Figure 8 groove

[JPensack Acker Drill]

Does anyone have any experience with an OD figure 8 oil groove? It is a .750 pitch over 15 inches and at the beginning and end it has a .6565 turnaround. It is more of a fishing reel that a roller follows to wind up wire. Okuma has a G34 threading function which seems like any change in the thread it possible. Such as changing leads at any point and staying in the thread to go back and forth. I'm assuming I can't use a G1 cause once were out of the groove its position is lost. Therefore I'll have to write it by hand. Does anyone have any experience with this type of operation?

[Scott Lundin Shopware Inc.]

I did this once on a rubber roller. I just programmed manual G-codes.

 

G00 X12.0 Z.10

G32 Z-12.0 F??? (as needed)

G32 Z.10

G28 U0 W0

M01

 

This created a diamond shape or figure 8 as you call it.

[Jack Neelands™]

Im surprised your not programming a right and left hand thread....did this for an object that required the same inside of a dia and then just offset the start and finish for second groove half the pitch.

 

 

HTH

[Josh T™]

We did this type of part for a food/medical company once. We did it on the Haas Mill with the 4th axis rotary table. Simple code really...

 

code:

---

T14 M06 (.2500 CEM)

G00 G90 G54 X-.25 Y0 A0

S1500 M03

G43 Z0.6 H14 M08

G1 Z.4425 F50.

G1 X0 F7.5

G91 X1. A360. L8

G91 X-1. A360. L8

G1 G90 X-.25

G0 G90 Z.6 M09

G0 G91 G28 Z0

G28 Y0 A0

M01

---

The G91 lines loop the code 8 times at the required pitch (1" in this case).

 

Good Luck

HTH

 

Josh

[JPensack Acker Drill]

Josh, we currently do this groove on our haas vf6 with the rotary head. It requires an 1/8th inch endmill to go an 1/8th inch deep and is 16" long. It takes a long time and sometimes goes through a couple endmills. I figure if we can groove it on the lathe it will be a big time savings.

 

Scott, Im thinking of doing the same thing but with a G34 because at the beginning and end there is a .6565 turnaround where the rest is a .75 pitch. The biggest thing I'm concerned about is where it turns around. We have rapid droop control set to .0004 so it should hold the overall length good but I'm not sure is the G32(haas) or G34(Okuma) will stay down in the cut when I switch directions. I wish verify did a better job at threading verification.

 

Jack, if I do this will it give me a contant radius where the roller should be turning around at or will there be a little fudging where the threads lead in and out?

[John Summers]

If you want to lay out a sine curve figure 8, here's a FPLOT program that could help. After you plot the sine curve, roll it on the appropriate diameter. You can edit the diameter and width in FPLOT.EQN.

 

dia = 1

width = 1

step_var1 = a

step_size1 = 5

lower_limit1 = 0

upper_limit1 = 360

geometry = lines

angles = degrees

origin = 0, 0, 0

x = sin(a)*width/2

y = 2*a*pi*dia/360

[Jack Neelands™]

You will have to fudge the ends of the threads on the lead in lead out if you cut it in the lathe...we were able to make a groove on the outside at both ends so that the start and finish would not be seen. but as you say there is a .6565 turnaround that needs to be repicked to finish the groove...Does this mean your pitch is changing on the last thread?....and can you do only half a thread to meet up with the .75 thread?

[Colin Gilchrist]

Hi John,

 

Can I just copy and past that code and name it "fplot.eqn"? When I try and run Fplot.dll, there are some default .eqn files, but no "fplot.eqn" file.

 

I've looked at the help file, but it just lists the math constants. Can we create our own equations and have Mastercam plot them? Is there a particular format we have to follow?

 

Thanks,

[John Summers]

FPLOT.DLL is a c-hook. When you run the c-hook, there is an option to read the -.eqn file (fig8.eqn). You may wish to edit the diameter and width first, with a text editor. The key to the figure 8 is that one cycle of the sine curve (360 degrees) wraps twice around the diameter. Put FIG8.EQN in the c-hook directory with the other examples.

In general, the math capabilities of FPLOT are supposed to be similar to the postprocessor capabilities, but it falls far short, as there are only two canned loops and no subroutines or other input source, such as a -.NCI file or buffer files. I'll send you both FIG8.EQN and FIG8.PST.

[Colin Gilchrist]

Thanks as always John...

[Ron Branch @ Verisurf]

John if you don't mind sharing I would like to have a copy.

[Colin Gilchrist]

Hi Ron,

 

You will need V9 to run the PST version of the files John mentions. I haven't figured out how to run them in Mastercam X yet...

[Ron Branch @ Verisurf]

I have stuff he has sent me over the years and will look and see if I ever brought it into X or not.