Agepi7o Is it there any smart way to do it? Any tips?
Apply force to compress the two tubes against each other while you turn the tubes.
I usually place the stuck tubes in between my two palms, apply as much force as I can to compress the two tubes against one another, then twist my palms.
For tubes that are more stuck, the tubes can slip on your palms. For those, I use small rubber sheets in between the tube and my palm, like the sheet shown here (notice all the marks on it :-)
One sheet of rubber on each palm.
The sheet shown is from packaging material, but you can find thin rubber sheets at Amazon.
For even sticker situations, I use silicone jar openers, but it is tricky since you also need to compress the tubes at the same time, so just get your spouse to help you :-).
https://www.amazon.com/gp/product/B07NKXLJYF
The key is to not deform the tubes from being perfectly circular, and the soft jar openers help.
For even stickier situations, I use filter wrenches like these:
https://www.amazon.com/gp/product/B06ZZLQH7C
They come in pairs, so you can use one on each side of the stuck tube. They tend to be less gentle that the above methods.
Do not buy the plastic wrenches. They are pretty much useless with stuck tubes. I have found the above rubberized metal ones to work well.
You can also warm the tube with the outer (female) thread with a butane lighter. If you warm the inner thread, you will make the problem worse :-). By inspecting the ends of the tubes, you can figure out which is the tube with the outer thread :-).
Just remember -- apply force to compress the tubes. That is what is causing them to bind.
The same trick is used for mounted filters that are stuck -- don't just twist them. Force the metal ring of the filter against the female thread first, before turning the filter.
Well-machined tubes and filters seem to be sticky less often. I have never had custom spacers from PreciseParts.com to ever stick -- perhaps they are also cleaned better before leaving the machine shop. On the other hand, ZWO tubes and filter trays are notorious for having rough threads.
Chen
