What is the best way to say connect an elbow with straight pipe? The spiral clamps just bend the stuff if you try and get it tight. Maybe a few sheet metal screws, but I have heard the inside thread can catch lint.
Ive not had any issues with just the friction fit of the one being smaller than the other, to make it work. Sort of like downspouts.
Ive seen self-tapping metal screws used to add surety to the joint.
I tape mine with some high temp metal tape and am done with it. No issues.
I use the flexible metal duct and then a spring ring style clamp for my dryer. You can leave enough of the flex so when you pull the dryer away from the wall it stays connected.
The foil tape suggestion is excellent, though, I just use the plastic clamps that are a lot like zip ties that can be easily released. Remember that this does not need to be a perfect, air-tight seal.
U use 4" duct metal pipe, crimp one end of the pipe ( need crimprers ) and point the crimped side away from the dryer, towards the vent outlet. Don't use crews, the lint will catch on to the screws and clog, no screen on the end cap either, just a flapper. Use foil tape to tape the seams and joints.
One of the disadvantages of having laundry machines on the first floor is that they are neatly set in a laundry room/closet. I have fooled with the dryer ducting twice. Each time the washing machine (heavy front loader) needs to be moved out of the way to get behind the dryer.