I really like the rolling knife sharpeners, but they have some flaws, in my opinion. The biggest is with a knife with a bolster. Sharpening the portion of the blade in that location is tough, the rotation is minimal in this area.

I decided that a rolling knife sharpener would benefit from a motor, so I added one.

The most expensive part of the sharpener are the sharpening disks. I found this set on Amazon. Any disk with a 12mm x 1.5mm thread will work. This set goes to 6000 grit and will give you a frighteningly sharp knife.

I ordered a 550 RPM motor. The motor turns the wrong direction, so solder the  motor so the sharpening disk rotates clockwise.

The power input cord from amazon, I use theses connectors a lot, so I bought a multi pack.

I had a 12V power supply to use, but this one will work.

You'll also need nine flat head 3mm x 16mm screws.

I made a storage base and it can be found here.

The assembly is very easy:

• attach the motor to the front face with 6 of the screws.
• Install a power wire in the threaded hole on the back side. The thread will be a little tight, but it will thread into place, be persistent. Be very careful to avoid cross threading. 
• Solder the red wire to the + (positive) on the 200 rpm and to the - (negative) of the 500 rpm motor. 
• Put the shell and the front motor mount together and attach with 3 of the screws.
• Put the drive piece on the motor. I made it with a tight fit so it stays in place. It will take some force.
• Put a sharpening disk on the sharpener and evaluate if the disk wobbles. If it does, the part called mini lathe tool holder can be used with an Xacto blade with a square nose to true the part up.

I found using the exacto blade with the flat surface up worked best to scrape the material away. Square it up to the ridge on the motor drive, bring it slowly to the edge. It will scrape rather than cut and remove a tiny amount of material. Do this until the sound the tool makes is uniform. Test with a sharpening disk to see if the wobble is gone, if it is or you're happy with the amount, you're done.

The block to hold the knife is easy to assemble too. Install three ½" dia x 3/16 thick Neodymium magnets. I used some thick CA glue to hold them in place. I then put a piece of leather on each end and trimmed it to size. The PLA I used is too slippery to effectively hold so I needed something with some friction. I had some leather close by, but anything will work.

Using the sharpener takes very little skill. I designed it that way to ensure that most people can find success sharpening their knives. Just put a knife on the sharpening block at the angle you want, press the knife against the flat surface the knife block is on. Put the 400 grit disk on the sharpener and bring the sharpener to the blade. Keep the disk flat against the blade, make contact across the entire surface of the blade. Move the sharpener, not the knife, slowly down the length of the blade. When the edge curves, the sharpening disk will only contact at a point, rotate the sharpener keep the point of contact away from the edge of the disk and you'll be fine.

Continue to use the coarse disk until you feel a burr on the edge. You know you've reached the apex of the blade when you feel this. Do the other side of the knife when you feel the burr. This time, make sure the edge is in the center of the knife. You should also feel the burr. When you are satisfied the knife is sharpened with this disk, clean the edge, grab a finer disk and repeat the process. Always start the next disk on the opposite edge you finished the coarser disk on. The finer disks should only need a few passes to feel the burr, you want to remove the scratches from the previous grit. Keep going until the knife is as sharp as you like, or you've reached the finest grit disk you have. Strop the knife to remove the burr from the final sharpening. Be sure to clean between every grit.

The first time you sharpen the knife it will take a while to establish the angle. After that, it will only take a minute to reestablish the edge. Letting the knife get dull will result in a longer sharpening time. Honing the edge after a few uses will keep your knife extremely sharp and takes less than a minute.