I didn't mean pinch when bleeding, I meant during removing calipers etc. I always lock something on the hose before I un do the caliper, that way you massively reduce the air entereing the system. You stiull have to bleed but not as much as if you didn't lock the line.
I've never used a vacuum or anything to bleed, always just done it the old school way, one person in the car pumping the pedal, the other person working the nipples.
A few questions just to problem solve (I'll also ask the dumb questions just in case, I know I've done stupid things before):
Why did you replace the calipers? If the brakes were soft maybe it was not the calipers and could be the master cylinder or hoses?
Are all the nipples in place? Are
Are you bleeding the top nipples?
What condition are the hoses in - even if they look perfect are they bulging?
Are there any leaks that you can see - including dripping down inside the wheel rim and not getting as far as the floor?
Thats about all I can think of straight away...