I am starting to think about vacuum bagging. Any thoughts on pumps would be appreciated, starting with the question of of dry vs oil. I understand oil pumps can draw a much deeper vacuum. My budget is probably a few hundred dollars, new or used.
Dry pumps usually work up to 100 mbar or so. Some dual stage ones do 20 mbar. Check before you buy.
Oil lubricated pumps draw a much deeper vacuum, many times 1 mbar or less.
0 mbar = absolute vacuum
1000 mbar = ambient at sea level (more or less)
For infusion you would like less than 20 mbar (5 mbar would be very nice)
you might also want to have a means of regulating the vacuum.
your budget involves buying either a used pump (Always a gamble) or a airco evac pump. The latter onese produce an oil mist while running.
The info above combined would probable have me buy an airco evac pump, a lossless vacuum regulator, an inline paper filter for the vacuum side, and an exhaust filter for the pump. (and a vacuum meter, if not included in the above)
This would allow me to run the pump at deep vacuum, which reduces or eliminates the oil mist, the regulator allows me to regulate the vacuum, the filter protects the regulator and pump, and the exhaust filter eliminates oil fumes that are inevitable during startup of the pump.
This setup is relatively cheap, but leaves the pump running all the time. You might be able to add a buffer tank and vacuum regulator (mechanical or electrical, the latter involves buying a power supply and a relais as well), which adds to the cost, and makes you fiddle with wiring, but can be beneficial.
If I find some time I will write a more extensive document with options that composite builders have.
Thanks for the good information. If you find time to elaborate, that would be great, but if not, that’s a start for me. If infusion means drawing the epoxy into the object, then maybe I don’t need the deepest vacuum. I am going to do what I think is called a wet layup, by saturating the laminations with a brush and rolling out.
I used to work with air compressors a lot in the business I used to run, and since a vacuum pump is a compressor going backwards, I’ll share my opinion based from experience: Oil-less are super simple to take care of, but destined for full rebuild or permanent mechanical failure WAY sooner than an oiled pump.
I’m not sure what your long term goals are, but buying quality tools to start with will save you money in the long run…but, that tool might be uncomfortably expensive in the beginning of a venture.
todd
This is the most popular and cheapest pump used in composites in the UK. You should be able to find it easy in Canada. It’s a cheap Chinese unit but it gets the job done. Several companies brand it and resell it. Both East Coast and EasyComposites sell it. I got one on eBay for £50 and its had countless hours of service, I’ve run it for over 24 hours several times with no issues. If it ever breaks, it’s cost a fraction of what the proper Edwards and Alcatel ones cost.
I have an Alacatel and it is quieter runs cooler and pulls a bit quicker and harder, but It weighs like 30 kilo. I normally use it to pull a bag down, then run cheapie while I cure parts in the oven:
http://www.ecfibreglasssupplies.co.uk/p-1903-vacuum-pump.aspx