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Proper speed for spincasting fiberglass resin ?

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  • Bri O
    Hi all, Just a basic question. Bri
    Message 1 of 9 , Sep 3, 2012
      Hi all,

      Just a basic question.

      Bri
    • Ray K
      I regards to centrifugal casting, there really is no proper speed; it can vary greatly depending on mold configuration, resin viscosity, etc. You will simply
      Message 2 of 9 , Sep 4, 2012
        I regards to centrifugal casting, there really is no "proper" speed; it can
        vary greatly depending on mold configuration, resin viscosity, etc. You
        will simply have to experiment and take good notes to determine what works
        for you. I have had some resin/mold combinations require 700 rpm, so it
        does really vary.

        Addtionally, there really isn't a such thing as "fiberglass resin"; it
        would be either epoxy or polyester-based resins, both of which can vary
        greatly on viscosity and cure times, thereby altering how it is cast
        successfully, I personally would much rather utilize polyurethane resins,
        and leave the "fiberglass resins" to building/laying up fiberglass boats.

        Just my opinion,

        Ray

        On Mon, Sep 3, 2012 at 11:28 PM, Bri O <oneill91764@...> wrote:

        > **
        >
        >
        > Hi all,
        >
        > Just a basic question.
        >
        > Bri
        >
        >



        --
        Ray Kotke
        Recumbent Casting, LLC


        [Non-text portions of this message have been removed]
      • Ken Burney
        I got my home made spin caster built this weekend. It is a small thing built out of a 20 inch box fan but works well. From the results I got I would say that
        Message 3 of 9 , Sep 4, 2012
          I got my home made spin caster built this weekend. It is a small thing
          built out of a 20 inch box fan but works well. From the results I got I
          would say that you will not get good results with a resin used with
          fiberglass unless you have a way to thin it out a lot. It is to thick,
          find yourself some polyurethane resin it is like water and will spin into
          the mold cavity much better.

          Ken the guy from AR

          On Tue, Sep 4, 2012 at 7:46 AM, Ray K <kleenax@...> wrote:

          > I regards to centrifugal casting, there really is no "proper" speed; it can
          > vary greatly depending on mold configuration, resin viscosity, etc. You
          > will simply have to experiment and take good notes to determine what works
          > for you. I have had some resin/mold combinations require 700 rpm, so it
          > does really vary.
          >
          > Addtionally, there really isn't a such thing as "fiberglass resin"; it
          > would be either epoxy or polyester-based resins, both of which can vary
          > greatly on viscosity and cure times, thereby altering how it is cast
          > successfully, I personally would much rather utilize polyurethane resins,
          > and leave the "fiberglass resins" to building/laying up fiberglass boats.
          >
          > Just my opinion,
          >
          > Ray
          >
          > On Mon, Sep 3, 2012 at 11:28 PM, Bri O <oneill91764@...> wrote:
          >
          > > **
          > >
          > >
          > > Hi all,
          > >
          > > Just a basic question.
          > >
          > > Bri
          > >
          > >
          >
          >
          >
          > --
          > Ray Kotke
          > Recumbent Casting, LLC
          >
          >
          > [Non-text portions of this message have been removed]
          >
          >
          >
          > ------------------------------------
          >
          > Yahoo! Groups Links
          >
          >
          >
          >


          [Non-text portions of this message have been removed]
        • doc
          ... Is there a reason why you can t reinforce PU resins with fiberglass? And just curious what you like about PU resins. DOC Try it my way. Any fool can do it
          Message 4 of 9 , Sep 4, 2012
            At 08:46 AM 04/09/2012, you wrote:


            >...



            >Addtionally, there really isn't a such thing as "fiberglass resin"; it
            >would be either epoxy or polyester-based resins, both of which can vary
            >greatly on viscosity and cure times, thereby altering how it is cast
            >successfully, I personally would much rather utilize polyurethane resins,
            >and leave the "fiberglass resins" to building/laying up fiberglass boats.

            Is there a reason why you can't reinforce PU resins with fiberglass?

            And just curious what you like about PU resins.


