Glue Guru needed

I have a situation that I need help with. I have a big bunch (3k) of brushes that need better tuft retention for a special application. The
brushes are 7" long x 3-1/2" wide and have 50 holes/tufts in them. Each hole is 1/2" deep x 9/32" dia. and each tuft is 3 flat wires bent 180 deg, and stapled into the hole with a 18 ga., 1/4" crown x 1/2" leg staple. I am thinking of injecting glue of some kind into the hole with the wire. These brushes are already made. If I can inject glue or epoxy into the holes, the material will have to be able to withstand the brushing action and not crumble or pop out. I wonder if carpenter's glue would work. I'm looking for leads for some type of powered dispenser too. My budget needs to be under a buck apiece including labor.
Apparently, the action of the brush in this application is way different than normal. They use the brushes in a linear motion that is parallel to the staples. They use the sides of the flat wire to break spoo up rather than the face of the flat wire to "sweep" like a normal use. This action has a tendency to rock the staples out even though the tuft retention is over 40 pounds pull-out strength. (Where's that Unabtaniun when I need it!)
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Yikes. Sounds like a manual operation no matter what you do, injecting into holes like that. I would first think of hot melt glue, but the labor will be way over a dollar I would think.
Jim
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You might try a polyurethane glue (gorilla glue or the like if buying a test sample at the hardware store - no doubt some other brand available cheaper if buying a 5 gallon bucket). A bit viscous, but sticks well to wood and metal. Industrial hot melt glue would be another possibility.
Yellow carpenters glue (alpahtic resin) would not be a good choice (brittle), the white stuff (PVA) might be worth trying, as it's a bit more flexible when dry, but it's not especially great glue (cheap, though).
Keeping the labor cost down is going to require a very good dispensing system - or perhaps a different approach entirely, such as laying the brushes on their backs in a pan of polyurethane varnish, and letting that fill the holes without injecting each one, then drain and dry (perhaps bake a bit) while keeping them on their backs - it's not exactly glue, but it might do the trick, at very low labor cost.
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On Thu, 20 Jan 2005 14:02:17 GMT, the renowned "Tom Gardner"

There are air powered metering dispensers that can be mated with automation to deliver the glue to each hole. I've been seeing them at trade shows (the first part) for many, many years- there are now knock offs. They can also be used to make no-tooling gaskets just by laying down goop in an arbitrary pattern on a surface. And for making a kind of keyboard. Popular with Asian manufacturers.
Best regards, Spehro Pefhany
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-SNIP under a buck apiece including labor.

it!)
viscosity is the enemy in filling small holes. It seems like a cyanoacrylic glue which has a number of viscosities available would be the ticket, CA glues are typically delivered with some sort of a dropper or syringe. The thinner CA's have pretty good wicking characteristics, especially where wood is in the mix, plus they are stronger than hell.
good luck, Ed Angell
PS- Did you ever get any samples of the .006 straight brass wire?
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On Thu, 20 Jan 2005 07:47:57 -0800, "Ed Angell" <edangellatcomcastdotnet> wrote:>-SNIP

Strong, yes. But CA is also brittle and impact can break the bond. I assume these brushes are to be used in a power tool of some kind.
--RC

"Sometimes history doesn't repeat itself. It just yells 'can't you remember anything I've told you?' and lets fly with a club. -- John W. Cambell Jr.
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I second the suggestion for gorilla glue. This seems like the perfect application for a foaming polyurethane glue
For a dispenser take a look at;
http://www.efd-inc.com/index.html
They are not particularly cheap (I got mine at a junk shop for $25), but I can attest to the fact that they are slicker than snot. They use a pulse of air pressure to dispense a discrete amount from a syringe and then a slight vacuum to keep the syringe from drooling.
Labor is going to be the killer though. It would be simplest to apply the glue before the bristles are inserted, but that would drag glue all over the inserting machine.
Even with the the dispenser, using a single tip, I can't see you getting the time below 90 sec each.
Using multiple tips and/or semi automating it seems the only way to go
Paul K. Dickman
On Thu, 20 Jan 2005 14:02:17 GMT, "Tom Gardner"

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Epoxies are too brittle, carpenter glues are too weak. I'd suggest either the solvent based adhesives or the hot melt set. In the solvent set you need something with good flow out which will mean fairly high solvent content and attendent smelly cure period.
Sounds like your brush has a 5x10 pattern. How about an aplicator that has 5 nozzels, pull the trigger 10 times and you are done. Perhaps 60 to 100 pieces per hour. Preheating the brush to 150 to 200 degrees would help flowout for either the solvent or hot melt glues.
Power applicators are available, pressure tank, hose, and gun affairs. Haven't used them lately, can't give you any sources. I'd probably give your cardboard box supplier a call and ask for some pointers.
Tom Gardner wrote:

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Mmmm. A five-wide hot-melt glue gun applicator. Tricky but it could be done. Feed one glue stick into a heated chamber with five outlets, each one with a small heater on it to keep the temp up near the outlets.
Jim
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My thoughts exactly. I'm sure there are lots of similar things glueing up 100,000 boxes a day.
jim rozen wrote:

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On Thu, 20 Jan 2005 14:02:17 GMT, "Tom Gardner"

You need low viscosity, particularly if not using vacuum. Scotchcast #3 Electrical Resin is very low viscosity (1600 cps at 23C), is designed to wet fine wires and has quite a long pot life (several hours) at room temp. Deposit a drop at the base of each tuft by means suggested by others, then put the workpieces in a 200F oven for about 8 hours. It will get even thinner under heat (25 cps at 200F, about like 5W motor oil), will wick down into the hole around the wires and then will cure hard but not brittle.
One worry might be that any glue might wick up the wires as well as down. Won't know that until you try, I guess.
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Pack brushes tightly into a square, bristles up. Tightly wrap some metal strip around the square. The top of the metal strip should be just slightly higher than the wood body of the brush. Pour adhesive on brushes.
Something cheap would be fiberglass resin.
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Tom Gardner wrote:

I have received knowledgeable advice from Dr. Muller(?) at Masterbond.
http://masterbond.com /
Kevin Gallimore
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axolotl wrote:
Dr. Muller(?) at Masterbond.

That's Dr. _Brenner_
Why can't I remember names?
Kevin Gallimore
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