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Laser build
« on: September 03, 2012, 09:36:24 PM »
Hi, I'm a new poster and have a Tormach 1100 that I'm retrofitting to become a fiber laser cutter.  I make titanium rings for a living and was looking for a powerful cutting laser.  I found that I wasn't using my Tormach much, as I also have a full size machining center and CNC lathe.  The cost of a finished cutting laser was well past the mid 6 digits, so I decided to attempt it myself.  I bought the fiber laser engine, and I'll be mounting a large laser head to the Z axis and will be doing a full sheet metal enclosure to block stray infrared.

The main challenge as I see it will be to get the capacitive height sensing circuit in the laser head to work.  The Tormach uses steppers, and the height sensor will output a DC voltage corresponding to how far away from a grounded sheet, eg. 1v for 1mm away, 2V for 2mm away, etc.  It sounds to me that it might be a simple thing to get that to work with a servo, but not necessarily so with a stepper.  My question is would it be easier to have my Z axis convert from stepper that's spec'ed with the machine to servo and use the output of the sensor as the driver for Z?  I know nothing about what it would take to do that.  Maybe there's another clever way to do it that won't take much reworking or reconfiguring the machine.  I am new to the electrical workings of the machines, although I'm pretty good on the g-code end.  I can certainly use some insight on the best way to go on that.  I can get by with programming Z for flat stuff short term, but I also plan on using it for titanium rings on a rotary axis that change thickness as they go around.  Is there an add on product or macro that might accomplish this?

Another smaller issue is that my rings are pretty close to 1" diameter, so it makes sense to always draw my rotary stuff as if it were flat and simply scale my artwork until it's exactly 3.6" tall.  Is there a simple way to have the rotary axis simply think it is a Y axis so that it is based on 3.6" and no feedrate calculations are necessary?  By scaling the artwork itself to exactly 3.6", it will always perfectly line up, as any diameter calculation errors will show up in a big way when the kerf is only .002".  I run a tabletop MicroKinetics machine this way with good results.  It doesn't even know it has a rotary axis.  I would like to set up my Tormach to do that.  It has an A axis, whereas my tabletop mill has no powered Y axis, so in the Tormach case, I would actually need to keep a working Y axis as well as an A axis that would look the same in CAD.  The difference would be in the g-code only.  The Tormach setup doesn't look to allow me flexibility in setting up axes like this, but maybe someone here will have some insight to that as well. 

Another thing I would like to tweak is the rotary axis speed.  I replaced the large 6" Tormach rotary axis with a small 3" Sherline rotary.  It will have more clearance for the laser head, less friction, and will have no cutting forces on it.  Right now it takes over a minute to do a full revolution.  Ideally I'd like to speed that up considerably and run it as it were a 3.6" linear axis.  I don't see any way to do that from within the Tormach software.  The laser itself will be capable of cutting about 40"/minute in that thickness.

Thanks for any input.

Bruce Boone
Boone Titanium Rings
Re: Laser build
« Reply #1 on: September 03, 2012, 11:33:00 PM »
It looks possible to design my parts for the rotary axis in a 3.6" length and simply always add a scale factor of G50 A100.  That's not too bad to do if setting up the rotary to behave like Y is not possible.  This would eliminate the possibility of using arcs and circles, but I could live with that if necessary.
Bruce Boone
Boone Titanium Rings

Offline Tweakie.CNC

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Re: Laser build
« Reply #2 on: September 04, 2012, 01:31:39 AM »
Hi Btboone,

On the Mach3 General Config page you can change your rotary axis setup from angular to linear by un-checking the appropriate box. In addition, by setting Rotation Diameter on the Settings page you can then adjust your Steps Per Unit in Motor Tuning to suit.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Laser build
« Reply #3 on: September 04, 2012, 09:06:57 AM »
I'll look for that, but I don't think the Tormach allows me to see such pages.  Is there a way to load only specific pages of Mach without affecting any of the settings or screens that they set up?
Bruce Boone
Boone Titanium Rings

Offline Tweakie.CNC

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Re: Laser build
« Reply #4 on: September 05, 2012, 01:28:32 AM »
A bit of lateral thinking here....

How about installing a second hard drive, copying the existing drive to the new drive, then you could boot to the new drive and change screens, settings etc without affecting or changing any settings within your existing setup. ??

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Laser build
« Reply #5 on: September 05, 2012, 08:00:07 AM »
That very well might be worth doing.  As I understand it (and I probably don't), all the critical stuff is stored only on a few files that could then be transferred back.  What are those files, and could I simply make a backup of those and then swap those once I have found the correct parameters for my application?

I love your laser project.  Very cool stuff and well documented.
Bruce Boone
Boone Titanium Rings

Offline Tweakie.CNC

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Re: Laser build
« Reply #6 on: September 05, 2012, 01:25:36 PM »
The machine settings are stored within the 'Mach3Mill.xml' file (or whatever profile you are using .xml). The screen specific stuff is stored in '1024.set' (or whatever screen you are using) and the Macros folder contains any macro's you use. Also don't forget to save your license file (Mach1Lic.dat). That is the basic stuff but be cautious because you may have more Tormach specific files stored elsewhere so don't delete anything or make any changes you cannot reverse. (This is really the reason I suggested the additional HD you could install the latest version of Mach3, copy over the files mentioned above, then make any changes you choose).

Thanks for the complements relating to the laser project, I am hopeful more will follow.
I believe that one day everybody with a CNC will have a laser attached (probably fibre rather than CO2) but it is a bit slow catching on at the moment.  ;D

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Laser build
« Reply #7 on: September 05, 2012, 02:15:11 PM »
The laser came today!!  It's huge!
Bruce Boone
Boone Titanium Rings

Offline Tweakie.CNC

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Re: Laser build
« Reply #8 on: September 05, 2012, 03:00:39 PM »
 ;D ;D ;D

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Laser build
« Reply #9 on: September 05, 2012, 04:01:29 PM »
Here it is.  It has measured peak power of 4680 watts.  Still waithing on the laser head and sheet metal for the enclosure.
Bruce Boone
Boone Titanium Rings