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PB - Can't wrap my head around FRN or DPM


Hi guys I've taken a new job recently, mainly cam work, and have been lurking the forum for advice since about 3 weeks now. Great resource btw. Found quite a few answers to many of the questions I had which is kinda cool (fanuc backgroud here btw).


One question that I have that remains a mystery is how to customized a two years old PB post I have here for FRN and/or DPM. We just took over a job that involves quite a few Variable contour tool paths so we have no choice to enable this functionality.


The 828D controller we have here (also new to me) can take both mm/min and degree/min. I've tried setting the values in PB > Machine Controls > Feedrates > to FRN for linear & rotary motions and DPM for rotary only but that didn't worked. The rotating speed would snap the cutter in an instant with these sort of feeds. I have a feeling that the controller's XYZA axis are sync'ed or that controller is setup for positioning only. Not sure which one, yet!


Any of you guys have a FRN/DPM enabled *.tcl file/script/example (anything) by any chance? I'm not looking for a complete post, just a hint so I can get back on track here :/


Thanks in advance

Charles NX 8.5


Re: PB - Can't wrap my head around FRN or DPM

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

FRN = inverse time (typically G93)

Note the value of F is (1 / time in minutes to cut this move). 

So if it takes .001 minutes to do a move, the G93 move will have "F1000." on that line

Note in G93 (typically) *every* line needs an F word.

And they are typically "large" values.


If they don't use G93, then in G94 mode (assuming Inch units) anytime a rotary axis is involved, the "F" value is interpreted as "degrees/minute"

So (again) the "F" value would be larger than a "straight line" (no rotary) F for the same (IPM) feed rate



Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled

Re: PB - Can't wrap my head around FRN or DPM


Hi Ken, appreciate the answer. After reading it twice it is slowly starting to make sense! I do great solid & surface modeling and can cut 3D Z level and contouring all day long but when it comes to tweaking post processors for simultaneous motions, something jams up in my brain :/ Grateful for any help.


In motion, it looks like this here with the 828D

G93 G1 A359 F1         > Taking a minute to complete (inverse time)
G94 G1 A359 F360     > Taking a minute to complete (828D automatically switch to deg/min)

However, when you add a linear axis in the picture; eg:

G93 G1 X50 A359 F1     > Taking the entire day loll (828D simply ignore the simultaneous motion)
G94 G1 X50 A359 F360     > Taking 360mm/min to complete, as in pretty quick :/

Could it be that the 828D is for indexing only? Not a 'true' 4axis? Or perhaps have been commissioned by a Siemens rookie? Expansive drill, no 3D?

I haven't tried converting a post in DPM instead of inverse time to be honest. That could do it I have no idea, even less know where to start to get a post done to outpu DPM.

Hence why I was asking if you guys had any quick TCL function to output DPM, or 'tweaked' FRM for the 828D.


Thank again



Re: PB - Can't wrap my head around FRN or DPM


For instance the code below seems spot-on you'll say but ran in the controller it will snap off the cutter right at the engage motion :/ The 828D just doesn't take the FRN and switch to the mmpm feedrate for some *&^*in reason. Hope to get my hands on a DPM enabled post for a try.


Below is a simple helix/one revolution with a pitch of 42mm (onto OD42). Really should take a min to complete but the 828D somehow does it in 7sec lollll


