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Hey Guys,
As the title states, where is the best place to buy 2.2kw water cooled spindle and VFD? there seem to be loads on eBay all stating they have higher grade bearings and original vfds. I dont want to pay extortionate prices but I also don't want to end up with some fake cheap tat that will fail in 6 months. I'd also prefer to avoid import duty if possible.
Cheers,
Charlie
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Charlie. It is mainly the vfd you have to watch out for see this one https://www.ebay.co.uk/itm/2-2KW-ER2...AAAOSwyy5dHuUtQuote:
Originally Posted by CharlieRam
the good ones are like this with the blue relay and two sets of terminal blocks also take a note of the front panel and the way it is laid out. you used to be able to get them from Germany (solar gene) but they seemed to have dried up.
Charlie,
As the most trusted manufacturer for the cheap Chinese VFDs and spindles seems to be Huan Yang it made sense to me to go direct to them and avoid the risk of getting a counterfeit unit. They have a store on Aliexpress called Haun Yang Drive which is where I bought mine a few months ago. By buying the spindle and VFD as a set I saved some money and was confident of getting components that matched and while setting up the VFD it appeared to have most of the programming already set to the values recomended elswhere on this forum for that spindle. Delivery was prompt and I have had no problems so far. The spindle arrived with a 4-pin socket with one pin already connected to the case. You will have to buy suitable cable and wire up the supplied plug yourself. You will also need to buy whatever size ER20 collets you require other than the 6mm one provided.
The only thing I didn't like was the absence of any reply to my pre-purchase enquiry about what warranty they offered but I think you'd be lucky to find anyone giving good answers to such enquiries at these prices.
I'm in Australia. Whether there's a European supplier (you are still in Europe for the time being even with Bozo in No.10 :wink:) that can save you signifficant import duty is for you to discover.
Kit
Cheers, I already have er20 collects for my mill and I have 1.5mm 4 core CY cable for the spindle, is that big enough?[emoji848]
I've found this one on EBay, looks right...what do you think?
https://rover.ebay.com/rover/0/0/0?m...2F262127534702
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That looks like it is similar to the one I linked to. 1.5mm is more that enough but make sure that you securely clamp the cable to the Z axis so that there is no strain on the plug as if the plug comes loose or breaks a wire it will let the magic smoke out of the VFDQuote:
Originally Posted by CharlieRam
Cheers Clive, the one you linked to was air cooled but I'd rather make a little more work for myself by adding water pump etc! [emoji23] I'll give it a whirl then. My machine is nearing the end after over 4 years!!
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Silly me l did not notice that I was mainly looking at the vfd. Yes go for the water cooled one
You should also take a look at these spindle motors:
http://www.jian-ken.com/
probably the best engineered stuff I've seen come out of China
Charlie,
When you do look at the cooling I found that using larger diameter water pipe greatly inreased the water flow from the pump I bought. The spindle fittings take 5mm id pipe but I get double the flow rate through 5m of 8mm pipe with short 5mm stubs at the spindle end than I did through 5m of 5mm pipe. PVC pipe diameters and wall thickness may vary the world over but the 5mm supplied by my local hardware store is a tight fit inside the 8mm size so gluing in the stubs was no problem using the standard glue for PVC plumbing. One of the plastic barbs supplied with the pump was just right for the larger tube, the 5mm size required an expensive extra brass barb so there's a saving to be made there as well!
Kit
Thanks, If I build another with atc I'll check those out. They look good but I'd already ordered the eBay one.Quote:
Originally Posted by Voicecoil
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I'm sure that Kitwn is right in saying that you could get much more coolant flow with bigger tubes, but in my own case (usual 2.2KW motor) I use a small pump designed for a caravan water supply, fed from a 5L bucket under the bench I have a switch that allows me to feed the pump from its design 12V, but almost always (except when filling) run it on 5V. Slow flow but the motor case temp never gets more than a few degrees above ambient. OK, I probably don't drive my machine that hard - I'm generally cutting things where other constraints rather than spindle power apply - but you might not need very sophisticated coolant setup. I've been running that spindle setup for a few years now, including runs of hours rather than minutes. As always, though, what you are going to do with the machine might change this.Most people use these big spindle motors because of the ER20 collet size rather than needing that much power.
Neale,
You're absolutely right about not needing a sophisticated set-up for cooling. We've seen people using radiators and fans normally used for PC cooling which is unecessary, but how are you supposed to know? I've seen no information from the spindle manufacturer on required water flow and the only clue you get is looking at the rough size of the pumps provided in the all-included kits Huan Yang sell.
What made me decide to replace the 5mm tube with 8mm was a test of the flow rate with and without the long length of tube. The pump capacity was just being wasted and I wasn't confident that 30l/min would be enough. I documented this elsewhere on the 'Plumbing a water cooled spindle' thread.
One thing that did surprise me was the difficulty in finding a small enough barb to fit to the pump, especially when the pump box didn't specify it's thread size. My local hardware store helped me identify the thread and we found a fitting, but I had to modify it in my lathe to make it fit. One of the plastic fittings in the pump box was just right for the 8mm pipe and I'd recommend going down that route just to avoid the problems I had. Those of you who live a little nearer to the centres of civilisation may well have less of a problem though.
