What kind of positive displacement rotary pump for epoxy?
 

Measuring epoxy is a pain. The mustard pumps are fine if you need 1 to 8 oz. (30 ml. to 200 ml.), but if you need a quart, they're a PITA.
Weighing is hard to do with the level of repeatable precision that i'd like. There's no practical and reliable way to precisely measure a small (5ml.) batch.
There are also commercial epoxy measuring pumps, the "Sticky Stuff Dispenser" and "Goo Grinder" from These folks which look like a good start, but seem overpriced to me. I'm envisioning perhaps a pair of gear pumps, geared tpogether at 5:1 or whatever. They could be operated by a hand crank or spun with something powered.

So, my question is this- Who can recommend a positive displacement rotary pump that is inexpensive and will tolerate the nasty chemicals of epoxy, hardeners and solvents?

Jim Conlin wrote:
Measuring epoxy is a pain. The mustard pumps are fine if you need 1 to
8 oz. (30 ml. to 200 ml.), but if you need a quart, they're a PITA.
Weighing is hard to do with the level of repeatable precision that i'd
like. There's no practical and reliable way to precisely measure a
small (5ml.) batch.
There are also commercial epoxy measuring pumps, the "Sticky Stuff
Dispenser" and "Goo Grinder" from These folks
http://www.michaelengineering.com/ which look like a good start, but
seem overpriced to me. I'm envisioning perhaps a pair of gear pumps,
geared tpogether at 5:1 or whatever. They could be operated by a hand
crank or spun with something powered.

So, my question is this- Who can recommend a positive displacement
rotary pump that is inexpensive and will tolerate the nasty chemicals of
epoxy, hardeners and solvents?

http://www1.mscdirect.com/CGI/NNLMK3...07854&PMPROD=9

I suspect a set-up based on industrial metering pumps would be more
expensive than a "Goo-Grinder" (they say 'call for price' which always
****es me off... is it some big secret?) unless you could find a couple
on E-Bay. There are several models that have built in digital
controllers, you could punch in any ratio you want and it would be very
precise. Another possible key word to try is "injection pump" although
sometimes this means a venturi type.

It is a real PITA to mix larger batches of epoxy but the real slow down
I'm experiencing is mixing in the fillers. I've been experimenting with
bond strength with micro fibers and they really do help a lot. It's
surprising the difference in rigidity between a panel laid up with
microfibers & one with straight resin. But it's slow & nasty to mix. Any
advice on this one?

Fresh Breezes- Doug King

It sounds like you're making a problem for yourself.

At least for System Three (the only one I'm really familiar with), the
measuring error tolerance is about 10% excess hardener and 20% excess resin.
Thus, it is better to err on the side of too much resin rather than too much
hardener, This tolerance combined with a 2:1 volume ratio make the purchase
of expensive metering equipment unnecessary. (Quote from "The Epoxy Book.")

Marked containers or weighing systems will give quite adequate accuracy.

For really small amounts, mix a larger amount and throw away the excess --
cheaper than a fancy piece of equipment that requires space and maintenance.

Roger

http://home.earthlink.net/~derbyrm

"Jim Conlin" wrote in message
...
Measuring epoxy is a pain. The mustard pumps are fine if you need 1 to 8
oz. (30 ml. to 200 ml.), but if you need a quart, they're a PITA.
Weighing is hard to do with the level of repeatable precision that i'd
like. There's no practical and reliable way to precisely measure a small
(5ml.) batch.
There are also commercial epoxy measuring pumps, the "Sticky Stuff
Dispenser" and "Goo Grinder" from These folks which look like a good start,
but seem overpriced to me. I'm envisioning perhaps a pair of gear pumps,
geared tpogether at 5:1 or whatever. They could be operated by a hand crank
or spun with something powered.

So, my question is this- Who can recommend a positive displacement rotary
pump that is inexpensive and will tolerate the nasty chemicals of epoxy,
hardeners and solvents?

I have the middle size West pump. It dispenses about 1 oz of resin+hardner per stroke and is fine up to about a pint. For larger volumes (sometimes a gallon or two in a batch) I pour the resin into a pail and use a standard graduated paint rule. The paint rule has scales for 2:1, 3:1 and 5:1 so I can use it for other epoxies. I use the cheaper 2:1 stuff for non-structural filling and ProSet is 3:1.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Jim Conlin" wrote in message ...
Measuring epoxy is a pain. The mustard pumps are fine if you need 1 to 8 oz. (30 ml. to 200 ml.), but if you need a quart, they're a PITA.
Weighing is hard to do with the level of repeatable precision that i'd like. There's no practical and reliable way to precisely measure a small (5ml.) batch.
There are also commercial epoxy measuring pumps, the "Sticky Stuff Dispenser" and "Goo Grinder" from These folks which look like a good start, but seem overpriced to me. I'm envisioning perhaps a pair of gear pumps, geared tpogether at 5:1 or whatever. They could be operated by a hand crank or spun with something powered.

So, my question is this- Who can recommend a positive displacement rotary pump that is inexpensive and will tolerate the nasty chemicals of epoxy, hardeners and solvents?

I bought one of the "propeller on the end of a stalk," Stainless Steel,
gadgets designed for use in a variable speed electric drill. (I suspect
very slow is the proper setting, based on kitchen mixer experience.) I
haven't mixed a big enough batch yet to justify cleaning it afterward, but
you might experiment with some of the cheap (disposable) equivalents sold
for mixing paint.

