Another nice thing: Rotatrims will slice off an unbelievably tiny sliver of paper with unquestioned precision. I have a 24" and 30" unit, both cut paper with the finesse of a scalpel. For trimming drymount tissue after tacking it to the print there is NO comparison with a Rotatrim.
The 24" unit will trim matboard without batting an eye, but the 30" unit takes some care since the rods are pretty long and can flex upwards if the matboard is extra dense (the blade can "jump" if that happens).
I also have 3 guillotine trimmers, a 12" Premier that I've used continuosly since 1960, a 15" Ingento with a beautiful hard Maple base, and an 18" Premier I picked up at a swap meet (remember those?) a few years ago. I use the two smaller ones routinly for general utility trimming. Guillotine trimmers can be professionally resharpened.
Be aware that both types distort the edge being trimmed off. Both are classified as "shear" slitters, and the unsupported edge will show some distortion because the upper blade must displace the paper as it descends past the bed knife. The thicker the material being slit, the greater the distortion. On a guillotine trimmer, the effect is most pronounced up against the squaring bar, where the "throat angle" is high. If I'm going to use both sides of the cut, I'll lay a 3" wide strip of plexiglass against the squaring arm which keeps the starting cut farther away from the throat.
Which type of trimmer do I prefer?... I use both, I need both, I even use a razor blade against a straight edge now and then.
The best Rotatrim units are the 2-bar "Mastercut" or "Professional" units. The double bar configuration is more robust and cuts matboard too.
For an entry level utility guillotine trimmer, Harbor Freight Tools sells a 15" unit for about $15. Kinda Klunky, but it works...
Have fun.
Reinhold
www.classicBWphoto.com