Dremel678 - Circle Cutter and Straight Edge Guide Rotary Tool Attachment - Fits Dremel Models 4300, 4000, 3000 and 8220

Using this circle cutter with straight edge guide is a great way to turn your dremel into an even more valuable power tool. The circle cutter has worked flawlessly cutting very clean and quick circles/holes. The alternative is to purchase very expensive hole saws that require a major drill for the larger and deeper holes. The dremel and spiral saw bit will allow you to cut very large holes quickly. Set up is a snap and the center point adjustment is super easy to set without any special tools. The hole sizing gauge is a bit general, but if you need a precisely sized hole, I use a tape measure to set the radius by measuring from the far side of the spiral bit to the center of the pivot point. The straight edge guide turns your dremel into a small router that you can use to do all sorts of helpful cuts. Often, whenever I am away from my router table, this is my go to tool for cutting a small and simple dado or rabbit, or cleaning up an edge. I love this attachment!

Take your time and you will create great circles with this product.

I used this with my Harbor freight rotary tool and it worked well so far. I used the edge guide for cutting a bridge slot for an acoustic guitar build. I will also be using this as a circle cutter for installing the rosette on my guitar. The one downside to this tool, is the inabillity to line up the bit by eye, as the base covers up the cutting bit, and cannot be seen when the bit is cutting or before it cuts. This makes it difficult to get it in the correct position for cutting. The cost of the product was very reasonalbe.

I used this to cut out holes for the subwoofers in my subwoofer box. It worked pretty well, but not perfect. Results were somewhere in-between a jigsaw and a router. I drilled a pilot hole for the center pivot piece as well as the cutting bit so I didn't have to ease it in at an angle or anything funny like that. With MDF it could take off 3/8" of material at a time, but I had to max the RPM on the Dremel which I normally don't like doing. The bit seemed to like cutting clockwise better than counter-clockwise (perhaps that's in the instructions I threw out, I don't know). The first pass took longer than the second.Make sure you have the circle you're cutting supported separately but at the same height as the main piece you're cutting from, otherwise when you get to the end of the cut it'll start dropping and you'll become inaccurate.Overall I would plan on making your cuts slightly larger or smaller (depending on if you're using the inside or outside of what you cut) and sanding it a bit to even it out. If you really want a PERFECT circle this probably isn't enough, at least for thicker materials or thicker/quicker cuts. But a proper router is incredibly expensive in comparison, especially if you already have the Dremel anyway and just have to buy this attachment. For one-offs it's fine, but if you plan on using this daily you have the wrong tool.

Typical Dremel quality, instructions and support

I used this to cut 3" circles in 3/4" plywood to make rings using dremel standard cutting bits. It took some broken bits until I was able get the right pressure. Created 4 rings, stacking 2 to create a way to install round fans in a camper shell. I also cut the same size hole in my fiberglass camper shell roof to install small round fans. This circle tool worked perfectly. Be patient, it's not a router.

I used this to cut holes into 1/8" MDF board as a template and two 6061 aluminum 1/4" sheets. You really have to make sure all the screws are securely tightened otherwise you will get a lot of wiggling. Don't use this if you actually need to use the circles. The actual hole is cut more accurately than the leftover material. You are more likely to ruin the circles than the holes. Take it slow and hold the tool tightly otherwise the Dremel bit can get caught on the material and ruin your cut. The bit that comes with the tool eats through wood very easily but if you are working with metal you have to be patient and take it extra slow otherwise you can break the bit.The description says you can cut as small as 3/4" in diameter but the smallest I was able to cut with this was a little over 2" in Diameter. The screws on the tool retainer get in the way of the center pin making the tool really wobbly and unstable if I go smaller than 2".The plastic holder that you screw your tool into is very thin and will easily split if you accidentally over tighten your tool. Also the mechanism used to adjust the height of the tool is kind of flimsy and doesn't feel very secure. I got a lot of vibration in the tool if I set the height too high but that could also be because I was primarily working with 6061 Aluminum.Overall its decent if you need something quick and cheap but for anything that needs serious work just get a drill press or better yet a router. It will save you a lot of time and will produce better quality work.

This is my second time purchasing this tool because I misplaced the first one. I used this to cut out round speaker holes for both HDF boards and ceiling boards. Of course HDF board take longer time to cut and after a couple of wholes (6" diameter) the cutting drill bit became somewhat dull. Cutting the ceiling boards is like cutting butter with a sharp knife, very easy and accurate cuts. It takes a little practice to figure out how to setup the position of the drill bit to a precise cut, but once you figured it out, it's pretty easy to setup. I recommend this tool.