
3) I've unchecked the boxes relating to overwriting my G54, but if I shut off the machine for the night, it will make the G54 X0Y0Z0 match where ever the machine was sitting when it was shut off. Right now I just bring it to X0Y0Z0 before shutting it down. Is there another way to save the position? Also related is machine coordinates. Does the table not have exact machine coordinates that are fixed, always the same? I ask for two reasons. One the machine coordinates change each time the machine is shut down. And two, the other day, between running two parts, the exact same part, the table suddenly came up with a new value for G28 and instead of moving up and preparing itself to run the program, it dropped down to well below the table's surface, fortunately off the X and Y axis, so it was spinning in the air, but without a quick E-stop right then, it would have moved into cutting the actual table.

I have another issue, but I'll add that one in a bit.

 
« Last Edit: June 09, 2008, 10:21:53 AM by GTRacer »

Offline Hood

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Re: Mach3 Release questions and the usual CV question
« Reply #5 on: June 09, 2008, 11:51:53 AM »
1) First off, I'm having some axis woes. I discovered that when ShopCAM installed and setup the machine initially, they never bothered to calibrate steps per pulse for each axis, so everything was being cut half an inch too big. Using a dial indicator, I used the Axis Calibration tool on the Mach3 Settings screen to set the X, Y, and Z axis dead on, with a repeatability of +/- .0005". When I run a program, which I did one with a 1/2" diameter bit and then a different program with a 1/4" diameter bit, the Y axis adds exactly 1/16" of an inch to the part, the X axis cuts perfect. That's axis problem number one.

 Make sure you dont have any scaling on the axis that is giving you problems.




2) Axis problem number two is what I would call Z axis drifting. To cut my part I specify the exact Z thickness of the part, and add .050 for breakthru, which is overkill, but the part still ends up with an onion skin once I get about 18" along the X axis. See the attached picture of a pocket that was cut where the bit should have been at the same Z depth the entire time, but it drifted. The other picture is of various cuts that were all specified in the code to be the exact same depth, but notice the variance, the further ones even lifting completely above the spoiler board.

 Check to make sure your "Spoiler Board" is sitting correctly on the bed and that it is running true with regards to your axis. You could do this several ways but the easies would be to start at one end and move the cutter down to just under half an inch and then move the axis up slowly and slip a 1/2" block under, when the block just slips under stop jogging up and confirm that the block is a nice sliding fit. Then jog to another area of the table without moving the Z and see if the block slips under with the same fit. Repeat this all over your table and see how good it is.
 I am not experienced with routers but I think the standard thing to do is when you place the sacraficial plate (spoiler board) on the bed for the first time you cut the surface all over to true it up to the machines axis.



3) I've unchecked the boxes relating to overwriting my G54, but if I shut off the machine for the night, it will make the G54 X0Y0Z0 match where ever the machine was sitting when it was shut off. Right now I just bring it to X0Y0Z0 before shutting it down. Is there another way to save the position? Also related is machine coordinates. Does the table not have exact machine coordinates that are fixed, always the same? I ask for two reasons. One the machine coordinates change each time the machine is shut down. And two, the other day, between running two parts, the exact same part, the table suddenly came up with a new value for G28 and instead of moving up and preparing itself to run the program, it dropped down to well below the table's surface, fortunately off the X and Y axis, so it was spinning in the air, but without a quick E-stop right then, it would have moved into cutting the actual table.

Does your machine have homing switches? The answer to this question will determine how you will proceed with this.


Hood


Re: Mach3 Release questions and the usual CV question
« Reply #6 on: June 09, 2008, 12:38:53 PM »
Quote
Make sure you dont have any scaling on the axis that is giving you problems.

Mach3 is showing no scaling on the main screens, but is there somewhere I should be checking that?

Quote
Check to make sure your "Spoiler Board" is sitting correctly on the bed and that it is running true with regards to your axis.
The table is out by a very small amount, which is why I decided to go with .050 break thru, that way it'll be really deep at the "high" end and shallow, but should still be right through at the low spots. That doesn't explain the picture with the roughly 6" pocket that has a single Z depth and the router cut the path while drifting on the Z.


