An absurd but maybe good idea for dispensing epoxy

Started by JasonGotaProblem, October 14, 2021, 01:50:05 PM

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jurelometer

#15
Quote from: Jeri on October 14, 2021, 11:24:45 PM
Most rod thread resins are mixed by volume, and an easy way to mix with repeated accuracy is to use plunger bottles. Like those used on some shampoos, sanitiser dispensers, etc, which is exactly what we have been using for the last 10 years plus. Simply depress the plunger and a set volume comes out of of the resin bottle, repeat on the hardener bottle, and mix. Multiples can be done for bigger rods or long rods, just don't lose count.

The bottles are usually opaque, so relative short term storage is rarely a problem, long term storage can be effected by storing in a dark cupboard. Doesn't need cleaning, though periodically we change the plungers and bottles - once every couple of years. Just have to do a little research initially to find the plunger bottle size that suits your application.

Sounds like a good idea for folks that are fairly regular mixing batches.  This is how some fiberglass shops measure/ dispense epoxy.  I think that syringes are a better tool for the home builder.  Not as fast for dispensing. , but smaller quantities, and you can measure  separately before mixing


BUT:  If it can be mixed by volume, it can be mixed by weight. and scales are cheap, and relatively fast.  And more accurate.  And no dispensing equipment to clean or refill.  

Plungers (and to a lesser extent syringes)  are fast, but not necessarily accurate.  Both plungers have to dispense the same volume (assuming 50/50) per stroke, and will only be accurate if you dispense in full strokes.  So you need a set of matched plungers of a useful volume that you trust to be manufactured accurately.   Plus the plunger starts sucking up air once you get toward the bottom, meaning that the last 5-10% of resin is not usable with the plunger. and any time you get an air bubble in the stroke, that batch is screwed  [update:  oops- Jeri also posted this].    Not a big deal for a regular builder, who can refill the bottle, but a home builder doing a few rods plus a repair or two per year should only be buying smaller quantities as needed.  Unlike Polyester resins, where a range of catalyst quantities will work- the two parts of epoxy form polymer chains (grids?), so any mismatch results in some unused goo mixed in with  the hardened product.  More accuracy is always better, although there is a point of diminishing returns.

You can get a digital scale that measures down to .01 grams for  like 12 $USD at any online web merchant. One drop of water is about .05 grams, so for mixing liquids anything that can measure down to .05 is going to be as accurate as you can pour, and far more accurate than you can measure by volume, especially for smaller quantities.

I find these cheap digital tools like calipers, scales and cameras to be surprisingly useful.   I wasn't sure that I had enough screws for a job, so I weighed one, set the scale to "count" and dumped the rest in.  How cool is that?

-J

Midway Tommy

I struggled with dispersing equal amounts when I first started. I save all those little unused cups that come with Pepto, Nyquil, etc. When ever I mix epoxy it's to do all the wraps, etc. on one rod, sometimes maybe two. I use Envirotex Lite in pint bottles for my finish because it never yellows & air bubbles dissipate quickly & easily. It's not overly expensive either @ $24 for 32oz, i.e. 16/16. I'm not real concerned about mixing a little too much since it's so cheap. Those little Pepto type cups are tapered, but not very much at the very bottom. I noticed that about 3/8" of mix in one was just about right for a 6' or 7' spinning rod. Before I mix I put a black line on the cup at 5 & 10 mm. I put the hardener in first because it's lighter, let it level out & then add the resin. After mixing I dump it into a 4" tin foil pan to keep it from getting hot, let it set for a couple of minutes for any bubbles to dissipate & then put it on the rod. Whatever is left over hardens in the pan. Once it's hard I cover it and use the same pan the next time I put finish on a rod. I'll dust it off, wipe it with an acetone rag & pour the next mix right on top. My current pan has finished probably twenty or thirty rods so the hardened epoxy is about an inch thick. That 5 & 10 mm measurement system I use is so simple it's crazy. No mess to cleanup or anything.       
Love those open face spinning reels! (Especially ABU & ABU/Zebco Cardinals)

Tommy D (ORCA), NE



Favorite Activity? ............... In our boat fishing
RELAXING w/ MY BEST FRIEND (My wife Bonnie)

oc1

We have plunger pumps that screw into the gallon and quart cans.  They can be calibrated but if it works on the first batch it will continue to work.  You do have to stop as soon as they start sucking air at the bottom of the can.

