CSS and feed settings for metric setup

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dmbgo
Posts: 547
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CSS and feed settings for metric setup

Post by dmbgo »

I have started to compile a document that I can refer to, in order to reference (and refresh my memory, (think "goldfish")) regarding the things that I am learning about the Acorn on my lathe. This is the section on CSS and feedrates, which I will use a lot when setting up a new job. I have started to answer some of my own questions, using the lathe manual and the internet, but there are some things of which I'm not all that sure.
Here is the Text that I have compiled so far, my machine is setup as Metric and I wonder if the assumptions I have made are correct? :?

Assumption 1:
Having setup my machine in mm, Intercon will always use mm as the default.
Assumption 2:
Feed per minute is in mm per minute
Assumption 3:
My surface speed, when I specify it in Intercon, will be in metres per minute.

Please correct me where I'm wrong here.

Centroid Acorn – Learning

1/ Q: I need understand what the metric measurements used by Acorn for CSS and F/R or F/M are.

1/Answer Feedrate:
Feed per revolution (F/R) can be toggled to Feed per minute (F/M) by pressing the F1 key whilst in the Intercon software.
In my case (because it is the Australian standard) I have chosen mm as the default unit of measure, so a value of 50.00, setup in F/R will travel 50mm in one revolution of the spindle, or 0.833mm per revolution. A machine’s feedrate can be set to Feed per revolution (F/R) (mm of travel of the tool per rev), or Feed per minute (F/M) (mm of travel of the tool per min). Feedrate is the feed of the tool, measured in the programmed or chosen units.
G98 - Feed per minute G98 sets the cutting feedrate mode in units/minute.
G99 - Feed per revolution G99 sets the cutting feedrate mode in units/rev.

Answer CSS:
CSS Stands for constant surface speed, this means that the spindle speed will increase, or decrease as changes are made to the radius, or diameter of the workpiece being machined, this will keep the amount of material being removed by the tool constant. G96 sets the mode for constant surface speed control in surface feet/min (sfm) or meters/min (This is probably determined by the units (mm or in) with which the machine is initially setup). S values are assumed as surface speed. When CSS is active, the spindle speed changes as the X position changes, to maintain a constant linear velocity at the tool tip. No matter how close X gets to X0, the spindle speed will not exceed the speed set with G50 or the machine’s maximum spindle speed, whichever is less. G97 cancels the constant surface speed control. Example: G96 S600 ; sets constant surface speed to 600 feet/min G01 X1 Z-3 F0.1 G97 S1200 ; cancels constant surface speed and sets spindle speed to 1200 rpm
dmbgo
Posts: 547
Joined: Sat Aug 15, 2020 9:21 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: 0035FF8A7F34-0730203594
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
Location: Bendigo Vic Australia
Contact:

Re: CSS and feed settings for metric setup

Post by dmbgo »

by dmbgo » Sat Feb 13, 2021 2:45 pm

I have started to compile a document that I can refer to, in order to reference (and refresh my memory, (think "goldfish")) regarding the things that I am learning about the Acorn on my lathe. This is the section on CSS and feedrates, which I will use a lot when setting up a new job. I have started to answer some of my own questions, using the lathe manual and the internet, but there are some things of which I'm not all that sure.
Here is the Text that I have compiled so far, my machine is setup as Metric and I wonder if the assumptions I have made are correct? :?

Assumption 1:
Having setup my machine in mm, Intercon will always use mm as the default.
Assumption 2:
Feed per minute is in mm per minute
Assumption 3:
My surface speed, when I specify it in Intercon, will be in metres per minute.

Please correct me where I'm wrong here.

Centroid Acorn – Learning

1/ Q: I need understand what the metric measurements used by Acorn for CSS and F/R or F/M are.

1/Answer Feedrate:
Feed per revolution (F/R) can be toggled to Feed per minute (F/M) by pressing the F1 key whilst in the Intercon software.
In my case (because it is the Australian standard) I have chosen mm as the default unit of measure, so a value of 50.00, setup in F/R will travel 50mm in one revolution of the spindle, or 0.833mm per revolution. A machine’s feedrate can be set to Feed per revolution (F/R) (mm of travel of the tool per rev), or Feed per minute (F/M) (mm of travel of the tool per min). Feedrate is the feed of the tool, measured in the programmed or chosen units.
G98 - Feed per minute G98 sets the cutting feedrate mode in units/minute.
G99 - Feed per revolution G99 sets the cutting feedrate mode in units/rev.

Answer CSS:
CSS Stands for constant surface speed, this means that the spindle speed will increase, or decrease as changes are made to the radius, or diameter of the workpiece being machined, this will keep the amount of material being removed by the tool constant. G96 sets the mode for constant surface speed control in surface feet/min (sfm) or meters/min (This is probably determined by the units (mm or in) with which the machine is initially setup). S values are assumed as surface speed. When CSS is active, the spindle speed changes as the X position changes, to maintain a constant linear velocity at the tool tip. No matter how close X gets to X0, the spindle speed will not exceed the speed set with G50 or the machine’s maximum spindle speed, whichever is less. G97 cancels the constant surface speed control. Example: G96 S600 ; sets constant surface speed to 600 feet/min G01 X1 Z-3 F0.1 G97 S1200 ; cancels constant surface speed and sets spindle speed to 1200 rpm
pep
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Re: CSS and feed settings for metric setup

Post by pep »

well, just the questions I have at the moment! Did you find out if your assumptions were right?

Assumption 1:
Having setup my machine in mm, Intercon will always use mm as the default.
Assumption 2:
Feed per minute is in mm per minute
Assumption 3:
My surface speed, when I specify it in Intercon, will be in metres per minute.
dmbgo
Posts: 547
Joined: Sat Aug 15, 2020 9:21 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: 0035FF8A7F34-0730203594
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
Location: Bendigo Vic Australia
Contact:

Re: CSS and feed settings for metric setup

Post by dmbgo »

Since the start of this year, I have seldom used the lathe, but I did today. However I'm pretty sure that assumption 1 is correct.
Assumption 2 is an unknown still, as I haven't really experimented to find out.
Assumption 3 is also a bit of an unknown. I am only guessing that it is right.
tblough
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Re: CSS and feed settings for metric setup

Post by tblough »

Units are controlled by F1 Setup/F3 Config/F1 Control. "DRO display units" and "Machine units" set what units are used in the DRO and in Intercon by default. You can always change program units by using G20/G21.

I recommend setting both DRO display units AND machine units to the same setting when switching between inch and metric. I have noticed some problems when both are not the same.

Feeds are units per minute. So if inch units are selected then feeds are inch/min. If metric is selected then feeds are mm/min.

Surface speeds are either feet/min or meters/min.
Cheers,

Tom
Confidence is the feeling you have before you fully understand the situation.
I have CDO. It's like OCD, but the letters are where they should be.
pep
Posts: 6
Joined: Mon Nov 15, 2021 9:04 am
Acorn CNC Controller: Yes
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Re: CSS and feed settings for metric setup

Post by pep »

Tnx!

That is a clear answer I can work with. Just gave the monitor a lesson in acrobatics but it failed to land safely. Shattered to bits...
As soon as the new monitor is delivered I will check it.
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