I have a quarter-sheet sheet sander and have always had a problem with the sheets lasting a couple of minutes and then tearing, unhooking from either end or generally becoming useless. I tried to make the sheets longer, shorter, about right, but nothing worked. Finally, I think I have a way to extend the life of sandpaper to my satisfaction. It involves a bit more work than I'd like, but it seems to be effective. Read on.
Step 1: Measure the Length You Need
I have been buying my sandpaper from a discount outlet in half-sheet form. The sheets are too long, so I measured how long the sandpaper should be and tested the lengths until I found pretty much the exact length I needed. I could get one full length and another half length from one sheet of the commercial sandpaper. I found that 5 3/4" was the right length for my sander. The width, as purchased, was 3 5/8", which was OK. The trick is to insert the sandpaper so that it does not tear out right away. We'll consider the half-length paper later.
Step 2: Prepare the Ends of the Cut Sandpaper
At first, I thought I would simply reinforce each end of the sandpaper with duct tape, and that would be enough. I soon learned that while it did the job of strengthening the ends, it would quickly tear out. I needed something more to hold it in place. I happened to have some 1/4" wooden skewers and found that if I cut them 3 5/8" wide--the width of the sandpaper, I could glue them to each end and then use duct tape over that assembly to make it strong. Now, I had sandpaper that would be firmly gripped by the sander clamps at both ends. You can see in the photos that I had the skewers, which I cut to length, and then I glued the ends of the sandpaper and attached the cut skewers to the inside of each end and let them dry. The second to last photo shows the step of duct taping the skewers to the sandpaper. The last photo shows how much to overlap the duct tape on the sanding side of the sandpaper. I found that about 3/8" did the trick.
Step 3: Insert the Prepared Sandpaper Into the Sander
This step seems like it would be easy, but isn't quite as easy as it should be. The skewers are just a bit too wide to easily slip into the clamps. I found that I had to use a vise grip to hold one clamp open and then hold the other with my fingers and then slide the assembled sandpaper from the side onto the sander. When you get to this point, you'll see what I mean and I think you'll be able to get the sandpaper inserted into the sander.
Step 4: After a Period of Time, You'll See Wear
After some time, you'll begin to see some wear, but I'm sure you will be surprised to see how long the sandpaper lasts. I didn't measure the exact lifetime, but it was in the neighborhood of an hour or two. I got a lot of sanding done with one sheet of sandpaper. I did find that even with the stabilized ends of the sandpaper, it would start to go sideways as shown in the photo. You can ignore this issue, it will continue to work. As you can see in the last photo for this step, the sandpaper does eventually wear out.
In the next few steps, I'll show you what I did with the part sheets of sandpaper that I had when I cut them.
Step 5: What to Do With Half-pieces of Sandpaper
I found that after cutting the 5 3/4" sheets, I would have enough sandpaper from each sheet so that I would have another half left over. I used duct tape to tape the two sheets together, and found that if they were treated with the skewers and duct tape end reinforcements, they would last about as long as the full-length sheets. I actually used several pieces of duct tape length wise as well as across the width of the sandpaper to make for a strong joint. You can see that nothing lasts forever, and that they finally do pull apart at the joint. But, they do last quite a long time. Again, I didn't measure the lifespan, but it was comparable to the full sheets.