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Re: Vacuum Chamber - WAS - Really old vacuum pump

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  • Ray K
    One other thing Rob; I was told by a professional prototyping engineer that has been doing moulding and casting for 20+ yrs that the oil should be changed
    Message 1 of 14 , Sep 30, 2012
      One other thing Rob;

      I was told by a professional prototyping engineer that has been doing
      moulding and casting for 20+ yrs that the oil should be changed regularly
      in the vacuum pumps because the isocyanates get REALLY concentrated in
      there after vacuuming resin.

      On Sunday, September 30, 2012, Rob de Bie wrote:

      > **
      >
      >
      > Ray, thanks, that's a very good point indeed. One that I hadn't given
      > enough thought I must admit.
      >
      > Regarding the oil mist, I was also afraid that it would deplete the
      > pump's oil quantity fairly rapidly. At work we have a big old vacuum
      > pump, and its oil mist filter contains a lot of oil after a couple of
      > months. It is poured back in the pump every now and then.
      >
      > Rob
      >
      > At 16:08 30-09-2012, you wrote:
      > >Rob;
      > >
      > >I vent my vacuum pump exhaust outside since that mist also contains
      > >isocyanates from your resin.
      > >
      > >On Sunday, September 30, 2012, Rob de Bie wrote:
      > >
      > > > **
      > > >
      > > >
      > > > Tyla, I've got a similar pump, a slightly bigger model I think. Mine
      > > > lacks an oil mist filter, and emits a fine white mist of oil at the
      > > > beginning of emptying the vacuum chamber. I tried to make all kinds
      > > > of filters, but it passes right through. Do you have the same problem?
      > > >
      > > > Rob
      > > >
      > > > At 05:15 25-09-2012, you wrote:
      > > > >I waited and waited not really knowing if I was procrastinating for
      > > > >safety reasons or just wanting a 'pretty' set up but I ended up just
      > > > >getting one like this:
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130747094881
      > > > >
      > > > >All complete, chamber and pump all inclusive and I'm fine with
      > > > >having paid good $$$ for it. I KNOW I COULD have made it for a
      > > > >fraction and I have made some of my own other tools. This, for some
      > > > >reason, I needed a pro's stamp of approval on and would do it again.
      > > > >
      > > > >The way I thought of it was - would I just pay someone in the know
      > > > >an extra $100 just to go out and get this done for me. The answer
      > > > >was yes so after the fact I'm happy with my choice and no looking
      > back.
      > > > >
      > > > >BTW I was happy with the 6CFM
      > > > >
      > > > >Hope this helps
      > > > >
      > > > >Tyla @ http://obscurecreationsbytyla.blogspot.ca/
      > > > >
      > > > >
      > > > >
      > > > >------------------------------------
      > > > >
      > > > >Yahoo! Groups Links
      > > > >
      > > > >
      > > > >
      > > >
      > > >
      > >
      > >
      > >--
      > >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]
    • Rob de Bie
      Ray, that s another thing I never considered. Do you possibly know how the isocyanates affect the oil, or the pump itself? My chemistry knowledge is way too
      Message 2 of 14 , Oct 1, 2012
        Ray, that's another thing I never considered. Do you possibly know
        how the isocyanates affect the oil, or the pump itself? My chemistry
        knowledge is way too limited to judge that.

        Maybe a membrane / diaphragm vacuum pump is the better choice here? I
        looked for one, to solve the oil mist problem, but found out they are
        at least double the price of a small rotary vane vacuum pump.

