Hi I have just started doing some windshields, and I now have some questions. Ive been reading old posts on drilling, heating etc but would like to expand on a few items. I see people saying the cure under pressure? After my last pressure cycle I get my pit resin ready, pop off the bridge (still in pressure mode) apply the pit resin and cover with film. IS THIS what is called curing under pressure? This expression was used referring to doing large stars etc. This made me think, are they saying that the cure (UV Light) was used with the bridge still in place, NOT removed from the damage area. Do you ever start a cure with the bridge still in position?
Poping a bulls eye. Ok I think I have an idea when to do this. One post was good identifying that the probe has to be smaller than the drill hole. The probe I was using was bigger, what a mess! Some mention using a needle. A needle, are we referring to a needle one would use in sewing or one used to inject drugs? I now know that to drill to pop a bulls eye just requires a very small depth (I was drilling for oil ) When you use a probe or needle do you just push on it? Tap it with something? Get out a hammer? Just wondering what kind of force is required to get this poped bulls eye? To practice this can I just drill a small shallow hole in my practice shield and then pop it or do I need to make some damage first? Lastly is the heat subject. I read to heat under vacuum, but cool under pressure. So go to vacuum cycle heat for a few seconds from the inside, then jump out of the car and put the injector into pressure cycle. These are the 2 points I have picked up in the heating posts . Is that what you do? Is there any rule of thumb when you should switch from vacuum to pressure when heating? Is a longer or shorter vacuum better? Thanks for any light you can shed for me. I did read old posts trying to find my answers. I just want to make sure my interpretations of what I have read ARE the same as what was trying to be conveyed. Thanks to all!
Jonnyques, Looks like you are covering a lot of ground in your posting. I will attempt to provide some degree of what I have learned and was taught in WSR school. To start with, curing under pressure means that while your injector is sealed at the point of impact, you apply UV light (either sun light or artificial to both sides of the seal next to the glass. I usually apply the light for at least 1 1/2 minutes to each side when using my UV lamp. I then release the pressure by slightly reversing my Pressure Injector to the vacuum mode. You then can remove your injector unit from the windshield without loosing your resin that you did not use. You are then ready to apply your Pit fillers, apply your curing film and apply your UV lamp or sun light again for a minute or more. You can then scrap off the buildup with your razor blade and polish the area. As far as poping bulls eyes are concern, you should be using some type of miniture bulls eye maker which consist of a needle and tappet. This is done very gently!! Once you create your miniture bulls eye, you are then ready to vacuum and inject your resin as you would a normal point of impact area of damage. You also mentioned the number of cycles of vacuum and pressure. I normally do at least two cycles of each, with applying a small amount of heat with my mini-torch to the damaged area from inside the windshield after the first complete cycle. I have also had incidents where I would need to do as many as three or possibly four cycles to ensure that I got evacuated as much air out of the break. Hopefully this will give you a view point from at least one WSR technician. Good luck
Curing under pressure does mean to leave the bridge in place when curing. I usually don't cure under pressure, however I always cure before placing the pit resin and cure tab over the pit. The theory behind this is that curing causes the forming of gases that cannot escape if the pit resin is already in place. Not being a scientist I'm not sure if that's what happens; only that my repairs look infinitely better when I cure this way. Curing under pressure should produce the same results. You will also find when repairing some bullseyes that there will be a pocket of air that stubbornly refuses to be removed. Under pressure these will be compressed. Curing under pressure will cause these to remain compressed allowing for a better-looking repair. Mainly it's a matter of personal preference and what works best for you.
As for popping a bullseye, I use a probe and smack it with a second probe. You can practice this simply by drilling into a windshield as you described. I believe the needle referred to would be a sewing machine needle. Much more sturdy than either of the needles you mentioned.
Great when reading those posts I thought , They cant mean cure with the bridge on... Guess they do! I thought that that would harden the resins in the injector and screw it up. Does anyone have a sugestion on where or what to buy for a probe/ tapit? What do you use? Could you please expand on the heat. Do you do it under preasure or vacuum? When do you alternate cycles (which ever is first) when heating. That is, if heating under vacuum, do I let it cool slightly, compleatly, as little as possible, before going to preasure? Thanks again to all!
I'm in agreement with mafsu on the pressure on stubborn bull. I have done this and the results are much improved. I will drill at the top of a bull that will not fill completely also. When I do an injection using that method it will fill immediately, the resin runs right thru the thing. Controlling the situation can be tricky though, you don't want air reentering the damaged area, another cure under pressure situation at times.
I use the FG2 drill followed by an awl to pop a bull. Just drill half way to the lami and pop (practice on a scrap piece for a couple of hours). If you want a good needle they sell large ones for canvas repair that will do the trick, I just picked up an awl from the local hardware and use the one I got with my kit for a striker. Easy does it on the hit, you can always increase the pop pressure if the first strike isn't enough. With practice I
My best mentor one said " be fair with your priceing but never too low, be honest with your customer/competition, when the day is done be sure you have done "good works", and always leave something of value on the barganing table!!
While my friend and trainer/ mentor Ray has moved on, his words live.
When I was in training at Delta, there's this one leg on a starbreak that just won't fill. I've tried everything so I gave the lighter a try. I heated the backside of the glass very gently, which closes the legs, then when it cooled, it opened up and the resin flowed in very easily. This is done under pressure btw. Dont always depend on the lighter. I always use mine as a last resort. Some say not to use the lighter. But if you learn how to use it correctly, it can save you alotta frustration.
Mikedoby wrote: To start with, curing under pressure means that while your injector is sealed at the point of impact, you apply UV light (either sun light or artificial to both sides of the seal next to the glass. I usually apply the light for at least 1 1/2 minutes to each side when using my UV lamp.
when you say "apply UV to both sides," does this mean you are appying light to the interior windshield?
Lakosbo, When I said "Cure Both Sides", I was referring to positioning your curing lamp on one side of your injector and then repositioning it to the opposite side of the injector to insure that the UV light gives you adaquate curing coverage. If you are curing outside in the sun light, it is not always necessary to use the UV lamp. The sun will usually cover the entire area that requires curing. 8)
) When you use a probe or needle do you just push on it? Tap it with something? Get out a hammer? Just wondering what kind of force is required to get this poped bulls eye? To practice this can I just drill a small shallow hole in my practice shield and then pop it or do I need to make some damage first? Lastly is the heat subject. I read to heat under vacuum, but cool under pressure. So go to vacuum cycle heat for a few seconds from the inside, then jump out of the car and put the injector into pressure cycle. These are the 2 points I have picked up in the heating posts . Is that what you do? Is there any rule of thumb when you should switch from vacuum to pressure when heating? Is a longer or shorter vacuum better? Thanks for any light you can shed for me. I did read old posts trying to find my answers. I just want to make sure my interpretations of what I have read ARE the same as what was trying to be conveyed. Thanks to all!