something strange on my orac

[rab4steam]

hi
i am trying to get my orac to produce some parts , but have got a strange problem , i have set up the tool offsets for the tools being used & got my Z zero set for the front face for tool 0 . i then dry run the program which seems to run correctly program ends
try again & the first tool is now 1.5mm nearer the tailstock & does not face the front face as before & does the same 1.5mm for every time you do this
i have had a look at the ball screw & nuts no backlash can be found
thought that that a timing pulley may be slipping or belt had come slack so jumping on pulling . all seem ok
machine is making a strange noise after certain moves that sounds like the single step mode makes in manual operation
has anybody any idea as to what is happening it only started today , your help is much needed
i didn't want to have to refit so soon hoping it would last a little longer
robert

[Martin]

I would say it is more likely to be stalling.

The stepper motor will stall if the load is not correct. I would consider tightening the jib strip up on the axis. You will need to release the locking nuts & adjust the grub screws to push the stip in a bit.

[triac]

Hi Rab

Are you sure it's not in the programming, 1.5mm consistently sounds as if it maybe ?

If you switch to manual mode immediately after the program run the Z offset will be showing, should be the same as program start position but will no doubt show the 1.50mm error.

Emgee

[rab4steam]

hi
thank you for your quick reply's i will have a look today to see if i can find anything
all the best
robert

[Lone_Ranger]

hi
thank you for your quick reply's i will have a look today to see if i can find anything
all the best
robert

I am with "triac" on the programming error theory, possible you haven`t gone back to absolute for the end of your program, here is a program that I ran today on my Orac, if you go through page by page as per this it should work. just move your tool post about 150mm away from the chuck in the Z and about 20mm off center on the X, make sure you set the Tool 0 with the axis in that position and then set Tool 1 in the same position just as if you were "touching off" the material, if this doesn`t run then there is something wrong with the machine.

Page 1 MM-UNITS
Page 2 ABSOLUTE-FORMAT G90
Page 3 PROGRAN DATUM
X 25
Z 2
Page 4 POINT-TO-POINT G00,G01
X 9.535
Z1.0
FEEDRATE 500
TOOL-NO 1
SPINDLE-SPEED 1000
Page 5 START-DO-LOOP
COUNT 12
Page 6 INCREMENTAL-FORMAT. G91
Page 7 POINT-TO-POINT G00,G01
X -0.225
Z 0
FEEDRATE 500
TOOL-NO 1
SPINDLE-SPEED 1000
Page 8 POINT-TO-POINT G00,G01
X 0
Z-96
FEEDRATE 600
TOOL-NO 1
SPINDLE-SPEED 1000
Page 9 POINT-TO-POINT G00,G01
X 0.1
Z 0
FEEDRATE 1200
TOOL-NO 1
SPINDLE-SPEED 1000
Page10 POINT-TO-POINT G00.G01
X 0
Z96
FEEDRATE 1200
TOOL-NO 1
SPINDLE-SPEED 1000
Page11 END-DO-LOOP
Page12 INCREMENTAL-FORMAT. G91
Page13 POINT-TO-POINT G00,G01
X -0.15
Z 0
FEEDRATE 200
TOOL-NO 1
SPINDLE-SPEED 1500
Page14 POINT-TO-POINT G00,G01
X 0
Z -96
FEEDRATE 100
TOOL-NO 1
SPINDLE-SPEED 1500
Page15 POINT-TO-POINT G00,G01
X 0.45
Z 0
FEEDRATE 1200
TOOL-NO 1
SPINDLE-SPEED 1500
Page16 POINT-TO-POINT G00,G01
X 0
Z 96
FEEDRATE 1200
TOOL-NO 1
SPINDLE-SPEED 1500
Page17 ABSOLUTE-FORMAT G90
Page18 POINT-TO-POINT G00,G01
X 25
Z 0
FEEDRATE 1200
TOOL-NO 1
SPINDLE-SPEED 1000
Page19 END-PROGRAM M02

I ran this program a dozen times today with spot on repeatability so I know it works.

