If this has been covered previously, my apology to the originator. When I purchased a multi tool a few months ago one of the things in mind was to see if it would serve cutting hinge slots. With a current build in progress, it was time to see.

First - I took the flush cutting head that was 1.25 inches wide and having a straight saw blade edge to the grinder and ground it down on each side to leave a cutting portion the width and depth of the hinges I use (Dubro #117). Keep it from getting too hot by dipping occasionally in water. A test piece revealed that the cutting teeth (at least on the Harbor Freight version) provided just the right thickness of cut for the hinges. In the test I also noted that the slowest speed on the multi tool worked best... so if a multi tool is in your future and you might use it for hinge slotting, I'd suggest a variable speed.

Second - I clamped a piece of oak hardwood to the bench edge to serve as a base reference for the cutting head. The hardwood strip needs to be positioned (shimmed up) to the approximate height of the hinge slot desired in the part that will lay just beyond the strip. Keep this simple with some spring clamps so that the shim can be changed easily as various height needs change.

Third - Lay a towel beyond the hardwood strip and place the surface to be slotted on the towel and bring it up to the hardwood strip. It can be rotated slightly to get the right height or the shim under the hardwood can be changed.

Four - With one hand, hold the part to be slotted to the hardwood strip and at the right height and rest the cutting tool on the hardwood strip and advance until to the depth of the shoulders on the cutting tool. Easy and fast. I made 38 slots in just a few minutes whereas by hand I'd been at it a couple of hours.

Hmm Interesting. I don't own a "multi tool", but...looking at the picture of one at Harbor Freight's web site..it appears to be very similar to the triangular sanding tool from Ryobi that I have sitting, mostly unused, in my tool drawer. I wonder if I did a modification on a flat piece of metal ...that I could make a "multi tool" out of IT! Thanks for the idea.
regards, Rich

Good idea on forming a tool head for the sander. The multi tool works great but as I was using it, the thought occurred to me that it would be nice if it was half the size. One of the small detail sanders might be the cat's meow.

During a visit to Harbor Freight for a replacement of the tool head that I ground down for hinge slotting, I noted that they in fact had a tool head that was 3/4 inch wide and thus needing no modifications. Cost was just a few dollars.

I just got the hinge slotting tool from great Planes for xmas.  At less than 30 bucks I think it is the only way to go.  it was so easy.  I wish I had bought it many years ago.

The problem you can run into with the Hinging Tool is that it has two blades, which is a good idea, but you must be careful. If a piece of balsa gets between the blades when you start it into the wood, the blades will spread as you plunge the blades in, making two seperate slots. If you are useing the Hinging Tool you should first start the slot with a #11 blade. I already had a Dremel Multi Tool which works great for making my hinge slots. But, if anyone is going to use a Multi Tool for hinging, you have to hold down your control surface fairly well because, unlike the GP tool, the Multi tool only has one blade and it's vibrating back and forth as you push it in. The GP tool has counter acting blades, so there isen't so much movement of the control surface.

Yeah... Plus, I think the multi tool is too large and difficult to handle for freehanding the slots without providing a base for the multi tool head.

Doing so was very simple to do as in the illustration and perhaps should be noted as a requirement. By holding the surface to be slotted to the base, there is no problem with the oscillation of the tool.