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CNC Crash Compilation
Meldonmech:
Hi Guys,
I have been thinking of buying a cnc mill/ router, but looking at these disasters, which appear to happen faster than the operators reactions, has put me right off. It seems to be quite a common occurrence, is this normally caused by a faulty program?
Cheers David
philf:
--- Quote from: Meldonmech on March 18, 2013, 03:12:52 AM ---Hi Guys,
I have been thinking of buying a cnc mill/ router, but looking at these disasters, which appear to happen faster than the operators reactions, has put me right off. It seems to be quite a common occurrence, is this normally caused by a faulty program?
Cheers David
--- End quote ---
Hi David,
Most, if not all, of my tool breakages have been down to carelessness on my part.
Not noticing feed speeds are in mm/sec rather than mm/min; setting the safe Z height too low so that it makes a fast move straight through my clamping fixture are the two that I had most problems with.
When I first set my machine up I set the Z home position so that the table moved towards the cutter. Most of the parts I was making were out of sheet and I was clamping the material to a piece of 18mm MDF which was fastened to the mill table. When I did a RefAllHome (which sets the axes to their home positions and is the first hing I do when I switch on) it would first drive the table up (so that the tool embedded itself in the MDF) before the table moved rapidly in the Y direction taking the end of the tool with it. :doh:
After about 4 broken carbide cutters I added an intermediate Z axis (hall effect) switch so now the table drives down away from the cutter before X & Y are set. :D
Commercial CNCs are often capable of unbelievable feed speeds and I guess no-one has reactions quick ehough to hit the E stop button.
Fingers crossed, I haven't broken a tool for quite a while!
CNC is fun - go for it!
:beer:
Phil.
sparky961:
--- Quote from: Meldonmech on March 18, 2013, 03:12:52 AM ---Hi Guys,
I have been thinking of buying a cnc mill/ router, but looking at these disasters, which appear to happen faster than the operators reactions, has put me right off. It seems to be quite a common occurrence, is this normally caused by a faulty program?
Cheers David
--- End quote ---
Being fairly new to running an industrial CNC VMC (vertical machining centre), I can attest to the fact that when you first start you will break things. I have run hobby CNC stuff for years now, but the commercial ones are a bit MUCH less forgiving.
ALWAYS assume that when powered the machine can move anywhere at any time and at any speed, as far as your body parts are concerned.
In my experience with smaller machines, you will more likely scrap the part not the cutter if it's big enough to handle the force, rather than always breaking the tool. Axes will often stall before too much damage is done. Smaller tools, well they just snap off and the CNC continues on it's merry way. :)
I wouldn't be put off by any of this. Some of the stuff you see in the video is due to very poor setup, others look like the program wasn't proven (run slowly without a part) before they hit start. Most of it can be prevented by a careful operator, which as a hobbyist who doesn't have a boss saying "FASTER, FASTER" you shouldn't have a problem with.
I don't remember where I saw the quote, but my own slightly modified version has become something of a mantra...
"First you get good, then you get fast" .... and my own addition ... ", then you really mess up and are very humbled by the experience, only to start the cycle all over again"
Stilldrillin:
During my 20yrs, as programmer/ operator of a Takisawa machining center. No programme was ever trusted, until I had single blocked all the way through.
This included the progs, I had used many times previously.......
Probably had 8 or 10 of such mishaps, over the years. I can still remember them, in fine detail. :palm:
David D
philf:
--- Quote from: Stilldrillin on March 18, 2013, 02:14:25 PM ---
Probably had 8 or 10 of such mishaps, over the years. I can still remember them, in fine detail. :palm:
--- End quote ---
David,
Didn't you think to video any of them for us?
Phil.
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