circular movment into linear

[JekylHyde]

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?)
thanks

[waltr]

One: an offset pivot connected to a rod with linear bearings (like a crank and piston).
Two: a worm screw and nut.
Three: a rack and pinon.

[JekylHyde]

ok thanks
any step by step guide on how to do that (with simple home parts?)

edit: i think a crank and piston will be good. any step by step? 

[waltr]

Not really but if you put a largish diameter "wheel" on the motor shaft and then a hole (or taped hole) offset from the center of the the "wheel'. A screw through a connecting rod into the hole on the "wheel" is the first part.
This connecting rod could be directly connected the what ever it is you need to move linearly if that part is constrained to a linear motion.

I don't know the purpose but if you open an old CD drive, the optical head rides on two polished rods. This could be adapted (or the idea) to your needs.


How much motion is needed?
How fast does it need to move?

[JekylHyde]

need to be able to push 5Kg objects (at least)...& to move 20cm back & forward,  back & forward,  back & forward... endlessly.

[Joker94]

Well in that case you will need a 11 cm radius wheel to attach to your crank shaft, may be if the distance does not have to be precises make it bigger to allow for error.

Attached is a simple picture of what is needed.

What other tools and materials do you have access to.

[JekylHyde]

it's a nice diagram. but it's all theoretic. couldn't you please guide me on this step by step?
lets say somthing like "take this part, put it there, that part, put it there..."

[Joker94]

Ok

1)Get a peice of lets say plastic as it is easy to work with and cut it into aa 22 cm diamiter disc. Then drill a hole in the very centre slightly smaller than the shaft. Drill a second hole 10 mm in from the edge of the disc which will connect to the spacer.

2)Get a spacer, an easy way is from a maccano set or something or you could go for a metal standoff, what wvere is easyest for you.
http://www.futurlec.com.au/Hardware.jsp

3)For the  push rod you could use an acrylic plastic push rod, for ease of use. Drill a hole at the top for the spacer attachment. Also drill a hole at the end of the rod to attach the shaft.

4)For the shaft you can use acrylic again, drill a hole at 1 end.

5)Assemble by, heating the hole on the plastic disc to make the plastic softer so it will harden around the motor shaft. Screw the stand off/spacer on to the disc and the push rod to the standoff/ spacer. On the end of the push rod and the start of the push shaft slide a lose fitting bolt through to allow to  for freedom of vertical movment.  Slide the shft throught the 2 o rings to directinalise the movment, mount the rig onto a peice of wood or plastic and the you are done.

For the sizes of the hole they depen on the screws you are going to use and what you may have laying around. And for the construction material,plastic may be to weak but it is alot easier to work with.

Apart from that it is alot of trial and error. 

If you have any other questions just ask.(and i hope i explained my self well).

[JekylHyde]

well
i have no problems with making the round disc & all...(after that it a mess for me )
i found this example:

the main problem i guess is for me is to make the joints. the disc is no problem (maybe in how to attach it to the motor? just making a hole & stick it hard? that will hold it?!?)

[corrado33]

To attach it to the motor, use a hub (or use an axel keyed, but that's more complicated).

http://www.robotmarketplace.com/products/hubs.html

Find a hub that fits the end of your motor, then screw it to your big round plate.

For the moveable joint (the one you see that changes angle all the time, up and down, up and down)... try small ball couplings...

Something like the ones seen on this page.
https://sdp-si.com/eStore/Direct.asp?GroupID=394

Or a universal joint (U-joint) like someone said above, seen on this page...
http://www.sdp-si.com/web/html/univjoints.htm

[Soeren]

Hi,

need to be able to push 5Kg objects (at least)...& to move 20cm back & forward,  back & forward,  back & forward... endlessly.

Might be a bit rough with 20cm, better make it adjustable (and with variable speed) and make sure it won't hurt *ahemm* vital parts.
(You can buy those ready made btw.).

[chelmi]

Hi,

need to be able to push 5Kg objects (at least)...& to move 20cm back & forward,  back & forward,  back & forward... endlessly.

Might be a bit rough with 20cm, better make it adjustable (and with variable speed) and make sure it won't hurt *ahemm* vital parts.
(You can buy those ready made btw.).

Mouhahahaha