Mach3 Problems problems problems.

Preying on peoples knowledge and kindness.
The mill is set up in metric units. Lack of knowledge and understanding determined this choice, it may have been better to have chosen imperial setup units but with metric ballscrews metric was the choice. Whilst running a small program with G20 in the first line the program executes moves that are wildly incorrect. A move of Z0.100" makes the Z axis move continually in the + direction until physically stopped by operating cycle stop. After lots of messing about a G21 was inserted in the second line of the program. It worked perfectly and accurately in Imperial moves. Absolutely no idea why!!!
Next problem is trying to setup soft limits. Now completely confused. Homed the system in Machine co-ordinates onto 3 limit switches and the system zeroed X Y & Z. Measured overall possible movements in X Y & Z in mm's. Entered these dimensions into homing and limits as positive distances in X & Y and a negative distance in Z. Whilst moving about manually with Soft Limits activated get a fault message "Soft Limits < Max Min". When executing the afore mentioned program again with Soft Limits activated the error message states " Machine out of Soft Limits for Soft Limit Activation". Are soft limits based on machine co-ordinates or component datums? If its component datum would they have to be adjusted to each different component manufactured?
Next, have subscribed to Artsoft Wizards on my "House" computer, they set and simulate well. Now need to transfer this permission to the "Workshop CNC" computer, how is this achieved? Is it just a file move from "House" to " Workshop CNC" computer, in which case which file or files?
Many thanks for any help received.

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Whilst running a small program with G20 in the first line the program executes moves that are wildly incorrect. A move of Z0.100" makes the Z axis move continually in the + direction until physically stopped by operating cycle stop. After lots of messing about a G21 was inserted in the second line of the program. It worked perfectly and accurately in Imperial moves. Absolutely no idea why!!!

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Before you start setting the soft limits you need to check what is setup wrong. You seem say when using G21 you are getting accurate moves with inches. Are you saying that if you command the machine X0 2 it moves 2" or 2mm?

It doesn't matter if you use inch or mm for setting up your motor steps per, if you've done it right the machine will run imperial or metric code accurately.
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The body of each feature in the code is simply in numeric units and G20 or G21 in the header tells Mach 3 if those units will be interpreted as (G21) mm or (G20) inches.
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G20 specifies imperial, G21 specifies metric so if you are getting accurate Inch moves with G21 then you have configured your system incorrectly and your steps per out by a factor of exactly 25.4 and your initial commanded moves in inches with G20 will have been simply huge!

- Nick

Firts thing are you running in Demo mode.? Not having license file can cause all sorts of strange things like this.

Next not good idea to run imperial G-code when set up for metric units. While G20 will scale the units it doesn't affect feedrate. So take the road runner g-code that comes with mach. The feed rate is set for inche's at 60 so because motor tuning is in metric units thats the feed you'll get.

It's far easier to setup another profile setup with imperial units and use that. Just copy the Metric profile and scale Steps per by 25.4. It removes any issues.

Why your getting those wrong moves I'm not sure and you'll have to explain a little clearer because not exactly sure what your meaning.? Are you 100% sure your using Metric units.

Soft lmits are relative to machine Coords. If you enter your X & Y travel in SOFT MAX put Zero in SOFT MIN. For Z Put Negative travel in SOFTMIN and Zero in SOFTMAX.
It should work then. I'm guessing your putting Z negative in SOFTMAX and that's the message.

Wizzards are just like Mach3 License file drop it in the mach folder.

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Originally Posted by magicniner

It doesn't matter if you use inch or mm for setting up your motor steps per, if you've done it right the machine will run imperial or metric code accurately.
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The body of each feature in the code is simply in numeric units and G20 or G21 in the header tells Mach 3 if those units will be interpreted as (G21) mm or (G20) inches.

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Not exactly correct as explained above.!! . . . It will scale the moves but not the feedrate.
Try it load road runner and put G20 on first line or type G20 in MDI before running.
The Feedrate in Gcode will be in inches minute but motors tuning is relative to MM/min. This is why you have to retune the motors if you change from metric to imperial units.

