Become a Member for free
access to this and other files on the site.See the Membership page for more details.
Already a Member? Log in Here
The scotch yoke is a simple, effective mechanism for converting rotary motion (the handle round the back) into reciprocating motion (the yoke and slider at the front). This project allows you to make your own working mechanism and learn how it works first hand. Members can download the parts for free, non-members for £2.50
Find out more about the scotch yoke mechanism here and here
Print the four parts sheets onto thin card. Score along the dotted and dashed lines and cut out the holes before carefully cutting out the parts.
Fold round and glue up the axle and the pin. Fit them in place in their respective holes in the wheel piece.
Fold the wheel piece in half and glue it together to make double thickness card. Make sure it stays flat as it dries. One the glue is dry carefully cut around the circle.
Glue the pin tab to the wheel 1mm above the wheel.
Roll the tab round tight and glue it down to make a circular pin.
Glue the two box sides to the box body as shown above.
Fit the box inner into place so that it runs across the centre of the box on either side of the hole.
Fold the box round and glue it together.
Make up the two box ends, thread the bushes through the holes in the box sides and glue them into place.
Thread the wheel through the box. Fix it into place using the washer. It must be free to rotate.
Fit the yoke vertical to one of the two shafts. Use the grey area for alignment. Repeat the process with the other half of the yoke.
Glue the two ends to the yoke vertical...
...and complete the yoke.
Fit one of the box sides into place on the end of the box. Line up the tab edge with the edge of the box to make sure that it is straight and square.
Thread the yoke into place as shown.
Fit the other end of the box into place making sure that it is straight and square.
Assemble the handle in three steps. Fold the two halves round and glue them to make two square section tubes. Fold one tube into the other and glue it down. Roll the long tab round and glue it down.
Complete the project by gluing the handle into place.
Turn the handle and the yoke/slider will move back and forth! Scotch yoke!
Keep up to date: Receive the latest blog post by email
Rate this post:
- ‹ previous
- 883 of 1009
- next ›
Comments
robives
Ericito got the first one!
hugo leandro
Very nice this mechanism, Rob. Congratulations!
Smelter
Do you get Scotch yokes inside scotch eggs? :-)
Marivi Garrido
Great mechanism! I just have bought both of your automata books, they are amazing!
michael42er
You're a sight for sore eyes to see this technology as a paper model.
Michael
Nice work Michael! - RI
umehta
The added colors on wheel, yoke and square bearings look nice - and yes, rob's web address too.
When nessie comes out, make a youtube video.
michael42er
From the original pattern, can be quite simply a crank arm with the radius of the crank pin create. In the animation and also in the video clip you can see that the poles at the ends insert a pause. The photos and the video clip show more than these words. With little effort, you can change the yoke in the model to "scotch yoke twice" or “scotch yoke round”.
http://www.youtube.com/watch?v=OikcRZsOq1I
michael42er
Photos for the previous comment
texmec
The additions in the YouTube post are fantastic, Michael!
Gut gemacht, so wie immer!
michael42er
Hi texmec, thanks for your watching. Do you come from a German-speaking country?
Michael
texmec
Not unless you consider Texas a German-speaking country!
Countesshansen
There are lots of German communities in Texas. Great food, friendly people!
texmec
Indeed there are, Countesshansen! Sadly, though the German patois language of those communities (which some of us affectionately call "TexDeutsch"), is fading away. Unquestionably my favorite part of the state, though!