WhatTheFlux!

10-09-2013, 11:48 AM

Ok we make a captive line of fasteners for a customer. Due to various "reasons" I have to be kind of vague. All those who have worked under those conditions, smile and nod and take a shot. :)

So the upper and lower thingy drop down a vibrating inclined track system, into a small air-punch-press. The force of the punch-motion drives the upper thingy into the lower thingy. I may have said too much. :rolleyes:

Anyway, the upper-thingy comes down the track too fast and I need to slow them down so I get one thingy every two seconds. I thought I had a "servo" designed that would slow the parts down to one every two seconds.. that's why I asked the math question.

So today I learned that DC motors can't be slowed down to far enough to make my wheel turn .875 RPM. Apparently, DC motors become unstable as you fiddle with the voltage/current?

So, first question is there a way to slow my motor down any further, right now I have a pot between the power supply and the motor. I can slow it down to a certain point then it becomes VERY unstable. Lots of surging. Any lower and the motor stalls.

This means... I am going to have to pick a motor RPM and gear it down.

Lets assume 30 RPM at the motor shaft. The rating is 60 RPM unloaded at 6vdc, I'm assuming I'll have half of that once I start attaching gears.

What would I need, gear-wise, to bring 30RPM down to .875RPM at a 3" wheel.

Once I figure out what I need to build my hypothetical gear-train, it's a matter of then transmitting that power to a very tight space, possibly via quantum ****ery or a belt-pulley.

Of course there is always the chance that I may win the Powerball between now and the due-date... if that happens I'm just going to retire and let someone else deal with it. :D

So the upper and lower thingy drop down a vibrating inclined track system, into a small air-punch-press. The force of the punch-motion drives the upper thingy into the lower thingy. I may have said too much. :rolleyes:

Anyway, the upper-thingy comes down the track too fast and I need to slow them down so I get one thingy every two seconds. I thought I had a "servo" designed that would slow the parts down to one every two seconds.. that's why I asked the math question.

So today I learned that DC motors can't be slowed down to far enough to make my wheel turn .875 RPM. Apparently, DC motors become unstable as you fiddle with the voltage/current?

So, first question is there a way to slow my motor down any further, right now I have a pot between the power supply and the motor. I can slow it down to a certain point then it becomes VERY unstable. Lots of surging. Any lower and the motor stalls.

This means... I am going to have to pick a motor RPM and gear it down.

Lets assume 30 RPM at the motor shaft. The rating is 60 RPM unloaded at 6vdc, I'm assuming I'll have half of that once I start attaching gears.

What would I need, gear-wise, to bring 30RPM down to .875RPM at a 3" wheel.

Once I figure out what I need to build my hypothetical gear-train, it's a matter of then transmitting that power to a very tight space, possibly via quantum ****ery or a belt-pulley.

Of course there is always the chance that I may win the Powerball between now and the due-date... if that happens I'm just going to retire and let someone else deal with it. :D