grinderpowertoolstools
I saw in the Internet a power tool with a proprietary attachment system that can transform the power base in a drill, in a cutter, in a jig saw, in a multi-too and so on… more than 10 different tools.
Is it possible to convert the rotary motion of a normal angle grinder to an oscillationg motion of a multi-tool? Does a similar universal adapter exists?
If you're talking about tools like this, then you can use them vertically.
The manual for the tool I linked to doesn't have any mention of the words horizontal, vertical, level, flat or upright, so if they don't warn you not to, you can assume it's OK to do it.
One thing to note is that to sand a vertical surface, you're going to have to hold the tool more tightly than you would if you were working on a horizontal surface. This will cause more vibration to be transferred to your hand and wrists, which will tire them out more quickly. If you're doing a large area, this can cause repetitive strain injury; when I sanded some window frames a while back, it took a couple of days afterwards for my wrist to feel OK again.
A few things I've done/do with my rotary tool that can't be done with a oscillating tool:
Overall, the oscillators have their uses, and replace other tools, but the blades can be hideously expensive. The bits can be cheaper for a rotary tool, and sometimes they're just better suited for a job -- cutting holes in drywall to fit an electrical box is one great example of a task where you can do it by hand, you can do it with an oscillator or even a reciprocating saw, but once you do it with a rotozip and the right bit you're just going to hate doing it any other way.
Best Answer
There are no universal solutions. All the powerheads are proprietary (as are the batteries/chargers)
An angle grinder is too fast, too heavy and too powerful for the precision that the oscillators provide, as a class.
Any combo you would jury rig in this fashion would not be worth the time, money and frustration.
I have the Rigid oscillator, and I think it's a bit heavy, vs the Fein single function, but I like the right angle impact driver for close quarters use
Good luck if you invent something, let us know.