        Rob

        At 04:54 01-10-2012, you wrote:
        >One other thing Rob;
        >
        >I was told by a professional prototyping engineer that has been doing
        >moulding and casting for 20+ yrs that the oil should be changed regularly
        >in the vacuum pumps because the isocyanates get REALLY concentrated in
        >there after vacuuming resin.
        >
        >On Sunday, September 30, 2012, Rob de Bie wrote:
        >
        > > **
        > >
        > >
        > > Ray, thanks, that's a very good point indeed. One that I hadn't given
        > > enough thought I must admit.
        > >
        > > Regarding the oil mist, I was also afraid that it would deplete the
        > > pump's oil quantity fairly rapidly. At work we have a big old vacuum
        > > pump, and its oil mist filter contains a lot of oil after a couple of
        > > months. It is poured back in the pump every now and then.
        > >
        > > Rob
        > >
        > > At 16:08 30-09-2012, you wrote:
        > > >Rob;
        > > >
        > > >I vent my vacuum pump exhaust outside since that mist also contains
        > > >isocyanates from your resin.
        > > >
        > > >On Sunday, September 30, 2012, Rob de Bie wrote:
        > > >
        > > > > **
        > > > >
        > > > >
        > > > > Tyla, I've got a similar pump, a slightly bigger model I think. Mine
        > > > > lacks an oil mist filter, and emits a fine white mist of oil at the
        > > > > beginning of emptying the vacuum chamber. I tried to make all kinds
        > > > > of filters, but it passes right through. Do you have the same problem?
        > > > >
        > > > > Rob
        > > > >
        > > > > At 05:15 25-09-2012, you wrote:
        > > > > >I waited and waited not really knowing if I was procrastinating for
        > > > > >safety reasons or just wanting a 'pretty' set up but I ended up just
        > > > > >getting one like this:
        > > > > >
        > > > > >
        > > > > >
        > > > > >
        > > > > >http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130747094881
        > > > > >
        > > > > >All complete, chamber and pump all inclusive and I'm fine with
        > > > > >having paid good $$$ for it. I KNOW I COULD have made it for a
        > > > > >fraction and I have made some of my own other tools. This, for some
        > > > > >reason, I needed a pro's stamp of approval on and would do it again.
        > > > > >
        > > > > >The way I thought of it was - would I just pay someone in the know
        > > > > >an extra $100 just to go out and get this done for me. The answer
        > > > > >was yes so after the fact I'm happy with my choice and no looking
        > > back.
        > > > > >
        > > > > >BTW I was happy with the 6CFM
        > > > > >
        > > > > >Hope this helps
        > > > > >
        > > > > >Tyla @ http://obscurecreationsbytyla.blogspot.ca/
        > > > > >
        > > > > >
        > > > > >
        > > > > >------------------------------------
        > > > > >
        > > > > >Yahoo! Groups Links
        > > > > >
        > > > > >
        > > > > >
        > > > >
        > > > >
        > > >
        > > >
        > > >--
        > > >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]
        >
        >
        >
        >------------------------------------
        >
        >Yahoo! Groups Links
        >
        >
        >
      • Ray K
        I was always under the impression that you can t pull a good enough volume or vacuum with a diaphragm pump. Don t really know, but that s what John told me
        Message 3 of 14 , Oct 1, 2012
          I was always under the impression that you can't pull a good enough volume
          or vacuum with a diaphragm pump. Don't really know, but that's what John
          told me (the prototyping engineer).

          As for the oil in the previous message, I understand that it causes the oil
          to break down rather quickly, and makes it "gummy"; hence the need to
          change it more often. Since they utilize their vacuum chamber almost
          continuously, they change the oil monthly in their pumps.

          On Mon, Oct 1, 2012 at 7:25 AM, Rob de Bie <robdebie@...> wrote:

