Saturday, March 15, 2014

How to build the Sit/Stand/Walk/Flowerpot Desk


This is Part 2 of a series of articles about the Sit/Stand/Walk/Flowerpot Desk, how to build it.  (See Part 1 for why.)  While I'm pleased with it, I wouldn't build this the same way a second time.  In Part 3 I cover what I would change.  This desk cost $1400 in parts (excluding the monitors but including the flowerpot) and took between 50 and 100 hours to design and build.

I tried to design the SSWF Desk with 3D modelling/CAD tools.  Google Sketchup stood out even though it dropped Linux support, but I found it more frustrating than powerful.  I ultimately was able to produce some diagrams like the one to the right, but it took forever to do anything, even after investing a few hours in the tutorials and practice, and I ended up working from paper sketches.

The desk comprises:
  1. Frame of pipes and Kee Klamps
  2. Monitor Bar
  3. Left and Right Tray
  4. Treadmill
  5. Pulley Assembly
  6. Counterweight
  7. Flowerpot
  8. Finishing

Frame

As is typical with documentation, I didn't keep my notes completely correct through the various tweaks, so here is a fresh set of diagrams I just made from the working model.  DISCLAIMER: I wouldn't build this the same way a second time; see Part 3 for why not.




These diagrams cover the pipes and Kee Klamps to hold them together.  Each Kee Klamp is represented by a simple circle touching all the of the pipes it affects.  The part number is in a box next to the circle.  In the Right and Left Tray and Rear diagrams there are some Klamp circles that don't have part numbers; these are already specified in the other diagrams.  Similarly, the unshaded pipes in the Rear view are already specified in the Left and Right Sides.

The distance specified for each Klamp is from the end of the pipe to the nearest edge of the Klamp.  Where there are several adjacent Klamps, measurements are only given for the one at the edge, and the rest of the Klamps are edge to edge.

The mistake I repeated most frequently during assembly was forgetting to slide the middle Kee Klamps (for the trays and monitor bar) onto the pipes before fastening the various pipes together.

Monitor Bar

Aside from refinishing the pipe, this was the most labor-intensive part of the project.

The monitor bar is a wooden board, 2x6x34, that rests on the front pipes and slides up and down.  It's secured to the pipes by a Kee Klamp M50s on each side.  These Klamps fit around each pipe so that they can't come off.  Each has one protruding tab, which forms the tenon for the mortise I cut out of the board.  A bolt (in this case, the long shaft of a big hook) holds each dado into the wood.  I added some U-clamps for insurance against the monitor bar coming away from the pipes.  The Klamps each have a sheet of teflon wrapped around the inside and glued in place.  The board/pipe interface is further mediated by bits of felt and, in an act of desperation that maybe works a little bit, a cut out section of teflon tube screwed to the board. This is the final design I settled on after much trial and error.  When properly counter-balanced, it moves up and down with firm but not strenuous effort, and when not being shoved, remains quite stationary.

The cheapish ($40 each) monitor mounts needed to be mounted vertically, but the monitor bar lies along the front pipes, which are angled.  I cut several wedges of wood and used long screws to hold the whole thing together.  So far it hasn't collapsed.  The monitor mounts have a few degrees adjustability, just enough to compensate for imperfections in the mounting bar.  I used HP Quick Release Mounts between the arms and the monitor backs to make it easy to add and remove the monitors.  (It is essential to lock the monitor bar in place with the Kee Klamp locking screws before adding or removing monitors or counter-weights.  I am extremely happy to report that I thought of this before I needed it for the first time and never forgot it, and in unrelated news, did I mention that I have 10 toes?)

The wire rope for the pulley goes through a hole in each board, is knotted in a figure eight stopper, and then secured with a clamp.  This feels extremely secure but I invite anyone competent with wire rope to tell me if this is a deathtrap.  (The US Navy and most regulatory bodies do not recommend the use of such clips as permanent terminations.)

Left and Right Trays

The trays work extremely well once you wrap your head around the fact that their degrees of freedom are polar, not Cartesian.  Actually, it's simpler to not wrap your head around that but to simply fuss with them until they are level.

Each tray is a plywood board, resting on and screwed to a Kee Klamp M58 Base Plate.  The Base Plate is bolted to one of the two flanges of an F50 Female Single Swivel Socket Member.  A toothed metal locking washer is extremely helpful in keeping the trays level over time and under load.  The other end of the pipe bolts to a Kee Klamp 10, which can be loosened to slide the tray assembly up or down the front pipe to switch from sitting to standing/walking.

Treadmill

I used the Confidence Power Plus Motorized Electric Treadmill because it was $250 new and somebody else had already figured out how to adapt it to a walking desk.  It makes more squeaking and clunking noises than I want, and it produces a strong ozone smell after about 28 minutes, and shuts off every 30 minutes, and waits three seconds to start after the start button is pushed, and does not remember the preferred speed.  These are all minor, acceptable faults for the price.  I struggled for a while with how to mount the controls, and ended up screwing some metal U-hooks into the back and hanging it off the monitor tray arm.