N10 ;Start of Program
N20 ;
N30 DEF REAL _camtolerance
N60 ;
N70 G40 G17 G710 G94 G90 G60 G601 FNORM
; ==========================================
; OPERATION : VARIABLE_CONTOUR   ( 0h 1m 5s )       
; ==========================================
; TOOL No.  : T1   D1
; Intol     : 0.100000
; Outtol    : 0.100000
; Stock     : 0.000000
; ==========================================
N80 _X_HOME=0.0 _Y_HOME=0.0 _Z_HOME=0.0
N90 _A_HOME=0
N100 _camtolerance=.2
N130 T1 M6
N160 G0 A-180.
N170 CYCLE832(_camtolerance,_FINISH,1)
N190 G54
N200 G0 X-157.702 Y2.513 D1
N210 G0 Z21. S800 M3
N220 G93 G1 X-158.647 Y2.021 F126.
N230 X-159.146 Y1.055
N240 X-159. Y0.0
N250 X-158.475 A-175.5 F76.249
N260 X-157.95 A-171. F76.244
N270 X-157.425 A-166.499 F76.242
N280 X-156.9 A-161.999 F76.248
N290 X-156.375 A-157.5 F76.258
N300 X-155.85 A-153. F76.257
N310 X-155.325 A-148.5 F76.247
N320 X-154.8 A-144. F76.242
N330 X-154.275 A-139.5 F76.247
N340 X-153.75 A-135. F76.256
N350 X-153.225 A-130.5
N360 X-152.7 A-126. F76.247
N370 X-152.175 A-121.5 F76.241
N380 X-151.65 A-117. F76.246
N390 X-151.125 A-112.5 F76.255
N400 X-150.6 A-108.
N410 X-150.075 A-103.5 F76.246
N420 X-149.55 A-99. F76.241
N430 X-149.025 A-94.5 F76.247
N440 X-148.5 A-90. F76.256
N450 X-147.975 A-85.5
N460 X-147.45 A-81. F76.247
N470 X-146.925 A-76.5 F76.241
N480 X-146.4 A-72. F76.246
N490 X-145.875 A-67.5 F76.255
N500 X-145.35 A-63.
N510 X-144.825 A-58.5 F76.246
N520 X-144.3 A-54. F76.241
N530 X-143.775 A-49.5 F76.247
N540 X-143.25 A-45. F76.256
N550 X-142.725 A-40.501
N560 X-142.2 A-36. F76.247
N570 X-141.675 A-31.5 F76.241
N580 X-141.15 A-27. F76.246
N590 X-140.625 A-22.5 F76.255
N600 X-140.1 A-18.
N610 X-139.575 A-13.5 F76.246
N620 X-139.05 A-9. F76.241
N630 X-138.525 A-4.5 F76.247
N640 X-138. A0.0 F76.256
N650 X-137.475 A4.5
N660 X-136.95 A9. F76.247
N670 X-136.425 A13.5 F76.241
N680 X-135.9 A18. F76.246
N690 X-135.375 A22.5 F76.255
N700 X-134.85 A27.
N710 X-134.325 A31.5 F76.246
N720 X-133.8 A36. F76.241
N730 X-133.275 A40.5 F76.247
N740 X-132.75 A45. F76.256
N750 X-132.225 A49.5
N760 X-131.7 A54. F76.247
N770 X-131.175 A58.5 F76.241
N780 X-130.65 A63. F76.246
N790 X-130.125 A67.5 F76.255
N800 X-129.6 A72.
N810 X-129.075 A76.5 F76.246
N820 X-128.55 A81. F76.241
N830 X-128.025 A85.5 F76.247
N840 X-127.5 A90. F76.256
N850 X-126.975 A94.5
N860 X-126.45 A99. F76.247
N870 X-125.925 A103.5 F76.241
N880 X-125.4 A108. F76.246
N890 X-124.875 A112.5 F76.255
N900 X-124.35 A117.
N910 X-123.825 A121.5 F76.246
N920 X-123.3 A126. F76.241
N930 X-122.775 A130.5 F76.247
N940 X-122.25 A135. F76.256
N950 X-121.725 A139.5
N960 X-121.2 A144. F76.247
N970 X-120.675 A148.5 F76.242
N980 X-120.15 A153. F76.247
N990 X-119.625 A157.5 F76.257
N1000 X-119.1 A161.999 F76.258
N1010 X-118.575 A166.499 F76.248
N1020 X-118.05 A171. F76.242
N1030 X-117.525 A175.5 F76.244
N1040 X-117. A180. F76.249
N1050 G94 X-116.508 Y-.945 F132.
N1060 X-115.543 Y-1.444
N1070 X-114.487 Y-1.298
N1080 ;End of Path
N1090 M5
N1100 SUPA G0 Z=_Z_HOME D0
N1110 CYCLE832()
N1120 ;End of Program
N1140 M30
; ==========================================
; ==========================================

Re: PB - Can't wrap my head around FRN or DPM

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Note (I think) I've seen where some controls do FRN in (1/time in *seconds*)


Is an 828D a Siemens control?  Or who?


