Vacuum Pumps

[JimC]

any recommendations on brand etc? I think I'm going to have to bite the bullet and get one, not initially for composites, but to hold down the top layer  of ply on an antique moth I'm cold moulding a new bottom for. I don't seem to be getting a satisfactory result with just staples, and after that there's a canoe mast that needs more carbon and another old boat that needs some deck ply patched...
And f anyone is thinking of trading up I'd happily consider a s/h small one...

[Clive Everest]

Hi Jim,
I brought one like this. http://www.ebay.co.uk/itm/3-CFM-single-stage-rotary-vane-vacuum-pump-HVAC-Air-AC-A-C-1400-RPM-B/131327526061?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D28111%26meid%3D548dcfe8681d4106b2d2f91601891925%26pid%3D100005%26prg%3D11472%26rk%3D2%26rkt%3D6%26sd%3D311169604981&rt=nc
It pulls a hard vacuum but takes a long time to get the air out and looses pressure quickly if there are any leaks.
 It is good for foils, spars etc where you can use poly tube and get a very good seal. I would be very hesitant about using it for a hull. The resin could easily cure before you had a good vacuum.
Fortunately Rog Angell has one that will pull down a hull hard.
Dairy milking pumps are supposed to work well.
Clive

[Ben Howett]

I have the same (or similar) model as Clives and have had much the same experience with it.

I stripped mine down completely and rebuilt it before running it the first time based on internet murmurings of people finding metal filings  in the internal workings due to poor quality control in manufacture but mine was absolutely fine.

I have a box of parts to add a vacuum reservoir system which I expect will improve the issues a lot but I haven't gotten around to putting this together yet.

[roland_trim]

Ditto - except my version is red and full of resin after being loaned to various people.

Used for the last 2 hulls, but any defect in your bag and there is trouble (ben see the roll decks you have now hopefully discarded). In the poor habit of using a Henry to get the bag down and in place and then switching on the little pump.

[JimC]

Umm, thanks folks, much food for thought. Especially If I try to do more than one strip at a time and am pulling down a large area which might include staple holes. As ever you do have to know a lot about what you are doing before you buy something to learn what to do...