Friday, January 4, 2008

Jorn assist panel department

More panels are made, this time core is 6 mm plywood, used for CMM parts and for beam recesses later.

Jorn is making a pleat in the vacuum bag.

Vacuum being applied.


Anonymous said...

Hello Mr. L,

When you vacuum bagged the inner and outer side of your floats, was one vacuum pump not powerful enough to achieve adequate vacuum? Is that why you have two pumps?

I am about to vacuum bag my F-32 float but I am not sure if one 1/2HP vacuum pump is powerful enough.

Thanks for your blog, John

MartinF said...

Hello John

One pump is enough if you make the bags small enough. I find it hard to make a big bag 100% airtight, I really admire those doing infusion like Henny building F39 Fram. So I bought another pump, and it was as cheap as the first, around $200.
The difficult thing for me was to make the foam airtight enough. Be sure to bog all holes and joints very carefully. With a bigger float like F32 I would do each float half in two bags, also the jobs gets easier to overcome. Building these boats is a lot of small steps.

Good luck
Martin Friderichsen

MartinF said...

I do not know how much air a 1/2 hp pump can remove, but I would have at least a 10 CFM (cubic feet pr minut) available. I know a small Gast 1/8hp pump can do 1.2 CFM and that is not much.

So the more the better ;-)

The company Legris fittings
is a cheap and good souce for vacuum fitings. I found mine in my local shop. That is the blue lines in the blog. Connections is simply pushed onto line.

Martin F

Fram said...
This comment has been removed by the author.
Fram said...

Hi guys,
The size of the vacuum pump is not very important, it just takes longer with a smaller pump to get enough vacuum. But vacuum is vacuum and once achieved that's it, no matter what size of the pump. However, a bigger pump will overcome a bad bag much easier than a smaller one. But since I am doing mostly infusion, the bag must be perfect, and this is much easier to achieve with a dry lay-up than a wet lay-up ;-) When doing infusion I think a small vacuum pump is better since the pump cannot get enough vacuum when there are (small) leakages. A bigger pump is able to hide the leakage, but till the moment the resin is going in and then you might have a problem. I do have a second pump, but that's for security reasons (as I also hire a gen-set when infusing the hull. A failure in pump or electric power would be a disaster)


MartinF said...

The bad bag is exactly why I prefer to have an extra pump. This way I can achieve a reasonable pressure in my wet layup. My main interest is to get a tight layup, not to get 100% vacuum each time (although I try my best)

Problem is that to check if a bag is OK it is not prefreable to have a gelling epoxy going (although I use Ampreg 22 with slow hardener).
So I prepare all materials, and set to work. I have not yet been able to fully close all those small holes in the foam, maybe it is to thin (10 mm). I have been pretty close to full vacuum but never as close as on the vacuum table.

So a bigger pump can help you out except if doing infusion.

Henny I think infusion is very clever and clean, but it is not for everyone, and wet layup is not as bad as some make it.

Fram said...

Hi Martin, you are completely right. My second pump was also convenient when I could not get enough vacuum in the wet bag and then placed it nearby the supposed leakage area. Most frustrating part of the wet bag is when the sealant tape gets wet, at least my problem is to keep the sealing area clean. (but then, I'm not an experienced "vacuum bagger" ;-)