Help me with fixit problem

[Muse]

This is an old plastic mixing spoon that's been in the family must be 50 years. It was my mom's and now mine. Yesterday my bread machine decided to take a nap and I had to remove the contents to a bowl and mix by hand. I instinctively reached for this spoon and started cranking on the stiff mixture and after a while the spoon snapped. :Q I figured that was that. I've never seen a similar thing for sale in the stores, and I've looked. It's around 10 inches long and a single virtually white substance throughout (stained on the outside to some degree), probably nylon.

I started thinking that I can maybe repair this thing. The cross section area of the break 1/2 way up the handle is about 1/8 square inch. Some kind of super glue might work but I figure my best bet is to heat the nylon at the break (i.e. both pieces simultaneously) and force the melted plastic together and hold firmly a few seconds until the melted plastic cools. I can then file off and sand any protruding globs of plastic.

At what temperature does nylon melt? I figure I'll have to be careful not to heat the plastic more than necessary so that it retains its integrity. Not sure how to do this. The break is nice and clean and almost in a plane, but not quite. Using a heated plate for both sides is a possibility but I think that holding both pieces on either side of a candle flame might be the best strategy, not sure. Preferable to that, maybe, would be a flame that burns cleaner than a candle. You know how a candle flame leaves carbon on surfaces? I figure that's not good. Maybe my stove top's pilot light would be better. Maybe I should file the surfaces flat and use a heated plate instead of a candle. How strong is super glue? Is there a glue strong enough for this?

 

[Fenixgoon]

depends on the nylon, but I think the most widely used nylon is nylon(6,6). One website I found had the MP between 375-500F.

Super glue is strong, but stiff and brittle (it's an epoxy). Chances are, it'd break again if you went to stir something very viscous/heavy.

 

[Jeff7]

I don't know, after 50 years, that stuff just might not be good anymore. Some old plastics become quite brittle as volatile plasticizers slowly leach out or evaporate over the years.

Devcon Plastic Welder might be able to handle it.
But its spec sheet doesn't list Nylon/polyamide.

Bond: PVC, fiberglass, ABS, FRT, PBT, PPO, PCBB, Metton®, Lomod®, Valox®, Noryl®, GTX, Minlon®, epoxy, RIM urethane, galvanized metal, wood, poorly prepared surfaces, and where outdoor weathering or solvent exposure is anticipated.

Edit: But the main page for all of their plastic adhesives says:

These two- part structural and one part instant adhesives are designed for difficult-to-bond engineered plastics, composites, PET, ABS, PVC, Nylon, Nylon 6, polycarbonate and acrylic. They come in a variety of viscosities and cure speeds for your specific application needs!

Be warned, you'll want to use the Plastic Welder outside, or with a good exhaust system. It smells pretty nasty.

 

[Muse]

Originally posted by: Fenixgoon
depends on the nylon, but I think the most widely used nylon is nylon(6,6). One website I found had the MP between 375-500F.

Super glue is strong, but stiff and brittle (it's an epoxy). Chances are, it'd break again if you went to stir something very viscous/heavy.

Yeah, thanks. I figure that a glued joint would break again. Right now I like the idea of my stove's pilot light and carefully melting both sides of the break and jamming them together and holding until set, then filing and sanding smooth.

 

[BoomerD]

I think that unless you drill a hole and insert some kind of peg in the center, even melting the halves won't give you a strong enough bond to be able to use the spoon.

You'd need an inch or so on each side of the break, maybe 1/8" diameter, and something strong...like stainless steel or titanium so it doesn't rust. (stainless would obviously be much cheaper)

Personally, I think you're gonna have to accept the fail...and toss the "family heirloom" spoon out...or live with a very short handle. The odds of a successful repair aren't in your favor.

 

[Jeff7]

Or else glue it together, have it encased in Lucite, and hang it on the wall.

 

[MikeyIs4Dcats]

it will not hold if you melt it or glue it.

The melted joint will just pop apart. There is no way for you to fix it, throw it away.

 

[Muse]

Originally posted by: BoomerD
I think that unless you drill a hole and insert some kind of peg in the center, even melting the halves won't give you a strong enough bond to be able to use the spoon.

You'd need an inch or so on each side of the break, maybe 1/8" diameter, and something strong...like stainless steel or titanium so it doesn't rust. (stainless would obviously be much cheaper)

Personally, I think you're gonna have to accept the fail...and toss the "family heirloom" spoon out...or live with a very short handle. The odds of a successful repair aren't in your favor.

BoomerD I think you have hit on the best idea. I'm gonna think about it. It'll be tough to do, though. I'll wait for a while and think about the options, there's no hurry. Good chance it'll wind up in the can, of course. I've fixed a lot of things, though, things people wouldn't believe were fixable. I have this motto: If I can't fix it, it ain't broke.

 

[Howard]

do what boomerD said

clamp in a lathe, drill out on both broken sides to allow for dowel insertion (allow for extra clearance)

epoxy dowel in along with epoxy on both sides

 

[Muse]

Originally posted by: Howard
do what boomerD said

clamp in a lathe, drill out on both broken sides to allow for dowel insertion (allow for extra clearance)

epoxy dowel in along with epoxy on both sides

You read my mind. The dowel will be steel and there will be sufficient play so that the two sides of the object will align properly, inasmuch as I'm sure there's no way I can drill the holes so that the center lines will align. I'll use the best epoxy I have or buy more if I'm not confident in what I have. Would Gorilla Glue be better than Epoxy? Actually, I'm thinking of two dowels because the cross section suggests this. Also, I'll rough up the dowels with my grinder to achieve better attachment to the glue. Or maybe I'll use portions of machine screws to get the same effect.

I don't have access to a lathe, though. I can clamp in a wood vise and use my dremel or one of my cordless drills.

 

[Muse]

Originally posted by: Jeff7
I don't know, after 50 years, that stuff just might not be good anymore. Some old plastics become quite brittle as volatile plasticizers slowly leach out or evaporate over the years.

Devcon Plastic Welder might be able to handle it.
But its spec sheet doesn't list Nylon/polyamide.

Bond: PVC, fiberglass, ABS, FRT, PBT, PPO, PCBB, Metton®, Lomod®, Valox®, Noryl®, GTX, Minlon®, epoxy, RIM urethane, galvanized metal, wood, poorly prepared surfaces, and where outdoor weathering or solvent exposure is anticipated.

Edit: But the main page for all of their plastic adhesives says:

These two- part structural and one part instant adhesives are designed for difficult-to-bond engineered plastics, composites, PET, ABS, PVC, Nylon, Nylon 6, polycarbonate and acrylic. They come in a variety of viscosities and cure speeds for your specific application needs!

Be warned, you'll want to use the Plastic Welder outside, or with a good exhaust system. It smells pretty nasty.

The Devcon might be worth a try. If it doesn't work, I can go to plan B. I'll look into it. There's a pretty good big hardware store not far away and they might carry it. If not, maybe I'll order it. Today would be a perfect day to do it outside, almost summer weather here in Berkeley, but it won't be today. Like I say, there's no hurry.

 

[Muse]

Here's a picture of the broken spoon. Unbroken, it's 10 inches long:

Broken Spoon