Air Cut Feed Rate

nugpot · 2005-03-02 23:17:14

Is there a way in optipath to change Air Cuts to a rapid move instead of a entered feed rate?

BillH · 2005-03-14 16:46:57

Hi,
Currently not. This is intentional, although the reason may have disappeared. In the "old days", G0 was an open-loop mode where each axis motor turned at maximum until the commanded position was reachec. The resulting motion caused the tool to not follow a linear path (sometime called a dog-leg motion). So we intentionally did not switch from G1 to G0 mode because of the possibility to introduce a collision.

Most modern controls no longer do this, and G0 motion is linear-interpolated more-or-less like G1. Could be a software enhancement.
Bill

Louis Bigelow · 2005-05-02 17:27:48

G0 For air cutting is not a good idea.
Most of out 3 axis mills are early- mid 80's machines and
All of them use dogleg rapids.
All of our newer machines are MDSI re-fits of older machines.
G1 is used in their high speed machining mode, where the machine
Doesnâ€™t actually drive through the point but w/in a tolerance of it.
(.0002) thus not slowing down for "corners" so to speak.
G0 however accelerates to max and decelerates to a stop at every
Point. 20 or 30 blocks in close proximity can make the machine
Shake like a sob. Using a high feedrate it runs smoothly in this area.
(Rigid nb-125 or Sundstrand om-80 in particular.)

On another thought, Bill I have a turbine sample file you may use in
Demo. (Since I give you such at hard time at V.U.E.)

Louis

P.s. *I* know it doesnâ€™t really hurt the machine. The operators don't,
And Maint. gripes about it too..

BillH · 2005-05-02 19:50:57

Hi Louis,
Yeah, old machines never die, they just keep getting rebuilt.

Actually, I just met someone from a successful aero-space job shop. They've done well with the idea that they can be more cost-effective buying more older rebuilt machines than less new "high-speed" machines. As long as you have the floor space and operators, and the finances make sense, why not?

Good point on the motion controller's different handling of G0 and G1. I can see us getting led down the path to add an option for OptiPath to output detected aircut motions in either G0 or in the current G1 mode. I guess it matters what best fits how your specific machine works. No one likes to see their machine "bouncing" around the shop because of the NC program.

I'll send you a separate email about the demo files.

Good seeing you last week,

Bill

vhubbard · 2005-05-11 19:43:57

Many Fanuc controls, even older ones (10-11M) , have a parameter option to set RAPID moves as linear, eliminating the dog leg. It may be a few milliseconds slower.t. All the CAM systems show RAPID/G0 as linear. Vericut can simulate the dog leg also.

This still does not answer why air moves can't be set as rapid. If some machines can do "linear" rapid then it should be an option.

Louis Bigelow · 2005-05-11 20:47:47

of the 49 cnc mills we have, only one is a fanuc, it's been broken
for years.(6M fossil.)
two of the remaining are compatables. (Yasnac.)
the other 46 are Okuma, boston digitals or mdsi refits.
except for 7 machines, everything is 5 axis.
about 3/4 of those are twin spindle.
okumas & fanuc compats dogleg.
all bd & mdsi straight line.
I have an option in my post to output all rapids as fast feed. (Used a lot.)
also to output feeds over a value as rapids. (Almost never.)
it's not the dogleg, it's kellering with machines that have high speed machining mode that causes fits and starts. see post above 5/3/05

Louis.

VERICUT Users' Forum

#1 2005-03-02 23:17:14

Air Cut Feed Rate

#2 2005-03-14 16:46:57

Re: Air Cut Feed Rate

#3 2005-05-02 17:27:48

Re: Air Cut Feed Rate

#4 2005-05-02 19:50:57

Re: Air Cut Feed Rate

#5 2005-05-11 19:43:57

Re: Air Cut Feed Rate

#6 2005-05-11 20:47:47

Re: Air Cut Feed Rate

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