BOB CAD

[Dave_C]

And now a word from our sponsor!

I think I have BOB-Cad working in a reasonable manner. I made a small Chess Pawn this afternoon by drawing it, generating the code and posting it to Mach3.

I'm very pleased with the way it cut given that this is made from 1" rd 6061-T6 Aluminum rod. The little ball on top is .400" in diameter and it cut the tight corner transition very well.

The finish is smooth as glass. I still need to get the spindle cover constructed so I can run the coolant!

I was concerned with the individual moves verses canned cycles but the radius or smooth as glass. I'll stop worrying now and make some parts.

Dave C.

[Bill Shields]

why would you be concerned about individual moves vs a canned cycle?

do you want to see the math of what the canned cycle does....to create individual moves? (at least the FANUC math)?

in general, there is no absolute guarantee that the control is going to do exactly what you think it is with a complex contour and often it is easier to do it as individual moves so that you have absolute control over what / where the tool goes.

I have an entire set of chess pieces done over the years...some are more milling than turning.

[Dave_C]

Bill,

With Mach3 the only way I could make BOB-Cad code run properly was to use "individual Moves". Their canned codes cycles would run some arcs properly and then reverse others for no reason.

I don't plan on making a whole set of pieces, I just made this one to have something to play with. It is sort of a chess piece!

Dave C.

[DICKEYBIRD]

Looks great Dave; it's wonderful feeling when things work like they're supposed to.

Were you running CSS or constant spindle speed? Unfortunately Mach won't do CSS & feed per rev at the same time but I've been running CSS with the feed set to in per min and it's OK. Pretty cool watching the spindle speed going up & down as the dia decreases/increases. Not true CSS but close enough for my piddlin' around.

[Bill Shields]

as I mentioned, depending on how the control wants the tool path defined for the cycle, some arcs may come out wrong.

doesn't do CSS with feed/rev?

yech...

[Dave_C]

Milton,

Would you mind posting the G Code section that you use for feed per rev? I have not gotten that far yet but that is my next step to try.

It would help to see it coded correctly before I do it by hand. Bob Cad may have it correct but I'm not sure.

Here is what I get:

N01 G18 G20 G40 G80 G90 G98
( )
(Machine Setup - 1 Turn Rough )
(TOOL #1 )
N02 T0101 M06 (Tool #1 Call)
N03 G50 S1000 (Sets max speed)
N04 G97 S500 (Sets Min Speed)
Deleted middle lines for clarity
N07 G01 Z-2.732 F.0075 (Feed rate is in Inches)

Bob-Cad puts the feed on every line.

So does this look right or is it broke? Are the header calls right for Feed Per Rev?

Does Mach3 recognize G50 and G97? (Maybe those are for CSS)?


Dave C.

[Bill Shields]

I don't know about Mach 3, but G97 generally sets a FIXED RPM, not a minimum speed.

G96 S<SPEED-FPM> (SPEED - FEET / MINUTE or METERS / MINUTE) is the more conventional format for CONSTANT SURFACE SPEED (RPM changes with tool X value)

There are other sets of G-codes where G92 S<SPEED-MAX-RPM> and LIMS=(Siemens) are used to set maximum RPM, but G96 is pretty universally used.

Also G99 is typically used for FEED / REVOLUTION, with some machines using G95

[Dave_C]

Bill,

I'm finding that Mach 3 has its own way of doing things and CSS along with Feed Per Rev is not all that well documented in their manuals.

I get confused between the two myself when setting the header. If I recall correctly one should not call the CSS feature until the tool is at the proper diameter.

So far, every time I call the CSS feature, the spindle goes to the max RPM I set. No variable at all.

I'll try using some of your calls and see what happens.

Thanks,

Dave C.

[DICKEYBIRD]

Mornin’ Dave; Happy 4th to you & yours! Sorry about the slow response; it got party-ish around here last night.

Here’s what Dolphin spits out with CSS (G96) selected and feed per min (G94). Unfortunately there’s a bug in Mach that makes it do wacky things if you try to run G96 & G95 at the same time. G95’s fine as long as it’s not combined with G96. Supposedly fixed in Mach4. G48 sets max spindle speed.

;()
N20 G20 G18 G64 G80 G90 M49 G40 G49
; TOOL definition
N40 M09
N50 G00 X1.0 Z1.0 M05
N60 ( CCMT 21.50.5 RH Turning tool )
N70 M06 T0303
N80 M03 G94 F2.0
N90 G48 S1200
N100 G96 S150

[DICKEYBIRD]

...and Happy 4th to you too Bill. You must've posted while I was plodding through mine.

[Dave_C]

Milton,

Thanks for the post. I printed it out and will give it a try some time this week.

Happy 4th everyone!

Dave C.

[Bill Shields]

Generally, calling G96 is best reserved until you are close to diameter, and should be shut off before you retract / change tools....no matter what you spend on the control.

Some controls hammer the spindle motor / gears as they try to rapid long distances and adjust speed at the same time, others just alarm and stop.

Not being able to combine CSS and feed / rev is a pretty annoying bug...and a very basic function.

Heck even the old General Numeric FANUC 2000 (before it was GE), GE550 and Allen_Bradley controls did that 40+ years ago.

Granted, the older controls required you to STOP at a clearance diameter and set and <argument> value so that the control knew exactly where it was...but it still worked.

Bang Bang everyone.

Time to get out the cannon and keg of black powder.

Dave C:

If you are going to make an entire chess set, remember the need to make them 'playable'

If you make the pawn too tall, then the King / Queen etc: to be proportionally scaled, will be so tall as to be top-heavy unless you have a very large base on them (remember the size of a standard chess board).

You always want to be able to topple a pawn over on the board without causing a domino cascade of everything around it.

(been there - done that)....started over...