Page 12 is where it goes to the Finish Pass
Notice that near the end I have to program it back to Absolute at Page 17 for the rapid move away from the material. This may be where your problem is

Hope that`s of some help to you

Regards

[rab4steam]

hi
thank you all for your reply's
the program i am trying to run is a small part made from 3/4" dia brass which is then turned & parted off , the program ends with tool no6 which is the parting tool ,so is it this that is causing my problem . so if i programmed a tool change back to the turning tool
tool no 2 before program end that could solve all my problems
i will give it a try later today & let you all know what happens
thank you
robert

[Lone_Ranger]

hi
thank you all for your reply's
the program i am trying to run is a small part made from 3/4" dia brass which is then turned & parted off , the program ends with tool no6 which is the parting tool ,so is it this that is causing my problem . so if i programmed a tool change back to the turning tool
tool no 2 before program end that could solve all my problems
i will give it a try later today & let you all know what happens
thank you
robert

Yes, more than likely it will be the offset for the Parting off tool or you haven`t allowed the correct amount between the parts for the part off, I am assuming you are doing a few at a time without moving the stock out each time ? ?

Regards
Rob

[rab4steam]

hi
thanks for reply , the part is about 32mm long so only doing 1off at a time
i will post my code this evening for you all to have a look at
robert

[triac]

Hi Lone ranger,

Think you have a typo somewhere in your program, seems to me each traverse in the loop moves the tool further from the bar end.
p8 moves to 94mm actual cut length, p9+p10 position tool at 4mm from bar end, that = 3mm from loop start position, this is multiplied by 12 for the program.


Rgds, Emgee

[Lone_Ranger]

Hi Lone ranger,

Think you have a typo somewhere in your program, seems to me each traverse in the loop moves the tool further from the bar end.
p8 moves to 94mm actual cut length, p9+p10 position tool at 4mm from bar end, that = 3mm from loop start position, this is multiplied by 12 for the program.


Rgds, Emgee

Well spotted, yes, it was my bad typing, should be OK now

See image below for the original

Orac Programming

ORAC PROGRAM.jpg (71.07 KiB) Viewed 9363 times

Regards
Rob

[triac]

Hi Rob

I believe you still have a problem with the program for the finished dimensions quoted, your workpiece will finish under the 15.80mm diameter, typo at p13 X needs changing, also you don't have any spindle start or stop commands in the program, do you start/stop manually ?

It may have been simpler to have gone ABS at p12 so p13 could be Z 1.00 and X 7.90,(finish diam).

Rgds, Emgee

[Lone_Ranger]

Hi Rob

I believe you still have a problem with the program for the finished dimensions quoted, your workpiece will finish under the 15.80mm diameter, typo at p13 X needs changing, also you don't have any spindle start or stop commands in the program, do you start/stop manually ?

It may have been simpler to have gone ABS at p12 so p13 could be Z 1.00 and X 7.90,(finish diam).

Rgds, Emgee

Nope, works fine, the old system is a bit odd compared with todays way of doing things

The Orac was always a manual spindle start, when started it is at a very low speed, motor is "cogging" really, a short press of the + key will speed it up and then when the program is started it then takes over the output of the 0~10V DC analog signal to the VFD spindle drive, very simple system.

The change at P12 is for a finish pass and has to be written outside the main program, that`s the way the manual has it shown to be done and it works OK for me , done loads of stuff on it, including threading which it does quite nicely indeed

Regards
Rob

[triac]

Hi Rob

The Orac I have does have programmable spindle start and stop functions (M03 & M05) and it's not even one of the latest variants, manual shows spindle commands for all Oracs listed.

Rgds, Emgee

[Lone_Ranger]

The plate on my Orac does not have the Bottom 3 lines on it, finishes at the G91 Incremental Format