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Fixture Save... questions?
« on: December 23, 2014, 11:09:41 AM »
I'm still very new to the CNC world and was wondering what the best practice and usage is for using fixture saves?

I assume a fixture save is for repeat work or multiple piece work so that stock positioning is taken out of the equation?

Does it make sense to do a fixture save, just in case, when starting a new project so that you can start where you left off in case something were to happen before the job finishes?

Is it possible to start a project that you quit if you didn't do a fixture save?


Adam,

« Last Edit: December 23, 2014, 11:22:28 AM by Adam_M »
Re: Fixture Save... questions?
« Reply #1 on: December 24, 2014, 07:59:00 AM »
What, no one uses fixtures??
Re: Fixture Save... questions?
« Reply #2 on: December 24, 2014, 08:54:56 AM »
Fixtures work and I use them, I home my machine after powering up and don't rely on anything trying to store it's position,

  - Nick

Offline ger21

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Re: Fixture Save... questions?
« Reply #3 on: December 24, 2014, 09:26:56 AM »
Quote
I assume a fixture save is for repeat work or multiple piece work so that stock positioning is taken out of the equation?

Actually, stock positioning would be more important, as it needs to align perfectly with the previously saved fixture location.
If you're going to use the same offsets (fixture location) for multiple sessions of Mach3, you need accurate home switches, and a method to mount the workpiece in exactly the same location every time.
The offsets are relative to the home position, so you must be able to home the machine to the exact same position each time you start Mach3.


Quote
Does it make sense to do a fixture save, just in case, when starting a new project so that you can start where you left off in case something were to happen before the job finishes?

Either that, or just write down the offset values and re-enter them. But again, this assumes you can accurately re-home to a repeatable position.
Quote
Is it possible to start a project that you quit if you didn't do a fixture save?

Yes, if you can zero your axis to the sane place you zeroed them the first time.

On my router, I have fences mounted at X zero and Y zero (in machine coordinates) and keep my G54 offsets at zero. All I ever do, is home the machine, place the workpiece against the fences, and start cutting. I never have to set or save offsets.
With one exception. I have a fixture for holding material vertically, and I use my G55 offsets (which are saved) for work mounted to the fixture. So again, I just have to start Mach3, home the machine, and it's ready to go. All my g-code that I use with the fixture has the G55 in it to automatically use the correct offset.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Fixture Save... questions?
« Reply #4 on: December 25, 2014, 07:22:27 PM »
Actually Fixture Save is intended to save the locations of multiple fixtures used typically to machine multiples of a part at different locations.  This elimininates needing to create g-code for each location.  So lets say you have 3 vises and you are making a large number of parts.  So you place stock in each vise, and the program machines one with the first tool.  A fixture change is called for vise 2 and you can rerun the same code to machine that part.  Call a fixture change and machine the piece in vise 3.  Change the tool, call fixture 1 again and machine the next step.

So unless this is the kind of machining you want to do you won't find many people using this.
Re: Fixture Save... questions?
« Reply #5 on: December 27, 2014, 07:11:52 AM »
Thanks for the reply's.

2 follow up questions...

Quote
Either that, or just write down the offset values and re-enter them. But again, this assumes you can accurately re-home to a repeatable position.


I don't understand how writing down the DRO settings and entering them is accomplished? If I zero the axes and I have a fixture that is in space that I have the coordinates (X,Y) written down for how do I enter the coordinates and get back to those settings and a power cycle? Is that a G55 offset then?

Also, wouldn't a fixture save and or a material save be somewhat interchangeable? I mean if your part is programmed from the fixture coordinates then your material would follow suit as it would be programmed from the fixture that holds the material, correct?

Adam,
« Last Edit: December 27, 2014, 07:13:45 AM by Adam_M »

Offline ger21

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Re: Fixture Save... questions?
« Reply #6 on: December 27, 2014, 07:48:36 AM »
I didn't say to write down the axis DRO values. I said the Offset Values. When you zero the axis, your setting an offset. So you can go to the Offsets page and write down what those offsets are. Then, when you restart your machine, you first Home it, then you can go back to the offsets page and re-enter the offsets you wrote down. This will put your zero position back to where it was previously.

It will only be a G55 offset if you have changed to the G55 coordinate system. G54 is the default in Mach3, and unless you change it, you're using a G54 oiffset.

Quote

Also, wouldn't a fixture save and or a material save be somewhat interchangeable?

Sounds like your using different terms for the exact same thing. There is no "material save" option.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html