[plnewton]

Hi All,


hoping you can point me in the right direction

I have built my own machine and done a little testing on a few bits a pieces and today I tried to mill my first real part but I am having a little issue

The part is simply a 50mm square with three 6.5mm holes right through, my issue is that as soon as the machine starts one of the holes it just about grinds to a halt as the feed rate drops down to about 0.60

I think the way I am setting up the tooling may be wrong as if I have a square pocket the machine runs fine but as soon as I try and do a pocket that is a circle the feed rate drops down to almost nothing?

is my problem the fact that I am trying to do a hole as a pocket?

Cheers

[bhurts]

The machine doesn't have time to accelerate to speed on such small moves. It is doing what it has to do to stay within the machines parameters.

Ben

[plnewton]

The machine doesn't have time to accelerate to speed on such small moves. It is doing what it has to do to stay within the machines parameters.

Ben

Hi Ben,

thanks for your reply but you have lost me mate

I do not understand why the machine would happily pocket a 20mm square for instance but as soon as it is a circle it (even a 20mm one) it runs so slow, at the rate it was running at it would have taken half an hour to do a 20mm hole in piece of 6mm mdf

Cheers

[bhurts]

On that I'm kinda lost. I only gave my opinion on why it would go so slow on a 6.5mm hole. If it is doing it on larger holes as well there is a real issue. To get to the root of the problem will require lots more info from you. Things like what machine, what control, and it's settings for velocity and acceleration. Also posting the code your running might give a clue.

Ben

[plnewton]

Yeah it is driving me crazy, any size pocket that is a circle drops the units per min down to about 0.6

This code is a pocket of 100mm square and runs just fine:
(BEGIN PREDATOR NC HEADER)
(MACH_FILE=3AXVMILL_MM.MCH)
(MTOOL T1 S1 D4. H40. DIAM_OFFSET 1 = 2.)
(SBOX X-55. Y-55. Z-25.4 L55. W55. H0.)
(END PREDATOR NC HEADER)

%
O100
(PROGRAM NUMBER)
(PROGRAM NAME - TESTSQUARE50.NC)
(POST - MACH 3 MILL METRIC)
(DATE - WED. 02/04/2015)
(TIME - 12:42PM)

N01 G21 G40 G49 G54 G80 G90 G91.1
N02 G53 Z0.


N03 M06 T1
N04 S7955 M03
N05 G00 G90 G54 X2. Y-2.
N06 G43 H1 Z2.54 M08
N07 G01 Z-6. F808.3001
N08 Y2. F1576.1853
N09 X-2.
N10 Y-2.
N11 X2.
N12 Y-4.
N13 X4.
N14 Y4.
N15 X-4.
N16 Y-4.
N17 X2.
N18 Y-6.
N19 X6.
N20 Y6.
N21 X-6.
N22 Y-6.
N23 X2.
N24 Y-8.
N25 X8.
N26 Y8.
N27 X-8.
N28 Y-8.
N29 X2.
N30 Y-10.
N31 X10.
N32 Y10.
N33 X-10.
N34 Y-10.
N35 X2.
N36 Y-12.
N37 X12.
N38 Y12.
N39 X-12.
N40 Y-12.
N41 X2.
N42 Y-14.
N43 X14.
N44 Y14.
N45 X-14.
N46 Y-14.
N47 X2.
N48 Y-16.
N49 X16.
N50 Y16.
N51 X-16.
N52 Y-16.
N53 X2.
N54 Y-18.
N55 X18.
N56 Y18.
N57 X-18.
N58 Y-18.
N59 X2.
N60 Y-20.
N61 X20.
N62 Y20.
N63 X-20.
N64 Y-20.
N65 X2.
N66 Y-22.
N67 X22.
N68 Y22.
N69 X-22.
N70 Y-22.
N71 X2.
N72 Y-24.
N73 X24.
N74 Y24.
N75 X-24.
N76 Y-24.
N77 X2.
N78 Y-26.
N79 X26.
N80 Y26.
N81 X-26.
N82 Y-26.
N83 X2.
N84 Y-28.
N85 X28.
N86 Y28.
N87 X-28.
N88 Y-28.
N89 X2.
N90 Y-30.
N91 X30.
N92 Y30.
N93 X-30.
N94 Y-30.
N95 X2.
N96 Y-32.
N97 X32.
N98 Y32.
N99 X-32.
N100 Y-32.
N101 X2.
N102 Y-34.
N103 X34.
N104 Y34.
N105 X-34.
N106 Y-34.
N107 X2.
N108 Y-36.
N109 X36.
N110 Y36.
N111 X-36.
N112 Y-36.
N113 X2.
N114 Y-38.
N115 X38.
N116 Y38.
N117 X-38.
N118 Y-38.
N119 X2.
N120 Y-40.
N121 X40.
N122 Y40.
N123 X-40.
N124 Y-40.
N125 X2.
N126 Y-42.
N127 X42.
N128 Y42.
N129 X-42.
N130 Y-42.
N131 X2.
N132 Y-44.
N133 X44.
N134 Y44.
N135 X-44.
N136 Y-44.
N137 X2.
N138 Y-46.
N139 X46.
N140 Y46.
N141 X-46.
N142 Y-46.
N143 X2.
N144 Y-48.
N145 X48.
N146 Y48.
N147 X-48.
N148 Y-48.
N149 X2.
N150 G00 Z2.54
N151 M09
N152 M05
N153 G53 Z0.
N154 G53 Y0.
N155 M02

