Good vacuum veneer pump available on eBay

[Josh]

I have no affiliation with this seller, other than I just bought an identical brand new pump from him. It seems to work spectacularly. It's a 1/3 HP Gast 72R rocking-piston pump that can suck about 28" Hg.

I'm pretty sure he's selling it so cheaply ($50 brand new out of the box, buy-it-now) because it's listed for use at 220-240VAC 50 Hz (European standard). Nowhere on the label or in any of the manuals does it say it can be used at 60 Hz, as would be standard in the US. Nevertheless, given that Gast sells a variant that runs at 115VAC/60 Hz which runs at 20% higher RPMs (go figure), I took a chance and bet that the motor doesn't really mind running at 60 Hz. I'd even go so far as to venture that it's the same exact motor, just wired for the higher voltage. At any rate, I got it, wired it up with a NEMA 6-15 plug, hooked up the starting capacitor (included), and stuck it in one of my

220V wall sockets. It totally sucks! And I mean that in the good way.

I stuck a vacuum gauge on it, hooked it up to my veneer bag, and it sucked it down to 26" Hg in about 20 seconds.

Anyway, I see that he's selling another one. It's a GREAT deal for this pump. I saw the same model (albeit the 115V version) for sale new from a store that sells equipment for pond aeration. They were asking almost $600.

Here's the link:

[Preston Andreas]

I looked at it and it looks like a great price. However, after doing a little research such as line voltage to frequency ratios, it seems that running it on straight 60hz will lead to premature failure. Also, on the Gast discussion forum, it is recommended that you only run it with a 50hz converter. Check out

question is, how much would a converter cost to handle this pump?

> Josh

>

[Josh]

At 600 watts or so, probably quite a bit.

At any rate (or frequency, as the case may be), it continues to work just fine for me. I veneered my first two panels this afternoon.

Josh

Prest> I looked at it and it looks like a great price. However, after doing a

>

[RicodJour]

> >

I'm sure you could do better than that.

R

[Josh]

Stepping the voltage is easy. It's just a transformer. It's the frequency that's difficult.

First you need to rectify the power to DC, then "invert" it to 50 Hz AC, and finally step it up to 220V.

I think you can buy European-standard uninterruptible power supplies like you'd use on a computer, which would output the correct frequency, but it may have to be fairly high-end if it has to accept 115V60Hz as an input.

Josh

RicodJour wrote:

> > >

and I'm sure you could do better than that.

[todd]

That's a voltage transformer. If I understand correctly, what they're looking for is a frequency converter to convert 60 Hz to 50 Hz.

todd

[Hambone Slim]

Actually, that shouldn't be neccesary. 50Hz motors are slightly less efficient than 60Hz motors, so they have a little more copper and iron inside. So a 50Hz motor will be a little heavier than a similar rated 60Hz motor, but efficiency and heat transfer will be fine when run at 60Hz. It will however run 120% faster.

The opposite isn't true, however. Running a 60Hz motor at 50Hz isn't a good idea: it will be underpowered, and may not come up to speed enough to trip off the starter circuit, if present.

-- Timothy Juvenal

[RicodJour]

Sorry I wasn't clear with that link. I don't believe you need to change the frequency. As I understand it, it's like you said, you can run a 50 Hz motor at 60 Hz, but not the other way around. There's also the application. This is for a woodworking vacuum veneering application where the pump would be running for a short time (assuming it's set up with a vacuum controller, which it should be). It's not continuous operation.

Will not changing the frequency shorten the life of the pump? Probably, but as the pumps Josh pointed out are rated for something like ten or twenty thousand hours, even a reduction factor of ten would be acceptable for all but fairly serious commercial applications. At a price of fifty, or seventy five bucks with shipping, that's hardly a problem.

R