Web Goblin cnc has begun

[Web Goblin]

Jonathan,
I did take it very easy with that cut. Depth of cut was only 0.5mm, step over was 20% which would be just under 1mm and feed speed was 10mm/sec for that cutter was 10mm/sec. The only cutter I was was not new so I did go slowly with it. The alu also has some hard sections in it so that was why the cutting fluid was generously applied. The starting point was a mistake, I for got to set my dxf to 0,0 in cad and I think cut2d picked that up.
I have had a look at the program file and cant see any G64 codes in it. Youll need to excuse my ignorance in G codes at the moment, I havent got round to learning them yet!!
Some photos are attched of the cut edge. Quality looks good for an old cutter.

[JAZZCNC]

Some photos are attched of the cut edge. Quality looks good for an old cutter.

Hi Ian,

Congrats on your first Hot Chip's. . . . . . . (Now the BUT.:lol:)
I think your single spindle mount is causing chatter/resonance looking at the edges I can see chatter lines.!
I know you say the cutter was old but that does look more like flex chatter..? Also when cutting it sounded ringy more like a resonate ring not a blunt cutter.

Too little DOC, too slow spend n feed or more importantly wrong chip load can be just as bad for cutter than too much, esp in sticky Ali. Don't be shy give the cutter some work to do as your going far too conservative. . . .Heat is the enemy so send it away with the chip.!!

[Jonathan]

I think your single spindle mount is causing chatter/resonance looking at the edges I can see chatter lines.!

Just what I was thinking - the vertical lines are a bit of a give-away.

Definately too low feed and stepover - with only 20% stepover you need to feed much faster to attain the same chipload, look up chip thinning. This explains some of it, though it is aimed at making you buy the program...

http://www.cnccookbook.com/GWCalcFeedsSpeeds.htm

The alu also has some hard sections in it so that was why the cutting fluid was generously applied.

I was joking when I said that was generous!

I have had a look at the program file and cant see any G64 codes in it.

Mach3 may have defaulted to it anyway, it depends.
G64 puts mach3 in constant velocity mode, so that within reason the feedrate remains constant. This means that external corners will become slightly rounded - more if the acceleration is very low.
G61 puts mach3 in exact stop mode, so it stops once it has got to the point specified by each line of code, then continues. This makes the motion very 'jerky', though depending on the situation it will make the final part more accurate.

Using constant velocity makes the motion a lot smoother, and a constant feedrate is clearly faster overall and kinder on the cutter. To try it just type G64 at the begining of the program. You'll notice the most difference when a program uses lots of small lines to approximate a curve.

[JAZZCNC]

G61 puts mach3 in exact stop mode, so it stops once it has got to the point specified by each line of code, then continues. This makes the motion very 'jerky', though depending on the situation it will make the final part more accurate.

Ye Try G61 with an high feed rate/accelleration and watch it turn into a "Darlick on Whiz" as it try's to break dance thru the workshop wall after it's destroyed all in it's path. . .:rofl: