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Inexpensive Epoxy Pump

inexpensive epoxy pump

This epoxy pump is made from West Systems pump bodies which cost around $8/pair from Aircraft Spruce or Wicks Aircraft and a set of Hefty freezer containers ($3 for 3) at Safeway.  The spacer in the hardener pump can be shortened to allow for 50% of the stroke to get the proper ratio on MGS L285 (or you can shorten it to allow 45% of the stroke on MGS L335 and  some other epoxies).  It's normally set for 20% of the stroke for West System epoxy.  I made the frame from some scrap pine laying around my shop.  The MGS epoxy hardener has a tendency to crystallize if exposed to CO2 so you must protect it from the atmosphere.  I do this two ways:

First, the holes in the reservoir lids are undersized (7/8") for a press fit  of the pump bodies and the lids have only a small razor slit to allow air to replace the used hardener/resin.   This works if the pump is kept in an environment where the temperature is constant.  If the temperature varies continuously, then the airspace above the hardener will expand and contract and eventually the hardener will get contaminated with CO2.  (A workaround for this would be to use a plastic bag above the epoxy that allowed air to come into the container to replace the epoxy as it is used, but keep that air from coming in contact with the epoxy.  For example, you could cut a section of a straw and hot glue it to the lid and then use a rubber band to attach the plastic bag to the straw inside the container.  This would fill with air as the epoxy was used and would not allow that air to come in contact with the epoxy.  --  Thanks Ray! )

Second, when finished with a layup, I cut the finger off a used latex glove and cover the hardener pump nozzle by securing it with a rubber band.  This prevents the pump nozzle from clogging with crystallized hardener.

I have had MGS epoxy in this pump for more than 6 months now and had absolutely no problems with crystallization of the hardener.

It's also a very portable setup.  My friend needed some epoxy to do some repairs on his LongEZ out at the airport and he was able to take everything with him with no difficulty.

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