Pulley

If it can hold a garage door, it can hold 100+ pounds of weight and counterweight.  About $10 each, secured to the top bar with a hook thing that has "WLL2T" molded into the side, which let's hope means something like "Working Load Limit: 2 tons".

Counter-weight

My original design contemplated a board secured to pulley wires at the corners, with a flowerpot resting on it.  I ultimately went with lead weightlifting weights, for their compactness and simplicity (gold would be even smaller, but somewhat more expensive) and hung the flowerpot from a stationary bar.  I needed 42.5 pounds to balance the monitor bar and monitors.  The weights rest on the middle of one of the 30" bars, which hangs on S hooks, which hang on thimbles in a loop of wire rope, which is then secured with clamps.

For a pretty cover for the weights, see my Counterweight Cozy Ravelry project.

Flowerpot

Flora Grubb. That's a Muehlenbeckia complexa, or "wire vine".  Altogether it weighs about 12 pounds.  Since it's not part of the counterweight assembly, that only matters for purposes of removing it to water it.  Which is required because it drips, and sits directly above the counterweight, of which the bar is sanded, unfinished steel.  Which is important because ...

Finishing

By far the largest amount of effort was finishing the pipes.  Based on my previous project, a little end table in black pipe, I thought I was ordering a sort of handsome industrial dark bare metal finish, with a hint of oil.  Much nicer looking than galvanized.


What I actually got, cut to my desired lengths and non-returnable, was steel pipe with a thick coat of semi-glossy lumpy, black paint.  Probably great for putting behind a wall for a hundred years, but not ideal for furniture.  The obvious solution was to sand it down by hand and then paint it.  This took a long time, and I want to share two lessons with you.  One, don't do this.  Two, if you do strip the protective finish from steel, don't leave your extra pipe out in the fog and rain.


I left the front pipes unfinished because the monitor bar and trays slide up and down them, and they have not rusted yet, but I keep the desk indoors.  I masked where the Kee Klamps would go plus a border around each, and left those bare sanded metal.  The rest was primed and then painted white.  I considered shellacking or clear coating, but was not pleased with the test results (yellowing, looked sticky), so the pipes are matte with visible brush strokes.  I left the Kee Klamps unfinished.

Bill of Materials

Here is the bill of materials for the SSWF desk version 1.0.  DISCLAIMER: I wouldn't build this the same way a second time; see Part 3 for why not. Prices exclude tax and shipping.  "Local" is San Francisco.  The list below totals around $1000; including other costs and mistakes, the actual cost of the whole desk was about $1400.  All pipe is 3/4" black steel plumbing pipe (1.050" outer diameter), cut to order.

Vendor Item Part Number Quantity Unit Price Total Price
Simplified Building Male Single Swivel Socket Member, 3/4" M50-5 2 $7.44 $14.88
Simplified Building Swivel Flange, 3/4" C58-5 4 19.42 77.68
Simplified Building 45° Single Socket Tee, 3/4" 12-5 4 10.97 43.88
Simplified Building Female Single Swivel Socket Member, 3/4" F50-5 2 8.1 16.2
Simplified Building Base Plate M58 6 9.98 59.88
Simplified Building Single Swivel Socket, 3/4" C50-55 4 17.03 68.12
Simplified Building Single Socket Tee, 3/4" 10-5 6 6.99 41.94
Local plumbing store Front Vertical Pipe, 90”
2 22.5 45
Local plumbing store Rear Vertical Pipe, 70”
2 17.5 35
Local plumbing store A-frame brace, 47”
2 11.75 23.5
Local plumbing store Rear Horizontal Brace, 30”
3 11.75 35.25
Local plumbing store Rear Cross Brace, 41.5”
1 10.375 10.375
Local plumbing store Left Tray Pipe, 8”
1 2 2
Local plumbing store Right Tray Pipe, 10”
1 2 2
Local hardware store Scrap plywood, 1' x 3'
1 1 1
Newegg Confidence Power Plus Motorized Electric Treadmill (Black)
1 250 250
Sporting goods store 45 pounds of lead barbell weights
45 lb
55
Local hardware store Felt Pads
6” square
about
150
Local hardware store bolts and washers
lots
Local hardware store Garage Door pulleys
2
Local hardware store Steel wire (1/8”, 10' long)
2
Local hardware store Steel wire clamps, etc
some
Local hardware store Paint
a few pints
Adorama Peerless PP740 Pro Universal Pivot Wall PP740 2 44 88
HP
EM870AT Quick Release Kit
EM870AT 2 19 38
McMaster-Carr Sheets Made with Teflon(R) PTFE, Adhesive Ready, .020" Thick, 6" X 6" 8711K92 1 8.59 8.59
Flora Grubb Hanging flowerpot
1

90
Flora Grubb Muehlenbeckia complexa
1


(All posts about the Sit/Stand/Walk/Flowerpot Desk Index

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