          > **
          >
          >
          > Ray, that's another thing I never considered. Do you possibly know
          > how the isocyanates affect the oil, or the pump itself? My chemistry
          > knowledge is way too limited to judge that.
          >
          > Maybe a membrane / diaphragm vacuum pump is the better choice here? I
          > looked for one, to solve the oil mist problem, but found out they are
          > at least double the price of a small rotary vane vacuum pump.
          >
          > Rob
          >
          > At 04:54 01-10-2012, you wrote:
          > >One other thing Rob;
          > >
          > >I was told by a professional prototyping engineer that has been doing
          > >moulding and casting for 20+ yrs that the oil should be changed regularly
          > >in the vacuum pumps because the isocyanates get REALLY concentrated in
          > >there after vacuuming resin.
          > >
          > >On Sunday, September 30, 2012, Rob de Bie wrote:
          > >
          > > > **
          > > >
          > > >
          > > > Ray, thanks, that's a very good point indeed. One that I hadn't given
          > > > enough thought I must admit.
          > > >
          > > > Regarding the oil mist, I was also afraid that it would deplete the
          > > > pump's oil quantity fairly rapidly. At work we have a big old vacuum
          > > > pump, and its oil mist filter contains a lot of oil after a couple of
          > > > months. It is poured back in the pump every now and then.
          > > >
          > > > Rob
          > > >
          > > > At 16:08 30-09-2012, you wrote:
          > > > >Rob;
          > > > >
          > > > >I vent my vacuum pump exhaust outside since that mist also contains
          > > > >isocyanates from your resin.
          > > > >
          > > > >On Sunday, September 30, 2012, Rob de Bie wrote:
          > > > >
          > > > > > **
          > > > > >
          > > > > >
          > > > > > Tyla, I've got a similar pump, a slightly bigger model I think.
          > Mine
          > > > > > lacks an oil mist filter, and emits a fine white mist of oil at the
          > > > > > beginning of emptying the vacuum chamber. I tried to make all kinds
          > > > > > of filters, but it passes right through. Do you have the same
          > problem?
          > > > > >
          > > > > > Rob
          > > > > >
          > > > > > At 05:15 25-09-2012, you wrote:
          > > > > > >I waited and waited not really knowing if I was procrastinating
          > for
          > > > > > >safety reasons or just wanting a 'pretty' set up but I ended up
          > just
          > > > > > >getting one like this:
          > > > > > >
          > > > > > >
          > > > > > >
          > > > > > >
          > > > > > >http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130747094881
          > > > > > >
          > > > > > >All complete, chamber and pump all inclusive and I'm fine with
          > > > > > >having paid good $$$ for it. I KNOW I COULD have made it for a
          > > > > > >fraction and I have made some of my own other tools. This, for
          > some
          > > > > > >reason, I needed a pro's stamp of approval on and would do it
          > again.
          > > > > > >
          > > > > > >The way I thought of it was - would I just pay someone in the know
          > > > > > >an extra $100 just to go out and get this done for me. The answer
          > > > > > >was yes so after the fact I'm happy with my choice and no looking
          > > > back.
          > > > > > >
          > > > > > >BTW I was happy with the 6CFM
          > > > > > >
          > > > > > >Hope this helps
          > > > > > >
          > > > > > >Tyla @ http://obscurecreationsbytyla.blogspot.ca/
          > > > > > >
          > > > > > >
          > > > > > >
          > > > > > >------------------------------------
          > > > > > >
          > > > > > >Yahoo! Groups Links
          > > > > > >
          > > > > > >
          > > > > > >
          > > > > >
          > > > > >
          > > > >
          > > > >
          > > > >--
          > > > >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]
          > >
          > >
          > >
          > >------------------------------------
          > >
          > >Yahoo! Groups Links
          > >
          > >
          > >
          >
          >



          --
          Ray Kotke
          Recumbent Casting, LLC


          [Non-text portions of this message have been removed]
        • Ted Quick
          I don t quite see how Isocyanates could collect in the vacuum pump, since that s the main reactive component in ANY urethane, and it will always react with any
          Message 4 of 14 , Oct 1, 2012
            I don't quite see how Isocyanates could collect in the vacuum pump, since that's the main reactive component in ANY urethane, and it will always react with any OH group whenever it comes in contact. Since oils contain many Os and Hs I always thought that they would react and start building up solids in the oil. Of course it IS highly out of ratio, so maybe it's possible.

            What I AM sure of is that polyls will separate out when under vacuum and migrate into the pump. That would likely cause the oil to degrade since polyol may look like oil, but they are really made up multiple alcohols and various additives that can't be premixed with the Isocyanate (because they would react with it).

            Incidentally I know a bit about this because in college I studied RIM (urethane Reaction Injection Molding) systems with F. Melvin Sweeney as my Prof. I met him within a week of his publishing the first ever book (not a collection of articles, but a BOOK) on the subject, in August, 1979. He didn't have any RIM machine but taught us out of his book anyway. He's a chemist first and foremost.


