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Tomnewry
03-08-2013, 03:42 PM
Hi guys I want to thank everyone for all the help I have been given, now I going to buy a new spindle so what i need help with is which one or type do I buy whithout going into big money and staying on single phase, do I need 2.2kw or bigger, water cooled or air cooled whats the benifits.
Im looking to be able to engrave maybe cut 5mm aluminum now and again bit of everything really.
Thanks for any help you can give.
Tom

JAZZCNC
03-08-2013, 04:20 PM
My suggestion is don't mess about with likes of Kress etc which are air cooled and buy either 1.5Kw or 2.2Kw WC spindle.
Personally I'd buy the 2.2Kw because it gives larger cutter range usng ER20 collets 1-13mm were the 1.5Kw use's ER11 collets 1-8mm which is more restricting.
The 2.2Kw will cut aluminium all day long no problem and engrave to very good standard. ( See here for the level of detail )
VIDEO0021.3gp - YouTube (http://www.youtube.com/watch?v=wjDvimSdH8M)

The advantage of water cooled is the duty cycle is 100% so basicly you can leave it running for days if needed, which I have done often.
Air cooled spindle often have duty cycles between 50-80% with only the better and expansive ones being any good for prolonged running, 8hrs +.
They are also very loud compared to WC spindles, I can stand next to mine while it's light cutting, such as engraving and talk on the phone.

Don't need any fancy plumbing either like you see some doing, just a plane submersible fish tank type pump dropped into a large-ish sealable container 20-25ltr of distilled water/anti freeze mix. The only requirement of the pump is it must have a head height capability higher than your Z axis goes. (most do at at about 2-3mtr)

It's No contest IMO unless you need really low speeds (lower than 5K rpm) for say cutting metal has nothing else off the shelf can touch them for power and money.
If you need low rpm speeds then It's completely different ballgame which won't get into now unless you do.?

Tomnewry
03-08-2013, 06:42 PM
Thanks Jazz I think that leave it a bit cheaper too.
Tom

Boyan Silyavski
18-08-2013, 01:27 PM
Hi,
you did not show us your machine.

I have 0.8kw spindle and never needed its bigger brothers. It depends from the stiffness of your machine and the type of bearings, but for most of the DIY machines the 0.8kw spindle is not the limiting factor when wanting to cut aluminum. You need at best a machine with at least 25 SBR or 20 Hiwin linear bearings to fully use a 2.2kw spindle for aluminum. ). 0.8kw spindle uses less power and will cost you 150eur +duty + 150eur for a brand inverter with shipping. I greatly encourage you to use a brand inverter, otherwise
you are begging for problems or will not have the same power from the spindle. You need a Constant Current vector VFD. Now calculate the same for 2.2kw spindle and see the difference. And the big bits are not cheap either
look for a spindle with 4 bearings, 24000rpm and i greatly recommend the Toshiba inverters / at least here in Europe/
When i was buying spindle the best inverter for the money was VFnC3 230V HP 1, nevermind the chinese stating 6a current from the watercooled spindle. Its actually 2A and 4A peak as far as i remember.
INVERTER VETTORIALE TOSHIBA 0,75 kW 230 Volt MONOFASE USCITA MOTORE TRIFASE 1 HP | eBay (http://www.ebay.it/itm/INVERTER-VETTORIALE-TOSHIBA-0-75-kW-230-Volt-MONOFASE-USCITA-MOTORE-TRIFASE-1-HP-/261167369803?pt=Elettronica_Industriale&hash=item3ccec9ce4b)

JAZZCNC
18-08-2013, 03:44 PM
You need at best a machine with at least 25 SBR or 20 Hiwin linear bearings to fully use a 2.2kw spindle for aluminum. ). 0.8kw spindle uses less power and will cost you 150eur +duty + 150eur for a brand inverter with shipping.

No not true at all I've built several machines that use the 2.2Kw running on 16mm rails. The rail size has nothing to do with spindle and everything to do with handling weights and loads of gantry and even the 16mm round rail easily handle most average DIY machine loads.
Where the round rail falls down with aluminium is the fact they are not accurate enough to hold tighter tolerances often needed when cutting aluminium, the actual size of rail is irrelevant.

The other benefit with 2.2kw is larger collet sizes so large shank tooling can be used which helps greatly with tool chatter in hard materials like aluminium. They are also useful if cutting woods and jobs were lots of material needs to be removed.

The rest regards VFD then I agree completely but must say the newer Chinese VFD's are getting much better and for the average user just cutting woods were exact spindle speed or power isn't critical they are fine.

Boyan Silyavski
18-08-2013, 05:10 PM
No not true at all I've built several machines that use the 2.2Kw running on 16mm rails. The rail size has nothing to do with spindle and everything to do with handling weights and loads of gantry and even the 16mm round rail easily handle most average DIY machine loads.
Where the round rail falls down with aluminium is the fact they are not accurate enough to hold tighter tolerances often needed when cutting aluminium, the actual size of rail is irrelevant.
..

Yeah,you are right. I was imagining the precision cuts with almost none finish work, the way i dream of.

Anyways for a correct answer the machine should be judged in its details and totality, cause there could be other weak spots which could make irrelevant or preferably the mounting of a 2.2kw spindle.

PS. I just advised the guy i am building a machine for to buy the 0.8kw spindle as he will run only 3d jobs with fine details due to the electricity cost here in Spain and especially when you pass over your home quote.

JAZZCNC
18-08-2013, 05:52 PM
Silyavski I wasn't saying the 0.8Kw is not suitable or any worse than 2.2Kw just the larger spindle gives more flexibility.

If the machine is only ever going to cut with small tools then yes 0.8Kw will be fine and cheaper to run. Has you say the correct choice can only be found looking at the total picture.

Tomnewry
25-08-2013, 05:35 PM
Hi guys thanks for your comments I have bought a 2.2kw water cooled so when I get it setup I will let you know how we get on. Thanks again.