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Restoring a WECo Black 500U

Started by cihensley@aol.com, February 04, 2011, 12:38:52 PM

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cihensley@aol.com

GG:

The nibble around the dial I eliminated by sanding. See the picture for how I fused the crack. First I super glued a thin strip of plastic packaging blister material to the inside of the phone over the crack, to strengthen it so my subsequent work would not open the crack. The crack was already poorly glue together when I acquired the phone. I say poorly because one side of phone at the crack was slightly higher than the other side. This I eliminated by sanding smooth.

I did not know what the crack had been glued with, so I used a cutting bit in a Dremel tool to cut a groove in the crack..  This ensured I removed any contamination of the plastic for subsequent fusing. I built a small dam out of Blu-Tack (I had previously determined that Blu-Tack is solvent impervious) around the crack. For this and the later work I had the phone in a bench vise (with padding of course) with the cracked end pointing up. I cut off two reinforcing ribs from inside the phone, cut them into small pieces and put them into a small glass bottle with a few drops of acetone. I capped the bottle and let it stand overnight. Done right, you end up with a liquid plastic about the consistency of heavy syrup (i experimented ahead of time).

I then put enough drops (from a glass dropper) of acetone inside the dam so everything was well covered. I let it stand about an hour (it takes about an hour for the plastic to really soften). then soaked up any standing acetone with paper towel corners. I then poured enough of the liquid plastic inside the dam so it was slightly higher than the surrounding area (I had previously determined that the liquid plastic shrinks somewhat as it dries). I let it dry for a couple of days, removed the dam and sanded the area smooth. Viola! - no crack. I should also add that I wrapped the whole phone in painter's tape, except the area I was working on, to protect it from any errant acetone.

Chuck


JorgeAmely

Brilliant! I am sending some of my cracked shells to you.
Jorge

Doug Rose

Chuck....you are amazing. Simply an outstanding job. You should be very proud....Doug
Kidphone

Dennis Markham

Chuck, is the housing on this project Tenite or ABS plastic?  I have been doing some experimenting with the Acetone with Tenite (302 housing).  I know that Acetone will cause the Tenite to have air bubbles or pock marks.  I'd like to give this another try but was curious if you were working with ABS or Tenite here.

cihensley@aol.com

Dennis:

Tenite. I also encountered the problem of air bubble on the blue 500U I restored. I smoothed-down the first pour (using riffler files) after it dried. Then I filled the air bubble holes with more liquid plastic and smoothed-down again. On one hole, as I remember, it took three applications.

Chuck

Dennis Markham

Thanks Chuck, I will give that another try.  

I was working on a typical 302 corner crack.  I followed your lead and bonded the crack with glue.  Once well dried I grooved the crack line and filled it in with some of the softened plastic.  But I did not create a dam as you showed.  Once dried I filed down the excess and repeated the process as you did, to fill the bubbles.  I filed, sanded and actually put on a third layer.  It looked pretty good.  I then went through the Micro-mesh process and got all the way from 600 grit to 2800 when I heard that awful snap.  I must have put too much pressure on it while sanding and popped it open again.  So I'm back to square one except the plastic is getting pretty thin as I also ground away some of the inside diameter to relieve the pressure against the chassis.

I'm going to give it another shot before I give up on this one.  The line was visible however as I was sanding it (when I re-broke the crack).  Perhaps I didn't make my groove deep enough.

Greg G.

#21
Quote from: cihensley@aol.com on March 25, 2011, 03:17:38 PM
GG:

The nibble around the dial I eliminated by sanding. See the picture for how I fused the crack. First I super glued a thin strip of plastic packaging blister material to the inside of the phone over the crack, to strengthen it so my subsequent work would not open the crack. The crack was already poorly glue together when I acquired the phone. I say poorly because one side of phone at the crack was slightly higher than the other side. This I eliminated by sanding smooth.

I did not know what the crack had been glued with, so I used a cutting bit in a Dremel tool to cut a groove in the crack..  This ensured I removed any contamination of the plastic for subsequent fusing. I built a small dam out of Blu-Tack (I had previously determined that Blu-Tack is solvent impervious) around the crack. For this and the later work I had the phone in a bench vise (with padding of course) with the cracked end pointing up. I cut off two reinforcing ribs from inside the phone, cut them into small pieces and put them into a small glass bottle with a few drops of acetone. I capped the bottle and let it stand overnight. Done right, you end up with a liquid plastic about the consistency of heavy syrup (i experimented ahead of time).

