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Just supposing it were possible ;)
If I wanted to fit an auto-tool-changer to my mini mill, what would be used for the spindle?
That seems to be the only stumbling block really, the rest is just building and macro stuff. There seem to be a few variations - carousel, straight bank etc but all need a spindle that can be released automatically.
Are ATC's for the rich boys only??
OR for those that can justify £1500 for automation because it will pay for itself! Few on Aliexpress starting around $2000
Bum, would have gone £5-600 just for the luxury but that's just too much ;)
Haven't seen any cheap DIY worth looking into I think this is about closest but not for me.
https://www.youtube.com/watch?v=jHofj3efzfo
The spindle is the hard part.
Quite a few people use the Tormach system (TTS), which I think is essentially a modified R8 spindle/collet setup.
You could go for a conventional ISO/BT spindle with a drawbar, and attach an airgun for loosening/tightening the drawbar.
Best option is some form of ISO/BT gripper spindle, but they are expensive. I'm sure I've seen ISO30 ATC spindles for around £800, however you need to add a motor to that.
I still have a DaleCNC ISO15 spindle cartridge sat in the workshop doing nothing if you're interested. It cost me about $1200, but I'm open to sensible offers as I've currently got no plans to use it on anything.
its not too bad at the low speed end but my spindle is a 24,000rpm water cooled job, my machine was built for aluminium really so it needs the speed. Looking at £1600-£2300 on Aliexpress :(
I saw this skyfire cnc cartridge a while back. I don't know if it was ever launched - there was quite a thread on cnczone but it wasn't clear if they ever shipped anything. Pretty cheap, although needs a motor and an air cylinder on the drawbar, and is 6000rpm max.
http://www.skyfirecnc.com/picshow.asp?id=24
Yep, plenty similar on Aliexpress, BT30, ISO25 sockets but all are low rpm so not really what i was after :)
There is a German company that does them for Kress and watercooled spindles http://www.sorotec.de/shop/Spindles/...ME-800-V2.html
Then you are going to struggle as once you go bigger on diameter to take a QC taper the bearings needed won't hold up to 24KQuote:
Originally Posted by Davek0974
If you can get away with just two tools, roughing and finishing then think about another 24K spindle mounted on another set of rails on the Z axis that can pneumatically push the second cutter down lower than the roughing cutter. Software then calls up the respective offsets and runs the second spindle.
You can get a completer second spindle and inverter for as low at £175 on Ebay.
Thanks John, thats a neat idea but my mill is very compact and not really enough space to mount two spindles.
I will consign the ATC idea to the bin - it was just a luxury really, very impressive but a luxury still, oh well...
Thanks for the link, interesting kit but I need the spindle as well, it seems easy in the 0 to 6000 rpm range but i'm in the 6000-24000 rpm range and then things get ££££ really quickly.
but that's the point of that powered draw bar, fit whatever spindle motor you want. providing the actual spindle it belt drive that powered draw bar will workQuote:
Originally Posted by Davek0974
Issues i see there...
Not sure a belt will work at 24,000rpm,
The spindles suitable for ATC use are all rated to 6000rpm only it seems, that means special bearings and balancing would be needed for that sort of speed.
Andy, That PDB has an impact wrench and a pneumatic actuator inside so is only suitable for screw in drawbars. For ATC at 24000, you need a totally different direct drive spindle such as those seen on Alibaba.
They should be balanced but I dare say that the tooling you get will not be.
im well aware how that drawbar I posted operates, the original post said cheap so I was just posting a cheap option.
No worries here ;) thanks for the thought.
It does seem that it's a non-starter at present due to the spindle speed I have.
I am now looking towards a bigger machine, maybe converting my Bridgeport or finding a donor with duff electrics that was built for CNC.
do you need such a high spindle speed?just think a large machine like a haas has an 8-10k spindle speed with bucket loads of torque and that can cut fast and deep. its not all about spindle speed but machine strength and torque. so could you get away with a slower but more powerful spindle?
Possibly, but this was built for small cutters in aluminium, small cutters are best in carbide, carbide likes high speeds, sort of horses-for-courses really.
I am sure my stuff can be done in HSS but not calculated the feeds, I will have a look.
Engraving really does need speed I think though??
Unless your using small tools then speed is required.!! . . . This is small light duty machine who's main operation will be with small tooling requiring high speeds 10K minimum.Quote:
Originally Posted by andy_con
Interesting,
Just calculated the speeds for a 2mm cutter in 6061T6 and it seems I am seriously under-using carbide anyway.
In Carbide, at full speed it needs 82,000rpm, HSS wants 23,000rpm
The reason I had not seen the high speed before was because I limited HSMAdvisor to calculate feeds based on my limit of 24,000rpm, removing this limit shows the full feed & speeds.
Anyone got an 82,000rpm spindle? :)
Anyway, HSS will do the job at say 6000rpm but it will be much slower.
Should that be "Unless your'e using large tools" there Jazz?? :)
My denford triac has a 4k spindle and I don't have any problems.
I do 2mm deep cuts using an 8mm cutter at f250
Nope said correctly Andy said Speed wasn't required. I Said "Unless using small tools" Then speed is required.Quote:
Originally Posted by Davek0974
Compared to me doing 4mm Doc at F900. 11000rpm!! . . . . BIG DIFFERENCE. . . Oh and that's on Router not a Mill.!Quote:
Originally Posted by andy_con
I stand corrected ;)
Yes, speed is needed, it can be done on a slow machine - i've used 1/16" on the old bridgeport before but the feed rate is microscopic!
The high speed spindle is very useful.