            DOC




            Try it my way. Any fool can do it the right way!
          • Mike Brose
            I agree with Ray. Polyester and epoxy get their strength from the reinforcement materials (mat, woven cloth, and chopped fibers, etc.). Without those
            Message 5 of 9 , Sep 4, 2012
              I agree with Ray. Polyester and epoxy get their strength from the
              reinforcement materials (mat, woven cloth, and chopped fibers, etc.).
              Without those reinforcements those resins can be quite fragile and
              brittle and not very durable at all. Urethane (cast in the same
              thickness as a polyester or epoxy casting) on the other hand is
              reasonably strong without any reinforcement being added. And there are a
              lot more varieties of urethane resin and picking one with the right
              properties can help you get what you need. Sure, if you cast urethane
              thin enough or use a more brittle variety, it can break easily too.

              As an example, I've built a number of professional puppets (heads,
              bodies, etc.) with polyester and epoxy with reinforcement (usually woven
              cloth hand lay up). Plenty strong. But I can build those same puppets
              faster and easier with urethane and do not have to fiddle with
              reinforcements. I can use my rotocast machine or core mold the urethane
              with relative ease and create strong, durable castings. I've dropped 'em
              on a concrete floor many times over the years. Try that with a
              unreinforced polyester or epoxy casting of the same thickness! You'll be
              picking up the pieces.

              Cheers,

              Mike Brose
              http://www.puppetsandprops.com
              http://puppetsandprops.blogspot.com/

              Ray K wrote:
              > I personally would much rather utilize polyurethane resins,
              > and leave the "fiberglass resins" to building/laying up fiberglass boats.
              >
              > Just my opinion,
              >
              > Ray
              >
              >
              >
              >
              >


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              The message was checked by ESET Smart Security.

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            • Ted Quick
              Doc, As already mentioned polyurethane resins are hardier than epoxies and polyesters since they are more flexible, therefore durable. The other possible
              Message 6 of 9 , Sep 4, 2012
                Doc,

                As already mentioned polyurethane resins are hardier than epoxies and polyesters since they are more flexible, therefore durable. The other possible problem is that since HO groups (which happens to include water) are what reacts with the ISO side there is a likelyhood that the fiberglass fibers will carry condensed water in wth them, which can ruin the urethane reaction.

                Urethane reactions NEED to be very accurately mixed, usually stated as being within 2% of the total mix, tough that level tends to skew the mechanical quantities rather too much. So if there's an uncontrolled amount of water included with the fiberglass your "strengthening" fiberglass may leave you with uncured mush.

                Of course you could always heat the fiberglass to drive out any water, but that would speed the reaction enough that it might not penetrate the fiberglass well enough, and/or not fill out the mold.

                IOW, fiberglass gets complicated when talking about urethane casting resins.

                Ted Quick




                >________________________________
                > From: doc <danieloconnell@...>
                >To: casting@yahoogroups.com
                >Sent: Tuesday, September 4, 2012 11:26 AM
                >Subject: Re: [casting] Proper speed for spincasting fiberglass resin ?
                >
                >At 08:46 AM 04/09/2012, you wrote:
                >
                >
                >>...
                >
                >
                >
                >>Addtionally, there really isn't a such thing as "fiberglass resin"; it
                >>would be either epoxy or polyester-based resins, both of which can vary
                >>greatly on viscosity and cure times, thereby altering how it is cast
                >>successfully, I personally would much rather utilize polyurethane resins,
                >>and leave the "fiberglass resins" to building/laying up fiberglass boats.
                >
                >Is there a reason why you can't reinforce PU resins with fiberglass?
                >
                >And just curious what you like about PU resins.
                >
                >
                >DOC
                >
                >
                >
                >
                >Try it my way. Any fool can do it the right way!
                >
                >
                >
                >------------------------------------
                >
                >Yahoo! Groups Links
                >
                >
                >
                >
                >
                >

                [Non-text portions of this message have been removed]
              • Mike Brose
                It can be done. I ve done it. Kind of a pain to do and a lot trickier to use than polyester or epoxy. Biggest problem is the snap cure of many urethanes
                Message 7 of 9 , Sep 4, 2012
                  It can be done. I've done it. Kind of a pain to do and a lot trickier to
                  use than polyester or epoxy. Biggest problem is the 'snap cure' of many
                  urethanes resins. You have to get a slower setting version of urethane
                  so you have time to saturate the fiberglass cloth properly. And....., if
                  you wait to long between layers, you will not get good bonding. Urethane
                  is a lot touchier about that.

