circular movment into linear - Electronic Circuits Projects Diagrams Free

JekylHyde · 17th October 2009, 12:49 PM

Hi!
i have a big motor i took from a mixer (kenwood).
i want to translate the circular movment into linear (to make it move a metal bar forward & backward).
any PRACTICAL ideas? (step by step?)
i need to be able to push 5Kg objects (at least)...& to move 20cm back & forward, back & forward, back & forward... endlessly.
thanks

**Nigel Goodwin** · 17th October 2009, 01:02 PM

A crankshaft, like in a petrol engine - it's really a VERY simple (and obvious) technique.

dknguyen · 17th October 2009, 07:19 PM

Like on a locomotive train or car engine, except backwards. Instead of the linear piston driving the rotating wheel, the rotating wheel drives the piston.

File:Walschaerts motion.gif - Wikipedia, the free encyclopedia
http://auto.howstuffworks.com/engine1.htm

Mike2545 · 17th October 2009, 07:30 PM

Here is an animation of a crankshaft:

YouTube - Engine crankshaft animation

Menticol · 18th October 2009, 05:55 AM

This is very cool
http://en.wikipedia.org/wiki/Hoekens_linkage

And check his "brothers"
Straight line mechanism - Wikipedia, the free encyclopedia

dknguyen · 18th October 2009, 08:41 AM

That's pretty neat. We take a lot more things for granted now....like machining straight lines.

ke5frf · 19th October 2009, 02:35 AM

Another way to do this, same principle as the crankshaft but somewhat different, would be an obtusely shaped cam.
A rod guided by a track or guideposts of some sort is held against the rotating cam by a return spring. As the more obtuse (longer) part of the cam is turned by the motor (usually gear reduction), it pushes the rod and stretches the spring, moving it outward in a linear fashion. As the cam moves around toward the shorter, rounder part of the cam, the spring pulls the rod back to its original position.

I wish I had an animation or the ability to animate it myself.

grim · 19th October 2009, 04:09 PM

trouble with a crank shaft is that the rotation to distance ratio varies, and the toque you can get out of it is inverse to that.

how about rack and pinion?

Mr RB · 19th October 2009, 05:39 PM

Yeah but he did say it has to move back and forth endlessly, so a cam or crank arrangement means the motor does not have to be continually reversed.

A properly design "pin in groove" cam can push and pull, and can have a cam shape to give more linear force than a crank, but the crank wins outright for ease of build and reliability. If he can use the middle portion (say 50%) of the stroke range it will be close to constant force.

ke5frf · 19th October 2009, 08:35 PM

Trying this out.

Had some time, so I drew up a diagram for the linear cam model.
Maybe someone can use it.

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17th October 2009, 12:49 PM	#1
JekylHyde	circular movment into linear Hi! i have a big motor i took from a mixer (kenwood). i want to translate the circular movment into linear (to make it move a metal bar forward & backward). any PRACTICAL ideas? (step by step?) i need to be able to push 5Kg objects (at least)...& to move 20cm back & forward, back & forward, back & forward... endlessly. thanks

17th October 2009, 01:02 PM	#2
Nigel Goodwin	A crankshaft, like in a petrol engine - it's really a VERY simple (and obvious) technique. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

17th October 2009, 07:19 PM	#3
dknguyen	Like on a locomotive train or car engine, except backwards. Instead of the linear piston driving the rotating wheel, the rotating wheel drives the piston. File:Walschaerts motion.gif - Wikipedia, the free encyclopedia http://auto.howstuffworks.com/engine1.htm __________________ Tanaka Sensei (avatar) says: Please spell it "ridiculous" correctly! Not "rediculous". ^^ Last edited by dknguyen; 17th October 2009 at 07:20 PM.

17th October 2009, 07:30 PM	#4
Mike2545	Here is an animation of a crankshaft: YouTube - Engine crankshaft animation __________________ Mike2545

18th October 2009, 05:55 AM	#5
Menticol	This is very cool http://en.wikipedia.org/wiki/Hoekens_linkage And check his "brothers" Straight line mechanism - Wikipedia, the free encyclopedia __________________ Felipe Last edited by Menticol; 18th October 2009 at 05:56 AM.

18th October 2009, 08:41 AM	#6
dknguyen	That's pretty neat. We take a lot more things for granted now....like machining straight lines. __________________ Tanaka Sensei (avatar) says: Please spell it "ridiculous" correctly! Not "rediculous". ^^ Last edited by dknguyen; 18th October 2009 at 08:41 AM.

19th October 2009, 02:35 AM	#7
ke5frf	Another way to do this, same principle as the crankshaft but somewhat different, would be an obtusely shaped cam. A rod guided by a track or guideposts of some sort is held against the rotating cam by a return spring. As the more obtuse (longer) part of the cam is turned by the motor (usually gear reduction), it pushes the rod and stretches the spring, moving it outward in a linear fashion. As the cam moves around toward the shorter, rounder part of the cam, the spring pulls the rod back to its original position. I wish I had an animation or the ability to animate it myself.

19th October 2009, 04:09 PM	#8
grim	trouble with a crank shaft is that the rotation to distance ratio varies, and the toque you can get out of it is inverse to that. how about rack and pinion? __________________ Drake Transformers Transformer Designer. 1992-1997 Dagnall Electronics / Clairtronic Transformer Designer. 1997-2009 Now going it alone

19th October 2009, 05:39 PM	#9
Mr RB	Yeah but he did say it has to move back and forth endlessly, so a cam or crank arrangement means the motor does not have to be continually reversed. A properly design "pin in groove" cam can push and pull, and can have a cam shape to give more linear force than a crank, but the crank wins outright for ease of build and reliability. If he can use the middle portion (say 50%) of the stroke range it will be close to constant force.

19th October 2009, 08:35 PM	#10
ke5frf	Trying this out. Had some time, so I drew up a diagram for the linear cam model. Maybe someone can use it. Attached Thumbnails