            Ted Quick




            >________________________________
            > From: Rob de Bie <robdebie@...>
            >To: casting@yahoogroups.com
            >Sent: Monday, October 1, 2012 7:25 AM
            >Subject: Re: [casting] Re: Vacuum Chamber - WAS - Really old vacuum pump
            >
            >Ray, that's another thing I never considered. Do you possibly know
            >how the isocyanates affect the oil, or the pump itself? My chemistry
            >knowledge is way too limited to judge that.
            >
            >Maybe a membrane / diaphragm vacuum pump is the better choice here? I
            >looked for one, to solve the oil mist problem, but found out they are
            >at least double the price of a small rotary vane vacuum pump.
            >
            >Rob
            >
            >At 04:54 01-10-2012, you wrote:
            >>One other thing Rob;
            >>
            >>I was told by a professional prototyping engineer that has been doing
            >>moulding and casting for 20+ yrs that the oil should be changed regularly
            >>in the vacuum pumps because the isocyanates get REALLY concentrated in
            >>there after vacuuming resin.
            >>
            >>On Sunday, September 30, 2012, Rob de Bie wrote:
            >>
            >> > **
            >> >
            >> >
            >> > Ray, thanks, that's a very good point indeed. One that I hadn't given
            >> > enough thought I must admit.
            >> >
            >> > Regarding the oil mist, I was also afraid that it would deplete the
            >> > pump's oil quantity fairly rapidly. At work we have a big old vacuum
            >> > pump, and its oil mist filter contains a lot of oil after a couple of
            >> > months. It is poured back in the pump every now and then.
            >> >
            >> > Rob
            >> >
            >> > At 16:08 30-09-2012, you wrote:
            >> > >Rob;
            >> > >
            >> > >I vent my vacuum pump exhaust outside since that mist also contains
            >> > >isocyanates from your resin.
            >> > >
            >> > >On Sunday, September 30, 2012, Rob de Bie wrote:
            >> > >
            >> > > > **
            >> > > >
            >> > > >
            >> > > > Tyla, I've got a similar pump, a slightly bigger model I think. Mine
            >> > > > lacks an oil mist filter, and emits a fine white mist of oil at the
            >> > > > beginning of emptying the vacuum chamber. I tried to make all kinds
            >> > > > of filters, but it passes right through. Do you have the same problem?
            >> > > >
            >> > > > Rob
            >> > > >
            >> > > > At 05:15 25-09-2012, you wrote:
            >> > > > >I waited and waited not really knowing if I was procrastinating for
            >> > > > >safety reasons or just wanting a 'pretty' set up but I ended up just
            >> > > > >getting one like this:
            >> > > > >
            >> > > > >
            >> > > > >
            >> > > > >
            >> > > > >http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130747094881
            >> > > > >
            >> > > > >All complete, chamber and pump all inclusive and I'm fine with
            >> > > > >having paid good $$$ for it. I KNOW I COULD have made it for a
            >> > > > >fraction and I have made some of my own other tools. This, for some
            >> > > > >reason, I needed a pro's stamp of approval on and would do it again.
            >> > > > >
            >> > > > >The way I thought of it was - would I just pay someone in the know
            >> > > > >an extra $100 just to go out and get this done for me. The answer
            >> > > > >was yes so after the fact I'm happy with my choice and no looking
            >> > back.
            >> > > > >
            >> > > > >BTW I was happy with the 6CFM
            >> > > > >
            >> > > > >Hope this helps
            >> > > > >
            >> > > > >Tyla @ http://obscurecreationsbytyla.blogspot.ca/
            >> > > > >
            >> > > > >
            >> > > > >
            >> > > > >------------------------------------
            >> > > > >
            >> > > > >Yahoo! Groups Links
            >> > > > >
            >> > > > >
            >> > > > >
            >> > > >
            >> > > >
            >> > >
            >> > >
            >> > >--
            >> > >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]
            >>
            >>
            >>
            >>------------------------------------
            >>
            >>Yahoo! Groups Links
            >>
            >>
            >>
            >
            >
            >------------------------------------
            >
            >Yahoo! Groups Links
            >
            >
            >
            >
            >
            >

            [Non-text portions of this message have been removed]
          • mark treutelaar
            The pieces are coming out quite well . We will have to do a small amount of sanding on the inside. We made 2 boxes so far. We have anotherfinished  mold we
            Message 5 of 14 , Oct 1, 2012
              The pieces are coming out quite well . We will have to do a small amount of sanding on the inside. We made 2 boxes so far. We have anotherfinished  mold we would like to put the vent holes in . What size sharpened copper tubing would achieve this?   Thanks Mark


              From: Ted Quick <rim_molder@...>
              To: "casting@yahoogroups.com" <casting@yahoogroups.com>
              Sent: Monday, October 1, 2012 9:09 AM
              Subject: Re: [casting] Re: Vacuum Chamber - WAS - Really old vacuum pump


               
              I don't quite see how Isocyanates could collect in the vacuum pump, since that's the main reactive component in ANY urethane, and it will always react with any OH group whenever it comes in contact. Since oils contain many Os and Hs I always thought that they would react and start building up solids in the oil. Of course it IS highly out of ratio, so maybe it's possible.

