Delrin hairline crack repair?

[northernone]

Well. Due to a situation I'd not like to talk about I have compromised the water tight nature of my scooter nose cone. A few teaspoons of water over a half hour. Hairline Crack. Any dirty repair tips that are applicable to UW?

Help welcome.
Cameron

 

[Akimbo]

Try this Google search: bonding delrin

ADHESIVES for DELRIN and ACETAL

 

[joe10540]

A coating inside and out with an epoxy should seal you back up and create a nice sized patch for some reinforcement. Sanded smooth and painted to match the existing should make it almost invisible. Not sure about which are safe for delrin but work great on boats and jet skis.

 

[Akimbo]

A coating inside and out with an epoxy should seal you back up and create a nice sized patch for some reinforcement.

I'm not so sure. Delran is notoriously slippery. Not as bad as UHMWPE but pretty close.

 

[lowviz]

...//... Hairline Crack. Any dirty repair tips that are applicable to UW? ...

I've repaired quite a few travelling cracks in plastic back when I was a productive member of society.

Job #1: drill a very small clean hole (in good material) just in front of each end of the crack. There is a huge stress concentration at the leading edge of a crack, that is why it keeps going. So now, the crack can only propagate into your hole and die.

Next, is the plastic thermoset or thermoplastic? You can "plastic weld" thermoplastics. (everything you want on YouTube)

For you: Bonding Acetal | Industrial Adhesives| Bond Plastics - Permabond

Sorry, man. Good luck!

 

[joe10540]

https://www.amazon.com/BONDiT-B-45TH-Adhesive-1-7-oz/dp/B01L0G4ZDA

Found an epoxy specifically designed to adhere delrin. Maybe you could source a piece of flat stock delrin to use as a patch on the exterior and then sand it down. This epoxy claims something like a 600-700psi adhesion.

 

[rsingler]

Cameron,
I know it seems counterintuitive - putting another two holes in your nose cone, but +1 to @lowviz .
We do the same thing with thin aluminum skin aircraft repair to prevent extension of the crack. Just 1/16" or less hole will do. The tiniest bit you can find.
Then whatever you come up with for Delrin adhesive goop. I have nothing to offer there. You might PM Randy Thornton with X-CCR. They have a Delrin scrubber case and head for their breather, and may have a recommendation.

 

[fmerkel]

Don't know about Delrin adhesives for sure, but JB Weld is awesome stuff. My Honda has a plastic top on the radiator. So it goes through heating/cooling and pressure cycles. I cracked it by leaning on it doing some other work where an air cleaner duct bolt bracket was attached....bad spot. I've done a modest amount of work repairing fiberglass and epoxy sailboard damage.
So....I sanded the area with like 120 grit, and put on a good sized quality epoxy patch heavily reinforced with glass cloth. Drove it about 200 miles on a trip in very hot weather....it held!!!! Yay! For a couple months and started leaking.

Ripped off the patch, cleaned the area up well, more sanding, and re-patched, this time using carbon cloth and good epoxy. It held longer this time, but started leaking.....again.

One more time, this time with JB Weld. Since it's a 'putty' and not a liquid, getting the patch on using carbon cloth was a bit of a hassle but it's going on 4 years now and still holding.

 

[lucca brassi]

If you want to glue delrin , you have to clean plastic on plasma . That's allow stronger bond between glue and plastic - tehnical description is OXYGEN PLASMA SURFACE ACTIVATION /CLEANING
Plasma Activation | Plasma Surface Activation | Plasma Etch, Inc. . ( in company we have it and I have try that with delrin )

Another problem is structural crack which have to be repaired. In which way cracks start and finish normally crack is stopped with small hole to prevent ''shear effect'' forward. Of course you don't want hole but you have to reinforce both sides of crack , probably with some delrin plate inside or outside.

Simplest way is to replace nose cone , by new or DIY from delrin block on turning machine.

 

[Akimbo]

Simplest way is to replace nose cone , by new or DIY from delrin block on turning machine.

Given the failure I think I would consider turning a replacement out of Aluminum instead. Both materials machine pretty easily. For other readers: "Turning" is slang for machining parts on a lathe.