Crack Expander Test

[GLASSTIME]

Hey Fellow WSR Tech,

I had a 6" crack saturday to repair. It was on the passenger side and was introducedith
A bullseye in the black of the glass and extruded a leg upwards.

From the inside when closing in towards the bottom of the crack with the "Crack Expander"
However the dash wasn't allowing me to set up the expander due to no room.

I decided to try and place it on the outside with caution. The crack filled perfectly.

Just curious even though my repair was a success is this method a no no?
I didn't know if applying flex one direction and resin filling the leg and then flexing in an opposite
Direction could possibly cause the resin in the leg to escape the leg somehow?

Has anyone ever performed a crack using a crack expander in this manner?

[screenman]

You were lucky in most cases that would have closed the crack up. Think of it with this excercise, place hands palm in about 1/2 inch apart elbows shoulder width apart and angled slightly downwards, with hands pointing skywards, now raise your elbows whilst pushing them together, the point of your wrists would be the PVB. This is the same effect a crack expander has. Damn that is a lot easier to show in person than it is to write about.10 points for anyone who understands what I am talking about.

[Frank EU]

Why would your solution be a no no? It did work for you right? However; what I don't understand is that you didn't tell what you did with the expander on the outside.... did you tighten it? Than you would normally have closed the crack. I have reasons to believe that you pulled a little to open the crack right? In similar future situations you may wish to use a large suction cup to 'open up' the crack (in a very cautious manner of course).

[Frank EU]

Oops, at the time I composed and posted my reply, Screenman has posted his just one minute earlier..... But Screenman is right.

[GLASSTIME]

Understood Screenman, great expanation/demostration!

Frank EU,
Yes, actually what I was thinking was in some way simulate the same effect caused from inside pressing outwards but outside pulling outwards.
Hope that's not confusing. No I did not twist expander leg downwards from outside. Although it prob. Wasn't as effective as a large suction but I applied the suction of the expander over top of crack leg!
Thinking this may cause some sort of vacuum? Fouranetly enough it worked and leg filled.

I know this is very non-techish, so if you guys have any other suggestions please advise! Thanks!

[Mr Bill]

Would this help? It grips and holds all smooth surfaces and has enough suction to pull a 15 pound object.

[screenman]

I always have one of those in my toolbox, it will certainly open a crack slightly when pulling from the outside. However I use it more often for securing my light by wrapping the flex around it when working on certain types of vehicles. I also use it to rest the light on when working on delicate breaks, by placing it under the break, saves pushing hard on the light suckers.

[GLASSTIME]

Cool!
Will purchase one ASAP!

So you would place this over the crack and give a very slight pull?

[adam@gtglass]

You would probably want to put it on either side of the crack rather than directly over the crack. If you were to put it directly over the crack, since it is a long crack and i assume it is cracked through the outside surface of the outer lite of the windshield, it would not form a proper seal. But for that application (opening a crack), placing it next to the crack where you wish to apply "opening" to the crack, and use gentle pull-pressure.