5-axis indexing question

[Bob W.]

I have a pair of holes that have a really tight true position to each other.  This part is machined on a 5-axis machine with a B and C axis.  One hole is bored at B90, C-90 and the other is bored at B0, C0.  The hole axis are normal to each other...  For accuracy sake my preference would be to bore the second hole at B0, C-90 so the C-axis position in space (thermal deviation, etc...) doesn't come into play for the true position of the hole.  The hole spacing would be a factor of the machine's y-axis accuracy only.  Is there a way to force this in Mastercam?  I have already played with the misc values which dictate whether the axis is biased + or -, but since both are at zero for the second hole it doesn't have any effect.  I have also tried making another plane which is rotated at 90 degrees about Z but that didn't work either.  Any thoughts?

 

Picture this link made from a solid piece of material with the bore at one end at 90 degrees rotated with respect to the other.  I can't show a picture of the actual part unfortunately, it would violate our customer's NDA.

 

[Bob W.]

Basically the second bore is done with the C-axis plate facing the machine spindle and I have no control over what position (in C) that the plate is in for this.  It could literally be any C value and the machine would be able to bore the hole.  The ideal orientation would be C-90 but I can't force that from what I can tell.

 

[Aaron Eberhard]

Bob - To my knowledge, there's no way to force that inside of Mastercam, and it'll have to come from the post.  If I recall, you use Postability posts, right?  You should be able to set the "Initial Secondary (more modern posts call it "Rotary Start")  misc integer to force it into position?

[Bob W.]

I do have those in my misc integers but haven't ever needed to use them.  It does have an effect on C but not what I'm after unfortunately.  I typed -90. and it posted at -180.  For some reason it really doesn't like C-90.  The B-axis is at 0. so there wouldn't be anything dictating that C needs to be at 0. or 180.

 

[Aaron Eberhard]

Try setting the C to something close to (but not) C-90.  Like, C-88 or C-91, I've seen that have an affect on the older MPFan based posts, but I don't think I've had to try that yet on a Postability post.  Might be worth a phone call to them?

[Bob W.]

Here is my post:

[POST_VERSION] #DO NOT MOVE OR ALTER THIS LINE# V24.00 P0 E1 W24.00 T1631223551 M24.00 I0 O0
# Post Name           : Generic Fanuc 5X Mill
# Product             : Mill
# Machine Name        : Generic
# Control Name        : Fanuc
# Description         : Generic Fanuc 5 Axis Mill Post
# 4-axis/Axis subs.   : Yes
# 5-axis              : Yes
# Subprograms         : No
# Executable          : MP 14.0

 

I have done a ton of mods to it as well.  But this is what I started with.

 

[Aaron Eberhard]

Ah, okay, using Generic MP..  I just downloaded the latest generic MP and it seems to behave?  I don't know if I have the same setup as you, though.    Either doing it as a single 5 axis path or two 3 axis paths seem to give me good results:

I didn't have to fiddle with any misc integers?

B axis only.MCAM-CONTENT

[Bob W.]

Can you get the B-axis to post at B180 or B0?  My current program bores the hole with the hole at 3:00 and I want it to bore with the hole at 12:00.

[Aaron Eberhard]

Seems like it, would you mind orienting the part I created in the correct order so I'm not guessing?

[Bob W.]

Here is a rough version of the part showing the position while boring the second hole (right hole, B0 C0)

 

Here is the position while boring the first hole (B90, C-90)

 

Here is the desired position for boring the second hole (B0, C-90)

[Bob W.]

The true positions of the holes are tight to each other (0.005 to ABC) and this is a production part we will be making for years.  I want a stable process that will yield perfect parts in the morning, noon, and night, summer or winter, etc...  The bore to the left is one of the datums.  Eliminating the C-axis index prior to boring the second hole will make the process more stable.  Also, there are other skewed features on the part that make 5-axis the preferred method for machining.  We make another variation of this part that is machined 4-axis and we hold .001 true position to ABC.  On the first article of this part we were at .003 and I'd like to make it better.

 

[MrFish]

Multiple Work offsets ?

[Leon82]

when we do extra tight true positions we set up seperate offsets and use a sub program for probing. for that part type we would probe the hole at b0 and copy the x value to the b90 offset and then come up to b90 and probe the rest of the part at b90. 

this is one example where the datum hole had to be probes at 90/ we have a shift at the end also so if you can offset for machine variances

M01
(SET G55 A TO -90.)
#5244=-90.
N50 T60 M6 ( 2MM PROBE OMP 600 )
M01
M132
G0 G90 G54 X-1.1811 Y-.1673 AX[4]=0. C0.
M131
G65 P9532 (PROBE ON)
G43 H60 T60
(PROTECTED POSITIONING CLEARANCE HEIGHT)
G65 P9510 Z1.2125
( PROBE Z SURFACE )
G65 P9510 X-1.1811 Y-.1673
G65 P9510 Z1.
G65 P9511 Z-.787 S54.
G65 P9510 Z1.2125
(PROTECTED POSITIONING)
G65 P9510 X0. Y-.1378 Z1.9999
( PROBE C AXIS ERROR COMP Y AXIS )
G65 P9510 Y-.7677
G65 P9510 Z-.3251
G65 P9518 X1.45 Y-.1378 Z-.3251 K3. B2. S54.
G65 P9510 Z1.9999
(C AXIS CORRECTION)
M24
G90 G0 G54 C0.
M23
(SET G55C EQUAL TO G54 C)
#5245=#5225
(PROTECTED POSITIONING)
G65 P9510 X0. Y-.1378 Z1.9999
( PROBE Y SURFACE )
G65 P9510 Y-.7677
G65 P9510 Z-.3001
G65 P9511 Y-.1378 S54.
G65 P9510 Z1.9999
(WCS CHANGE RETURN Z TO ZERO)
G90 G0 G49 G53 Z0
M132
G90 G0 G55 AX[4]=0. C0.
M131
G43 H60
(PROTECTED POSITIONING X AND Y)
G65 P9510 X0. Y0.
(PROTECTED POSITIONING Z)
G65 P9510 Z2.
(PROTECTED POSITIONING)
G65 P9510 X0. Y0. Z2.
( PROBE BORE )
G65 P9510 X0. Y0.
G65 P9510 Z-.1378
G65 P9514 D.8661 S55.
G65 P9510 Z2.
G65 P9533 ( PROBE OFF )
G49 G53 Z0
G5.1 Q1
G91 G28 Y0.
G90
(G54X EQUALS G55 X)
#5221=#5241
G91G10L2P1X#700
G91G10L2P1Y#701
N30T3M6(1/4 SPOT DRILL)

[Aaron Eberhard]

Right!  Horizontal 5 axis!  Do you do the axis inversion thing in the control def?

The default MPFan seems to work fine in that arrangement, although it came out as C90 B90/0 instead of C-90.

Check out Op1 - the 5 axis drill cycle.

B axis only.zip

[CEMENTHEAD]

sometimes I'll force a tool change. and the rotary will correct itself.

[crazy^millman]

Linking move for the win. Use Curve 5 Axis with tilt lines to force the move like you need and then it cannot get out of control.