077 Prism Repair

[Woody Banks]

Thanks to the USPS I now have a prism on one 077 that was sheared off of the post. Has anyone been successful in finding the proper glue to reattach this type of plastic?

[midlife]

You will probably want something with good adheasion that will remain transparent. Check with a glass shop that deals also with plexi glass assembly.

[Mr. Widget]

I am fairly certain the material is a type of cast acrylic. The best glue to use for acrylic is Weldon #3 or #4. It is water thin and will melt the two pieces a very small amount and fuse them together. Use caution not to drip any on any part of the prism that isn't to be glued as it will damage the surface. You need to make sure the two halves are held tightly together before glue application and while it dries. It sets up rather quickly... a minute or so, but doesn't reach full strength for several hours.

The best way to use it is to use a hypodermic syringe or applicator bottle and apply a drop or two to the break. You should have the parts clamped together, (tape?) and place the tip of the needle at the crack and allow capillary action to draw the glue in. If a drop catches the edge of your clamping jig, or tape, it will draw the glue into that area and mess up the finish.

http://www.ipscorp.com/weldon


Widget

[robertbartsch]

...that blows!

...Hope you insured the package. They must have crushed the package a bunch to cause this damage. What happened to the horn assembly?

Any damage to the diaphragm? I've never seen anything like this so I can;t offer any suggestions about a possible fix but I would be worried that the blow from the bad shipping may have caused other issues.

Let us know how this turns out.

[Woody Banks]

Widget

Thanks for the tip. I will be sure to give it a try.



[quote=robertbartsch;280311]...that blows!

...Hope you insured the package. They must have crushed the package a bunch to cause this damage. What happened to the horn assembly?

The package was insured and a damage claim has been filed. There was very little damage to the shipping box. The seller shipped these tweeters on their sides with very little cushioning material. Three people screwed up here. The seller for improper packing, the postman for dropping the package, and ME for buying from eBay.

[BMWCCA]

I seem to remember using dichloromethane or methylene chloride in shop class 45-years ago when attaching plexiglass to itself. Or something like that. Made a bond that allowed several pieces fused together to be worked as one.

[toddalin]

I'd just use a small amount of cyanoacrylate (super glue).

[Steve]

Aloha Woody Banks

One of the best resources I have used for plastics, glues and all sort of info over the years
has been Tap Plastics. http://www.tapplastics.com/
If there is a shop nearby, drop in and they will tell you, help you or even do the repair.
Mr. Widget is correct in the use of a hypodermic syringe or applicator bottle. I used to repair plexiglass windows and parts on older airplanes etc. back in mid to late '60's for people in exchange for air time. Head his warning to be super careful with the glue as he states as it will damage the surface, lesson learned. Shouldn't be a problem though if using the correct amount of glue.
I recommend a dry fit for alignment and marking it so it can be assembled with ease and no hassle when actually doing the gluing. Very little if any adjustment time is available. Getting the glue to pieces being glued with the prism in place might be a problem. Bending the needle and having it wick in? I seem to remember that the glue was less viscous than water or at least it ran down the plastic faster and wicked in better than water did.
I can't imagine needing or using more than a very small drop for that repair.

Do your self a favor, pick up a plexiglass rod the same diameter and cut it or break it and practice gluing it back together numerous times. Cheap insurance and you will then be familiar with the characteristics and properties of the glue when using it on an irreplaceable item.

Has anyone ever tried to remove the post and prism from a driver before? Might be the best way to glue the post and then re-install it. I seem to remember long ago on ebay there were crystal prisms being offered by themselves " as a way to upgrade yours" as was listed in the auction text.

If you can, please post a pict of the the prism when you finished and how you did it.

Just a thought.
Have you tested the driver to see if it actually works ok.
I have had drivers arrive with no visible and others with visible damage and the magnets have been knocked out of alignment, and other nightmares.


Steve

[lgvenable]

I've glued these materials many times. Its easy to get too much solvent
in the glue line (in your case fracture line. If you do that the solvent will run out and mark the piece.


Plexiglas is best glued with a chlorinated solvent, such as methylene chloride.Alternately you might be able to use perchloroethylene. You can also add small scrapped Plexiglas to the solvent (to give it a small percent solids of the correct plastic to be glued). Just allow the Plexiglas shavings to sit overnight in the solvent. (covered or capped bottle).

Once bonded, like anything else allow time for the glued fracture line to set before applying a load to it. It may take two to three days for it to harden completely... be patient.

Practice with some scrap Plexiglas rod is a really good idea, to get good technique.

if you align the prism with its base, and just apply enough ch2cl2 to the fracture line, you can see and tell as its fully wetted. Repeat until fully wetted, then hold the prism to the fracture line with a load, to maintain intimate contact of the two surfaces.

Good luck, I'd suggest that you use am artists brush, and remember, the solvent if it gets on the prism surface it will mark it.

FYI I've built display boxes, models etc always used a brush to just add the solvent right to the bond line, it'll run in an wet the two surfaces> easy to see visually.

Good luck.


BTW dont use cyanoacrylate it will not adhere correctly

[Sam Cogley]

and ME for buying from eBay.

This always gets me.

1) You didn't buy anything from eBay, you bought from an independent seller using eBay as a marketplace for his/her goods.

2) When buying anything valuable or fragile, it's worth discussing proper packaging with the seller.

3) It's not hard to weed out good and bad eBay sellers. Check feedback and look at the ads themselves. If the ad is poorly worded and put together, likely you're dealing with someone who's a few marbles short.

4) If you're unhappy with eBay, feel free to stay off of it. Keeps prices down for everyone else when there are fewer players in a marketplace. Obviously when I'm selling, I want more people on there.


/rant

[Mr. Widget]

This always gets me.


4) If you're unhappy with eBay, feel free to stay off of it.

I am and I do.

Let's all use Audiogon.

I've had a much better experience over there as a buyer and as a seller.

As for the original post, I find it hard to believe that a poorly packed 077 could be broken as this one was, but it does drive home the point about the importance of packing... even something as seemingly bomb proof as an 077.


Widget

[Allanvh5150]

I have never had a problem with Ebay as such and I have had a lot of goods delivered down under. More to do with muppetts that cant pack stuff properly I think. Just specify how yuo want your goods to be packed.

Allan.

[lgvenable]

I agree
I always specify shipping and packing & guarantee negative feedback if they follow the mutually agreed on plan. Oh, and I generally only buy from someone like me 100% positive.

[robertbartsch]

I've had lots of bad experiences with Feabay sellers/shippers.

As far as leaving negative feedback; I don,t waist my time anymore. I left negative feadback a few times and MANY sellers then refuse to sell to you if you have a history of leaving negative feedback to unrealated third parties.

[Sam Cogley]

I guess I have a very good BS detector. I have quite a few feedbacks over the past decade (or more) and only one transaction went sour.