I would ask the machine mfg (or their local distributor) for some help on how to do this on your machine.

Once you get (possibly hand edited) code working, then its just a matter of replicating this in the post.



Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled

Re: PB - Can't wrap my head around FRN or DPM


Thanks for the heads up Ken, according to the limited documentation RE G93, it seems to be minutes but hell yes, I'm with you... that could explain why I've found a scale factor function in the FRN pb_cmd today.


The 828D is a siemens, well, who knows for sure. Its one ctrl they call 'inteligent' with nano bit precision. Only works with linear moves and only when you have the Adv Surface compressor set to ON at all time. Omit the cycle832 and it bugs & stop at every lines of code swinging a 4tons machine like a puppet on the shop floor - scary to watch. Helix/holes ends up looking like HEX also. Just took me one week to figure this one out (doc reads 200 lines look ahead, all was confusing indeed loll).


Siemens staff (rep?) where I am located (not in the USA btw) are unfamilliar with this ctrl, and only good at loading-up scripts given to them by their HQ apparently. They are 17 years old or look like. I've been told by my employer last week, I don't know, haven't tried/seen them.


Last time they've been on site was to fix the tool management and the machine when offline for 4 days so my boss is kinda relunctant to get them to do anything to this particular machine.


So here I am begging for help on the internet Smiley Wink

Re: PB - Can't wrap my head around FRN or DPM


I have 2 828d control machines. They are 4+1 5 axis machines. You need to switch to DPM for moves with linear and rotary.


Don't feel bad. Support for 828d in US isn't good either. My machines came from a Taiwan builder.

I just got a Grob G350 and support for the controller from Grob is excellent (Uses a 840d though Smiley Happy )


Dennis Rathi
Creations Unlimited

Re: PB - Can't wrap my head around FRN or DPM

Here is a degree per minute. Going around a part at 80 ipm.

N10 ;Start of Program
N20 ;
N60 DEF REAL _camtolerance
N70 ;
N80 G40 G17 G700 G90 G60 G601 FNORM
N90 ;Start of Path
N100 ;
N120 ;TOOL NAME : SM_.500_.625_2.250
N130 ;TOOL TYPE : Milling Tool-Ball Mill
N140 ;
N150 ;Intol : 0.000000
N160 ;Outtol : 0.000200
N170 ;Stock : 0.000000
N180 _camtolerance=0.000200
N190 ;
N210 ;
N220 SUPA G0 Z-.1 D0 M5
N230 SUPA X-8. Y12.
N240 SUPA G0 A0 C0 D1
N250 ;First Tool
N260 T="SM_.500_.625_2.250"
N270 M6
N280 T="SM_.500_.625_2.250"
N290 SUPA G0 Z-.1 D0
N300 S8000 M3 M8
N310 ;Initial Move
N320 CYCLE832(_camtolerance,1,1)
N330 G55
N350 CYCLE800(1,"TABLE",0,39,,,,-0.243,-90.,0.,0.,0.,0.,-1,1.)
N360 G0 X-.248 Y-9.3759 D1
N370 A-90. C-.243
N380 TOFFL[1]=R100
N390 Z2.7251
N400 ;Approach Move
N410 Z2.6021
N420 ;Engage Move
N430 G1 X-.2477 Z2.588 F80.
N440 X-.2467 Z2.5741
N450 X-.2448 Z2.5602
N460 X-.2422 Z2.5464
N470 X-.2388 Z2.5328
N480 X-.2346 Z2.5194
N490 X-.2298 Z2.5062
N500 X-.2241 Z2.4934
N510 X-.2178 Z2.4809
N520 X-.2108 Z2.4688
N530 X-.2031 Z2.457
N540 X-.1947 Z2.4458
N550 X-.1857 Z2.435
N560 X-.1762 Z2.4247
N570 X-.1661 Z2.415
N580 X-.1554 Z2.4059
N590 X-.1443 Z2.3973
N600 X-.1327 Z2.3895
N610 X-.1207 Z2.3822
N620 X-.1083 Z2.3757
N630 X-.0955 Z2.3699
N640 X-.0825 Z2.3648
N650 X-.0691 Z2.3604
N660 X-.0556 Z2.3568
N670 X-.0418 Z2.354
N680 X-.028 Z2.3519
N690 X-.014 Z2.3506
N700 X0.0 Z2.3501
N710 ;Cutting
N720 C-1.143 F1949.86
N730 C-2.041 F1949.56
N740 C-2.939 F1951.9
N750 C-3.841 F1950.5
N760 C-4.748 F1950.07
N770 C-5.649 F1949.27
N780 C-6.546 F1951.42
N790 C-7.439 F1950.66
N800 C-8.329 F1949.34
N810 C-9.219 F1951.99
N820 C-10.108 F1949.94
N830 C-10.998 F1949.83
N840 C-11.89 F1949.61
N850 C-12.786 F1951.57
N860 C-13.685 F1949.15
N870 C-14.59 F1950.99
N880 C-15.501 F1950.51
N890 C-16.42 F1951.89
N900 C-17.346 F1948.77