Thanks for that Jazz, that's interesting.
Given the simplicity of the conversion I'm shocked that they didn't make motor tuning/feed rate automatic for changes in G Code units, I had assumed this was the case but only ever work in Metric,
Regards,
Nick

Many thanks for your replies. The mill is having mechanical parts modified at the moment and as soon as it is reassembled I will do some investigation and get back to you all. Once again thanks.

Right the mech parts are now modified ok, back to the problems. could you please check over the following calculations for steps per.
By the way this is a fully licenced version of Mach3. Have re-installed Mach3 and chosen inch base units.

Motor Steps= 1.8deg =200 steps per 1 motor rev.

Motor Micro steps =10 therefor 200x10 = 2000 micro steps per 1 motor rev

Pitch of ball screws = 5mm = 0.19685 inches per 1 motor rev

No of motor revs to move 1 inch = 1/0.19685 = 5.08 revs

No of micro steps per 1 inch move = 2000 x 5.08 =10160 micro steps per inch

Z axis is a 2:1 reduction ratio so 10160 x 2 = 20320 micro steps per inch

Many thanks ( More to follow )

Yes that's correct go to top of the Class.:applouse:

After a quite successful re-set on the miller we now have Imperial units. The machine homes properly onto 3 limit switches and runs a simple program ok and accurately.
The issue now is what to specify in soft limits and soft limit slow zones. I honestly have not got a clue. I can accurately measure the distances that the machine is capable of moving in all axis.
These dimensions are from the home positions. X +19.000" Y+7.375 Z-13.500.
Any help most gratefully received.

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Originally Posted by ECCO

The issue now is what to specify in soft limits.

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As soon as you need limits your job is toast.
Plan ahead and ensure that your job fits in the machining envelope and that you have your work offset or your zero set such that the job which will fit the envelope is within the envelope,

- Nick

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Originally Posted by magicniner

As soon as you need limits your job is toast.
Plan ahead and ensure that your job fits in the machining envelope and that you have your work offset or your zero set such that the job which will fit the envelope is within the envelope,

- Nick

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Sorry Nick don't agree. Softlimits work good because they won't allow code to run unless it fits within the machines cutting range. They also stop you accidently running into the hard limits which can be pain.
The only thing is that the machine must be homed first for them to work properly.

ECCO: First Slow zones don't work so forget them.

Setting the Soft limits is easy. Set Soft Max for X & Y to +19 & 7.375 and Soft Min =0. For Z axis Soft Max =0 Soft Min -13.500

Remember you must always Home when first starting machine or after resetting for soft limits to work correctly.

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Originally Posted by JAZZCNC

Softlimits work good because they won't allow code to run unless it fits within the machines cutting range.

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I struggle with the concept of unknowingly creating and running a job that doesn't fit within a machine's envelope but I can imagine that with the right approach that should be possible ;-)

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Originally Posted by magicniner

I struggle with the concept of unknowingly creating and running a job that doesn't fit within a machine's envelope but I can imagine that with the right approach that should be possible ;-)

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Yes I understand and agree to point but there's more to it than that. The fact you can't run into the limits is worth the trouble of the 1min it takes to setup. Very useful on small machine that can run from one side to other in blink of eye while jogging.

Ok gentlemen the soft limits are now functioning as they should. X & Y movements are declared in Soft Max and the Z negative movement is entered in Soft Min. Even slow limits work. Many thanks for your assistance. Regards ECCO.

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Originally Posted by ECCO

Even slow limits work.

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If your meaning Slow Zone then it doesn't work like you probably think. It's only used when jogging NOT when homing. So when approaching the limits it will slow down gradual at the distance entered.

When homing the Speed% is used which is % of the velocity set in motor tuning for that axis but will travel at this speed over the full distance each axis has to move.

JAZZCNC thanks for the advice. Can we presume that when running a program that the cycle would not exceed the soft limit envelope? ECCO.

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Originally Posted by ECCO

JAZZCNC thanks for the advice. Can we presume that when running a program that the cycle would not exceed the soft limit envelope? ECCO.

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When soft limits are turned ON then Mach will give a Soft limits warning when you press cycle start if out of limit range.

Many thanks. Great stuff.