Live Tool Lathe - Planes & Cutter comp question,

[Brian Pallas]

Hello,

 

I have a couple of questions about milling cross holes on a Live tool lathe with Y axis.  

For plane selection - I am looking for some insight into how MasterCam works with the plane selection.  I used the C-view utility to get the planes for a radial tool circle mill operation at C180.  Then I used the front plane and created a circle mill operation.  The operation I created the code looks just how I think it should.  On the other one with the front plane though it doesn't do the G19 plane selection until the cutter comp on line, which the machines don't like.  And also on what I programmed has two snap ring grooves, 1 X + and 1 X-.  On the operation with the front plane the X+ cutter comp is G42, and the X- is G41.  The correct looking operation has both cuts being done with G41, which seems correct to me.

 

I was curious on an explanation of how/why the output is coming out as it is.  Right now I have a good program, but I would like to understand this aspect of MasterCam better.

 

And also on plane selection, with the correct looking operation, it turns on G19 before any movement takes place.  Is that the correct way to do that?  Or G18, position above the hole, then G19 and cross milling?  I would also appreciate any insight into common practice on that.

 

Thanks.

[jlw™]

What post are you using?  Can you upload a file?

[bd41612]

Look at this thread:

 

http://www.emastercam.com/board/topic/82089-lathe-c-axis-is-on-the-wrong-side/

[ScottBro4]

I'm sure i can help you but I'd like to see a file to better understand what you're trying to do. Normally you will be in WCS top and tool and construction will be cross upper top.

Send a file. 

[Colin Gilchrist]

All Lathe Toolplanes for positioning the C-Axis must start as the "BACK" plane, and must be a rotation of the BACK plane, rotating around the Z-Axis.

 

If you look at Mastercam's "Back" plane, you will see that the X+ direction of the plane is actually aligned with the -X direction of the TOP WCS. This is important.

 

You should use the C-View utility like you've done, starting with the Back Plane, and rotating it around the X Axis to get the rotation you want.

 

All of the output (and I do mean all of it), is setup and controlled by a special section inside the Lathe Post. (Gen Fan 4X MT_Lathe Post). You can reverse the axis direction, change the plane code based on the type of cut, swap the G2/G3 directions, and much more.

 

Here is the section that controls the output of the Gen Fan 4X MT_Lathe Post:

# --------------------------------------------------------------------------
#Machining position turret/spindle settings
# Switch strings based on turret position top/bottom-left/right and cut type.
# Turret position is based on the Mastercam settings (see lathtype).
# Strings are re-assigned for output in the routine psw_str_mult.
# The string variable sw_string holds the place position value to determine
# how to assign the strings.  Planes are relative to the view from Mastercam.
# Assign the 17 digit string following the alpha columns below:
# A - C axis, 1 = axis winds, 2 = axis signed, 3 = indexer, 4 = shortest direction
# B - Spindle direction, 0 = normal, 1 = reverse
# C - Plane 0 arc/comp, 0 = normal, 1 = switch
# D - Plane 1 arc/comp, 0 = normal, 1 = switch
# E - Plane 2 arc/comp, 0 = normal, 1 = switch
# F - Plane 0, 0 = G17, 1 = G19, 2 = G18
# G - Plane 1, 0 = G17, 1 = G19, 2 = G18
# H - Plane 2, 0 = G17, 1 = G19, 2 = G18
# Decimal (required)
# I - Plane 0, X axis, 0 = normal, 1 = switch sign from basic
# J - Plane 0, Y axis, 0 = normal, 1 = switch sign from basic
# K - Plane 0, Z axis, 0 = normal, 1 = switch sign from basic
# L - Plane 1, X axis, 0 = normal, 1 = switch sign from basic
# M - Plane 1, Y axis, 0 = normal, 1 = switch sign from basic
# N - Plane 1, Z axis, 0 = normal, 1 = switch sign from basic
# O - Plane 2, X axis, 0 = normal, 1 = switch sign from basic
# P - Plane 2, Y axis, 0 = normal, 1 = switch sign from basic
# Q - Plane 2, Z axis, 0 = normal, 1 = switch sign from basic
use_only_tl  : 1     #Use only Top turret/Left spindle settings (below) for
                     #all Mastercam turret/spindle selections
                     #When configuring for multi-spindle/turret set to 0

#Columns-       ABCDEFGH.IJKLMNOPQ #Turret/Spindle            #Path Type
scase_tl_c1  : "10000222.000000000"  #Top turret/Left spindle, Turning cut
scase_tl_c2  : "11000012.000000000"  #Top turret/Left spindle, Right Face cut
scase_tl_c_2 : "11110012.000000000"  #Top turret/Left spindle, Left Face cut
scase_tl_c3  : "10010102.000000000"  #Top turret/Left spindle, Cross cut
scase_tl_c4c : "10000111.000000000"  #Top turret/Left spindle, Y axis subs. Cycle
scase_tl_c4  : "10000222.000000000"  #Top turret/Left spindle, Y axis subs.
scase_tl_c5  : "10000222.000000000"  #Top turret/Left spindle, Multisurf Rotary

