I'm not sure you are answering my question. Let me put it another way. Assume you know the distance of the mass from the center. And assume it's not possible to do any testing at this time. But you know the dimensions.
Once the wheel is spinning it doesn't take a lot to keep it spinning. Friction and air resistance mostly unless it's also being asked to translate the spin back to some sort of work. Then let's say the need changes and now 2.5 seconds are required to bring it up to speed instead of 5 seconds. What size motor then? > -----Original Message----- > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > Sent: June-16-22 6:56 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Acceleration question. > > Knowing the mass of the wheel is not enough, you need to know how far the > mas is from the center of rotation. They call this "Moment of inertia" > There are ways of calculating this for simple wheel shapes like a plain > disk but for anything else you are best off if you just measure it. > > The simplest way you can find your answer with not much math is to wrap a > string around the wheel and attach a weight to the string and time how long > it takes for the weight to fall some distance. The weight will apply a > torque to the wheel equal to the weight times the radius of whatever you > wrapped the string around. > > Make the weight bigger until it works, then buy a motor that can supply > that torque, plus a bit more. > > if you really want to calculate the moment, perhaps because you have not > yet built the wheel then remember that the wheels moment is equal to the > some of the moments of the parts of the wheel (the parts add up) So divide > the wheel into (say) a rim, a thin disk and a hub find the moment of each > and then add them. > > But the string experiment is easier. > > On Thu, Jun 16, 2022 at 5:53 PM John Dammeyer <jo...@autoartisans.com> > wrote: > > > OK. I realize this will be a dumb question but please bear with me > > especially since I've included the ability to accelerate in my Electronic > > Lead Screw project. > > > > A friend and I were discussing bringing a 300 pound flywheel up to speed. > > Vz=0 RPM, Vf=50 RPM. Reduction drive to the flywheel shaft is 32:1 so > > final speed of motor is 1600 RPM. > > > > Assume we're happy with 5 seconds to accelerate for Tz to Tf. Motor > > voltage is 12V. > > > > We have the mass, we have the velocity, we have the time and motor > > voltage. The question is what are the calculations to determine how much > > current the motor will require to create this acceleration? Assuming of > > course the motor is 100% efficient. > > > > We're getting all confused with F=ma and 1/2*a*t^2 etc. > > > > What size motor is actually needed to do this? > > > > Thanks. > > John > > > > "ELS! Nothing else works as well for your Lathe" > > Automation Artisans Inc. > > www dot autoartisans dot com > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
