pfordmedia

Also, I would like everyone to notice that no where in the cold pull article are temperatures mentioned for when the pull should occur, it just says "let it cool down". Perhaps Ultimaker could publish a table for this?

Thanks for clarifying for me. I will try a cold pull at around 90 or so. And @tinkergnome I actually did this yesterday with one of my non-clogged BB cores out of an abundance of caution and it seemed to work well! Thanks for the tip! I'm going to be honest (and no I shouldn't have done it), but last night I just took a very small drill bit and drilled through the gunk in the nozzle, it all game out fine, but I have yet to test it. If nothing else, it will make a cold pull much easier and clear the last little bits down in the tip of the nozzle.

Also, @gr5 and @SandervG what's the right temp? One says it needs to cool down more, the other says it should be higher for a cold pull. Cold pull to me has always meant close to room temp. When you swap a printcore, it doesn't heat the core, but when you swap materials, it does so what gives? And before you ask, yes the firmware is up to date. It seems to me that nobody knows what the hell is going on. Ive worked with numerous printers for almost 3 years now and never have I had a problem like this until PVA came into my world (probably my own fault for letting it absorb moisture though). I don't know, maybe I'm just frustrated. I may leave it and come back to it in a few days.

@gr5 Yes, head was in the corner when I pulled and rods are fine. I'll keep trying.

This is a great idea, I may give this a try. I was making a strong bond, but I think I cooled too much. Problem is, hotpull doesn't do anything either. Which makes me think the outside of the nozzle looks like the outside of it, with hard, black carbon cakes onto it.

@ultiarjan Seems like I read somewhere that UM PVA has less alcohol content which means it doesn't absorb as much moisture, but gets stickier and other PVA isn't as sticky, but absorbs more moisture. I could be just trippin though. Looks like if I want to be successful I'm going to have to take better control of my print environment. That seems to be a common theme. @SandervG Oh definitely, but PLA was what I have on hand. And I would have let it cool down more, but 35 was pretty close to ambient temp so that's why I pulled it then.

@tomnagelI appreciate and hear what you're saying. But I'm afraid you don't know what I'm dealing with. I just did a PLA hot push into the PVA hotend at 270. Let the nozzle cool down to 35 and then tried to cold pull it. It might as well have been welded to the hotend because it snapped off close to the nozzle, and nothing came with it. I just dissassembled the core and the nozzle is filled with black, burnt plastic that has most assuredly carbonized (which is the hardest element on earth). It's literally a rock inside the nozzle. I always use Cura profiles, the PVA is UM. Once I get a decent way to store the PVA both while printing and storing hopefully it will eliminate this problem. My experience with PVA thus far has not been a good one, to say the least (although the prints I did when the roll was new were quite good). And @Dim3nsioneer yes I think the extreme temps like everyone suggests is a terrible idea since all it seems to do is burn the material and harden it to the hotend.

@Brulti I just tried this for about an hour and a half to no effect. It seems like it's just so burnt inside there that it's literally like a rock and won't even melt. I'm out of options... I really don't wanna shell out more money for another printcore, but nothing seems to work. Why is PVA such a PITA? short of putting it in a vice and drilling it out of the bowden tube with a tiny drill bit, I don't know what else to do...

I am having this same problem right now. Not only does PVA absorb water like crazy, when it burns it off in the nozzle, any residual water when the nozzle cools down begins to dissolve the PVA into that glue-like substance inside the nozzle, thus creating the clog. I'm going to try 250C with a hot pull and see if I can pull all that burnt stuff out. Anybody got any other ideas?