#Columns-       ABCDEFGH.IJKLMNOPQ
scase_bl_c1  : "10000222.000000000"  #Bottom turret/Left spindle, Turning cut
scase_bl_c2  : "11000012.000000000"  #Bottom turret/Left spindle, Right Face cut
scase_bl_c_2 : "11110012.000000000"  #Bottom turret/Left spindle, Left Face cut
scase_bl_c3  : "10010102.000000000"  #Bottom turret/Left spindle, Cross cut
scase_bl_c4c : "10000111.000000000"  #Bottom turret/Left spindle, Y axis subs. Cycle
scase_bl_c4  : "10000222.000000000"  #Bottom turret/Left spindle, Y axis subs.
scase_bl_c5  : "10000222.000000000"  #Bottom turret/Left spindle, Multisurf Rotary

#Columns-       ABCDEFGH.IJKLMNOPQ
scase_tr_c1  : "10000222.000000000"  #Top turret/Right spindle, Turning cut
scase_tr_c2  : "11000012.000000000"  #Top turret/Right spindle, Right Face cut
scase_tr_c_2 : "11110012.000000000"  #Top turret/Right spindle, Left Face cut
scase_tr_c3  : "10010102.000000000"  #Top turret/Right spindle, Cross cut
scase_tr_c4c : "10000111.000000000"  #Top turret/Right spindle, Y axis subs. Cycle
scase_tr_c4  : "10000222.000000000"  #Top turret/Right spindle, Y axis subs.
scase_tr_c5  : "10000222.000000000"  #Top turret/Right spindle, Multisurf Rotary

#Columns-       ABCDEFGH.IJKLMNOPQ
scase_br_c1  : "10000222.000000000"  #Bottom turret/Right spindle, Turning cut
scase_br_c2  : "11000012.000000000"  #Bottom turret/Right spindle, Right Face cut
scase_br_c_2 : "11110012.000000000"  #Bottom turret/Right spindle, Right Face cut
scase_br_c3  : "10010102.000000000"  #Bottom turret/Right spindle, Cross cut
scase_br_c4c : "10000111.000000000"  #Bottom turret/Right spindle, Y axis subs. Cycle
scase_br_c4  : "10000222.000000000"  #Bottom turret/Right spindle, Y axis subs.
scase_br_c5  : "10000222.000000000"  #Bottom turret/Right spindle, Multisurf Rotary

If you look at the code I posted, there are four different groups of settings. Only the first group (Top turret / Left Spindle) is used by default. To use all the different Turret/Spindle settings, set 'use_only_tl' to '0'. (That enables each group to control a different turret/spindle combination.)

 

Take the "Top turret/Left spindle" group as an example. There are 7 different rows of strings. Each row corresponds to a different "type of cut". There is "Turning", Right Face cutting, Left Face cutting, Cross cutting, Y Axis (Y Axis Sub), and Multi-surf.

 

For each different "type of cut", you can control every aspect of the post output, by changing the individual digits in the string on that row. What does that mean? If you look at the string definition, each individual digit controls some different aspect of the code output.

 

Let's say for Turning, my Arc/Comp directions (G2/G3, and G41/G42 directions) are reversed from what I need at the machine. That option for "Turning" is set in the first row, of the first group (top/left). There are 17 different settings that are set in this string. Looking at the instructions, the "Plane 1" (G19) is what we want to switch. So we change the "D" (4th) digit from '0' to 1'.

From this:
scase_tl_c1  : "10000222.000000000"  #Top turret/Left spindle, Turning cut

To this:
scase_tl_c1  : "10010222.000000000"  #Top turret/Left spindle, Turning cut

That is the proper way to handle setting up Planes for use in Lathe, and the proper way to configure the post output...

 

Hope that helps,

 

Colin

[Brian Pallas]

Awesome.  Thanks for the detailed response Colin.

 

 One other question - The other day I used the C-view utility and it created the view and toolpath, but when I went to the view manager to give the new view a work offset, the new view wasn't listed there.  Is there something you need to do after the C-view utility to "lock" it in?  I know sometimes if I change views if I don't hit "Top (WCS)" the T/C planes aren't actually selected.

[Colin Gilchrist]

Someone liked my response above, and I realize there was a bit of a mistake in what I said.

The Z-Axis Vector of the Back Plane sets the C-Axis Zero Position. You must rotate this plane, with a "locked X-Axis orientation", about the X-Axis of that plane/WCS.

The Back Plane, and the Top WCS, have the X-Axis Positive Orientation "opposed". The point opposite of each other.

Any "Lathe T/C Plane" you create, must have the "positive X-Axis direction", pointing away from the X+ orientation of the Top WCS.

This setup, is by-far, one of the more confusing "rules" in Mastercam, and is really only dictated by the setup of the MP Lathe Post Processors, and how they were designed to read "Plane Matrix Data", and some of the processing rules and checks for 4-Axis.