Oscillating / Reciprocating Motion

[iNCiSiVe]

Good morning / evening ladies gentlemen.. And sleep deprived creatures..

I have an application that requires me to build a mechanism similar to a jigsaw, it has to have a fairly high RPM and around a 1.5 to 2 inch stroke.

Does anyone know of a linear actuator or off the shelf system that will provide me what I need?

It is going to be mounted onto an XY gantry, so ideally I would like to control the speed relative to the feed rate.

I throw the floor open to those brighter than myself (ie everyone)

 

[quark]

Why can't you go for a rack and pinion?

 

[ScottyUK]

What about a standard motor with a crank and piston?



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If we learn from our mistakes,
I'm getting a great education!

 

[iNCiSiVe]

Rack and pinion to my mind is a last resort, it wears far too quickly...

Its my fault I should have mentioend I plan to run the mechanism nearly 8hrs a day

As far as a crank and piston.. I have that one up my sleeve as a last resort, the whole motor assembly will be rotating on a C Axis, the lighter and more balanced I can make the load... The better

Thanks a heap guys... Keep that grey matter simulated

 

[ScottyUK]

Define this a bit more clearly in terms of strokes/minute and what load is on the actuator arm/ram/piston etc.

If your rate of operation is not too high, you might be able to use an pneumatic actuator.



----------------------------------

If we learn from our mistakes,
I'm getting a great education!

 

[Laplacian]

How about an electromechanical actuator like the Wagner power painters use?

 

[jraef]

A "linear actuator" is typically just a rotary motor connected to a ball-screw drive or belt drive that converts the motion to linear. I seriously doubt if you can find any linear actuator that can provide sustained repetative back-and-forth action remotely close to that of a jig saw. A cam action drive mechanism is probably your only hope. That is how they do it on jig saws. Laplacian's idea is another posibility, but the problem there may be your stroke length. The little mag-drive reciprocating piston pumps used in those painters don't have to move far or exert much force.

"Venditori de oleum-vipera non vigere excordis populi"

 

[UKpete]

If you are not looking for high forces, try a permanent-magnet linear actuator. These have been around for a long time - an existing application is a loudspeaker voice-coil, a future application is as vehicle engine valve actuator. There are a number of suppliers, or you could even make your own!

Try a search on "voice coil actuator".

 

[SERVOCAM]

define "fairly high RPM" and what kind of forces do you need to produce? Voice coils are fast, but low force. Linear motors can produce the force, but not the speeds like voice coils, but are going to be faster than screws or tangential drives.

Many applications I run into like this, the solution usually ends up being a cam follower (cause voice coils can't produce the force, and linear motors are too expensive).

-cam

 

[DickDV]

This is a little out of my field but some of the best oscillator mechanisms I've seen are simply a high quality ball bearing mounted eccentrically on the driving shaft. The outer race of the bearing is helding in a ring assembly that is attached to the oscillating output mechanism.

The immediate benefit I see is the standard, easy to replace bearing with essentially zero free play.