New CNC programmer here - many questions....

Art Miller · Apr 25, 2017

Hello Everyone,

So I'm working at a very small metal shop doing custom stair and modern railings. A lot of cable rail. Stainless. Gun blue. ---- Rows of holes (Think simple Drill Array)

And in the interest of saving time, the boss man bought a $20k Revolution CNC with M400 intercon. It's big and Blue.........

I figured out how to set up a drill array and put our 9 or 10 holes right down the middle of a 1.5" sq. tube. Good Times.

I wanna do more fun stuff with it. Mill some intricate designs. A little bit of hobby stuff on the side.

I gotta figure out my Feeds and Speeds, I know.

Well, I love metal art. I'm down with grinding some cool shapes out of AL to start. I know I have to get down to production eventually, but right now, it's practice time.

Art Miller · Apr 25, 2017

ok here's a question.
I am going to mill into a 2" sq block of AL.
Cut a 1 3/4' hole in all 6 sides leaving a 1/2" island in the middle of every 1.75" hole.

How to best program (with a .375" end mill) the 1.75" hole with .5" island?

1. A circular frame just inside the 1.75" hole. THEN a circle frame outside of the .5" round island in the middle?

2. A circle pocket with cleanout and an .5" center island specified.

The circle it cuts is going to be 5/8" wide. (1.75 hole with .5 center island) I want it to cut out the 5/8" ring [Repeat to Depth]. I'd like to do it in about 5 lines of code, right? The depth should be about .75"

(The end result is a 2" cube with a 1/2" 6-prong-jack in the middle)

Oldwrench · Apr 25, 2017

Not familiar with your machine but first you should read its operator's manual to see if it takes G code. If so, draw the part and locate the points. Buy a textbook (the Mike Lynch one used in most first-semester courses is a good one). Oh, and don't forget to tighten the vise.

Hazzert · Apr 25, 2017

I'd set my home as the center of the cube and use a helical interpolation like
G21 G40 G90 G80
T1M6 (3/8 2fl endmill)
S7500M3
G00 X0. Y0.
G43 H1 Z4.
G01 Z0.1 M08 F80.
Y.3125
Z0. F15.
G03 R.3125 Y-.3125 Z-.125
G03 R.3125 Y.3125 Z.-.250 (repeat as needed and adjust depth of cut to suit)
G03 R.3125 Y-.3125 (to close the loop and take taper out of floor)
Z0.1
G00 Z4.0
Z12.0
M30

Something like that anyways but it's been a while since I hand wrote code.

If you wanted to get complicated you could use a sub call up and incremental mode to cut the feature but I'd stick with the long hand for a little while until you find your footing.

Art Miller · Apr 25, 2017

Thanks Oldwrench.... my machine has 'Intercon' conversational programming that converts to G code.

I'm just working out some basics for tool path here for a 5/8" wide ring. I want a 1.75 o.d. and .5" round island diameter. I could program two circles. The 3/8" mill bit would overlap ok. But I would want to go back and forth >> Outside circle > Inside circle. I can't go 3/4" deep with one diameter wide.

So...
> Do the 2 circles
> drop a tenth and do 2 more circles.....

I can do this in 20 lines of code. Still doesn't have any finishing pass though.

Art Miller · Apr 25, 2017

Thanks Hazzert, I'm super noob here but,
I actually can follow most of that. Even though my machine has the form-fill software so I don't even have to know g-codes quite yet.

S7500M3. I checked my spindle speed today > it maxed out at 3500. I think that will be my cutting speed

tay2daizzo8 · Apr 25, 2017

Hazzert said:
I'd set my home as the center of the cube and use a helical interpolation like
G21 G40 G90 G80
T1M6 (3/8 2fl endmill)
S7500M3
G00 X0. Y0.
G43 H1 Z4.
G01 Z0.1 M08 F80.
Y.3125
Z0. F15.
G03 R.3125 Y-.3125 Z-.125
G03 R.3125 Y.3125 Z.-.250 (repeat as needed and adjust depth of cut to suit)
G03 R.3125 Y-.3125 (to close the loop and take taper out of floor)
Z0.1
G00 Z4.0
Z12.0
M30

Something like that anyways but it's been a while since I hand wrote code.

If you wanted to get complicated you could use a sub call up and incremental mode to cut the feature but I'd stick with the long hand for a little while until you find your footing.

at the end before z.01 you should move x away from outside wall before going up

plastikdreams · Apr 25, 2017

Art Miller said:
Thanks Oldwrench.... my machine has 'Intercon' conversational programming that converts to G code.

I'm just working out some basics for tool path here for a 5/8" wide ring. I want a 1.75 o.d. and .5" round island diameter. I could program two circles. The 3/8" mill bit would overlap ok. But I would want to go back and forth >> Outside circle > Inside circle. I can't go 3/4" deep with one diameter wide.

So...
> Do the 2 circles
> drop a tenth and do 2 more circles.....

I can do this in 20 lines of code. Still doesn't have any finishing pass though.