(END OF PROGRAM)

N156 M30
%

This Code is a circle of 100mm and as soon as it plunges the units per min drop down to 0.61:
(BEGIN PREDATOR NC HEADER)
(MACH_FILE=3AXVMILL_MM.MCH)
(MTOOL T1 S1 D4. H40. DIAM_OFFSET 1 = 2.)
(SBOX X-55. Y-55. Z-25.4 L55. W55. H0.)
(END PREDATOR NC HEADER)

%
O100
(PROGRAM NUMBER)
(PROGRAM NAME - TESTHOLE50.NC)
(POST - MACH 3 MILL METRIC)
(DATE - WED. 02/04/2015)
(TIME - 12:23PM)

N01 G21 G40 G49 G54 G80 G90 G91.1
N02 G53 Z0.


N03 M06 T1
N04 S7955 M03
N05 G00 G90 G54 X.73 Y0.
N06 G43 H1 Z2.54 M08
N07 G01 Z-6. F808.3001
N08 G03 X.73 Y0. I-.73 J0. F1576.1853
N09 G01 X2.73
N10 G03 X2.73 Y0. I-2.73 J0.
N11 G01 X4.73
N12 G03 X4.73 Y0. I-4.73 J0.
N13 G01 X6.73
N14 G03 X6.73 Y0. I-6.73 J0.
N15 G01 X8.73
N16 G03 X8.73 Y0. I-8.73 J0.
N17 G01 X10.73
N18 G03 X10.73 Y0. I-10.73 J0.
N19 G01 X12.73
N20 G03 X12.73 Y0. I-12.73 J0.
N21 G01 X14.73
N22 G03 X14.73 Y0. I-14.73 J0.
N23 G01 X16.73
N24 G03 X16.73 Y0. I-16.73 J0.
N25 G01 X18.73
N26 G03 X18.73 Y0. I-18.73 J0.
N27 G01 X20.73
N28 G03 X20.73 Y0. I-20.73 J0.
N29 G01 X22.73
N30 G03 X22.73 Y0. I-22.73 J0.
N31 G01 X24.73
N32 G03 X24.73 Y0. I-24.73 J0.
N33 G01 X26.73
N34 G03 X26.73 Y0. I-26.73 J0.
N35 G01 X28.73
N36 G03 X28.73 Y0. I-28.73 J0.
N37 G01 X30.73
N38 G03 X30.73 Y0. I-30.73 J0.
N39 G01 X32.73
N40 G03 X32.73 Y0. I-32.73 J0.
N41 G01 X34.73
N42 G03 X34.73 Y0. I-34.73 J0.
N43 G01 X36.73
N44 G03 X36.73 Y0. I-36.73 J0.
N45 G01 X38.73
N46 G03 X38.73 Y0. I-38.73 J0.
N47 G01 X40.73
N48 G03 X40.73 Y0. I-40.73 J0.
N49 G01 X42.73
N50 G03 X42.73 Y0. I-42.73 J0.
N51 G01 X44.73
N52 G03 X44.73 Y0. I-44.73 J0.
N53 G01 X46.73
N54 G03 X46.73 Y0. I-46.73 J0.
N55 G00 Z2.54
N56 M09
N57 M05
N58 G53 Z0.
N59 G53 Y0.
N60 M02

(END OF PROGRAM)

N61 M30
%

[plnewton]

my machine is a home built machine running nema 34 steppers, mach3 is setup in mm and the maximum Velocity is set to 750mm per minute

[bhurts]

Your code is asking for a feedrate more then 2x what you have allowed in mach3. I don't know if that is the problem but you can check by changing the F808.3001 to F600.0 And your F1576.1853 to F600. 0 as well. Also when you output code you can leave out anything after the decimal for feedrate but keep the decimal.

Ben

[plnewton]

I have tried to set the feed rate in bobcad before I post and also change it in the g code directly and it makes no difference.

I also just tried to pocket out something with the letter U in it and it begins fine until it hits the arch at the bottom and feed rate again drops down to almost nothing so it is anything with any kind of arch or radius in it

[jrmach]

Can you .zip your .bbcd file and the PP you are using ?
I don't think your problem lies here with BoB,but if we can have a look we can be sure.

[plnewton]

Files attached, thanks for you input

[jrmach]

Sorry,see nothing on the BoB end of things.
Try posting over here http://www.cnczone.com/forums/mach-s...oft-software-/

[plnewton]

Yeah, I have just run one on the circle wizards in mach and it does the same thing so certainly nothing to do with bob so I will post over there and see how I go

Cheers

[Claude Boudreau]

Have you check the CV feedrate in Mach 3 ?
at the very end of this page.

http://www.machsupport.com/wp-conten...ettings_v2.pdf
There is also a setting in tool selection called Arc slowdown

[Claude Boudreau]

There is a setting called arc slowdown when you do your tool selection

I have tried to set the feed rate in bobcad before I post and also change it in the g code directly and it makes no difference.

I also just tried to pocket out something with the letter U in it and it begins fine until it hits the arch at the bottom and feed rate again drops down to almost nothing so it is anything with any kind of arch or radius in it

[gerfmate]

by the looks of the code you could get a speed variation with the g01 linear motion between the arc moves you will get an issue if your machine does not have a look ahead function so reading line for line would probably cause to happen . with the square pocket it's just linear so there are no issues , but if there are arcs in the pocket it may change