I then put enough drops (from a glass dropper) of acetone inside the dam so everything was well covered. I let it stand about an hour (it takes about an hour for the plastic to really soften). then soaked up any standing acetone with paper towel corners. I then poured enough of the liquid plastic inside the dam so it was slightly higher than the surrounding area (I had previously determined that the liquid plastic shrinks somewhat as it dries). I let it dry for a couple of days, removed the dam and sanded the area smooth. Viola! - no crack. I should also add that I wrapped the whole phone in painter's tape, except the area I was working on, to protect it from any errant acetone.

Chuck

These instructions should go in the forum's technical library.  At the very least, I've bookmarked it for my own use.  Everything you used can be done with relatively easy to get materials and tools.  Except I'm not sure what "plastic packaging blister material" is.  Is it this stuff?  http://en.wikipedia.org/wiki/Blister_pack

Blu-Tak:  http://en.wikipedia.org/wiki/Blu-Tack
The idea that a four-year degree is the only path to worthwhile knowledge is insane.
- Mike Row
e

cihensley@aol.com

Brinybay:

The plastic packaging blister material you find on many items in a grocery store and especially in a hardware store. It is that clear plastic material that we sometimes find frustrating to open. I buy cut fresh fruit at the grocery store. The 2 lb size comes in a lidded plastic container. The lid has quite an expansive area with no bends or reinforcing ribs that I cut out and use for the plastic strips I mentioned.

Dennis:

I know the problem of having to sand the inside corners of a 302 shell to make it more properly fit the base. The sanding also weakens the plastic. I have done the opposite. I use a grinding wheel to thin the metal corners of the base. With the application of feathered-in Rustoleum flat black, it is hard to notice the corners were cut back. If you use this technique, it can provide room to glue a blister material strip inside to reinforce the crack repair. Or, I can send you a non-cracked H mount shell to save worrying about it. Let me know.

Chuck

Dennis Markham

Thank you for that offer, Chuck.  This particular phone was intended to be a learning experience.  It belongs to someone else and I offered to see what I could do to fix it up.  There was no expectation of perfection.  I will bond the crack one more time and see if I can hide it using the melted Tenite.  In the future I will try modifying the chassis as opposed to the plastic.  I have read discussions collectors have had regarding which method they think is best.  Especially on a housing that has not yet cracked. 

Thank you for the information.

Ed D

Does anyone know how/why the air bubbles form in the melted Tenite?  I would suspect that when stirring the mix that air gets trapped in the thick goo and cannot escape.

Does that about cover it?

Ed

Dennis Markham

Ed, I think it has something to do with the reaction of the acetone with the plastic.  I'm just guessing but don't think it has anything to do with stirring in air into the mix.  The bubbling appears when the acetone is just applied to the plastic.  When it dries there will be these tiny bubbles (sounds like a song) in the plastic.  I think it's just a chemical reaction within the make-up of the plastic mixed with the acetone.

cihensley@aol.com

Dennis:

I agree that there is some reaction between the Tenite and acetone. The Tenite is apparently changed in some way. This results in a slight ghosting of the dried plastic mixture. When the plastic is sanded and polished the ghosting can still be seen by sighting the shell perpendicular to a light source. By the way, your problem with the crack re-opening. I don't know what glue or epoxy you used, but acetone is used to clean fresh epoxy from tools, etc. I was concerned about this when I was testing this patching method. Tests showed me that dried Araldite epoxy was not readily dissolved by acetone.

Chuck


Dennis Markham

Thank you, Chuck for the additional information on the Araldite epoxy.

Ed D

Dennis and Chuck,

Thanks for your answers.

Chuck, I do have a question about the Araldite epoxy.  Could you please provide a product number for this epoxy?  Looks like they have more than one epoxy product.

Thanks,
Ed

cihensley@aol.com

Ed:

Even though Araldite is made in the US, it is available for industrial applications only in the US. It is available in foreign countries in the 5 minute and 90 minute configurations. I don't know any product numbers. On the Net, I found it at a couple stores in England that sell it, but the cost of shipping is high. I purchase mine from a Site in Hong Kong: dealextreme.com  Shipping is free.

Chuck