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Old 02-27-2021, 09:30 AM
lawnboy lawnboy is offline
Join Date: Mar 2019
Location: miles city
Posts: 24
Default scale for epoxy?

what is everyone using for a scale to measure out epoxy? I don't know how to tell how accurate they are when buying one. if anyone has any advice id appreciate it.
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Old 02-27-2021, 09:41 AM
PhatRV PhatRV is offline
Join Date: Mar 2018
Location: Buena Park, California
Posts: 436

You can buy the epoxy pump that meters out a fixed ratio of epoxy and hardener. West System has the pumps that sets the 5:1 ratio for its mixture.

Alternatively, if you are using only small amount of epoxy, a postal scale works fine as the densities of epoxy and hardener are similar. In the case of the West System, measure the components by weight. This is the system I used most of the time since I don't mix a lot of epoxy for the RV8. Also, pumping put too much epoxy will make it flash off very quickly, rendering most of the epoxy unusable.
RV8 standard build: Empennage 99% completed
Wing -- Closed
Fuselage -- Canopy Done. Fiberglass 80%
Avionics Installation -- 90%
Firewall Forward -- Prep for cowl install
Electrical -- 90%

Donation paid through 2021
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Old 02-27-2021, 09:42 AM is offline
Join Date: Jan 2017
Location: Battle Ground WA
Posts: 186

Amazon has bunches and bunches of digital scales. Most any one will get the job done. Put mixing container on first, then turn on, add desired amount of resin, use calculator to do the math. Put in reading off scale and multiply times 1.10 for a ten to one to one ratio. That is the new weight of resin and hardener. Pour, mix, don't drink.
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Old 02-27-2021, 09:46 AM
Kyle Boatright Kyle Boatright is offline
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,460

I have one of these. Works great. There are a thousand similar ones.
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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Old 02-27-2021, 09:56 AM
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jcarne jcarne is offline
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,647

I used this one. Pretty much anything that measures in grams will be accurate enough for sure! West systems 105/206 has a pretty wide envelope you can be in. If you measure by weight on West it is 5.36 to 1 but 5 to 1 also is in range.
Jereme Carne
RV-7A Flying as of 03/2021
Exempt but gladly paying!
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Old 02-27-2021, 10:36 AM
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wirejock wirejock is offline
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 4,383
Default Mix by weight

Read every thread Dan Horton posted. I wrote as much as I could in a document. Fiberglass. Look in my blog.
Harbor fright has some nice small digital scales as well. I keep epoxy and hardener in dispensing bottles. Easy to measure down to drops. Very accurate.
I also have a calculator on my blog. It helps reduce waste.
Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 01/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
Empennage, wings, fuse, finishing kit, now FWF
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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Old 02-27-2021, 10:53 AM
John Tierney John Tierney is offline
Join Date: Jan 2006
Location: Vonore, TN
Posts: 447

Walmart digital kitchen scale in a gallon size zip lock bag.
John Tierney
Vonore, TN
RV-7A - N777JT Flying
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Old 02-27-2021, 12:11 PM
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9GT 9GT is offline
Join Date: Jan 2010
Location: Southern Michigan
Posts: 2,111

Be careful buying the cheap digital scales. They vary greatly in accuracy. Had the metered Sticky Stuff pump building the Cozy, but sold that and opted for the scale method on the RV. West pumps are good but they do spit at times after long periods of inactivity. Not really concerned though as I only use West Systems for final fill and finish. MGS is my go to for anything structural. HF sells a small digital pocket scale that is very accurate and sensitive. I use that for small batches of epoxy and for measuring out flamemaster tank sealant, but for the larger 16 oz clear plastic deli containers from GFS, those don't fit well on that scale and I end up using the larger 10# capacity postal scale I use here at home. The digital kitchen scale I have at the hanger is junk IMHO and needs replacement. Not at all sensitive enough and I question its accuracy every time I use it.
David C.
Howell, MI
RV-10: #41686 Under Construction
RV-9A: #90949 Under Construction
RV-10: #40637 Completed/Sold 2016
Cozy MKIV:#656 Completed/Sold 2007
"Donor Exempt" but donated through Dec. 2021
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Old 02-27-2021, 12:40 PM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 9,950

Old Faithful. Rescued from a trash can 40 years ago.
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Barrett IO-390

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Old 02-27-2021, 12:56 PM
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Longez Longez is offline
Join Date: May 2009
Location: KS
Posts: 198

Like David, I used a Sticky Stuff pump for large layups when building my Long-EZ, but now that I only do small projects, I just use a triple beam scale. I picked an OHaus used in like new condition for $35. I tried the digital scales, but they are too "nervous", and I probably never had one that was good enough to trust. I totally trust the triple beam.

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Like Larry, I like to put hardener and resin in dispensing bottles like sold for ketchup.

The triple beam has a knob/weight on the end that lets you zero out the scale for the common size plastic cup you like to mix with. If you stick with the same size container, you just have to do this once.

I keep a card near the scale that has resin and hardener mixing weights for all the batch sizes I will typically mix. With the triple beam, you start with the hardener, and set the weight down to the 0.1 g that you need, and then just dribble in the hardener while watching the beam end pointer until it rises up to the zero mark. There is no trying to remember the digital target and watching the numbers jump around. Just nice, well damped, movement up to the center as you add material.

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After the hardener has been added, you just slide the pointers up to the total weight of hardener and resin, and dribble in resin until the beam pointer again reads zero and you are done.

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