Digging thru the "Goo Grinder" web site I found a price of $297 USD for the
smallest which tallies with the "Type A Pump" that System Three used to sell
for $300. A friend had one for use in building his experimental aircraft,
and for that kind of job it seemed to pay off. Rather a different
application than coating plywood.

Roger

http://home.earthlink.net/~derbyrm

"DSK" wrote in message
.. .
Jim Conlin wrote:
Measuring epoxy is a pain. The mustard pumps are fine if you need 1 to 8
oz. (30 ml. to 200 ml.), but if you need a quart, they're a PITA.
Weighing is hard to do with the level of repeatable precision that i'd
like. There's no practical and reliable way to precisely measure a small
(5ml.) batch.
There are also commercial epoxy measuring pumps, the "Sticky Stuff
Dispenser" and "Goo Grinder" from These folks
http://www.michaelengineering.com/ which look like a good start, but
seem overpriced to me. I'm envisioning perhaps a pair of gear pumps,
geared tpogether at 5:1 or whatever. They could be operated by a hand
crank or spun with something powered.
So, my question is this- Who can recommend a positive displacement
rotary pump that is inexpensive and will tolerate the nasty chemicals of
epoxy, hardeners and solvents?

http://www1.mscdirect.com/CGI/NNLMK3...07854&PMPROD=9

I suspect a set-up based on industrial metering pumps would be more
expensive than a "Goo-Grinder" (they say 'call for price' which always
****es me off... is it some big secret?) unless you could find a couple on
E-Bay. There are several models that have built in digital controllers,
you could punch in any ratio you want and it would be very precise.
Another possible key word to try is "injection pump" although sometimes
this means a venturi type.

It is a real PITA to mix larger batches of epoxy but the real slow down
I'm experiencing is mixing in the fillers. I've been experimenting with
bond strength with micro fibers and they really do help a lot. It's
surprising the difference in rigidity between a panel laid up with
microfibers & one with straight resin. But it's slow & nasty to mix. Any
advice on this one?

Fresh Breezes- Doug King

Subject

I buy epoxy resin in 500 lb drums (55 Gal) and hardner in 40 lb pails (5
gal).

I mix this 5:1 by weight, 4:1 by volume.

Designed and built a resin pumpng system consisting of a pair of 1/2"
NPT Oberdorfer bronze gear pumps that are coupled together in the proper
ratio by chain and sprockets.

The entire thing is then powered with a 1/2HP motor controlled by a foot
switch. driving a 7:1 belt reduction set of sheaves.

Use a drum heater in the winter to keep the resin viscosity under control.

Typical batch is about 1.5-2 quarts at a time.

Use a Jiffy mixer, powered by a drill motor, controlled by another foot
switch to do the mixing.

It has worked well for years now.

Lew

Can you recommend a source for the pumps?

"Lew Hodgett" wrote in message
ink.net...
Subject

I buy epoxy resin in 500 lb drums (55 Gal) and hardner in 40 lb pails (5
gal).

I mix this 5:1 by weight, 4:1 by volume.

Designed and built a resin pumpng system consisting of a pair of 1/2"
NPT Oberdorfer bronze gear pumps that are coupled together in the proper
ratio by chain and sprockets.

The entire thing is then powered with a 1/2HP motor controlled by a foot
switch. driving a 7:1 belt reduction set of sheaves.

Use a drum heater in the winter to keep the resin viscosity under control.

Typical batch is about 1.5-2 quarts at a time.

Use a Jiffy mixer, powered by a drill motor, controlled by another foot
switch to do the mixing.

It has worked well for years now.

Lew

An Update:


Snip

Use a Jiffy mixer, powered by a drill motor, controlled by another foot
switch to do the mixing.


Sooner or later it is time to clean the Jiffy Mixer.

Since it is S/S, a 2,800F propane flame does a great job of burning off
the hardened epoxy with out harming the S/S mixer.

Don't try this on plain carbon steel mixers.

Lew

Jim Conlin wrote:
Measuring epoxy is a pain. The mustard pumps are fine if you need 1 to
8 oz. (30 ml. to 200 ml.), but if you need a quart, they're a PITA.
Weighing is hard to do with the level of repeatable precision that i'd
like. There's no practical and reliable way to precisely measure a
small (5ml.) batch.
There are also commercial epoxy measuring pumps, the "Sticky Stuff
Dispenser" and "Goo Grinder" from These folks
http://www.michaelengineering.com/ which look like a good start, but
seem overpriced to me. I'm envisioning perhaps a pair of gear pumps,
geared tpogether at 5:1 or whatever. They could be operated by a hand
crank or spun with something powered.

So, my question is this- Who can recommend a positive displacement
rotary pump that is inexpensive and will tolerate the nasty chemicals of
epoxy, hardeners and solvents?

I'm using an inexpensive digital scale. It was about $40.

Reads to 12 kg +/- 5 grams when over 2000 grams. That's max
of 0.25% and close enough for me. Cover it with plastic and
keep the epoxy off it. I regularly mix up to 8-9 kg batches
with no difficulty.

Below 2000 grams it is accurate to +/-1 grams which is good
down to about 50 grams if I am careful. 5ml is sooo tiny I
can't even think about it. Perhaps a syringe??

Evan Gatehouse