Hi Jon, How did you come up with the constant 0.0318? " So, that 100 oz-in motor (0.52 lb-ft) would produce 0.52/0.0318 = 16.35 lbs of linear force (neglecting friction)."
And how did you work out the 5G? "So, if your machine has a 200 Lb table, and the leadscrew were to produce 1000 Lbs linear force, it would accelerate at 5 G? It would be handy to have a spreadsheet where once can key in motor in oz-in or Nm, max RPM, reduction ratio, and table weight. Maybe even in addition to screw pitch and an acme or ball tweak factor. Heck I'll whip up a Lazarus Free Pascal program with all the entry fields for this. It would run on Linux, PCs, MACs, Beagles and Pi computers. I just need a bit more of the math/constants behind it. John Dammeyer > -----Original Message----- > From: Jon Elson [mailto:el...@pico-systems.com] > Sent: July-21-20 7:31 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Need help with Bostomatic BD18-2 to linuxcnc > > On 07/20/2020 11:49 PM, Tom Smart wrote: > > So my 3500 rpm rated motor at 180vdc would be 2916 rpm at 150 vdc and 2333 > > rpm at 120vdc? > Yes, exactly. > > If my ballscrew is 5tpi then at rated voltage i would get 700 ipm at 150vdc > > 583 ipm and at 120vdc 466ipm feeds? > Yes. > > If i keep the amps at the rating of 9.1 I should keep my 31.3 IN-LBS or 2.6 > > FT-LBS? > > > > So 2.6 / .0813 would be 81.76 lbs of linear force? > That denominator s .0318 but your result is correct. > > So if my table weighs 200lbs my acceleration would be .41 G? > > > > I'm wondering if I've done a calculation wrong or is this a good setup? > > > Well, 81 Lbs sounds pretty weak for a milling machine. Is > the motor directly driving the leadscrew or is there a belt > reduction? My Bridgeport setup is kind of anemic, but it > has a 2.5:1 belt reduction on the motor. That gets me to 23 > In-Lb at the leadscrew, for 700 Lbs of linear force. > > Now, the 9.1 A rating of the motor, is that a continuous > (stall) rating or a peak rating? If that is stall, then the > motor can handle more current during acceleration peaks, at > least twice, possibly 4 X. > That will help. > > Jon > > > _______________________________________________ > 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