The lab pipettes may not be strong enough to use with thick resin and they will leave too much resin stuck inside the disposable tip.  Syringes often only work once before the rubber tip starts pulling loose from the plunger rod.  I hate that.

You can measure any resin by volume.  If the directions say to use weight you just have to weigh a known volume once to make a correction factor and adjust the volume ratio.

For small batches of only a milliliter or so, I squirt the two parts onto a piece of plate glass and eyeball the size of the puddles.  If the two parts have similar viscosities it works fine.  The glass plate is a good mixing surface too and you can pry the left over resin off after it dries.

Jeri

We all have favoured ways that we work with rod resins, other resins might need a variation on a theme or a completely different approach. Once we started investigating the various options of plunger type bottles, we found that components from the same source were remarkably close in the measure that they dispensed, and with the Covid situation many more plunger type dispensers have become available, even down to very small quantities being dispensed from 1 or 2oz bottles. Recycling those would no doubt answer the issues raised. Storing in dark cupboards between builds is an option for the occasional builder, just like storing un-used resin in the original containers.

One by-product of the use of plunger dispensers in the workshop has been their use with other liquids, not necessarily for mixing dual liquids, but just handy dispensers for the likes of de-nat alcohol and thinners and the like. Handy, clean and relatively spill proof.

As said there are many different ways of dealing with a problem which in some instances might be worrisome for some folks, we find this system to be simple and fairly idiot-proof; thus removing the worrisome issue for some folks.

I do however like the idea of using a glass mixing plate. That's the beauty of this site - sharing experiences to hopefully all move forward............ :)

DON3099

I use CRB syringes and thread master epoxy. Color coded and put them in a sealed baggie.

smnaguwa

Pricely but Jason may be on to something. Lab pipettes may come with disposable tips.

DON3099


JasonGotaProblem

Quote from: smnaguwa on October 15, 2021, 12:07:33 PM
Pricely but Jason may be on to something. Lab pipettes may come with disposable tips.

That's the exact one I was looking at. Honestly I'd skip the tip entirely. I'm not trying to fill a small test tube. I need precise measure not precise placement.
Any machine is a smoke machine if you use it wrong enough.

steelfish

Jason, I was also very concerned on mixing the equal amount of epoxy when mixing small amounts of it, I think everyone that starts on rodbuilding hade to go over that phase because normally we start buying 2oz or 4oz epoxy kits.
https://alantani.com/index.php?topic=19968.0

Quote from: steelfish on December 06, 2016, 01:03:00 AM
I dont care is the customer is paying for the epoxic I just hate to trow the unused part to the trash (maybe its just me but dont feel too good wasting good product)

on that time I was concerned of the "normal" advice of not mixing less than 3ml of epoxy to ensure a more equal mix but thats a lot of epoxy for one guide repair or even two guides, after some comments, tips and advices from our seasoned and experieced Rodsmithers of the at.com communitty now I only mix 1ml and still have some waste at the end but not that much, I have even mixed 0.5ml using 3ml syringes and I have gotten good results and not much waste but feel too comfortable with the 0.5ml mix.
But in my case, I always apply a second coat to a fishing guide since 100% of my rod repairs are on saltwater rods, so now I mix 1ml or 1.5ml with not worries of the possible waste, apply a light coat to the wrap of the guide, save the rest of the epoxy on the freezer for 3-4 hours, then warm that same frozen epoxy with the heat gun in low and apply the 2nd light coat, normally after the 2nd coat I still have some residual epoxy on the cup but ooh well I can live with that, I did the math and seems that I was worry to save $0.03 - $0.10 cents (or even less) of epoxy if I want to reduce the 1ml mixing per guide as minimun.

but I have my eyes open for a secure method of mixing less than 1ml of epoxy but I dont think I will spend $30 dlls or more for that, I will need to wrap 100 or more rods to get even

The Baja Guy

oc1

Quote from: smnaguwa on October 15, 2021, 12:07:33 PM
Pricely but Jason may be on to something. Lab pipettes may come with disposable tips.

