/diy/ - Do It Yourself

Quick question OP, you doing this just for the DIY project involved or to save money, or because you think it'll be better than a commercial motorised coffee grinder?

>>435862
>a few rotations a second
It'll last about 5 minutes like that before you break it.
Try 1-2rpm.
Or better yet, get a real coffee grinder. That thing is for show only.

>>435881
Mostly just for fun. I don't know if it would be any better or worse than a commercial one.

>>435888
>1-2rpm
That's ridiculously slow. I hand crank it at maybe 1 rps, and even then it takes a good while to grind one cup worth of coffee.

I don't know from mechE, but just considering the force on the end of the crank and the distance of its travel, one radian/sec times one Newton-meter should equal one watt (one Newton*meter/sec) of power transfer.

2 rev/sec (a quick but not crazy grinding speed for a human turning the crank) is 13-ish radians/sec, multiply by two for mechanical losses and round up and figure you'll want a 50-watt motor or 1/15 horsepower.

Looking at battle bots sites: a motor-and-gearbox should run you about $30 I guess?

>>435891
Then get a real coffee grinder. That thing is an antique inteded to be ornamental, not practical.

>>435891
>1-2rpm
Damn, I'm just not awake at all today.
I meant 1-2 revs per *second*, maximum.
If it's meant for hand-cranking then you don't crank it faster than you could crank it by hand, even with a motor.

I still stand by this though: Get a real coffee grinder, that thing is an antique.

>>435862
Microwave tray motor.

>>435901
>a motor-and-gearbox should run you about $30 I guess?
..and for that much money you can buy a nice, new, modern coffee grinder that will do a better job, is easier to clean, etc etc etc then you can spend your time doing something useful instead of ruining antiques.

>>435918
>>435921
for $30 you will get a blade grinder. i havent really seen a burr grinder (which is what OP is using) for that cheap. plus he can probably salvage parts to save money. plus its a project.

so does anyone have actual advice about how to add a motor to this one?

>>435862
My aunt had a couple antique grinders almost identical to OP but she didn't used them for coffee, rather for fine herbs like rosemary and shit.

If you want to make a potful of coffee you'd have to reload it plenty times.

Just get a commercial one which will also come in handy if you get an espresso machine which usually require more finely ground coffee.

>>435920
This.

/tread

OP back.

Don't worry about me ruining some "antique." The grinder I have is a recently produced, kitschy thing.

Anyway, I'll look into the microwave motor suggestion. Seems clever.

Just use a blender to grind coffee. It works well and holds a lot.

>>435862
>measure

OMFG! you actually thought and measured something! no i'm not being ironic, i do shit like, umm, measure? and people think i'm nuts.

your project remains a bit hare-brained, but hey!

>buy
true enough; but you could counter with the argument (that i actually think is shit, but whatever) that high-speed grinding harms the coffee, whereas low speed doesn't (localized heating or some shit) therefore your lowspeed grinder is over 9000 times better.

wow, i remain impressed, actually measuring torque and being able to think through the process.

that should not be a rare skill, but it is.

>>437006
>It works well
No it doesn't

>>437006
>>437008
Standards on this vary. A lot.

How about pic related? That would be easy to do.