[bd007]

I'm confused on a 3kw spindle on ebay.
NEW 3KW AIR-COOLED SPINDLE MOTOR ENGRAVING MILL GRIND p | eBay

Its listed as 3kw but only 10amps. Isn't that closer to 2.2kw?
Isn't it 3000watt/220volt=13.6 amps?

Thanks

[keebler303]

Is the 6HP motor in your shop vac that is the size of a blender really putting out 6HP? Maybe for a couple seconds when you turn it on?

It's all marketing, based on peak values that cannot be achieved in continuous operation.

Matt

[Al_The_Man]

But..In a motor, one function of HP is RPM, the shop vac runs up to 25,000+ rpm.
0 rpm = max torque - zero HP.
Al.

[keebler303]

Al

You are correct. I would assume the power consumption would be highest while it is spinning up so peak horsepower might be at 24,999 RPM just before it reaches steady speed. Maybe I will have to install a current shunt and tachometer on my shop vac to investigate.

In any case, you cannot expect to get 6 HP of sustained mechanical work from a vacuum cleaner motor nor should you expect to get 3kW from a $400 chinese spindle.

My $0.02
Matt

[rowbare]

I'm confused on a 3kw spindle on ebay.
NEW 3KW AIR-COOLED SPINDLE MOTOR ENGRAVING MILL GRIND p | eBay

Its listed as 3kw but only 10amps. Isn't that closer to 2.2kw?
Isn't it 3000watt/220volt=13.6 amps?

Thanks

It is a 3 phase motor, calculations are a bit different and you have to multiply by sqrt(3)

Thus you get 220 * 10 * 1.732 ~= 3800 w

Once you multiply that by the power factor of the motor, you are probably close to 3KW

bob

[kevincnc]

I looked at lot of Chinese spindles before buying mine. Most of the 2.2kW on ebay claim 10 amps at 220V. According to their website, Ugra's 2.2 is rated 8A, and their 3.0kW is rated 14A, and weighs 25lb. The one I bought is rated 3.0kW 12A and I just weighed it at 19lb although the ones that look identical on ebay (big green power connector) claim 9-11kg- see this thread for a picture of the spindle nameplate (engraving).
http://www.cnczone.com/forums/diy-cn...ese_3_0kw.html
Moral of the story is that anyone can claim whatever they want, especially if it's from China, and without a Dyno there is no way to prove/disprove the clamis other than for weight.

[louieatienza]

Bob beat me to the punch... Though it reminds me of all the Craftsman stationary tools I have.... develops 5HP....

[bd007]

Thanks for the replies. I think I'm going to go ahead and make an offer on it. Even if its not a true 3kw spindle I'm sure it will be better than the Craftsman 2hp router I'm currently using. Plus at 10amp it looks like Hitachi VFD won't cost as much.

Anyone know how low will they accept as "best offer" on ebay.

David

[Al_The_Man]

You can often come in with a low offer and they can always make a counter offer to you if they wish.
Sometimes works, depends on the seller and his profit?
Al.

[danhamm]

I have been using the 3 kw china spindle for just about 2 years now, picked up the second one about 6 months ago for a backup..its still in the box, I have set the amps up to 13 amps before shutdown, reason ...cutting 1 in. pine in one pass was pulling about 9 amps and once it shut down on me.. I raised the amps and its been fine ever since..that is on the china VFD.

[victorofga]

i think they are refer to the input of single phase..
inverter require 3 kw from 220, but out put will be """1kw""" as we use for 3phase

3 times the 1 kw...

i know a 3phase 1kw motor, i used in europe was definetely larger than this 1.5 kw motor.. (chinese spindle)

we roughly said each kw require 6 amp at breakerbox.. per phase...

so 3kw of these motors (chinese spindle) need 18 amp (just a rough estimate) with single phase, or 3x 6amp if it is 3 phase..

[danhamm]

746 watts equal 1 electrical hp. so 2238 watts with perfect effiency would equal 3 electrical hp.
The HSD, the Colombo, The pearks, all of them that run of single phase are rated the same.
I have a HSD and I have the China spindle which is copied from the HSD, my 4 hp. hsd will run fine on the 13 amp china VFD.they are not advertised as 3 hp. they are rated at 3 kilowatts, 13 amps at 230 volts are damn close to being 4hp.
So you play all the number games you want to put down the chinese spindles, but in reality they are pretty damn nice for the price of a PC router
and personally I have as good of service from them as I have had with the HSD. just sayin...

