Escapement Cradle #1

New project, using gravity to power a cradle via escapement “inspired” mechanism.


Counterweight Desk #3

Smooth operation achieved, time to complete the surface and fine tune the balance.


Counterweight Desk #2

New, stronger, frame, improvements and destructive testing on the prototype.

Counterweight Desk #1

Prototype complete. Ordering a few parts this week and getting an improved version underway!

Standing Desk: Concept Art

A counterweight powered standing desk has been on my mind for quite a while. Standing desks have a lot of advantages, but some tasks benefit from sitting (or when you are particularly tired) and having two desks is inefficient. A desk of variable height seems like an ideal solution. Many commercial options rely on screw type linear actuators which require electricity in addition to being slow and noisy.

Counterweights, on the other hand, require no electricity, have a reliability standard equal to that of gravity (high) and can be easily adjusted by changing the lever length. In that vein I’ve drawn up some “concept art” for my standing desk project. It raises 16″ (40 cm), from 30″ to 46″ (76 cm to 117 cm), which is a comfortable height for me. (Note that I am rather tall at 6′ 4″ (193 cm))

I’m planning to use hickory for the legs due it’s toughness, the bottom back joint needs to be strong. A 200 lb person leaning on the edge 30″ from the joint will produce 500 ft-lbs (680 N-m) of torque at the joint. While their are two legs I think it’s best to assume one carry the entire load as a load might be applied only on one corner. Add in things on the desk and a safety factor and you see why it needs to be a robust joint!

Standing Desk 01

Standing Desk 02

Maps and Granite Blocks

It would seem that the maps are firmly under the “distraction” category at least as far as mechanical projects are concerned. We’ve made a lot of progress in the last few months and you can see our site here: Michigan Lake Maps

The plywood storage issue was solved in an almost disappointingly simple fashion. My neighbor runs a CMM service business (coordinate measuring machines: Wikipedia) and they have ultra-flat granite blocks left over from old machines. These blocks range in size from 18x24x3 inch blocks (seen below at about 128 lbs (58 kg)) to 16 feet long and 30,000 lbs (13,575 kg). These machines measure in the micron range (and occasionally sub-micron) so they need an ultra-flat, uniform reference plane, granite fits the bill. Apparently cast-iron was the original material of choice but faced severe restrictions in the World War era and was replaced with granite, which has been the standard ever since.

In any case, I am able to obtain these blocks at no cost and they do a great job of keeping things flat. The least accurate stones are flat to within 0.001 inches and many are better! If I’m able to move them there are several large pieces that will make great work tables, we’ll see . . .

Plywood Storage

Maps: Distraction or Project Opportunity?

We’ve been hitting the maps pretty hard of late but that hasn’t taken my mind off mechanical pursuits. In fact, several smaller things have come up which will be good small projects.

We use quite a bit of 1/4″ and 1/8″ ( 6 and 3 mm) plywood in map production (frames are domestic hardwood however, made in-house too!) The 1/4″  behaves well, but 1/8″ quickly warps when left alone. Weight helps but a slight over correction is necessary to counteract spring-back. After cutting the plywood into 18″ x 24″ (455 x 610 mm) rectangles we stack them spanning two blocks and place a 40 lb (18 kg) weight to make them “sag” slightly.

This is an effective system and virtually eliminates the taping and frustration previously required to prepare for laser cutting. Unfortunately it does require one to remove and replace the weight each time, where the second step is not always completed. Even removing the sheets in batches is not ideal, despite consistent moisture conditions (verified with a meter) the boards will begin to curve in a few minutes, making single sheet removal the preferred method.

All this brings me to the ideal solution: a weighted counter-curve piece which sits atop a stack of plywood and can be lifted slightly to easily remove a single sheet. This device should also be able to accommodate a stack of variable height, which complicates things. A clam shell bucket style mechanism used to friction grip a shaft should do the trick nicely. Sketches to follow in the next few days.

In the meantime: a few more map photos. The second type begins as an 8/4 (about 50 mm rough-sawn) board and is then carved on the CNC machine with lake contours.