"Also, the stepper motors have 32 steps per revolution with an internal gear train often stated as a 1:64 ratio, but actually the ratio is slightly less at 1:63.68395."
Seems a bit strange. Are they not gears?
"Also, the stepper motors have 32 steps per revolution with an internal gear train often stated as a 1:64 ratio, but actually the ratio is slightly less at 1:63.68395."
Seems a bit strange. Are they not gears?
By coincidence I recently read a paper from a trade magazine that discussed this: http://static.micromo.com/media/wysi...uction_use.pdf
If you use gear ratios with an integer ratio, say 3:1, for example a 10 tooth spur with a 30 tooth pinion, the same sets of gear teeth will constantly mesh. If there is a defect in one of the teeth on one gear, it will cause wear in the same spot on the companion gear.
If you use a non-integer ratio, the wear will be more evenly distributed and the gear set should last longer.
The stepper motor I am using has gear set pairs of the following:
wheel pinion ratio 32 9 3.555555556 22 11 2.000000000 26 9 2.888888889 31 10 3.100000000 63.683950617 final
Oddly, the second set is an integer ratio. Well, I didn't design the thing; I'm just using it.
Last edited by DickB; 12-22-2015 at 08:35 AM.
Very interesting. Thanks for the explanation.
It still seems very strange to design a stepper motor without a final integer gear ratio.
Design News accepted and published my metric clock Gadget Freak submission:http://www.designnews.com/author.asp… I built this clock for a customer in the UK, knowing that I would spend way more time on it than what I charged him. But it was a fun project, and I figured that it had a good chance of being accepted as a Gadget which, when published, earns a $500 stipend.
This is my third published Gadget.
Last edited by DickB; 12-22-2015 at 05:17 PM.
Outstanding project, write up, and presentation. Truly amazing Dick. Thanks also for educating us on metric time. I had never even heard of it before.
A customer asked to have a clock made, posting this picture and story:
"My father is retiring in April 2016 after decades of working as a software engineer. He started at Digital Equipment Corp in the late 70s. The original plant overlooked the mill tower (pictured) in Maynard, Massachusetts. At the employee's 20 year anniversary with the company they got a mantle clock with a small replica of the mill in it. Digital equip Corp was sold 3 months before my dad got "his clock." I'd love to be able to give him what he earned so many years ago... My mom says she thought the clock was metal in glass, my dad appreciates natural materials so I think it would look amazing in wood."
I said I could do it, although I wasn't sure how I was going to fabricate the bell tower on top.
Later, she found a photo of one of the original clocks:
Good - no bell tower!
I just finished the clock today:
The customer is going to add a small metal plaque.
I designed the clock using several rectangular carve regions and the 3D Extrude and Sweep tools. I did use my table and band saws to make the miters and a few other cuts. There are 14 pieces to the clock and three clock movements.
Very cool clock.
Time for you to go grasshopper!
Steve
Beautiful clock, but does it have wooden gears?
Clint