Quote
Does your machine have homing switches? The answer to this question will determine how you will proceed with this.
The machine does have a homing setup, when I tap the home key on my keyboard, it moves up into a nice safe position. It's the G28 command that is in the NC code that is the concern I have.


Re: Mach3 Release questions and the usual CV question
« Reply #7 on: June 09, 2008, 01:07:28 PM »
Quote
My ideal is you calculate first, and use the axis calibration tool to check your answer is correct.

My X and Y are belt driven gears, my Z is a gear screw. I'll try to figure this out.

Quote
Mach 3 can then make allowances for tool diameter. All tools MUST be entered into the tool table, and the tool number selected correctly

I have a single spindle, each tool change is a new program to keep it simple and allow for the top of material to be referenced after each tool change. I have no tool info saved in Mach3, MasterCAM X2 takes care of all the tool offsets. However if the issue was with tool offsets, why is the X axis perfect and the Y axis out?

Wait a minute, where did your reply go jimpinder....

Quote
I agree with Hood about your Z axis - Is is Z moving, is is your table slightly out of true. I mounted a steel (6mm) plate on my table, and had the machine skim it true to the axis one evening. You can write the program and leave the machine to do it

The table not being level doesn't explain the 2nd picture above. That pocket was cut at one specified Z depth and it ended at a different level then it started. The Z is clearly "drifting" as the machine moves, what would cause that variance?

Quote
Your machine has two DRO readouts on your axis. One is machine co-ordinates and the other is program (or work) co-ordinates. When the machine co-ordinates button is lit, the display is machine co-ordinates, when not lit, program co-ordinates (and you can toggle between the two.
 
The machine MUST know where it is. There are two ways to tell it. (and you probably know all this)
One is have a set of home switches fitted. If you then press "Ref All Home" the table and the cutter will settle to these switches. The machine-cordinates will go to zero. The machine is happy - it knows where it is. Is is not likely that these home switches will be in a convenient position for useful work to take place, and therefore the table and cutter will need movng.
You can - as you seem to be doing, use an offset - and then tell the machine to go to it's new 0.0.0  position - now your machine-co-ordinates will show the offset, program co-ords will show 0.0.0 - and you can run your program.
Alternatively you can move the machine to a convenient position to start your program, ignore the machine co-ords, set the program co-ords to zero and start.
 
In Mach 3 machine co-ordinates can only be zeroed by using "Ref all Home". There is a problem in that if no home switches are connected, you can still "ref All Home" - but all that will happen is that the machine co-ordinates go to zero - whereever the machine happens to be. If there are no offsets set, I think it takes the program co-ordinates to zero too.
 
You may be finding (if you have not set up the homing switches) that this is causing your offsets to change, if you inadvertently zero the machine co-ordinates.

I'll go and take some pictures of the Mach3 screens to help troubleshoot what is going on, I'm really lost.
« Last Edit: June 09, 2008, 01:26:00 PM by GTRacer »
Re: Mach3 Release questions and the usual CV question
« Reply #8 on: June 09, 2008, 01:14:37 PM »
  Does the Z DRO reflect the ammount of drift ? Or does it stay at the programmed value ?
« Last Edit: June 09, 2008, 01:36:49 PM by Overloaded »

Offline Hood

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Re: Mach3 Release questions and the usual CV question
« Reply #9 on: June 09, 2008, 01:45:31 PM »
Sorry the second pic wasnt showing at the workshop so never noticed that it ended up in the same X Y but higher in the Z.
 Make sure there is no scaling set in your code, G51 Y*

Ok as you have home switches first thing you want to do is go to homing and limits and choose the Auto Zero option. Next go to General config page and have the Persistant DROs and Persistant Offsets checked, also make sure you dont have Copy G54 to G92........ checked.
 Next time you start Mach and do your homing move it should set the machine coords to zero but your work offsets should reflect you last saved offset.

Hood