Dennis Rathi
Creations Unlimited

Re: PB - Can't wrap my head around FRN or DPM


Wow, thanks for the sample code. I appreciate.  I’ll have a look if I can get anyone (possibly myself) to set-up the swivel feature on the controller, whether this will help or not. The way Siemens commissioned it, in our case, is by using the Easy Extent button. Shipped it to us that way e.g. X,Y,Z,A & SP1. That’s it - that’s all. They swear it is the way they set-up these 828D 4ax so I’ll take their word for it.

Interesting to find out that DPM is the way to go (thank you btw). When you talk to Siemens over the phone they tell you that there is no reason that FRN wouldn’t work. When asked if they have a PP for the 828D (either frn or dpm), they say they’ll get back to you but never called back (that was a week ago). Reminded them once, totally ignored. So my guess is they know the Sinumerik 828D just doesn’t/won't work. To add to the awkwardness, messages on this forum are read by Siemens and literally goes unanswered. Or if they do read them, they kindly shoot you over a library which is about half the size of the entire Internet.

I’ve actually proposed to the owner to get rid of this machine this morning or, if any sentimental value, move it away from the prod shop floor and keep it as a static and dumb drilling machine. The part that needs to be simultaneously cut was outsourced this afternoon btw… cheaper for us to do this instead of setting-up another machine here  - or reading 1000 page long PDFs.



Re: PB - Can't wrap my head around FRN or DPM


Regardless, I've rigged a post on my free time using bits and peices from a post I've nicked from my friend so to output DPM. Feels like stitching. PP is working, I mean "the output" is, but again when ran on the great and intelligent Sinumerik 828D 4ax, that ctrl overides everything in MMPM and the cutter rip throug the parts at 360mmpm lollll


What a waste of precious time, no support, read my DOC!


