Rapid Linear Moves

[TheePres]

Today scrapped a part using a remachining routine to detail some small corners. I used "Keep tool down" feature, all looked good in backplot and Verify, but machine does not rapid in straight line, so milled of a protuding boss on rapid to next "Z" level.

My question is, is it possible to set machine parameters to force straight linear rapids, and if not could MasterCam somehow employ this condition into code or backplot?

[cadcam]

Sorry to hear this , I have had this happen to me on a fadal before.

 

there is no settings to acount for the machines actions.

 

Haas has one way and fadal has another.

I suggest making sure the tool pulls up and away from the part.

[Paul Elliott]

You might want to try MCU to check your toolpath; it lets you use either interpolated or dog-leg rapids. It's installed as a light version with 9.1, or can be installed separately from the 9.1 CD, or by downloading from our website (link below). During the first 30 days, you also get our verification which understands both rapid motions. After 30 days, you still have the backplot available.

[cadcam]

Paul any relation to bill by chance?

[Paul Elliott]

Yes, he's my brother. If you see the two of us together, he's the one gesticulating wildly while he talks.

[chris m]

TheePres

 

Depending on what kind of machine you have there may be a parameter change you can make to stop the machine from the "dog-leg" rapid moves; I believe that newer Okuma OSP controls have this and I think I've seen it in one of our Fanucs as well.

 

This parameter is usually near the "rapid Z first if positive, rapid XY first if Z negative, rapid simultaneously regardless" parameters

 

On some machines there are also parameters to force the machine to rapid over the "inside" or "outside" of the triangle. My advice is to break out the parameter book (yuk) and start paging through, sometimes its amazing what you find in there ("Oooooh; so THAT'S why the machine does that.....).

 

The one thing you must keep in mind if you change this is that stuff that cleared before may not anymore because of your parameter change; so just keep that in mind.

 

Hope this helps a little

 

C

 

[ 04-11-2003, 07:25 AM: Message edited by: chris m ]

[Surface]

In another topic, it was discussed, changing G0 (rapid) with G1Fxx (liniar-mill max-feedrate). The idea behind this was that the machine's control can work faster because it doesn't switch Gcode. I think this would solve the problem in question, but I havn't tried it (yet).

[cadcam]

Paul Elliott I just spent some time with bill at the show at the MC booth.

I take it you did not make it.

 

quote:

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he's the one gesticulating wildly while he talks.

---

I know what you are saying.

[CPeast]

TheePres,

 

Is the problem simultaneous movement in Z ?

 

If so, some controls have a parameter to force XY movement before Z.

 

Also You can set the post up to force this as well (better option IMHO).

 

==============================

In post should read:

 

nobrk : no #Omit breakup of x, y & z rapid moves

==============================

 

Comparison of time saved by having simultaneous Z rapids:

 

1000 Rapid moves at 1000 in/min

Assume Simultaneous Movement Saves 4.14 Inches Each (move from X10. Y0. Z10. To X0. Y0. Z0.)

 

(1000 X 4.14)/1000 = 4.14 Minutes

@$50/Hr = $3.45

 

Vs.

 

New Inserts $50

New Face Mill Mill $400

New Vice (cheapo) $400

Spindle repairman $800/day

Resetup Job $200

Ridecule from co-oworkers .....

Including nicknames like "cutterbuster" "crash" "Vicemuncher" ...Priceless

 

 

Dave/CAMmando/CPeast

[Rick Damiani]

quote:

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...Priceless

---

...and so was that post.

[cadcam]

What I found with the fadal that is does the dog leg ,when it see's it go into a "GO" and then it will take for example a "Z" on the first line and a "X"Y" move on the next line and run them togeather instead of moving in "Z" first then do the next line.

This is the control not the program.

 

This has bitten me before. But now I know.

[CAM-mando]

Ive never used the Fadal Control, but that sounds scary. I'm having a hard time thinking of a reason why that would be a good thing to do in any situation.

 

Is there a parameter that precludes this behavior ?

[Thad]

quote:

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What I found with the fadal that is does the dog leg ,when it see's it go into a "GO" and then it will take for example a "Z" on the first line and a "X"Y" move on the next line and run them togeather instead of moving in "Z" first then do the next line.

This is the control not the program.

---

Jay, if I heard that statement from the "average Joe," I would just pass it off as operator error. But you've really got me thinking on this one. I've run Fadals (of varying ages) for about 8 years and have never seen this or heard of it before. If this is true, that is a SERIOUS flaw that needs to be addressed. Have you contacted Fadal about this?

 

That's almost as crazy as "I don't know why, but every once in a while, the control just rapids to Z-20." It's just not right!

 

Thad

[cadcam]

Thad I have spoken with Fadal and others and most are aware of it.

 

Some times it matters on the style of cut.

When it happened to me I was trying close tricky stuff.

 

I even tested the code in varfication and there was no trouble. But the operrator even said this happens.

 

As for the Z taking off in a -Z I have had this to and this was do to no ground rod for grounding.

[TheePres]

This one wasnt a case of simultaneous "Z" move, though by reading my original post I see how that can be infered.

Just a simple X,Y rapid that went off in "Dog-leg" motion as you all call it.

 

YES!!! this was a FADAL!!!! YIKES!!!!

 

I have used "stay down" feature with no worries in past, but now this FADAL has me frightened and overly cautious. And was hopeing just a FADAL parameter switch, So I could continue with my tried and proven programming techniques.

[Trevor Bailey]

Today on my Fadal, I was jogging the table. Switched to x from z and the z kept coming down. The control did not pick up the switch. I switched the axis, walked away, came back in about 5 minutes and tried to jog. What a piece of junk!!!!!

[chris m]

quote:

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And was hoping just a FADAL parameter switch, so I could continue with my tried and proven programming techniques

---

Does that mean it isn't a parameter for Fadal? Did you call Fadal (YUK!, by the way) and ask them if you could force straight-line rapid moves? This sounds like its definitely worth some legwork if you can fix it.

 

C

[Eric S.]

Hello

 

I program for a HAAS VF2 and VF3 and they both do not rapid in a straight line. I do not find it much of a problem, you just have to keep it in mind when programing in MC. The reason why they dogleg is that when the machine does a rapid move the x and y axis both are at max speed. So what happens is you get a 45deg angle move toward the next position. When one of the axis gets to the desired coordinate it then stops, then the other one continues to catch up. So then you get a straight line move for the second half of the rapid move.

I hope you understand.

So I think if you want the machine to move in straight lines you might have to make them max feed moves and not rapid.

 

Just a thought.

 

Eric

[Surface]

I don't understand the anti Fadal sentiment from this forum. I have used a wide variety of machines in my lifetime and when I went into business for myself, the first VMC I purchased was a Fadal. Granted, it is not the greatest machine, but also not the worst.

While typing this the machine is running at 9500 RPM @100 IPM. This machine has been doing that for the past three years (not the same part)

My experience with Fadal has been very favorable, but in the end I ask myself if I would buy another one. I answer yes, but in the meantime I am looking at a two year old Mazak from a company down the street who is going out of business. In the end, I guess the best machine is the one, which can make money.

[chris m]

As I am one of the more consistent Fadal bashers in the arena, I must say that they aren't a bad machine...

 

...as long as you don't mind axis growth, spindle rebuilds, clunky controls, columns that won't stay square for more than a week...