Hi.

For a number of reasons surrounding very large water cooled lasers, I need one of these. It's to replace a single-phase equivalent in a large refrigerated water cooler unit I rescued from a scrapyard and completely rebuild last year. I had to replace the pump with a near identical one I had, then get everything powder-coated, paint the innards having removed the rust, rewire it, etc, but it came up like new and saved me about £3000 on the cost of a new one!

However, it's almost too good, the flow rate is ridiculous. For the 100W laser I'm currently using, it's fine, but I want to also be able to use it with a smaller unit and at the moment it's like plugging a coffee maker into Niagara Falls...

Not to mention it's quite loud as a result.

Altering the speed of a single phase motor is a right sod, and often almost impossible. Never cheap however you do it. On the other hand, changing the speed of a three phase motor is easy and I have a spare inverter lying around that would do the job nicely. Having hunted about for a drop in replacement for the fairly standard size pump that's in the unit, I settled on that specific on as being the cheapest, as well as the closest in size and flow rate.

This particular company is by far the least expensive place I can find to get it from, at about £62 at the moment. That's only 60% of the cost of the cheapest supplier I can find in the UK, and under a third of the price of most of them! I've tried contacting the company in Italy to find out if they'd ship to the UK, and if so how much it would be. They did finally respond saying, basically, 'Yes', which isn't entirely helpful. No indication of price, you note

Having created an account on their online shop, I tried to set the shipping destination to the UK but it's about the only European destination not offered... Possibly they've jumped the gun on Brexit?

I was wondering if anyone who spoke Italian might be able to contact them and talk to someone to find out a shipping price and relay it. Obviously, it might be so high it's cheaper to get the one off Ebay for a hundred quid, but hopefully it would be more reasonable. I know I can send something of that weight TO Italy for about ten pounds, so...

Anyone able to help?

pca

This laser project wouldn't have anything to do with making a political statement as to the advisability of Brexit, now would it?

No, just for cutting wood and plastic.

Although I do personally feel that particular decision was one of the most brain-dead ones taken in recent political history. Once again, proving that people vote on things they don't, and often don't want to, understand

Ah well. All we can do is live with it, then in five years or so point and say, "I told you! Didn't I tell you? What did you think was going to happen?"

Of course, I may be wrong, and would like to be, but I don't think I am...

pca

I assume that's supposed to be "water cooled lasers"? On initial reading, I was wondering why you'd be so pissed off with people gossiping by the water fountain that you'd want to apply such extreme measures as directed energy weapons.

Though, now I think about it, that's not such a bad idea...

Yes, indeed, I did mean water cooled, not cooler.

Although I would agree there are use cases to be made for the latter.

Have you explored the idea of putting a suitable capacitor in series with one leg the the AC supply? This works extremely well for me here with smaller motors (15uF for a 0.7amp motor). Near 100% efficient, so one just needs suitable non-polarized metal/poly film capacitors rated for 450V.

It's a permanent split capacitor motor so it already has one to generate the phase difference. Yes, changing the capacitance would alter the speed a little, but not that much, and certainly nothing like as much as a 3 phase one running from a variable inverter. Not to mention that it's not adjustable on the fly.

Plus you run into the problem with single phase motors that most methods I'm aware of for changing the speed tend to make the torque fall off a cliff very fast, which means they stall and/or overheat horribly.

All in all the 3 phase approach is preferable, irritatingly enough. But I do at least have the most expensive part sitting in the garage! Just need to get the pump.

pca

I've always wanted a reverse microwave. No more tepid beer or white wine. And all those cold dishes that have been out a few minutes too long...

-jk