              What I AM sure of is that polyls will separate out when under vacuum and migrate into the pump. That would likely cause the oil to degrade since polyol may look like oil, but they are really made up multiple alcohols and various additives that can't be premixed with the Isocyanate (because they would react with it).

              Incidentally I know a bit about this because in college I studied RIM (urethane Reaction Injection Molding) systems with F. Melvin Sweeney as my Prof. I met him within a week of his publishing the first ever book (not a collection of articles, but a BOOK) on the subject, in August, 1979. He didn't have any RIM machine but taught us out of his book anyway. He's a chemist first and foremost.

              Ted Quick

              >________________________________
              > From: Rob de Bie <mailto:robdebie%40xs4all.nl>
              >To: mailto:casting%40yahoogroups.com
              >Sent: Monday, October 1, 2012 7:25 AM
              >Subject: Re: [casting] Re: Vacuum Chamber - WAS - Really old vacuum pump
              >
              >Ray, that's another thing I never considered. Do you possibly know
              >how the isocyanates affect the oil, or the pump itself? My chemistry
              >knowledge is way too limited to judge that.
              >
              >Maybe a membrane / diaphragm vacuum pump is the better choice here? I
              >looked for one, to solve the oil mist problem, but found out they are
              >at least double the price of a small rotary vane vacuum pump.
              >
              >Rob
              >
              >At 04:54 01-10-2012, you wrote:
              >>One other thing Rob;
              >>
              >>I was told by a professional prototyping engineer that has been doing
              >>moulding and casting for 20+ yrs that the oil should be changed regularly
              >>in the vacuum pumps because the isocyanates get REALLY concentrated in
              >>there after vacuuming resin.
              >>
              >>On Sunday, September 30, 2012, Rob de Bie wrote:
              >>
              >> > **
              >> >
              >> >
              >> > Ray, thanks, that's a very good point indeed. One that I hadn't given
              >> > enough thought I must admit.
              >> >
              >> > Regarding the oil mist, I was also afraid that it would deplete the
              >> > pump's oil quantity fairly rapidly. At work we have a big old vacuum
              >> > pump, and its oil mist filter contains a lot of oil after a couple of
              >> > months. It is poured back in the pump every now and then.
              >> >
              >> > Rob
              >> >
              >> > At 16:08 30-09-2012, you wrote:
              >> > >Rob;
              >> > >
              >> > >I vent my vacuum pump exhaust outside since that mist also contains
              >> > >isocyanates from your resin.
              >> > >
              >> > >On Sunday, September 30, 2012, Rob de Bie wrote:
              >> > >
              >> > > > **
              >> > > >
              >> > > >
              >> > > > Tyla, I've got a similar pump, a slightly bigger model I think. Mine
              >> > > > lacks an oil mist filter, and emits a fine white mist of oil at the
              >> > > > beginning of emptying the vacuum chamber. I tried to make all kinds
              >> > > > of filters, but it passes right through. Do you have the same problem?
              >> > > >
              >> > > > Rob
              >> > > >
              >> > > > At 05:15 25-09-2012, you wrote:
              >> > > > >I waited and waited not really knowing if I was procrastinating for
              >> > > > >safety reasons or just wanting a 'pretty' set up but I ended up just
              >> > > > >getting one like this:
              >> > > > >
              >> > > > >
              >> > > > >
              >> > > > >
              >> > > > >http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130747094881
              >> > > > >
              >> > > > >All complete, chamber and pump all inclusive and I'm fine with
              >> > > > >having paid good $$$ for it. I KNOW I COULD have made it for a
              >> > > > >fraction and I have made some of my own other tools. This, for some
              >> > > > >reason, I needed a pro's stamp of approval on and would do it again.
              >> > > > >
              >> > > > >The way I thought of it was - would I just pay someone in the know
              >> > > > >an extra $100 just to go out and get this done for me. The answer
              >> > > > >was yes so after the fact I'm happy with my choice and no looking
              >> > back.
              >> > > > >
              >> > > > >BTW I was happy with the 6CFM
              >> > > > >
              >> > > > >Hope this helps
              >> > > > >
              >> > > > >Tyla @ http://obscurecreationsbytyla.blogspot.ca/
              >> > > > >
              >> > > > >
              >> > > > >
              >> > > > >------------------------------------
              >> > > > >
              >> > > > >Yahoo! Groups Links
              >> > > > >
              >> > > > >
              >> > > > >
              >> > > >
              >> > > >
              >> > >
              >> > >
              >> > >--
              >> > >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]
              >>
              >>
              >>
              >>------------------------------------
              >>
              >>Yahoo! Groups Links
              >>
              >>
              >>
              >
              >
              >------------------------------------
              >
              >Yahoo! Groups Links
              >
              >
              >
              >
              >
              >

