I definitely recommend the 4 bladed easel, the vt1400 is the V-Track right, I have one they're nice. So here's what I do. First I sacrifice a sheet of the enlarging paper, then on the back I carefully layout and mark my borders. Then I put the paper in the easel making sure that paper is positioned all the way in the slot and slid to the left hand side. Next I align the easel blades, with the border lines I marked on the paper. I also use the paper composing and focusing. When printing just make sure that you position the paper all the way in the slot and slide it to the all the way to the left. This method will give you very consistent borders.
Echo most of that from another Roger, but I don't find it necessary to sacrifice a sheet. I have the V track too - possibly the best easel ever made, certainly the best I ever used. I generally print 6x6 negs to 7.5"x7.5" leaving narrow 1/4" borders on the short side. Just set all four blades by the scale on the side to 7.5 and you're good (or 7 if you want 7x7 with 1/2" borders or whatever.)
On 11x14 paper I similarly print 10.5x10.5.
For larger prints I just got a 16x20 two blade easel and I'll just have to trim the excess. I also picked up a rotary trimmer so it shouldn't be too bad.
A combination of a four-bladed easel and cutting down paper.
I cut 11x14 paper down to 11x11 and print negatives from my Rolleiflex at 10x10.
I take one sheet of paper, cut it down, develop it, unexposed, then dry it and flatten it. I put that sheet of paper in the easel and center it up the way I like. Then I take a fine-point sharpie and trace the outline of the blades onto the paper. On the top corner, I write the "FOCUS SHEET - 10x10" or whatever size I am making.
I make a focus sheet for every size that I like to print. When I change sizes, it's a simple matter of pulling out the focus sheet for 8x10, 4x5, 11x14 or whatever size, put it onto the easel then move the blades until they touch the outlines drawn on the paper.
If you use red ink (or whatever color matches your safelights) the writing will be virtually invisible under working conditions so you can use it for composing and focusing without being bothered too much by the writing on the paper.
My hardest problem printing square pictures doesn't have much to do with technical stuff. It's because I have a hard time finding square mattes. They either have to be special ordered or custom cut.
(One of these days, when I get rich, I'm going to have to invest in a matte cutter. )
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FWIW, you can use the back of an unwanted print as a "Focus Sheet"
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2