I have two of those from a previous life.  The spring inside is not strong enough to draw something as thick and viscous as resin.

jurelometer

I don't understand the value in purchasing a small volume measurement set..

A digital scale ($12 USD ) is  a couple dollars more than a syringe kit.

With my cheapo scale, I can accurately measure  exactly enough to coat a saltwater fly head (less than a single foot freshwater guide wrap) all the way up to 14 ounces.

Place the mixing cup on the plastic tray on the scale.  Hit the tare button.  Add part A.  Hit the tare  button.  Add part B.   No cleanup, unless you miss the cup, in which  case you wipe off the tray with isopropyl alcohol, and recheck your measurement. 

Jeri's plunger trick s just the ticket if you want something even faster and do enough volume of rodbuilding.  if you are satisfied with your results from eyeballing your measurements in medicine cups, glass plates or whatever, more power to you.

   But I don't  see any advantage  in actually buying small  volume based  measurement dispensing tools, other than skipping the step where you multiply the part A weight by some ratio to get the part B weight.

And there are so many uses for a scale, even just for rod building.   For example, if you want  to see how much difference guide weight really makes for your wrapping style, saw off a 4 inch section of scrap blank.  Weigh the blank.  Weigh the guide.  Wrap the guide on the blank and coat  with epoxy in your preferred style.  Now weigh the whole mess.  You will now know more about the effect guide weight has on swing weight.  You  may be surprised...

-J

oc1

Here's my method for weighing out 5 grams of 1:1 resin.  Tare the mixing cup and add 2.5 grams of Part A.  Oops, it came out to 2.7 grams so we'll make it a 5.4 gram batch.  Tare the cup again and start pouring Part B.... very carefully this time.  It's coming out like a thin thread and when the scale finally, finally reads 2.7 I jerk my hand away and a little bit of resin falls on the scale weigh pan, but it can't be enough to matter.  After a second the scale reading then reverts back to 2.6.  OK, I'll add just a smidgen more of Part B.  Being very careful and precise, the resin is taking forever to start coming out (like the ketchup commercial).  Then a big blob comes out all at once and the scale jumps to 2.9.  No problem,we'll make it a 5.8 gram batch by adding, uh let's see, that would be 0.2 grams more of Part A.  This is starting to become annoying and so maybe I tilt things a little more to get the Part A coming out a little quicker.  The same result, a big blob comes out at once, the scale jumps 0.3 grams but that includes the stuff running down the side of the cup onto the scale pan.  Screw it.  That's good enough.

Swami805

Be careful what you use for measuring and mixing that it doesn't have silicone in it, many medical supply products do. You get fish eyes in your finish. If it doesn't say no silicone maybe don't buy it.
Do what you can with that you have where you are

philaroman

I'm not that old, but extra-vintage RE: lab equipment
"pipette" means glass (pref., graduated Pyrex)
no concerns about chemical interaction; appropriate weak acid, if clogged

Brewcrafter

Lot of good ideas here, and let me start by saying I have only mixed up rod epoxy a handful of times for my somewhat crude guide repairs.  But I was wandering through the lab today (as per usual thinking about fishing) and thought about these little guys:
We use them both in a sterile form for lab work (I know the AT Ohana do great work, but I suspect sterile sealed pipettes might be overkill  :D) but then we also keep these same "non-sterile" ones around for tasks that are not sanitation critical.  I they measure either 2 or 3 ml and do it in .5ml increments.  And at something like $20 for a box of 500, they are pretty much meant to be single use items however for many of our non-sterile applications we will just keep reusing the same one with the same chemical/oil/compound until it seems like a good time to change it out.  The tip orifice is fairly open (I would say 1-2mm) and while the most viscous fluid we use it with in the breweries is soda syrup (64 Brix if that means anything to anyone) they pretty much handle it no problem.
If anyone wants to play around with the idea to see how it works go ahead and PM me and I can toss a few in an envelope...Apologies, ever since the Gallery went away I have no idea how to actually insert an image, so it's and attachment. - john