                  Second biggest problem is viscosity. A lot of urethane resins are so
                  low in viscosity that it does not stay where you put it on the
                  fiberglass cloth during the hand lay up process. So if it is not a flat
                  piece, like the heads and bodies I make, it will puddle in the bottom of
                  the mold or other recesses, and create real thick spots. So you need a
                  more viscous urethane resin to help prevent that situation.

                  I used Polytek's 1512 (I can control the set time with their part X
                  additive), which has a nice viscosity to it and is slow curing. I made a
                  special prop that is used by a performer in New York. It's been used for
                  hundreds of performances for almost a decade, has taken a lot of abuse,
                  but is tough as nails.

                  But its very tedious and time consuming as is all hand lay up. Would
                  have worked just as well to use polyester or epoxy (my personal
                  preference), or a rotocast or core molded version without reinforcement
                  would have been plenty strong enough. Here's a head I made with epoxy
                  glass........

                  http://www.puppetsandprops.com/Images/LeprechaunFiberglass11.jpg
                  http://www.puppetsandprops.com/Images/LeprechaunFiberglass2Med.jpg
                  http://www.puppetsandprops.com/Images/LeprechaunFiberglass3Med.jpg
                  http://www.puppetsandprops.com/Images/RustyMalick1.jpg

                  Very lightweight, thin and strong. I would have had trouble doing this
                  same project with urethane resin hand lay up because of the complexity
                  of the sculpture, and the bonding between layers would have become an
                  issue (that is much easier to control with polyester or epoxy) with
                  potential for delamination.

                  Cheers,

                  Mike Brose
                  http://www.puppetsandprops.com
                  http://puppetsandprops.blogspot.com/
                  > Is there a reason why you can't reinforce PU resins with fiberglass?
                  >
                  > And just curious what you like about PU resins.
                  >
                  >
                  > DOC
                  >
                  >


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                  The message was checked by ESET Smart Security.

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                • Stephen
                  It had been my experience as a modeler (end user) rather than a caster of parts for model airplanes, that the fiberglass items with polyester or epoxy resins
                  Message 8 of 9 , Sep 5, 2012
                    It had been my experience as a modeler (end user) rather than a caster of
                    parts for model airplanes, that the fiberglass items with polyester or epoxy
                    resins are much more flexible, than the solid cast resin items. Also the
                    problem modelers have been having with resin castings made in ex-iron
                    curtain countries is warpage of larger parts, such as airplane wings.

                    Stephen



                    _____

                    From: casting@yahoogroups.com [mailto:casting@yahoogroups.com] On Behalf Of
                    doc
                    Sent: Tuesday, September 04, 2012 11:26 AM
                    To: casting@yahoogroups.com
                    Subject: Re: [casting] Proper speed for spincasting fiberglass resin ?





                    At 08:46 AM 04/09/2012, you wrote:

                    >...

                    >Addtionally, there really isn't a such thing as "fiberglass resin"; it
                    >would be either epoxy or polyester-based resins, both of which can vary
                    >greatly on viscosity and cure times, thereby altering how it is cast
                    >successfully, I personally would much rather utilize polyurethane resins,
                    >and leave the "fiberglass resins" to building/laying up fiberglass boats.

                    Is there a reason why you can't reinforce PU resins with fiberglass?

                    And just curious what you like about PU resins.

                    DOC

                    Try it my way. Any fool can do it the right way!





                    [Non-text portions of this message have been removed]
                  • Jack
                    ... Bri, You are talking about either epoxy or polyester resin I assume. Neither is very well suited to spincasting. Both are higher viscosity and take a
                    Message 9 of 9 , Sep 5, 2012
                      --- In casting@yahoogroups.com, Bri O <oneill91764@...> wrote:
                      >
                      > Hi all,
                      >
                      > Just a basic question.
                      >
                      > Bri
                      >

                      Bri,

                      You are talking about either epoxy or polyester resin I assume. Neither is very well suited to spincasting. Both are higher viscosity and take a long time to cure unless specially formulated. They also usually have a lot of shrink.

                      What are you wanting to cast? Matching material and process to the product is very important.

                      Polyurethane resin is the most suitable resin to spin-cast since it can be made to kick off fast for a fast cycle time.

                      Sounds like you have some homework to do to determine best material and method of making your item.
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