Drop a tenth and you might as well cut air...lol

Hazzert · Apr 25, 2017

tay2daizzo8 said:
at the end before z.01 you should move x away from outside wall before going up

With the way that's programmed, if you move away from the wall you gouge the center island...

Art Miller · Apr 25, 2017

plastikdreams said:
Drop a tenth and you might as well cut air...lol

ok yeah I broke a couple bits. That was yesterday. Now I'm actually thinking about Feed Speed and Tool Path

But cutting air is no solution. A properly structured line of code is.

Art Miller · Apr 25, 2017

Hey guys I appreciate all of your replies.

This is my Manual. Chapter 10 has the cycles I want to use such as circle pocket, with cleanout, and with an island.

Or I could simply mill a 1.75 OD circle and the a 0.50 ID circle and let the 3/8" end mill bit overlap.

But really.... I don't want to program 2 circles, it should be one wide circle. (The 5/8" wide circle path)

http://www.centroidcnc.com/downloads/centroid_v3.16_mill_operator_manual.pdf

Hazzert · Apr 25, 2017

Hazzert said:
I'd set my home as the center of the cube and use a helical interpolation like

G21 G40 G90 G80 G54 safety line: inch mode, cancels cutter comp, absolute mode, cancels canned cycles, calls work coordinate system 1

T1M6 (3/8 2fl endmill) calls tool 1 and does a tool change

S7500M3 spindle speed 7500rpm clockwise

G00 X0. Y0. Rapid to home location, center of block in this case

G43 H1 Z4. Tool height offset calling tool 1 offset and moving to 4.0 above part

G01 Z0.1 M08 F80. Feed moves to .1 at 80 ipm above top of part, turns on coolant

Y.3125 Y feed move at 80 ipm (from last line) cutters at 12 O'clock

Z0. F15. Feeds at 15 ipm to Z0 top of block

G03 R.3125 Y-.3125 Z-.125 CCW arc move radius of .3125 to 6 O'clock and .125 deep

G03 R.3125 Y.3125 Z.-.250 continue the arc to 12 again and move another .125 deep to .250

G03 R.3125 Y-.3125 one more arc move to 6 with no Z move to clean up the floor and give a flat bottom

Z0.1 feeds at 15 ipm to .1 above part

G00 Z4.0 Rapids to 4.0 above

Z12.0 Rapids to 12.0 above

M30 program reset to top

Apologies for repeating myself but hopefully the annotations help.

plastikdreams · Apr 25, 2017

Art Miller said:
ok yeah I broke a couple bits. That was yesterday. Now I'm actually thinking about Feed Speed and Tool Path

But cutting air is no solution. A properly structured line of code is.

You do realize that a tenth is equal to .0001" correct? What is a bit?

3500 rpm isn't very much, you can still go fairly hard with a 2 flute endmill...I'd say 50 or so ipm roughing and 20 for a nice finish.

Art Miller · Apr 25, 2017

Hazzert said:
Apologies for repeating myself but hopefully the annotations help, can't figure out how to add colour.

Wow thanks. That is awesome. I'm going to go through all of that and have a go at it in the morning.

Art Miller · Apr 25, 2017

plastikdreams said:
You do realize that a tenth is equal to .0001" correct? What is a bit?

3500 rpm isn't very much, you can still go fairly hard with a 2 flute endmill...I'd say 50 or so ipm roughing and 20 for a nice finish.

Ok when I dropped it a tenth.... I put the 1 just after the decimal. ( 0.1 ) During the day I still measure metal in fractions.

I did some speed calculations and I thought that 6000 RPM sounded right, but if I'm limited to 3500 and my horsepower is plenty strong... then I just need to balance my Tool, Feed, and Speed.

*But this thread was mostly about programming my circle.

plastikdreams · Apr 25, 2017

So you want each side of the square to have a 1.75 id bore with a .50 "island" in each correct? This would leave a .625 gap all around. Are we on the same page?

Art Miller · Apr 25, 2017

plastikdreams said:
So you want each side of the square to have a 1.75 id bore with a .50 "island" in each correct? This would leave a .625 gap all around. Are we on the same page?

Yup. And the depth of cut is .625 so it should leave a .50 cube in the middle with a .50 round "island" sticking out all six sides.

And yes, I am definitely going to have to clamp it real good on the last cut out.

plastikdreams · Apr 25, 2017

Art Miller said:
Yup. And the depth of cut is .625 so it should leave a .50 cube in the middle with a .50 round "island" sticking out all six sides.

And yes, I am definitely going to have to clamp it real good on the last cut out.

Where is the cube coming from?

Hazzert · Apr 26, 2017

It sounds like he wants to make something like a turner's (miller's?) cube.

plastikdreams · Apr 26, 2017

Hazzert said:
It sounds like he wants to make something like a turner's (miller's?) cube.

That's what I'm thinking but the dimensions vs the explanation don't add up in my walnut sized brain

New CNC programmer here - many questions....

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