Kit
Kit - do you really mean 30l/min, or is that a typo? That sounds more like a bath tap flow! I doubt if my system is pushing much more than a few litres a minute through the system. I think the pump is rated at something lkke 10L/min at 12V and from watching the speed of odd bubbles running through the pipes, I would guess at rather less than half that at 5V.
So, trying to put a bit of science behind these finger in the air estimates, I come up with the following. Does this make any sense?
Let's assume motor running flat out, absorbing a total of 2.2KW. As a rough rule of thumb, an electric motor might hit around 75% efficiency, so about 550W is wasted and appears as heat in the motor, the rest being absorbed by the load. 550
W (and here I have to go back to my schoolday units which is where I was supposed to have learned this stuff) is about 132cal/sec. Starting with an assumed flow rate of 1lit/min, that's 1000/60g/sec, that is 16g/sec. That heat input into that amount of water suggests that the water will be heated by 132/16 = 8degC (I'm rounding a bit here). So, with this low flow rate and the motor running flat out, the water coming out will be around 8C hotter than the water going in. I'm probably running at about 5l/min, so temp differential in/out through motor will be about 1.6degC. Given that I have around 8-10m of pipework (my cooling pipes run through the cable chains) and the surface area/volume ratio of the pipes is pretty high, I'm probably dissipating a lot of heat through the pipe walls anyway. And that is with a motor running at max load, which I doubt many of us achieve in a home machine. Looking at those figures, I'm not surprised that my motor case temp never seems that much above ambient!
Does this make any sense? There are other drivers, of course - pump availability, and the problem of different fitting sizes on pump and motor. I made use of a local yacht chandler who stocked a wide range of plastic tube of various sizes to find one size to fit the pump, another to fit the motor, and which fortunately also fitted inside each other with the aid of some small jubilee clips.
Oooops!
That should have been 30l/hour. 500ml/min which didn't seem like much to me at the time, especially as I'd measured 4 times that with a short 250mm stub of the 5mm tube from the same pump.
I have no problem with your calorific maths, it all looks fine to me.
One thing I do, which I think we exchanged some comments on in the 'plumbing...' thread I mentioned above, is leave the pump running continuosly when the VFD is switched on. This ensures the bearings get maximum cooling between sucessive jobs. This is done to avoid the 'Perth Transformer Effect'. A few years back I worked for the WA power utility company. If we had a sudden spell of hot days in summer there would be a rash of transformer failures on the third day...Maximum load is around 4pm when everyone gets home from work ( we tend to work 7 - 3:30 over here) and switches on their air-con. The transformers heat up on day one and cool down overnight, but start day two hotter than they started day one. Day two follows the same pattern. On day three the starting temperature is so high that by early evening there are plenty lof angry, sweaty poeple around and plenty of power company workers missing dinner but earning lots of overtime replacing burst transformers. That was a massive problem in 2003-4-5 with everybody fitting the ever-cheaper but more power-hungry refrigerative air-conditioning and peak demand changed from heating in winter to cooling in summer.
Kit
PS You never know what you might learn reading MYCNCUK!
Ah! That sounds better! And I would agree that 0.5l/min seems a little on the low side. I think a better value would be "a few" - and it's really not that critical, I would think.
Science is great for giving us some insight into what's going on, but a bit of real-world experience helps a lot - like your Perth transformer example. I always remember the story of the physicist who was asked to analyse some data to do with egg production due to his mathematical background. He came up with an answer, backed by pages of analysis and calculation, but qualified this with the proviso, "but it's only true for a ideal chicken in a vacuum!"
As for the original "where to buy?" question, though - that's in the realm of advertising and marketing hype, and no help from science there... My HY inverter and spindle came from a UK supplier who charged a bit more but reckoned that they were reselling kit from a trusted Chinese supplier. That one came with preconfigured inverter, ready to go, and it's been running for about 7 years now with no problems. I've even changed the cooling water a couple of times!
Sounds great:)Quote:
Originally Posted by Neale
"An ideal chicken in a vacuum", I'm going to remeber that one. It's near my bedtime here, but if we're going to talk science and in view of the recent anniversary, my most startling discovery of the last month was that when the Saturn V lifted off the pad back in July 1969 it took the power equivalent to fifty-five modern diesel railway locomotives just to run the fuel pumps!!!!!
As I've always said "Rocket science isn't that complicated. It's just BIG!)
Kit
Wow! I never expected the question to provoke such a response [emoji1787] just for info I had purchased a cheap 240 l/hr pump, I'll see what the flow is like once I get it.
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Even if the pipework throttles the flow back to half that, it sounds about right. One reason I run my own pump on 5V rather than 12V is that the makers only rate it for 15mins max running at 12V, even though it is submerged in water. Runs for hours at 5V, though.
Charlie,
240l/hr is what it will manage completely un-choked, no barb, no pipework, no head. Half or even a quarter of that should be enough though.