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Hi from Perth Australia
PekkaNF:
--- Quote from: PK on July 08, 2015, 12:30:39 AM ---Seriously, go with plain shank toolholders. Maybe take a look at how Tormach do theirs.
--- End quote ---
Yea but, no but. I like taper, dogs are optional. Your preference is high speed, my mills are more often 20-50 mm dia than under. Now I have MT3 tooling, but next one should be ISO30 or 40 - manual mill, but let's see. I really could get away with ISO20 if I would have completely different mill, but that tooling is not for hobby price range.
--- Quote from: PK on July 08, 2015, 12:30:39 AM ---'Brushed DC is really the best power density per buck at low RPM's maybe add an encoder and run it from a Gecko DC servo drive.
As you've figured out, adding an encoder gets you a brushless servo which can deliver high torques at low RPM's for medium bucks. IIRC I bought a 600w Servo for about AU$650 landed a year or so back.
--- End quote ---
If I were into brushed integrated spindle my firs choice would be kress
http://cnc-plus.de/en/Spindle-Motors---Spare-Parts/Milling-Spindle-Motors/Kress-1050-FME-1-Milling-Spindle-Motor-with-1050W.html
Really no point of putting dremel/router or such when you can have this. This has limited life ofcourse and I have heard people using them on cnc routters pretty good time.
I'm seriously pondering between AC/BLD spindle motor, but it should have relatively low rpm (4000-6000 rpm ideal) and pretty close to 200w of power for a 1/2 minutes or so. Normal AC good insulation class AC motors you can run that hot, you don't want to touch them. There is latitude on duty cycle, specially if you have external fan.
Normal 0,25KW/3000 B14 frame SKg 63-2B 3-phace motor works out 3310 rpm on 60 Hz 0,30Kw and 68% efficiency. 4,2 kg, diameter 126 mm and total lenght 214 mm, body length 191 mm. It's not too heavy, but it is a bit big for QCTH.
Pretty much it all comes down to how low price and speck I can afford to go. Obiviously I don't want to get too cheap here but I can't bring myself to pay over 200 USD/EUR on chinese 200w spindle motor.
--- Quote from: PK on July 08, 2015, 12:30:39 AM ---Have you considered a little high speed spindle? I just bought a 60KRPM 350W job. Its about 48mm diameter... If you go to 80mm you can get 1Hp at 24KRPM. Simple, but limited to small cutters... PK
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I have considered, that would be "the other" spidle. Care to tell which motor/drive you got? There seems to be a lot of nearly/seemingly identical ones on ebay.
Thank you very much.
Pekka
Meldonmech:
Hi Paul
Welcome to the forum, your Rockets look very interesting, can't wait to see more posts.
Cheers David
PK:
--- Quote from: PekkaNF on July 08, 2015, 03:26:13 AM ---Yea but, no but. I like taper, dogs are optional. Your preference is high speed, my mills are more often 20-50 mm dia than under. Now I have MT3 tooling, but next one should be ISO30 or 40 - manual mill, but let's see. I really could get away with ISO20 if I would have completely different mill, but that tooling is not for hobby price range.
--- End quote ---
You are right, I missed the bit where you said you want to run big tools. There's a reason all big machines use tapered spindles and draw bars under stupendous tension!
--- Quote ---If I were into brushed integrated spindle my firs choice would be kress
http://cnc-plus.de/en/Spindle-Motors---Spare-Parts/Milling-Spindle-Motors/Kress-1050-FME-1-Milling-Spindle-Motor-with-1050W.html
Really no point of putting dremel/router or such when you can have this. This has limited life ofcourse and I have heard people using them on cnc routters pretty good time.
I'm seriously pondering between AC/BLD spindle motor, but it should have relatively low rpm (4000-6000 rpm ideal) and pretty close to 200w of power for a 1/2 minutes or so. Normal AC good insulation class AC motors you can run that hot, you don't want to touch them. There is latitude on duty cycle, specially if you have external fan.
--- End quote ---
There are a lot of mods for BLDC motor controllers that involve adding hall sensors to brushless motors. The RC stuff is junk (as I guess you know), shafts and bearings just aren't up to the job, check out endless sphere for some guys doing really intetresting and open source stuff with controllers and motors for EV use...
--- Quote ---Normal 0,25KW/3000 B14 frame SKg 63-2B 3-phace motor works out 3310 rpm on 60 Hz 0,30Kw and 68% efficiency. 4,2 kg, diameter 126 mm and total lenght 214 mm, body length 191 mm. It's not too heavy, but it is a bit big for QCTH.
--- End quote ---
yeah, thats about the size of a mini mill head.. Which is too big for a QCTH......
--- Quote ---Pretty much it all comes down to how low price and speck I can afford to go. Obiviously I don't want to get too cheap here but I can't bring myself to pay over 200 USD/EUR on chinese 200w spindle motor.
--- End quote ---
I reckon it all comes down to whether you want to abandon the idea of getting this thing in a tool holder. If we look at, even small, commercial horizontal turning centers that have live tooling, then we see that that tooling is mounted in a turret that weighs a hundred Kg. Which brings up the other point: Even if you come up with a 1KW , 50mm diameter, 500rpm motor that weighs 5 Kg and mounts in your toolpost. You don't have any thing like enough mass around the thing to run those RPM's, it'll vibrate like a b*#ch..
--- Quote ---I have considered, that would be "the other" spidle. Care to tell which motor/drive you got? There seems to be a lot of nearly/seemingly identical ones on ebay.
--- End quote ---
So I've got/had three of them. My first was a water cooled 800W 80mm motor. You can get air cooled motors, which would be more useful in your application. It had an ER11 collet.
My next was a 1.5KW water cooled motor on our full sheet router. The most recent is the little 60KRPM model shown here: http://www.westcoastmakers.com/threads/going-fast.1291/
I really don't think it matters what drive you get. You are running these things at 400-1000Hz so flux vector is useless.
Its hard to describe how good these spindles are on small machines.
On my little router, metal removal rates went up by a factor of 10 when I replaced the 7500 rm spindle with the 800W 24Krpm jobbie. This is entirely because a cutter at 24KRPM (even a single flute) can only excite the machines structure at 400Hz. The resonant frequency of my router was around 300Hz so it just stopped ringing. This translated to massive reductions in cutter deflection, less broken tools, higher chiploads, it made me taller and more attractive to women.... Now if your machine weighs a ton then you won't see this improvement, but if you're putting the spindle in QCTP then you definitely will..
PK
PekkaNF:
I hear what you are saying. It is all about getting the tool that will 80% job really well and rest of it I can make do.
I have one mill, it weight about 1500 kg or bit more, but it has no drilling spindle, and top speed is in order of 700 or 900 rpm. It has maybe 3 or 5 kW motor and seven speed box. Haven't stalled it yet. Not even with 25 mm drill. Although cranking knee up and down is excercise.
But I need something lighter, like bridgeport or RF45 size for drilling mainly.
And then I need something even smaller to slip into lathe and make 2-6 mm short holes (often smaller) and "spotting". This is work under progress (and sometimes impasse with myself, gobble something together and figure that it almost works, but nothing to get excited about). Experiments show that I "just" get away with 200w when holes are about 5-6 mm and 3 mm holes probably need 100W max, so there is room for optimisation and no reason to go overkill here.
I'm purely hobby person in home machine shop. I'm trying very hard not to take a step in the dark side (NC).
Pekka
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