Messages

5591

Mach4 General Discussion / Re: Cannot use G53 incremental

« on: January 01, 2018, 08:07:57 PM »

Hi,
I found this on page 385 of Peter Smids book 'CNC Programming Hanbook' 2nd ed. related to the use of the G53 command.

The upshot is that G53 is ALWAYS an absolute command.

Craig

5592

General Mach Discussion / Re: First Run on CNC machine

« on: January 01, 2018, 07:43:37 PM »

Hi,
well reasoned and I stand corrected it doesn't change the fact that OP is trying to spin a 6mm tool with a cut depth of 6mm and a feedrate of 1200mm/min
with a 100W spindle, thats la-la-land stuff.

Even the much slower rate that he actually achieved 1mm depth at 150mm/min occasioned excess vibration which is not to be wondered at at 2700rpm.
I would be aiming for a surface speed of 500m/min in MDF, with a 6mm tool thatworks out to 26500 rpm. I would allow a 1-2% of diameter per tooth per rev
as a feedrate, with a two flute tool that is 3-6m/min. I could well imagine that a several kW spindle would be required to do it which then begs the question
whether the machine could contain the cutting forces generated, as a previous poster commented it seem unlikely if the machine is equipped with a 400W
spindle from new.

If you wish to cut any material at high speed and reasonable cut depths a powerful spindle is mandatory which in turn demands a rigid machine. Thats plain
physics.

Craig

5593

General Mach Discussion / Re: First Run on CNC machine

« on: January 01, 2018, 03:59:59 PM »

Hi,
power is proportional to the square of the voltage, if you are running your spindle at 1/4 rated voltage expect 1/16 rated power, 25W.


Craig

5594

Mach4 General Discussion / Re: Darwin Buffer Error - Motion out of bounds

« on: December 31, 2017, 11:46:23 PM »

Hi,
no I don't think so. Mach will run for 5-6 minutes before it needs to be reset if it is in Demo mode. If the Sim(ulator) plugin is the active motion controller
then Mach runs without limit, of course you can't control an actual machine with the Sim plugin.

Craig

5595

General Mach Discussion / Re: First Run on CNC machine

« on: December 31, 2017, 03:08:47 PM »

Hi,
if you wish to cut metals, steels in particular you'll need a spindle which spins fairly slow but with a great deal of torque.

A good surface speed for mild steel is about 150m/min. With a 13mm tool that means an rpm of 3670 rpm. The same tool in aluminium you could spin
at three times that, say 10000 rpm.

High speed spindles are generally poor at low speeds and have low torque. They're great for engraving, cutting wood and do pretty well in aluminium but
they don't do so well in steel and even worse in stainlees steel.

I have a 750W 24000 rpm spindle and its great for a lot of things but hopeless in steel. I have cut steel with it, a 3mm tool spinning at 9000 rpm, the lowest
effective speed without overheating, but the cut depth and feed rate had to be so slow because the spindle is so inclined to stall given its low torque.
I have since made a spindle with a 1.8kW servo and drive and its max is only 3500 rpm but it has a continuos rated torque of 6Nm, it makes mincemeat of steel!

Download HSMAdvisor for a free trial and look at the recommended speeds and feeds for different materials and then look to the required spindle power
and torque. Very useful software tool, so much so I bought it.

Craig

5596

Mach4 General Discussion / Re: Darwin Buffer Error - Motion out of bounds

« on: December 30, 2017, 06:41:42 PM »

Hi,
I was unaware that you could load or run Darwin without a licence.

I was likewise unaware that you could load and have active any motion control plugin without Mach4 being run time limited because it is unlicenced.

Craig

5597

General Mach Discussion / Re: Flat bottom Hole

« on: December 29, 2017, 07:13:44 PM »

Hi,
bugger, sorry about that. How about grinding spare drill with a flat instead of a point. I have done it before, it squares the outer diameter of the hole quite well
but I've never achieved a center cutting grind.

The most recent application was to square the bottom of a hole to accommodate the head of a capscrew with a smaller diameter through hole for the screw, ie
I didn't need center cutting.

Craig

5598

General Mach Discussion / Re: Flat bottom Hole

« on: December 29, 2017, 03:55:53 PM »

Hi RT,
I have used with my high speed spindle which is way too fast and not enuf torque for a drill so used a smallish diameter endmill with circular interpolation.

The hole you are drilling is quite deep so the biggest diameter endmill you can use is going to be required otherwise it will flex to hell. A long 1/4" endmill
might do the trick.

Craig

5599

General Mach Discussion / Re: mach3

« on: December 29, 2017, 03:49:18 PM »

Hi,
that OP is removing Mach3 from his computer suggest to me that he hadn't got around to buying a licence anyway.

Notwithstanding the learning curve of LinuxCNC it is within OPs budget, free.

Craig

5600

General Mach Discussion / Re: mach3

« on: December 29, 2017, 04:10:32 AM »

Hi,
I just put that in to highlight the point that even the more expensive Mach controllers are chicken feed compared to the admittedly high spec Fanuc and Siemens
controllers. In fact Siemens annual software licence fees are rather more than a Mach controller, even an expensive one.

With Mach3 at $175 and Mach4 (Hobby) at $200 with a perpetual licence makes a very capable CNC solution available very cheaply. Anyone who whinges about a few dollars
here or a few dollars there should either wake up to what OEMs pay for CNC solutions or be directed to go the free way with LinuxCNC, very politely of course.

Craig