Gelcoat spray system recommendations (chopper combo?)

Discussion in 'Fiberglass and Composite Boat Building' started by T Brown, Jan 8, 2023.

  1. T Brown
    Joined: Oct 2022
    Posts: 7
    Likes: 1, Points: 3
    Location: Chesapeake, VA

    T Brown Junior Member

    So I am getting ready to start the plug build, but I am trying to get my ducks in a row here with the tools I am going to need.. especially the expensive stuff.

    We are talking about a 30 foot catamaran mold here, and I really hadn't considered that maybe it's not going to be efficient to mix and spray gelcoat into the mold with a cup gun. So I wanted to get some peoples' opinions/recommendations on a fairly entry level but competent spray system, one that mixes the mekp at the gun.. I see there are external mix and internal mix guns, airless, air assist... It's all kind of giving me a headache.

    I'll be following up the gelcoat with a layer of chopped glass from a chopper gun, at least that was the plan. Are there systems that can switch from gelcoat to chopper gun fairly easily?
     
  2. comfisherman
    Joined: Apr 2009
    Posts: 645
    Likes: 324, Points: 63, Legacy Rep: 10
    Location: Alaska

    comfisherman Senior Member

    I was down this same rabbit hole not long ago, ended up being able to demo a Phoenix system unit on a large project I helped with. It clearly isn't the mainstream favorite, but for the Un initiated like myself it was exactly what I wanted. My second big project is currently in stasis, but when the light turns green it's what I'm ordering. I'm told it's feature light and kinda a simplified gun, so the big shops don't use it as much. For me coming from an alloy background it was all I needed.
     
  3. T Brown
    Joined: Oct 2022
    Posts: 7
    Likes: 1, Points: 3
    Location: Chesapeake, VA

    T Brown Junior Member

    I actually just ran into one for sale on this very forum.. I had not come across it but he's asking like $3k which is a considerably less than what I had been seeing from Binks and Magnum Vetus. Maybe that's just what the doctor ordered.
     
  4. KD8NPB
    Joined: Mar 2018
    Posts: 162
    Likes: 39, Points: 28
    Location: South Carolina

    KD8NPB Senior Member

    Cup gun spray = ~50% transfer efficiency

    Meaning, for every 5 gallon you spray, 2.5 gallon ends up as overspray on the walls, floors, and exhaust fan. With tooling gelcoat, this cost adds up quickly.

    What you're referring to is plural component spray equipment.

    Modern type uses two pumps. A small pump is slaved to a big pump, they are air-over-piston driven, and use two check balls to build pressure.

    Atomization is via hydraulic pressure (like a pressure washer) as opposed to using air to break up the fluid stream.

    Internal mix
    External mix

    Internal mix is generally favored for resin
    External mix is generally favored for gelcoat

    Internal mix requires a mixer assembly before the spray tip, and uses a check valve in the gun head to build catalyst pressure slightly. Pump pressures are higher.

    External mix shoots out a fluid stream in the middle, and has one or two nozzles that fire a fog of catalyst in to the fluid stream. They typically also use air assist to refine the fan slightly and further increase mixing. The downside is because external mix does use air to atomize catalyst & for refinement, it does generate more overspray. In my experience, external mix sprayguns are harder to keep clean because of the amount of fine overspray.

    Gelcoat is usually 5000 to 12000 cps visocity
    Open mold resin is usually 400 to 1000 cps viscosity

    Meaning, to pump and atomize gelcoat requires more pump pressure. This is where your "ratio" comes in.

    Gelcoat requires a minimum >12:1 ratio. Higher is generally better. Most production shops use 20:1 or 30:1 gelcoat pumps.

    Resin pumps are usually 7:1 or 11:1 ratio.

    You can shoot resin out of a high ratio pump, you just run the drive air pressure lower.

    If you're on the east coast, stick to either Magnum Venus Products or Phoenix Spray Equipment.
     
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  5. ondarvr
    Joined: Dec 2005
    Posts: 2,932
    Likes: 579, Points: 113, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    Magnum equipment is very popular, parts are easy to get, and many people know how to use them. By far they are the most used systems in the industry. Other brands may be OK, but they will be harder to find, troubleshoot, and parts may be less available.

    If there's a slump in the boat or RV industry Magnum equipment may come up for sale at penny's on the dollar.
     
    T Brown likes this.
  6. T Brown
    Joined: Oct 2022
    Posts: 7
    Likes: 1, Points: 3
    Location: Chesapeake, VA

    T Brown Junior Member

    Thank you for all the replies. As I did not get a response from the person who had the phoenix system for sale in the classifieds section, I am going to look to Magnum Vetus and probably Phoenix at least for comparison sake.
     

  7. KD8NPB
    Joined: Mar 2018
    Posts: 162
    Likes: 39, Points: 28
    Location: South Carolina

    KD8NPB Senior Member

    I've travelled to assist with toolbuilding before. You can find pictures on our facebook page.

    If you want some seat time, we use;
    MVP Minipro 11:1 internal mix w/ Talon spraygun & RC1000 chopper (resin)
    MVP Minipro 22:1 external mix w/ ATG3500 spraygun (gelcoat)

    We bring both.
     
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