Custom Fiberglass Extended Swim Platform

[Scott Danforth]

Ted, do you think a simple pump-up garden sprayer and ball-valve could operate as a pressure pot?

I dont know, however its a thought

https://www.homedepot.com/p/Chapin-...nd-Home-Project-Sprayer-20002-20002/301459877

 

[tpenfield]

Ted, do you think a simple pump-up garden sprayer and ball-valve could operate as a pressure pot?

I dont know, however its a thought

https://www.homedepot.com/p/Chapin-...nd-Home-Project-Sprayer-20002-20002/301459877

Yes, that is brilliant I probably would have to modify the tubing for greater diameter or use it to pressurize a larger resin pot.

I greatly appreciate the suggestions you've had along the way, very helpful. :thumb:

 

[Scott Danforth]

I was thinking you pick up 5 or 6 of these, use them as the resin pot, then throw away when done. first practice on a hatch.

 

[tpenfield]

I could do 2 pump sprayers for the infusion of the mold and 3 more for the infusion of the platform. I'm good with the hatch molds as they are albeit with a bit of touch-up.. For the hatch parts, considering that they are small and coming from female molds, I think I can just put the cloth in place, pour in the resin and vacuum bag them . . . no infusion.

 

[froggy1150]

Another idea..... What about wet it out then bag it

 

[froggy1150]

Nevermind that's what I get for posting then reading the last post

 

[Scott Danforth]

nevermind that's what i get for posting then reading the last post

lmao

 

[tpenfield]

Yes, 40 sq. ft x 3 layers, so 120 sq ft. . . . not something you can lay out and wet out in 5 minutes and then set up a vacuum bag in a few more minutes before the resin sets up.

I figure that I need to infuse about 3-4 gallons of resin in about 5 minutes, then take another 5 minutes working any issues before the resin gels up.

 

[tpenfield]

Just checking my material estimates on the platform mold . . .

These online calculators are pretty handy. I plan on using 3 layers of 1.5 oz CSM, which should yield me about 1/8" thick glass.


.
I'll be using the 50" wide mat. I noticed that the catalyst calculation is for the resin and gelcoat combined. I currently have 4.25 gallons of poly resin left, so it should be enough to do the mold and associated stiffeners.

One thing that I am noticing is that with vacuum infusion, I am using less resin than the calculators indicate. On the second hatch mold, the resin calc was for 40 oz of resin. The mold was pretty much done with about 1/3 of the resin left . . . which hardened in the bucket right before my eyes :facepalm:

 

[fishrdan]

Been lurking on your progress from the beginning, heck of a project! I'm not an expert on vacuum bagging, never done it, but a couple of thoughts.

What are you using as a source of vacuum? I see a shop vac in the back ground, is that it? I would think you'll need a better source for vacuum, a real vacuum pump. I've borrowed one from the local chain auto parts store for car AC work, though not sure it would have the capacity for the platform, and I wouldn't tell them you're using it for polyresin vacuum bagging...

Infusion and vacuum at the same time, I think that would be a disaster, unless you have some way to accurately control to pressure and cut it off when needed. Again, never done bagging, but that's just my perception.

Using the wrong viscosity of resin might be a stumbling block. Any option to return what you haven't used and get a thinner resin?

 

[tpenfield]

I just realized something . . . If I use the pump buckets that Scott suggested, and considering that the mold will be fully enclosed in plastic, there will be little, if any fumes in the air.

This could become an eco-friendly project :thumb:

 

[tpenfield]

Been lurking on your progress from the beginning, heck of a project! I'm not an expert on vacuum bagging, never done it, but a couple of thoughts.

What are you using as a source of vacuum? I see a shop vac in the back ground, is that it? I would think you'll need a better source for vacuum, a real vacuum pump. I've borrowed one from the local chain auto parts store for car AC work, though not sure it would have the capacity for the platform, and I wouldn't tell them you're using it for polyresin vacuum bagging...

Infusion and vacuum at the same time, I think that would be a disaster, unless you have some way to accurately control to pressure and cut it off when needed. Again, never done bagging, but that's just my perception.