              [Non-text portions of this message have been removed]




              [Non-text portions of this message have been removed]
            • Rob de Bie
              Ray, I used a Vacuubrand pump in a lab long time ago. So I checked out the Vacuubrand website, and they categorize their pumps as down to 70 mbar , down to 7
              Message 6 of 14 , Oct 2, 2012
                Ray, I used a Vacuubrand pump in a lab long time ago. So I checked
                out the Vacuubrand website, and they categorize their pumps as 'down
                to 70 mbar', 'down to 7 mbar', 'down to 1.5 mbar' and 'down to 0.6
                mbar'. I'm not sure what is exactly needed, I'm currently going down
                to less than 0.6 mbar because the equipment allows it. The simplest
                pump in the 'down to 1.5 mbar' categorie is the MD-1, and I see that
                on the net for 2400$ new. Ouch!

                Rob


                At 15:31 01-10-2012, you wrote:
                >I was always under the impression that you can't pull a good enough volume
                >or vacuum with a diaphragm pump. Don't really know, but that's what John
                >told me (the prototyping engineer).
                >
                >As for the oil in the previous message, I understand that it causes the oil
                >to break down rather quickly, and makes it "gummy"; hence the need to
                >change it more often. Since they utilize their vacuum chamber almost
                >continuously, they change the oil monthly in their pumps.
                >
                >On Mon, Oct 1, 2012 at 7:25 AM, Rob de Bie <robdebie@...> wrote:
                >
                > > **
                > >
                > >
                > > Ray, that's another thing I never considered. Do you possibly know
                > > how the isocyanates affect the oil, or the pump itself? My chemistry
                > > knowledge is way too limited to judge that.
                > >
                > > Maybe a membrane / diaphragm vacuum pump is the better choice here? I
                > > looked for one, to solve the oil mist problem, but found out they are
                > > at least double the price of a small rotary vane vacuum pump.
                > >
                > > Rob
                > >
                > > At 04:54 01-10-2012, you wrote:
                > > >One other thing Rob;
                > > >
                > > >I was told by a professional prototyping engineer that has been doing
                > > >moulding and casting for 20+ yrs that the oil should be changed regularly
                > > >in the vacuum pumps because the isocyanates get REALLY concentrated in
                > > >there after vacuuming resin.
                > > >
                > > >On Sunday, September 30, 2012, Rob de Bie wrote:
                > > >
                > > > > **
                > > > >
                > > > >
                > > > > Ray, thanks, that's a very good point indeed. One that I hadn't given
                > > > > enough thought I must admit.
                > > > >
                > > > > Regarding the oil mist, I was also afraid that it would deplete the
                > > > > pump's oil quantity fairly rapidly. At work we have a big old vacuum
                > > > > pump, and its oil mist filter contains a lot of oil after a couple of
                > > > > months. It is poured back in the pump every now and then.
                > > > >
                > > > > Rob
                > > > >
                > > > > At 16:08 30-09-2012, you wrote:
                > > > > >Rob;
                > > > > >
                > > > > >I vent my vacuum pump exhaust outside since that mist also contains
                > > > > >isocyanates from your resin.
                > > > > >
                > > > > >On Sunday, September 30, 2012, Rob de Bie wrote:
                > > > > >
                > > > > > > **
                > > > > > >
                > > > > > >
                > > > > > > Tyla, I've got a similar pump, a slightly bigger model I think.
                > > Mine
                > > > > > > lacks an oil mist filter, and emits a fine white mist of oil at the
                > > > > > > beginning of emptying the vacuum chamber. I tried to make all kinds
                > > > > > > of filters, but it passes right through. Do you have the same
                > > problem?
                > > > > > >
                > > > > > > Rob
                > > > > > >
                > > > > > > At 05:15 25-09-2012, you wrote:
                > > > > > > >I waited and waited not really knowing if I was procrastinating
                > > for
                > > > > > > >safety reasons or just wanting a 'pretty' set up but I ended up
                > > just
                > > > > > > >getting one like this:
                > > > > > > >
                > > > > > > >
                > > > > > > >
                > > > > > > >
                > > > > > > >http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130747094881
                > > > > > > >
                > > > > > > >All complete, chamber and pump all inclusive and I'm fine with
                > > > > > > >having paid good $$$ for it. I KNOW I COULD have made it for a
                > > > > > > >fraction and I have made some of my own other tools. This, for
                > > some
                > > > > > > >reason, I needed a pro's stamp of approval on and would do it
                > > again.
                > > > > > > >
                > > > > > > >The way I thought of it was - would I just pay someone in the know
                > > > > > > >an extra $100 just to go out and get this done for me. The answer
                > > > > > > >was yes so after the fact I'm happy with my choice and no looking
                > > > > back.
                > > > > > > >
                > > > > > > >BTW I was happy with the 6CFM
                > > > > > > >
                > > > > > > >Hope this helps
                > > > > > > >
                > > > > > > >Tyla @ http://obscurecreationsbytyla.blogspot.ca/
                > > > > > > >
                > > > > > > >
                > > > > > > >
                > > > > > > >------------------------------------
                > > > > > > >
                > > > > > > >Yahoo! Groups Links
                > > > > > > >
                > > > > > > >
                > > > > > > >
                > > > > > >
                > > > > > >
                > > > > >
                > > > > >
                > > > > >--
                > > > > >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]
                > > >
                > > >
                > > >
                > > >------------------------------------
                > > >
                > > >Yahoo! Groups Links
                > > >
                > > >
                > > >
                > >
                > >
                >
                >
                >
                >--
                >Ray Kotke
                >Recumbent Casting, LLC
                >
                >
                >[Non-text portions of this message have been removed]
                >
                >
                >
                >------------------------------------
                >
                >Yahoo! Groups Links
                >
                >
                >
              • Rob de Bie
                Ted, thanks for the chemistry lesson! Resin casting just got a bit more complicated for me :-) I will keep an eye on the oil. Rob
                Message 7 of 14 , Oct 2, 2012
                  Ted, thanks for the chemistry lesson! Resin casting just got a bit
                  more complicated for me :-) I will keep an eye on the oil.

                  Rob

                  At 16:09 01-10-2012, you wrote:
                  >I don't quite see how Isocyanates could collect in the vacuum pump,
                  >since that's the main reactive component in ANY urethane, and it
                  >will always react with any OH group whenever it comes in contact.
                  >Since oils contain many Os and Hs I always thought that they would
                  >react and start building up solids in the oil. Of course it IS
                  >highly out of ratio, so maybe it's possible.
                  >
                  >What I AM sure of is that polyls will separate out when under vacuum
                  >and migrate into the pump. That would likely cause the oil to
                  >degrade since polyol may look like oil, but they are really made up
                  >multiple alcohols and various additives that can't be premixed with
                  >the Isocyanate (because they would react with it).
                  >
                  >Incidentally I know a bit about this because in college I studied
                  >RIM (urethane Reaction Injection Molding) systems with F. Melvin
                  >Sweeney as my Prof. I met him within a week of his publishing the
                  >first ever book (not a collection of articles, but a BOOK) on the
                  >subject, in August, 1979. He didn't have any RIM machine but taught
                  >us out of his book anyway. He's a chemist first and foremost.
                  >
                  >
                  >Ted Quick
                  >
                  >
                  >
                  >
                  > >________________________________
                  > > From: Rob de Bie <robdebie@...>
                  > >To: casting@yahoogroups.com
                  > >Sent: Monday, October 1, 2012 7:25 AM
                  > >Subject: Re: [casting] Re: Vacuum Chamber - WAS - Really old vacuum pump
                  > >
                  > >Ray, that's another thing I never considered. Do you possibly know
                  > >how the isocyanates affect the oil, or the pump itself? My chemistry
                  > >knowledge is way too limited to judge that.
                  > >
                  > >Maybe a membrane / diaphragm vacuum pump is the better choice here? I
                  > >looked for one, to solve the oil mist problem, but found out they are
                  > >at least double the price of a small rotary vane vacuum pump.
                  > >
                  > >Rob
                  > >
                  > >At 04:54 01-10-2012, you wrote:
                  > >>One other thing Rob;
                  > >>
                  > >>I was told by a professional prototyping engineer that has been doing
                  > >>moulding and casting for 20+ yrs that the oil should be changed regularly
                  > >>in the vacuum pumps because the isocyanates get REALLY concentrated in
                  > >>there after vacuuming resin.
                  > >>
                  > >>On Sunday, September 30, 2012, Rob de Bie wrote:
                  > >>
                  > >> > **
                  > >> >
                  > >> >
                  > >> > Ray, thanks, that's a very good point indeed. One that I hadn't given
                  > >> > enough thought I must admit.
                  > >> >
                  > >> > Regarding the oil mist, I was also afraid that it would deplete the
                  > >> > pump's oil quantity fairly rapidly. At work we have a big old vacuum
                  > >> > pump, and its oil mist filter contains a lot of oil after a couple of
                  > >> > months. It is poured back in the pump every now and then.
                  > >> >
                  > >> > Rob
                  > >> >
                  > >> > At 16:08 30-09-2012, you wrote:
                  > >> > >Rob;
                  > >> > >
                  > >> > >I vent my vacuum pump exhaust outside since that mist also contains
                  > >> > >isocyanates from your resin.
                  > >> > >
                  > >> > >On Sunday, September 30, 2012, Rob de Bie wrote:
                  > >> > >
                  > >> > > > **
                  > >> > > >
                  > >> > > >
                  > >> > > > Tyla, I've got a similar pump, a slightly bigger model I think. Mine
                  > >> > > > lacks an oil mist filter, and emits a fine white mist of oil at the
                  > >> > > > beginning of emptying the vacuum chamber. I tried to make all kinds
                  > >> > > > of filters, but it passes right through. Do you have the
                  > same problem?
                  > >> > > >
                  > >> > > > Rob
                  > >> > > >
                  > >> > > > At 05:15 25-09-2012, you wrote:
                  > >> > > > >I waited and waited not really knowing if I was procrastinating for
                  > >> > > > >safety reasons or just wanting a 'pretty' set up but I
                  > ended up just
                  > >> > > > >getting one like this:
                  > >> > > > >
                  > >> > > > >
                  > >> > > > >
                  > >> > > > >
                  > >> > > > >http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130747094881
                  > >> > > > >
                  > >> > > > >All complete, chamber and pump all inclusive and I'm fine with
                  > >> > > > >having paid good $$$ for it. I KNOW I COULD have made it for a
                  > >> > > > >fraction and I have made some of my own other tools. This, for some
                  > >> > > > >reason, I needed a pro's stamp of approval on and would
                  > do it again.
                  > >> > > > >
                  > >> > > > >The way I thought of it was - would I just pay someone in the know
                  > >> > > > >an extra $100 just to go out and get this done for me. The answer
                  > >> > > > >was yes so after the fact I'm happy with my choice and no looking
                  > >> > back.
                  > >> > > > >
                  > >> > > > >BTW I was happy with the 6CFM
                  > >> > > > >
                  > >> > > > >Hope this helps
                  > >> > > > >
                  > >> > > > >Tyla @ http://obscurecreationsbytyla.blogspot.ca/
                  > >> > > > >
                  > >> > > > >
                  > >> > > > >
                  > >> > > > >------------------------------------
                  > >> > > > >
                  > >> > > > >Yahoo! Groups Links
                  > >> > > > >
                  > >> > > > >
                  > >> > > > >
                  > >> > > >
                  > >> > > >
                  > >> > >
                  > >> > >
                  > >> > >--
                  > >> > >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]
                  > >>
                  > >>
                  > >>
                  > >>------------------------------------
                  > >>
                  > >>Yahoo! Groups Links
                  > >>
                  > >>
                  > >>
                  > >
                  > >
                  > >------------------------------------
                  > >
                  > >Yahoo! Groups Links
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  >
                  >[Non-text portions of this message have been removed]
                  >
                  >
                  >
                  >------------------------------------
                  >
                  >Yahoo! Groups Links
                  >
                  >
                  >
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