Half of my cutting is on 2.5mil, half is on 5.0mil. Which blade should I go with?
3.5 and below 45deg
Above consider a sharp 45deg, a double cut with a 45deg or a 60deg single cut
So lately I've had to increase the gpf or gpi cut pressure on all cuts. And now, when I do weeding the vinyl is kind of ripping and not a smooth break. I'm guessing that's just a dull blade.
When I am not getting a clean tear, I often find that it is due to a dull blade. It is hard to see a dull point on a blade unless you can magnify the image. I examine blades with a binocular microscope at 30X magnification. Sometimes I amazed at how worn the point can become. In the grand scheme of things, blades are disposable and relatively inexpensive. I have also found that there is a limit to how much you can increase downward force to make up for a dull blade.
Is replacing a blade on a BN-20 easy enough for a non-technician to perform?
Yes, it is a matter of loosening the brass thumb screw, lifting up the blade holder, pushing the blade plunger, carefully extracting the blade and replacing with new one.
Always check your blade tip, easy to chip and give you bad cuts. Even brand new blades can chip if wrong force is used.
There is also a replace tools options which will bring the blade over the platen.
As Dennis stated check tip under magnification you usually will see it is chipped, if not chipped then dull, if perforated also check cutting strip for damage. it is normal to increase force over time, if the force is significant then damage blade, usually!
I replaced the blade and the cuts are very crisp now, and require less pressure. I couldn't magnify the old blade or see damage, but it sure had a lot of fuzz/debris all around it. New blade cuts like a dream!