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harmonograph free plans: how to make a
Large Harmonograph
Basic Description

watch the
animated intro
A harmonograph is a pendulum-based drawing board that produces beautiful curvaceous drawings. After you give the large hanging platform a gentle push, gravity works its magic while a pen records the results. Each swing is almost identical to its predecessor: the minute discrepancies are responsible for the remarkably sinuous curves. The version that we have detailed in the plan below allows you to make drawings on paper or on an erasable whiteboard. You can set up the harmonograph in a garage or basement and hoist it out of the way when not in use; it ends up taking virtually no space at all. We love to enjoy the mesmerizing action, but it makes a great conservation piece at a party and kids absolutely love it! It takes some patience to get everything working right, but it is definitely worth the fine tuning that this project requires; as always, we will walk you through all of the steps.

step:                 7      

With the drawing board completed, we can focus on the pen holder. The pen holder needs to be stable and have an adjustable height feature. It should also accommodate for various sized pens. This part of the project is much more like a standard woodworking project, so we have simply provided a drawing for you to use as a guide.
underside of pen holder
Begin by making the base for the pen holder. It is simply made out of pieces of pine and spanned by a piece of plywood. Cut a rectangular hole (drill some 1/2" (13mm) holes to make room for your jigsaw blade) in the plywood to snugly accept the upright. You can cut the slot in the upright with a scrollsaw or jigsaw, but making both sides of the slot parallel to each other is difficult to perform. Therefore, we recommend that you cut a strip slightly more than 5/16" (8mm) this slot acts as a clearance slot for the bolts) wide out of some pine, and then glue it between two pieces ripped (on the table saw) out of the remaining piece. After the glue is completely dry, you can send it through a thickness planer to flatten the faces.
pen holder base in upright position
Firmly fasten the upright to the stretcher beneath the plywood as shown in the image on the right. At this point, you can cut some pine to serve as gussets for the upright. This will make it much more stable. The vertical extension also has a half lap to accept the hinge support. By putting the hinges further apart we are achieving drastically increased stability. Drill the two holes in the vertical extension at the same time that you drill the holes for the backer piece, that way you can be sure that they are in line to receive the bolts.
completed pen holder from behind
The arm is made in the same way as the upright. Rip a strip of pine 5/16" thick and rip the remaining piece in half. Glue these together to get the slot for the counterweight and the slot that will receive the pen. Once the arm is dried you can pass it through a thickness planer to clean up the faces and then make a half lap as you did before to accept the hinge support. Also drill a hole for the pen clamping bolt. Attach the hinges. You can also drill some wider holes at the end of the arm to accept larger pen diameters. Lastly drill some through holes in some dense scrap wood to create a counterbalance for the pen. When a pen is clamped in place the arm should be very well balanced. You can use some extra washers to fine tune the balance; just slide them over the prodruding bolt.
completed pen holder, side view

◄ step 6   —   step 8►

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