Quote:
Originally Posted by 908/930
I don't think you will need to drill if you can bond it properly, was the stress that caused the crack internal? With the #4 it will flow through just about any space like water but you need to be able to force it together to get the material to bond. How long is the crack and how thick is the material?
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My experience is that if you can trace the crack with a needle and apply, the Weldon fuses the plastic, the tighter the crack the better. Of course without equipment gravity is all you have. You may have to do both sides to get the surface right. One trick is to use clear packing tape to trap the solvent. That's what it is. Look up the MSDS for Weldon-4.
I think I have at least thought of using silicone caulk as a dam and peeling it off after fusing. I don't remember but I know there is no tape that will resist the solvent.
I have then gone through what is essentially removing the orange peel from auto paint and polished with auto products, You know 3M is the best here.
My experience is with acrylic furniture. I usually make radial stress cracks disappear. Really aggressive compounding removes a lot of sins. IIRC, no more than 1000 RPM on a circular wool pad. And even then you have to keep moving or go back to sanding. New 220 wet or dry gets this going quickly and then progress to 600. I never found the need for 1000, 1500 or 2000 grit. The cutting compound seems like 320.
Cleaning the cracks before mending is a whole 'nother ball game.
One last tip that I'm not too used to is to use a small flame. Again, I'm not called on to do this often so other than edge annealing a new assembly, YMMV with the heat.
I've got a clear acrylic plant stand in the shop right now. I just got my Weldon. It doesn't last long even in the original container. I may try keeping this batch in the fridge or freezer. I have to research that. Doesn't work well with cyanoacrylate because of the moisture. Cyanoacrylate doesn't seem suitable for a lot of plastics.