I’ve been using a cheap mini rotary tool for a while now, and I’m very happy with it. It’s quite a bit better than the finger nail polishing ones. I modified mine by drilling the collar’s ID a little larger so that it could accept a Dremmel 4486 keyless chuck. You can find these sold under a variety of brand names and colors. They have a micro-usb port for charging, the battery lasts a reasonable amount of time, they have 3 speed settings, and is great for small projects.
The collet size is another point. The Nail Files and some others are not the same collet/shaft size (like ancient Inch for Dremel and rest of modern world Metric. I did the same bore out but not for the ones I use on the trains.
I have a cordless dremel that I like, but it is weak on power. It works OK for most hobby applications, but if you put even a slight amount of excess pressure, it shuts down.....not stops, but shuts down completely. To get it working again, you have to shut the switch off and then restart. I pretty much rely on my corded one to avoid the hassle. I also have an old Black&Decker one that uses 1.5 volt stick batteries........plenty of power, but only 2 speeds, so it mostly gets used for heavy grinding and cut-off duty. As noted, cutting track can be a problem with fatter units, but for that I have one of these https://www.micromark.com/Dremel-Flex-Shaft.
I bought few years ago this little jewel for 25 Euros (with all the things you see in the picture) It comes with 5 different collets and it is also compatible with dremel chucks and tools. Battery lasts fairly long, electronic continuous speed regulation gets always the right speed. Since I have this, my expensive and corded dremel has never gone out of its box. I am still amazed by its quality, even the box, despite having fallen few times on the floor does not have a crack.
I'm going to sound spoilt, but anyway... I have the Dremel 8220 (cordless) and the 4300 (corded). Bought both as refurbished from CPO at a good saving, and they came as brand new. Initially started with the 8220, but it too heavy to use handheld, and was getting a little hard to use that with the Flex shaft. I now use the 8220 for any cordless work. And the 4300 at my desk, with the flex shaft and a foot pedal (search for a woodworkers pedal) to turn on and off the tool. This is great, as you can quickly pick up and put down the tool - Else it requires you to shuffle a tiny model and a live rotary tool. I wish Dremel allowed for a variable speed trigger, like most die grinders - But the foot pedal is a reasonable alternative. Also, get a good vise with the Dremel - One which can hold the tool or a small scale model. Sometimes you'll lock the model down and hold the tool - While at other times, you'll hold the tool down and hold the model. What I've written would probably hold true for all rotary tools - Just buy a brand where replacement parts, accessories and brushes are easy to find, and you'll have a tool which you can use for many years.
Quote It is very hard to find these super thin abrasive cut off discs, don’t make very small gaps in the rail but still way bigger than a razors saw. Jeff, it is easy to get .007 thin cut off disks. I use them in my lab all the time. They are very fragile because of their thinness, but they sure make thin cuts . They are sold in a box of 25 and you need a good mandrill also. I'm not in my lab now, but if anyone is interested I can get you the price that I pay for them . Contact me at lorensnyder18@gmail.com