Here goes the prog with DPM in metric. 1 (one) revolution helix - simple. A one minute program that zip in 7 seconds instead. What can I say....... MACHINE FOR SALE Smiley Wink


N70 G40 G17 G710 G94 G90 G60 G601 FNORM
N80 _X_HOME=0.0 _Y_HOME=0.0 _Z_HOME=0.0
N90 _A_HOME=0
N100 _camtolerance=.2
N130 T1 M6
N160 G0 A0.0
N170 CYCLE832(_camtolerance,_FINISH,1)
N200 G54
N210 G0 X1.298 Y2.513 D1
N220 G0 Z26.1 S300 M3
N230 Z24.5
N240 G1 Z21. F132.
N250 X.353 Y2.021
N260 X-.146 Y1.055
N270 X0.0 Y0.0
N280 X.525 A4.5 F343.12
N290 X1.05 A9. F343.1
N300 X1.575 A13.501 F343.17
N310 X2.1 A18.001 F343.12
N320 X2.625 A22.5 F343.08
N330 X3.15 A27. F343.16
N340 X3.675 A31.5 F343.11
N350 X4.2 A36. F343.09
N360 X4.725 A40.5 F343.11
N370 X5.25 A45. F343.15
N380 X5.775 A49.5
N390 X6.3 A54. F343.11
N400 X6.825 A58.5 F343.09
N410 X7.35 A63. F343.11
N420 X7.875 A67.5 F343.15
N430 X8.4 A72.
N440 X8.925 A76.5 F343.11
N450 X9.45 A81. F343.09
N460 X9.975 A85.5 F343.11
N470 X10.5 A90. F343.15
N480 X11.025 A94.5
N490 X11.55 A99. F343.11
N500 X12.075 A103.5 F343.09
N510 X12.6 A108. F343.11
N520 X13.125 A112.5 F343.15
N530 X13.65 A117.
N540 X14.175 A121.5 F343.11
N550 X14.7 A126. F343.09
N560 X15.225 A130.5 F343.11
N570 X15.75 A135. F343.15
N580 X16.275 A139.499 F343.08
N590 X16.8 A144. F343.19
N600 X17.325 A148.5 F343.09
N610 X17.85 A153. F343.11
N620 X18.375 A157.5 F343.15
N630 X18.9 A162.
N640 X19.425 A166.5 F343.11
N650 X19.95 A171. F343.09
N660 X20.475 A175.5 F343.11
N670 X21. A180. F343.15
N680 X21.525 A184.5
N690 X22.05 A189. F343.11
N700 X22.575 A193.5 F343.09
N710 X23.1 A198. F343.11
N720 X23.625 A202.5 F343.15
N730 X24.15 A207.
N740 X24.675 A211.5 F343.11
N750 X25.2 A216. F343.09
N760 X25.725 A220.5 F343.11
N770 X26.25 A225. F343.15
N780 X26.775 A229.5
N790 X27.3 A234. F343.11
N800 X27.825 A238.5 F343.09
N810 X28.35 A243. F343.11
N820 X28.875 A247.5 F343.15
N830 X29.4 A252.
N840 X29.925 A256.5 F343.11
N850 X30.45 A261. F343.09
N860 X30.975 A265.5 F343.11
N870 X31.5 A270. F343.15
N880 X32.025 A274.5
N890 X32.55 A279. F343.11
N900 X33.075 A283.5 F343.09
N910 X33.6 A288. F343.11
N920 X34.125 A292.5 F343.15
N930 X34.65 A297.
N940 X35.175 A301.5 F343.11
N950 X35.7 A306. F343.09
N960 X36.225 A310.5 F343.11
N970 X36.75 A315. F343.15
N980 X37.275 A319.5
N990 X37.8 A324. F343.11
N1000 X38.325 A328.5 F343.09
N1010 X38.85 A333. F343.11
N1020 X39.375 A337.5 F343.16
N1030 X39.9 A341.999 F343.08
N1040 X40.425 A346.499 F343.12
N1050 X40.95 A351. F343.17
N1060 X41.475 A355.5 F343.1
N1070 X42. A360. F343.12
N1080 X42.492 Y-.945 F132.
N1090 X43.457 Y-1.444
N1100 X44.513 Y-1.298
N1110 Z24.5
N1120 G0 Z26.1
N1130 ;End of Path
N1140 M5
N1150 SUPA G0 Z=_Z_HOME D0
N1160 CYCLE832()
N1170 ;End of Program
N1190 M30

; ==========================================
; ==========================================

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