I want to make peanut butter and almond butter. My food processor heated after a couple of minutes last time, so this time I first used a mortar and pestle to grind it a little and then use the processor. After 3-4 minutes, the motor just stopped and I had to press the reset button. I'm a kid and have to use my mum's food processor, so I'm really scared that I'll break it. Any other way to make the butter? I don't add any oils or anything and would prefer not to.
There usually is no good way to do this, since most home appliances in an average kitchen are simply not suited for making nut butters.
If you really want to do it, the preferable tool would be a masticating juicer. It is an expensive thing which also uses up quite a lot of counter space, and the process is messy.
All other electric tools you can misuse - food processors, blenders, mills, etc. - run into the problems you already noticed, because they are not designed to make nut butter. For all, it is easy to burn them out. If you take the risk and grind away, and the motor survives, you are as likely to end up with a collection of nut pieces and nut dust as you are with a butter. And not adding oils reduces your chances of success.
The mortar and pestle approach would work, but you will probably have to spend several hours for a jar of nut butter. It is usually not worth your time when compared to buying the nut butter.
See also earlier questions like What features should a food processor have in order to make nut butters?, What features should I look for in a hand grinder (for peanut butter)? and How to make ground almonds creamy?.
There are a few recipes for nut butters on the Internet, which use a food processor. They recommend using raw, unsalted nuts, without skins. Begin by lightly roasting the nuts, then, placing them in the food processor while still warm. In bursts, begin to grind the nuts. While you stated that you didn't want to add anything, it might actually be necessary. They suggest 2 tablespoons of mild flavored honey, and 5 tablespoons of fat (coconut oil or palm oil), per 2 cups of nuts. This aids in the emulsification process. They suggest grinding in shorter bursts. Do the initial grind of 1 - 3 minutes (before adding emulsifiers), then allow to cool for 10 minutes. Add 1/2 of the emulsifiers, grind for 5 minutes, cool 10 minutes. Add rest of emulsifiers, grind for 5 minutes. Adjust seasoning, grind for an additional minute.
Making nut butter is easy:
- you have to soak your nuts for so many hours
- add some avocado in one of those new blending machines.
The above is a bit of a trial and error, maybe add a touch more avocado or just a touch more water if you do not like avocado,
In my 1000 W blender it works like a charm.