Thread: Anyone need a vacuum generator if I get stuck with one?

I saw that in the newsletter too. My interest shot up as ive been considering vacuum turning for bowls for some time. Also, I've been keen on a vacuum pump for veneering on my boxes.

Which pump are you considering?

Im in the same boat as you two gents. Wanting to use a dedicated pump rather than a compressor driven one (just the thought of a compressor turning over all the time annoys me).....

Ill start by using the pump for vacuum chucking, then slowly build up my stabilization setup from there.

This is the one I have been looking at, but I have no idea what I need or what the cost should be. Its just that this one seems to tick the boxes (Of the information I glean from a few facebook pages etc) and its local to me so I can pick it up.

3CFM 2 Stages Refrigerant Vacuum Pump Refrigeration Gauges Tools Air Condition | eBay

That said, when I do get round to purchasing one, I'm sure I'll get into Neils (Dai Sensei) ear to make sure I'm looking at the right thing.

Keeping my eye on this thread to see what pumps other are recommending though

I think that's the exact same pump (or at least very similar) I've been looking at, Gabriel!

This isn't your intention for the compressor, but do you think this would be good for a veneer vacuum press?

The ad doesn't mention the power of the vacuum generated, simply the air moved in CFM. Leaving it on for and hour might burn the thing out!

I ask as the "good" (i.e recommended) one from the US is evil in price. The local one is 6 times more evil.

The key for me is the 15 micron. That's what we use on vehicle AC. Normal pull down time is up to an hour to boil all the moisture out of the system so it should handle the time OK if it's designed for AC.

Vacuum Pressure - Units Converter

Hi gents, I have done a lot of cactus juice stabilizing in the last couple of years. I have moved from the vacuum pumps to the vacuum generator after killing three pumps.
The resin gets in to the oil, half bakes, clogs the vanes and jams the system.
There are numerous methods for reducing this but in my experience will occur eventually.
The compressor method is noisy, but you only need to run it long enough to pull a vacuum if you install a ball valve to seal the system off once at vacuum, then you just occasionally pull the vacuum back down when it starts to creep up.
Happy to discuss the issues with anyone interested but don't want to derail your thread.
Cheers
Matt

I don't think that's a derail Matt, go for it! Interested to hear what you ran into.

Did you try out a resin catcher in the between the tank and pump?

Originally Posted by rtyuiop

I don't think that's a derail Matt, go for it! Interested to hear what you ran into.

Did you try out a resin catcher in the between the tank and pump?

I did try a resin trap. I tried the commercial in-line versions and I also made one. I think mine was better. I used a PVC container that I placed filter foam in. The idea was that the combination of filter and volume would allow the resin to be more effectively captured. Either way, the resin wound up in the pump.

Some ways to mitigate it are as follows;

In-line filter (as mentioned)

Extra clearance from lid to resin. The resin boils quite violently upon initial vacuum and additional clearance will assist in preventing it being sucked up.

Clean after every use. Dump the oil, store it in a container when the pump isn't in use and clean the pump thoroughly. Issue with this is its a hassle pulling the pumps apart, and most don't allow access to all of the system so they can never be completely cleaned.

Always, always, always run your pump before connecting to the system to warm it up. One of my more expensive pumps had a lever to allow it to be isolated. The cheaper ones do not so just run it disconnected and away from anything that may get sucked in to the pump until you connect it. If the resin does get sucked up and ends up in the pump and the oil is cold the resin mixes in to the oil. If it is hot oil the resin will, mostly, vaporize and be ejected out the exhaust port.

It is my opinion, however, that the pump will eventually get jammed. I think it is vaporized resin and as the trap allows free airflow I think it allows the resin through. It is a bit of a slow process, but once in the pump the heat and oil makes a very sticky gunk that gets in to all the working parts. My good pump just had one of the vanes snap. I got a replacement and then some part I could not access jammed.

I think that any warrantly claims would be rejected once they examined your pump so please don't rely on that.

The cheaper pumps just jammed eventually. After nearly $1000 worth of dead pumps I have given up on them completely. It is not financially viable for a little less noise and a compact system.

I am sure there will be plenty of people to tell you the pumps are fine. I am no expert so perhaps I was doing something fundamentally wrong. If it had been one pump I'd be inclined to think that, but three pumps, lots of experiments and research and I am convinced it is not a good system. At the end of the day rotary vane vacuum pumps are designed to be used in air-conditioning systems for gas, not resin.

The vacuum generator, or venturi system is definitely loud, but the system itself is so simple that even if it did get gunked up, which is unlikely as the vapor will be evacuated, you could just clean it and continue.

As mentioned, have a ball valve on your chamber so that you can isolate your chamber from your pump. Once under vacuum close the valve and allow the timber to sit under vacuum. If it starts to lose vacuum just restart the vacuum. Has worked well for me.

Again, I'm no expert but I have stabilized hundreds, if not thousands, of timber blocks and scales for knife handles. I do not like wasting money and will happily try to save you doing the same. If you only do one or two blocks here and there then a pump might last you ages, but then a vacuum generator will too and the noise will not be regular.

Any questions feel free to ask.

Cheers

Matt

Thanks for the in depth answer matt, great to know and looks like I better do more research before I part with my pennies. As I already own compressors, it was only a noise issue I was worried about, but maybe I'm just a panic monger....

Thanks again! !

Gab

Yeah, great to have that input Matt! I don't own a compressor so I will have to investigate some more...

Geez Matt, good or cheap vac pump makes no real difference to your problems, you must be packing your chamber with way too much and your resin level too close to the intake. Taking the oil out is extreme too, but if you are regularly getting resin in your oil, it would be a good idea. I've been doing vac stabilisation for years and only once had an issue with resin (or what ever it was) in the pump. These days I have a liquid trap (modified fuel filter), a moisture trap (to catch any accidental moisture from the timber) and a decent length of tube (although at full vacuum it doesn't take long to get through the tubing) and only replace the oil after effectively ~1 week of vacuum. My pump wasn't a real cheapy, but not a real expensive one either, although it is on its last legs.

Anyway back to your generator Danny, they work well for vacuum chucks and I still have mine for that very use, as the vacuum is very easy to control. They do work for vac chambers too and can be used although they struggle to hold full vacuum. The biggest issue is having a decent compressor to run them, they take a lot, and can cook a smaller cheap compressor quickly.

Couldn't one build a big vacuum storage container out of PVC pipe? (or an old compressor barrel, or big gas bottle?). Put that in the line, drain it of air, therefore giving you a large "reserve" of vacuum to draw on?

Would it work like this?

Also, this might help any crud that gets pulled up to "precipitate out" before it reached the vacuum generator(?). Perhaps one could jam some roofing insulation into the PVC pipe to act as a surface for the cruft to cling to.... a primitive filter...

Dai sensei, that could be the issue, but I always kept at least around 4 inches from the intake and always watched and controlled the amount the resin boiled.
Whatever the cause I got sick of replacing the pumps and am satisfied with the generator. Good to hear you've not had the same issues though, and good for thought for those deciding which way to go.

Originally Posted by woodPixel

Couldn't one build a big vacuum storage container out of PVC pipe? (or an old compressor barrel, or big gas bottle?). Put that in the line, drain it of air, therefore giving you a large "reserve" of vacuum to draw on? .

No, not for vacuum stabilisation anyway. As soon as you released your chamber to the chamber with resin to be vacuumed, the level of vacuum would drop rapidly, and for stabilisation you need full vacuum for extended periods. Even at full vacuum it can take hours and hours to vacuum out the air at depth.