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01-03-2013 #1
Thought it might be an idea to centralise some info on the commonly used 2.2Kw Chinese supplied spindle.
This is what I'm looking at:
- China supplied
- 2.2Kw
- Includes power supply
- Including postage
There are a ton of "different" suppliers on EBay, at this time (01/03/13) they all charge £252 (inc. P&P) for the spindle and power supply.
I'm hoping if people manage to get a cheaper deal they can post up where they got it from and how much for.
Spindle:
- Current thinking is to buy only one with "German bearings" However every one I could see stated they have these. Has anyone proven a difference with these bearings?
Power supply:
- I asked one of the sellers about the pictures showing a lower wattage power supply than required, I was assured the matching supply would arrive with the spindle and the pictures are just recycled from other sales.
- Are different VFD's supplied? If so, which ones are better?
Water Pump:
- The pump commonly supplied by the motor sellers to go with the spindle appears to commonly be a 4000l/h, 4m head pump that looks like a converted pond pump. Cost ~£65 (inc. p&p)
- Do we know the actual pumping requirements of the motor?
For example:
Energy absorbed (J/s) = Mass (Kg/s) * specific heat capacity of water * change in temperature (K)
Q = m * c * DeltaT
(assuming the entire power of the motor is converted to heat = 2.2W = 2200J/sec)
(assume the difference in temperature achieved is 15deg Kelvin (or Celsius, doesn't matter)
2200 = Mass(Kg/s) * 4200 * 15
Mass(Kg/s) = 2200 / 63000
Mass(Kg/s) = 0.0349206
(convert to litres per hour. NB: 1litre = 1kg)
l/hour = 0.0349206 * 60 * 60
l/hour = 126
This would be the required flow rate for a temperature difference of 15 degrees from room temp to spindle temp assuming the spindle dumped 2.2Kw of power straight into the water. BUT bear in mind there are some big assumptions throughout this, it's going to be affected by the heat exchange from motor to water, radiator efficiency, pumping pressure requirements, the efficiency of the motor, etc.
If anyone else can add to this, theoretically or with practical observations, we can start to see what pumping requirements the motor actually has. A 4000l/h pond pump equivelant could be massive overkill and instead a computer water cooling pump could be used? Far less power consumption, less space taken up, more reliable for the same money as UK version can be bought.
- What pumps do other people run? What temperatures do you see with these setups?
Radiator:
- Where do people source their radiators from?
- What size / specification?
- Are radiators needed?
- Do people use fans or just use them passively?
Cable:
Cooling Tubing:
Coolant
Collets:
Links:
General Advice:
[Jonathan:
- It's best to use distilled water for the coolant so you don't cover the inside of the spindle in calcium carbonate. Also put something in it to prevent algae growing, like anti-freeze, or just keep it in a dark box.
- Always clean the collet, collet nut, and spindle tapered bore thoroughly before putting the tool in, otherwise pieces of swarf can be squashed between them which will make the runout worse over time.
- If the water cooling gets blocked then compressed air can clear it and you can dissolve the deposits by pumping water with NaHCO3 (bicarbonate of soda) dissolved in it through the spindle.
- Don't bother with the air cooled spindles since they limit you to only using fairly high speeds due to the lack of cooling.]
Hopefully some questions can be answered and maybe shed some light on this voodoo
Husky :)Last edited by Lee Roberts; 17-10-2022 at 10:45 AM. Reason: Added quotes and section for coolant
Just... One more project...
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