Cynthia,
About a year ago, I was in the market for a rotary tool to replace a 20+ year old rotary tool that had finally worn out. I purchased a Dremel tool at one of the big box stores as a replacement. Took it home and it vibrated so bad that it was unusable. It appeared that there was too much give in either the bushings or the bearings (I really believe that Dremel tools like the ones shown in your link are only bushings and not bearings). I took it back to the store and exchanged it for a replacement. That one worked better, and I was able to finish up the project that I was in the middle of when the old one died. But the replacement also vibrated quite a bit more than the one that I had used for 20+ years. I may have used that new Dremel for a total of 30 minutes. A few months go by and I have a need for for the rotary tool again. Started using the new Dremel, and after about 20 minutes of use, it got hot, sparks flew, and the smoke escaped. Now we all know that once the smoke escapes, the electric tool will never work again.
At that point, I was not interested in spending the time and energy required to get the unit fixed under warranty.
I started looking for a higher quality replacement. My search lead me to the Proxxon 38481 IB/E Professional Rotary Tool (
here). I have been very happy with this unit. I have used it quite a few times since I purchased it and it is very smooth and when free running is almost vibration free.
I also have several air powered rotary tools. I have 2 large ones (Similar to these
straight and
90) that will accept 1/4" shank tools. They are very heavy consumers of compressed air. It does not take long for a single tool to pull down the pressure in the tank (60 gallon tank, 11 CFM compressor). They are also very noisy when in operation. Add the noise they produce to the noise that the compressor makes and it can get really loud in the shop. To the point of needing hearing protection (to keep what hearing I have left). I tend to use these when I'm doing heavy duty metal shaping or really heavy wood cutting.
I also have a 1/8" shank air powered rotary tool. It is similar to the one shown
here. It does not use nearly as much air as its larger cousins and it is not as loud either. I found the sound of it running reminded me of being at the dentist office. It is louder than the Proxxon when it is running. The 1/8" shank air unit also does not have much torque and would tend to stall very easy. Another reason that I purchased the Proxxon.
You will need to be careful if you are going to use air powered rotary tools around wood projects. Almost all air powered rotary tools that I know of require oil lubrication in the air supply. This oil is carried through the air supply and exhausts out the front or back of the tool. While it will not be that heavy, you might want check before you start to finish to ensure that the oil has not contaminated the wood surface.
And yes, the air tools are from harbor freight. I have had good luck so far with their air tools and they are not at all expensive. I just can't see spending a lot of money on something that I don't use that often. I deceided to spend more on the Proxxon since I always tended to go back to the electric rotary tool due to the convenience, and noise from the tool and compressor.
There are other options such as flex drive units and I don't have any experience with one of those. If I was going to look at doing carving with a rotary tool, I might look into one of the flex drive units.
So, I believe that what is best for you is largely dependent upon what you intend to do with it and how much you intend to use it.