Speed control by pedal force or movement?

[DonInReno]

On 4/17/2019 at 3:49 AM, Gymnast said:

So why do designers new fighter aircrafts and Commercial jets make force activated stics with no movement. They could easely make some movement on such sticks for the electronics, but they dont.

Um...99.99% of all speed/volume controls use some movement - it works.

[Gymnast]

I just discovered, that the Swiss sewing machine manufacturer, Elna have used air foot control for some years:

https://www.sewingpartsonline.com/air-foot-control-elna-436410-20.aspx

They marketed this inovation in the early 1980s.

I think than my version on the thread start picture is cheaper

[Gymnast]

I have tried to measure force and displacement of an ordinary foot pedal and the force controlled pedal I got. The measurement results are in the diagram below. For the force measurements, I used a digital kitchen weight.

I have tried only a couple of industrial sewing machines, so i am not so sure about the normal pedal behavior of them, so I hope you can help me with your experience. I suppose you got a industrial sewing machine with a servo motor on it.

When you press down the speed pedal with your foot, then first you need to apply some force before the pedal starts to move downwords. You need to overcome a spring pulling up the pedal to a stop. In the diagram you should look at the red dashed line, and for this pedal it starts to move with a pressure of 10 N or about 1 kg. When you press down further then the pedal moves downwords. At about 15 N force the machine starts to turn. In the diagram below it is when the pedal have moved about 3 mm down. When you press further down the force needed increase and the speed increase. At some position you reach max speed of the machine. This is at about 43 N force and 28 mm displacement on pedal. However it is possible to press the pedal further down, but the max speed is maintained. At some position the pedal go against a stop, and it do not move further even if you press harder with your foot.

Apart from the numbers - is this text an accurate technical description on how your pedal work?

Do you think the numbers for your machine is much different?

[Constabulary]

Sorry to say that but for "just operating a sewing machine" this is a bit too much science for me. Pedal down force? Really? For what? Honestly I do dot care and I´m not event trying to follow all this. But as we say in German "Jedem Tierchen sein Pläsierchen"  Good luck with this!

[DonInReno]

Everyone has a different preference for length of movement, force required, and how fast the force increases.  Personally I like 2”-3” of movement and very light constant pressure on what is essentially an automotive pedal.   

[sheathmaker]

Boy, if I have ever seen a solution looking for a problem, this is a classic example.  Force, movement,....who cares?  I just want my machine to sew correctly when I turn it on and to start and stop when I say Go and Whoa.  Now before anyone gets their feelings hurt, the foregoing is just my personal opinion and is not intended to sway anyone one way or the other, or criticize others for their opinions.  I'm a believer in the old "If it ani't broke, don't try to fix it" camp and my Cobra machines have been (with servo motors)  sewing just dandy since I brought them into the shop.  Good luck!

 

Paul

Edited October 23, 2019 by sheathmaker