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Author Topic: 4 Axis Waterjet Cutting In Mach3  (Read 5224 times)

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4 Axis Waterjet Cutting In Mach3
« on: April 13, 2009, 01:39:04 PM »
Does anyone have anyone have experience with 4 axis waterjet cutting running through Mach 3.  I am unable to get it to work properly.  When the head rotates it is naturally higher than when it is at 90 degrees.  I guess is there a way in Mach to have it compensate a Z and x movement to hold the head in the same position above the material as when it is doing straight 2d cut. 

Thanks
nick

Offline jimpinder

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Re: 4 Axis Waterjet Cutting In Mach3
« Reply #1 on: April 14, 2009, 03:58:01 AM »
I have no experience of water jet cutting, but I understand the problem. Clearly (if you are going, shall we say, for an angled shot) yes, as the head rotates, the Z axis could drop as the distance to the target increases. To keep the nozzle the same distance from the target, Z would have to drop as the cosine of the angle. This would be alright for small values of angle, but the distannce (nozzle to target) would increase rapidly as the angle got greater - so much so that you could not make up by dropping Z.

What sort of distances and clearance are we talking about.
Not me driving the engine - I'm better looking.
Re: 4 Axis Waterjet Cutting In Mach3
« Reply #2 on: April 14, 2009, 07:22:59 AM »
Thanks for the responce.

Thicknesses vary from 1" to 4", angles from 10 to 45 degrees.  There also needs to be an offset in the x axis (as it is in the y axis that is being beveled).  Right now I am generating code using Sigmanest and then modifying it in the text program.  I am wondering if there is a way in Mach to have it account for the compensation.  I have another waterjet that holds the nozzle in the same position right in the controller.   Setup times between the 2 machines vary from 10 minutes on the one that automatically compensates to up to 3 hours (to get accurate parts) on the machine controlled by Mach.

Offline jimpinder

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Re: 4 Axis Waterjet Cutting In Mach3
« Reply #3 on: April 15, 2009, 07:12:40 AM »
I had got off on the wrong foot in my first reply, thinking that what you were wanting to do was hold the cutting head at a constant height above the target, much as I understand they have to do in plasma cutting. What you seem to be indicating is that what you are wanting to do is alter the X or Y position so that when the jet is pointing at an angle, the same spot is targeted, as when the jet is vertically above.

The amount of offset is clearly dependent on the mean height of the cutter above the target, and the angle at which it is shooting.

I am trying to think of the easiest way to implement this. Becasue I am used to macros my first thought is a macro.  e.g. M1001.
The macro would take in the present position and height of the jet, and the angle at which it is, and if it is not vertical, compute the offset and apply it to X or Y as required. This would mean adding the M1001 (or whatever you use) to your GCode, whenever you want the offset to take place. That I could see working, although how practical it would be to implement would have to be seen.You could, as below, use B or C in your code, and a simple "replace" task would insert the Macro which would then write the GCode.

The alternative may be a brain, but I have very little experience of them. You may, for example be able to program the plan of the cut say as though it were a B or C axis, and then the brain instantaneously translates this into offsets for X and Y dependent on the angle of A. Perhaps some "brainy" people might comment.

All in all, a "post processor" might be the answer, where you run your raw GCode through the computer, and it looks at it and applies offsets where required, and rewrites the GCode before you apply it to your machine.

Sorry I can't be much more help - but someone out there must know.







Not me driving the engine - I'm better looking.
Re: 4 Axis Waterjet Cutting In Mach3
« Reply #4 on: April 16, 2009, 03:34:52 PM »
Thanks, I appreciate the input.  I believe a macro would be the way to go.  It will take me a little time to develop but it could be worth it in the long run. 

vmax549

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Re: 4 Axis Waterjet Cutting In Mach3
« Reply #5 on: April 18, 2009, 12:29:36 AM »
I think what you are looking for it Kimatics??? So that when it rotates it all stays pointed correctly. I don't think MACH does kematics at this time BUT your cam should be able to do the cutting with no problem.

You just will NOT have coordinated movements when jogging and such.

Another thought MACH does have a MACH channel for each axis IF you can do the math to do the correction.


Just athought, (;-) TP

Offline RDR

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Re: 4 Axis Waterjet Cutting In Mach3
« Reply #6 on: November 03, 2014, 09:00:41 PM »
Hi Nick
Was just wanting to know if you figure out your issue we built a 5 axis water jet and we also have sigmanest we now have everything working nicely our head design keeps the nozzle at the same height as it tilts and we also can up with a THC for it to.  I can post pics if you need help yet on that

Tim