Using the wrong viscosity of resin might be a stumbling block. Any option to return what you haven't used and get a thinner resin?

I am using a shop vac for the vacuum. It seems to work fine . . . I take the vacuum tube and insert into the hose of the vacuum, so the shop vacuum is pulling external air as well. I can regulate the pressure by how far I put the vacuum tube into the hose of the shop vac.

I supposed I could get a vacuum gauge to see what the internal pressure drop is. I figure if I get down to about 1/2 an atmosphere (7 psi) it should be good. I won't be doing the platform mold for a couple of weeks, so I can do some testing and check out some options.

A bigger challenge with pieces of this size is ensuring no air leaks in the bagging material and related seal.

The only other vacuum bagging project that I have done was the fiberglass pram dinghy that I made back in 2011. I tend to go through a few shop vacs

 

[mickyryan]

thin resin i bet problem will be solved,

I have also come to realize that gel coats need at least 2% catalyst, otherwise it sits there and laughs at you.
^^ true story! i watched Gel coat for a day once cause i was worried about heat and went 1% now i don't even bother going under 2% and still it takes off when it decides too lol.

 

[tpenfield]

I found a vacuum pump that has very good ratings and seems to pull about 25-30 Hg according to the reviews. It seems to fall within the spec's recommended on the fiberglass web sites, in terms of capacity, etc. for this size of job.



I have this pump, some extra oil, and a gauge on order for around $110 . So, it seems worth it to get this for the project.

This should be a lot better vacuum, and give the shop vac a rest

Thanks fishrdan for the suggestion.

 

[tpenfield]

thin resin i bet problem will be solved,

I have also come to realize that gel coats need at least 2% catalyst, otherwise it sits there and laughs at you.
^^ true story! i watched Gel coat for a day once cause i was worried about heat and went 1% now i don't even bother going under 2% and still it takes off when it decides too lol.

Yes, one of the bottles of catalyst that I have states. . . " 1.5% for polyester and VE resins, 2% for gelcoats "

 

[tpenfield]

I also ordered a viscosity measuring cup and a pint of styrene resin thinner. You can't really thin the resin much without adverse effects, but maybe 3-5% would be the limit. I also understand that the VE resin is thinner than poly resin . . . we shall see. From what I have been able to research, these resins have about 35% styrene content.

The credit card is getting a work-out and is becoming exhausted.

 

[Scott Danforth]

Ted,

one of these rubber caps fits perfectly over the hose from a shop vac. then drill a few holes in it and you can have multiple vacuum tubes.

https://www.homedepot.com/p/2-in-PVC-DWV-Flexible-Cap-PQC-102/100372303

A shop vac is good for an initial high-volume evacuation of air, however will be limited in how low of a vacuum it can pull before the fan stalls. the vac pump will draw down significantly more

 

[Grub54891]

I found a vacuum pump that has very good ratings and seems to pull about 25-30 Hg according to the reviews. It seems to fall within the spec's recommended on the fiberglass web sites, in terms of capacity, etc. for this size of job.



I have this pump, some extra oil, and a gauge on order for around $110 . So, it seems worth it to get this for the project.

This should be a lot better vacuum, and give the shop vac a rest

Thanks fishrdan for the suggestion.

I have a similar vac pump, not to expensive either. They work well. I wouldn't even think about using a shop vac for infusion. I've tested a few runs with it on a small scale, it worked well.

 

[tpenfield]

The idea of pressurizing the resin to force it into the vacuum bag/mold has got me thinking . . . Under vacuum, one of the things that works against the resin flow, is the compression of the fibers as a result of the vacuum. So the resin flows only at the rate at which the cloth/mat can absorb it.

I am wondering how a process modification would work, where the vacuum is reduced or nearly eliminated for a couple of minutes, while the resin is pumped under pressure into the mold, then once the resin has been injected, the vacuum is re-applied to force the resin throughout the mold area. Not sure if that will work . . . perhaps I can do some research to see if anyone has tried variations of the common vacuum/infusion theme. :noidea:

Just thinking out load . . . I could always try it on the ladder hatches to see if it will work.

 

[oldrem]

I have one of these - twin 4" inlets that will suck the wings off an eagle lol