[victorofga]

yes they are good quality.. not to mention about their price.. they are also very quiet..

i could never afford a good brand

[miqtidar]

Hey guys,
I am looking to buy Chinese spindle for cutting Almunium on my CNC I am building.
So if its 3kw spindle and has 14 amp on 380 or 220v is it true 3kw spindle?
If its description does not say it will cut Almunium will it cut the metal or Aluminum with this spec
3kw 14amp 24000rpm max and precision 0.01mm
Kindly reply
Thanks

[aarggh]

Hey guys,
I am looking to buy Chinese spindle for cutting Almunium on my CNC I am building.
So if its 3kw spindle and has 14 amp on 380 or 220v is it true 3kw spindle?
If its description does not say it will cut Almunium will it cut the metal or Aluminum with this spec
3kw 14amp 24000rpm max and precision 0.01mm
Kindly reply
Thanks

I've cut aluminium with the 800w spindle on my older 6040, so you'll have no trouble at all with a 3kW spindle!

Cutters and lube all factor in to the equation as well though, but the spindle itself will be far more grunt than you'll need to do aluminium.

cheers, Ian

[wizard]

I'm confused on a 3kw spindle on ebay.
NEW 3KW AIR-COOLED SPINDLE MOTOR ENGRAVING MILL GRIND p | eBay

Its listed as 3kw but only 10amps. Isn't that closer to 2.2kw?

As has already been mentioned that is the current input to a three phase motor. As such the line current is lower due to being shared across phases.

Isn't it 3000watt/220volt=13.6 amps?

Single phase yes. That would likely be your input to the inverter plus adjusting for losses.

Thanks

I don't know the specifics about what machine this will go on but I have to point out that 3KW is a lot of power for many home built machines and even a few commercially built ones. A lot of users never fully load even a smaller spindle so that is something to consider here.

[miqtidar]

Okay so what do you suggest 2.2 kw is good enough.
What about cutting steel with 3Kw or 2.2 kw

[aarggh]

Okay so what do you suggest 2.2 kw is good enough.
What about cutting steel with 3Kw or 2.2 kw

Sorry, I didn't answer the steel machining part of the question. 2.2kW would be more than adequate to cut steel, but probably not with one of these spindles. Although these spindles are insanely powerful, I think aluminium is the hardest practical material to machine with them. For steel I really think you'd need a proper belt or gear driven quill/spindle, designed for steel. My large 750kg knee mill can machine steel with ease, but the weight of the mill, and more specifically, the 3hp (2.2kW) motor powering the large and heavy quill is designed for it.

I don't think they're at all suitable myself, and strongly suspect if you tried anything more than simply engraving steel with the cheaper Ebay spindles, it might cope for a time but at the very least you'd blow the bearings in no time as it's simply not designed for such a high impact job like steel. They're not even designed for aluminium strictly speaking, it's only because they're so powerful and alu is so easy to machine given the right circumstances that it's fine for most.

cheers, Ian

[wizard]

Okay so what do you suggest 2.2 kw is good enough.

I wasn't trying to suggest anything just that 3.x kW is a lot of power for a home built machine. In that regard only you know what your machines structure is.

What about cutting steel with 3Kw or 2.2 kw

The big problem with these spindles is that the low end RPM wise is rather fast for machining steel. I don't know the specifics of the spindle in question but many of them don't run well under 6000 RPM. So what you would need to do is to get the specs on the spindle in question and see if it can be operated at an RPM suitable for the tool you intend to use in steel. Most likely torque will be wanting which is where a larger spindle might help.

In general though I doubt very much that your machine will be stiff enough for "cutting steel". At least in the the way I'd expect to machine steel. Aarggh mentioned engraving but even here I suspect quality would be an issue. That being said I have no idea what your machine is like. Even commercial manufactures dismiss the idea of maching steel on their machines.

[victorofga]

pending on tool diameter you can cut steel even with 60K

so rpm not really important..

but... as wizard mentioning above it is your machine rigidity.. just because all router can engraving steel with a sharp point engraving bit, it doesn't mean you can mill steel on a router

on other side, I have a Chinese mill with 2.2 kw motor and can cut steel with 3/4 dia and a 1/4 depth.. but that is a mill, that is not a router..
so 3 kw plenty power to cut..

you will likely go with multiple passes, shallow passes..

cutting alu with a 1/4 or larger bit and making certain passes, that's need a rigid router.. with a decent mass...

by a general thumbrule, every kw need 6 amp fuse... so a decent 3kw motor will pull 18 amp... these spindles are different somehow..
my 2.2 kw motor on the mill as large as a 5-7 kw spindle.. in dimensions..

this youtube video shows 9500 rpm and about 120 ipm in steel...

endmill about 5/8 dia

https://www.youtube.com/watch?v=XMSyHU_-CzA