Vacuum pump advice - Page 1
Forum section: electronics / general

author: apelly
author_rank: Unknown
timestamp: September 03, 2014, 02:30:54 am
content: Hi guys,Another thread got me thinking about varnishing my own coils. I Understand that this requires a vacuum chamber. I've done some looking about online, and learned some things, but I'm hoping someone with some experience can give me some tips.Varnishing coils is kind of cool, but there are a bunch of other cool things to do with vacuums too: Freeze dry stuff, vacuum distillation, degas moulding compounds, vacuum filtration and so on.You Yanks appear to be able to pop into Harbour Freight and select from a range of pumps. Over here in NZ, Bunnings has a significantly reduced breadth of offerings. There is a crowd here in Auckland, called Ash Air, that I have dealt with in the past, and it looks like they do have quite a selection of vacuum stuff. I will pay them a visit sometime soon, but I don't really want to be "that guy" who uses a salesman for an hour then buys from aliexpress. To be fair, based on research so far, it looks likely that that's where I'll get the pump from, but Ash has a very cool selection of pipe, hoses, gauges and fittings, so I can probably spend a couple of hundy there.So, in no particular order:Can anyone recommend a place for glass vacuumware?Can anyone recommend anyspecificglass flasks/domes/bells?This will be in my lounge. An oil pump sounds problematic. Need it be? Is the oil expensive?As usual I want to spend as little as possible. I'd hope so spend of the order of NZ$500 for some hose, glassware, pump, guage, valves etc. Am I pushing shit up hill?As an occasional use item I think I could compromise on flow rate/power, but I find it hard to visualise what a realistic value is.Importantly, what is a sane minimum pressure to aim for? It appears that water boils at room temperature between about 2 and 3kPa. As I sit here, I don't have my earlier research with me. I can't remember if cheaper pumps reached 1 or 10 kPa. 10kPa doesn't seem low enough.Oh, of course; and can anyone recommend a specific pump?Thanks for your advice guys, I feel like I ask a lot of questions here, but I am grateful that some of you guys do take the time to help me out.

author: nanofrog
author_rank: Super Contributor
timestamp: September 03, 2014, 03:20:16 am
content: Found a used lab grade rotary vane type on eBay.com.au that might do (here). It's in the US, but it's dual voltage with a little rewiring and a new plug (have the diagram on the motor). Based on their current model, specs would be: 1.33 x 10-2 Pa to 3.3 Pa.Contact the seller for shipping rates to NZ to see if it's worth it.Seeing oil for ~16AUD on eBay.com.au, and a bell jar for ~90AUD. Hopefully will come close to making your budget if the shipping cost is doable (these types of pumps exceed $1k in the US new, and go for more in your part of the world it seems).Edwards RV8 Rebuild How-Towith pics that might be of use (began as a thread here, and Jeff made an instructable out of it).

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 03, 2014, 03:37:58 am
content: An old refrigerator compressor makes a pretty good vacuum pump.

author: vindoline
author_rank: Unknown
timestamp: September 03, 2014, 05:29:53 am
content: I would definitely avoid an oil vacuum pump for a living space. The pump outlet will over time discharge a fine mist of oil that will get all over. Also, it's relatively easy to spill out of the pump if it tips over. My recommendation would be to pick up a used KNF (or similar) pump on eBay. For example:http://www.ebay.com/itm/KNF-Neuberger-Vacuum-Pump-/321366453615?pt=BI_Pumps&hash=item4ad2eeed6fThe prices seem to be all over the place, but you can get good deals (at least in the US). These are high performance "dry" diaphragm pumps. The pump head and diaphragm are all teflon. I've had and used dozens of these pumps over the last 25 years as an organic chemist. I don't know anything about varnishing coils, but I assume that you need to pull the air out of the windings so that the varnish "soaks in" all the way. You could use an old vacuum desiccator for this. Here is another eBay example:http://www.ebay.com/itm/Desiccator-with-moveable-vacuum-valve-/281419296571?pt=LH_DefaultDomain_0&hash=item4185e5af3bYou might also want to go with something like this:http://www.ebay.com/itm/3-gallon-Vacuum-chamber-VAC-IT-PRO-degassing-silicone-epoxy-resin-more-/271394254610Good luck!Quote from: apelly on September 03, 2014, 02:30:54 am

author: David Hess
author_rank: Super Contributor
timestamp: September 03, 2014, 10:46:03 am
content: For low duty cycle applications like vacuum varnishing, removing gas from varnish, resins, or potting compounds, and other low vacuum applications, you can also use a standard air compressor with the inlet supplying the vacuum.The rotary vane vacuum pump that I use to power my vacuum desoldering head has a trap to keep the oil from leaving the pump when it is operating but I still have to be careful when moving it because tipping will let the oil run out.

author: neslekkim
author_rank: Super Contributor
timestamp: September 03, 2014, 01:41:00 pm
content: This dude have done some vacuum stuff: