Mixing stations?

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TUGMYWAY
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Mixing stations?

Post by TUGMYWAY » Fri Aug 02, 2013 11:03 am

Could some of you builders give me some pointers on you mixing stations. Did you use pumps? What type? Other ways of mixing? Even better maybe some photos?
Thanks.
Randy

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Bill CNC
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Re: Mixing stations?

Post by Bill CNC » Fri Aug 02, 2013 12:03 pm

Tug,

I use pumps and/or weigh my mixes. It all depends on the size of the job. If it's 8-16 oz or so, IO use the pumps for speed, If it's under that, I weigh it as the pumps will pump to much. If it's over that, ... I also weigh it because I don't want to have to count 20 pumps. I also keep my epoxy at 75-80*.

I get my pumps from the epoxy MFG's (I use more than one MFG) as it's designs to meter the epoxy for that particular brand. When mixing, I start by scraping the sides and bottom, then mix as normal by continually rotating the container around as I mix and after (2) revolution of the container, I scrape the sides and bottom again doing this until fully mixed. I don't pour into another cup and remix as valuable time is wasted in my opinion, ... I just don't use the bottom 3/16". Some think I'm wasting epoxy, but I think switching to another cup is wasting a cup because what's left in the old cup, ... is about 3/16" of epoxy.

Bill
Bill

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BayouBengal
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Re: Mixing stations?

Post by BayouBengal » Fri Aug 02, 2013 2:03 pm

I've used SystemThree epoxy products exclusively on this latest build and have been very happy with the results of mixing strictly by weight. Weighing gives you very accurate portions and allows you to do the whole operation in a single disposable cup without trying to eyeball any lines. Also, it allows you to mix any amount you want. You don't have to use any number of full pump strokes or mix an amount commensurate with the lines available on your measuring cup.

Having accurate portions will give you piece of mind that your joints are going to hold and your laminations are going to remain true. If you don't have accurate portions of part A and B, you will be left with uncured resin or hardener in your epoxy. When you go to sand your boat, you'll know this because your sandpaper will clog instantly. I just finish sanding down my build with almost no clogging, and I can tell you that this never happened when I was eyeballing lines on a cup.

I use cheap disposable plastic cups of varying sizes, but particularly like the wider shorter cocktail cups because it's easier to mix and remove the epoxy from these. I mix everything on the scale with a calculator nearby. I weight the cup and zero the scale. Put in some part A, then calculate the total weight I should come to with the part A and B mixed together. For example; most SystemThree products are ratiod to 44 parts Part B hardener to 100 parts Part A resin, so if I pour in 100 grams of resin, I need to add part B hardener until the scale reads 144 grams. I slowly add the part B to reach that weight. If working with very small volumes, I'll use a syringe to slowly inject the part B so that I can control it. Very easy to do and everything can be done in a single cheap unmarked throw-away cup.

I probably should use a better scale. I use a cheap one from Harbor Freight which if like most everything else Harbor Freight sells, it's probably not that accurate. But I expect it's still quite a bit more accurate than eyeballing lines on a cup.

Randy, I'm excited about you starting your build and have viewed some of your other postings. Sounds like you already know this, but FYI, you'll be working with epoxy a lot, a whole lot. With that being said, I strongly recommend reviewing the SystemThree's Epoxy book (whether you use SystemThree or not) http://www.systemthree.com/reslibrary/l ... y_Book.pdf. It's something that I wish I had read before my first build. Good Luck.

khundley
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Re: Mixing stations?

Post by khundley » Fri Aug 02, 2013 9:03 pm

ON the guitar building side, I use System 3 as well as other epoxies, and we have always recommended to each other to do the initial mix, then pour into another container and mix some more. This helps for a number of reasons....it eliminates any globs stuck to the sides mixing at the last second in one container, helps if there is contamination (wood flour or or glass or whatever) getting picked up and mixed at the last second, and ensures that whatever ends up in the second container is ALL that will get mixed in, and then gets mixed as well as or long as you mix for. I poo pooed that the first couple times and tried it the second few times, and there was a noticeable difference in the quality of what I applied, both in clarity and consistence. Just a thought. I will continue to use this method when I start.
Ken Hundley
http://www.nocturnalguitars.com

So, my big brother was playing guitar and I figured I'd try it too.
- Stevie Ray Vaughan

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Ibrew2be
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Re: Mixing stations?

Post by Ibrew2be » Sat Aug 03, 2013 5:59 pm

I really like the idea of measuring by weight whenever possible. It's simply more accurate than doing things by volume.

This leads me to a question for those folks measuring their epoxy by weight: Do you correct for differences in specific gravity? I've not researched this exhaustively, but from what I've seen in the physical properties cited in manufacturers' Material Safety Data Sheets, there can be a difference of over 15% between the SG of the resin vs. that of the hardener.
Barry Shantz

Imp built and launched. Thinking hard about Boat 2.0

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