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Pedestal greenhouse or general-purpose table

Jan Steinman's picture
Submitted by Jan Steinman on Wed, 03/29/2017 - 5:37pm
Tool Concept
Stage: 
Ready to Build


Primary problem statement:
I am a farmer and I want a tool to elevate greenhouse starts for easy access without buying expensive greenhouse tables. because my back hurts working on the ground, or even on low greenhouse tables!.
Read more about this problem statement

 

License:

 

Description: 
Straight table legs get in the way and are fragile without lots of bracing. A pedestal base with 45 and 30/60 geometry uses 40% less lumber than a 6-legged table, is self-adjusting on un-level ground, and is much stronger than a 6-legged table (and MUCH stronger than a 4-legged table!). It uses a combination of tension and compression to keep the table top from deforming under load. It allows tables to be placed closer together, as a wheelbarrow can run between tables beneath the table top.
Documentation
Image Gallery:
 
  • The table is easily sturdy enough to hold a human — or even 400+ kilograms of water-saturated sand, heating infrastructure, and plants!
  • After materials are cut, pedestals are assembled using polyurethane glue and 3" deck screws, toe-screwed in from the column into the base.
  • "Toppers" have conventional legs, and are intended for supporting lightweight material like bird netting or greenhouse plastic.
  • Assembling "topper" conventional straight legs, using a completed pedestal table as a work surface.
  • Table height was designed for convenient work, rather than the "bend over" height of conventional greenhouse tables.
  • Tables are heated with dis-asembled baseboard heaters, and covered by plastic, so we don't have to heat the entire greenhouse.
  • Happy plants, with heated tables on left.
  • Tables are heated with heating elements from free baseboard heaters. Two 5kW elements in series on 120 VAC use only 600 watts, and keep plants above at 20°C, even in cold weather.
  • A 3" "bathtub" is constructed from 3/8" plywood and poly.
  • The "bathtubs" are filled with sand and saturated with water, and wired to a standard baseboard heater thermostat.
The table is easily sturdy enough to hold a human — or even 400+ kilograms of water-saturated sand, heating infrastructure, and plants!
  • After materials are cut, pedestals are assembled using polyurethane glue and 3" deck screws, toe-screwed in from the column into the base.
  • "Toppers" have conventional legs, and are intended for supporting lightweight material like bird netting or greenhouse plastic.
  • Assembling "topper" conventional straight legs, using a completed pedestal table as a work surface.
  • Table height was designed for convenient work, rather than the "bend over" height of conventional greenhouse tables.
  • Tables are heated with dis-asembled baseboard heaters, and covered by plastic, so we don't have to heat the entire greenhouse.
  • Happy plants, with heated tables on left.
  • Tables are heated with heating elements from free baseboard heaters. Two 5kW elements in series on 120 VAC use only 600 watts, and keep plants above at 20°C, even in cold weather.
  • A 3" "bathtub" is constructed from 3/8" plywood and poly.
  • The "bathtubs" are filled with sand and saturated with water, and wired to a standard baseboard heater thermostat.

 

Attached Files: 
Plain text icon Greenhouse Table.skp_.txt
Documentation Wiki: 

Rename the file "Greenhouse Table.skp_.txt" to "Greenhouse Table.skp" for a SketchUp Model that can be rotated, modified, etc. using the free SketchUp software. (You really should allow SketchUp ".SKP" models to be uploaded.)

Construction of the pedestals is from painted 2x6 stock, salvaged from a fence. Diagonal struts are 2x6 stock ripped in half; bottom tension strut is 2x6 ripped into thirds.

Tables are assembled using polyurethane glue, clamped together, then screwed together with coated 3" deck screws.

Heated tables have a 3" "bathtub" made from 3/8" plywood and poly film. The bathtubs are then filled with clean sand, and saturated with water.

Disassembled 5kW baseboard heater elements are attached to the bottom. Two are wired in series through a standard baseboard heater thermostat, and when run on 120 VAC, each table consumes only about 625 watts. Three tables won't "fit" in a standard 15 amp circuit, so we then put two of the tables in series, reducing their load to about 300 watts each, so all three tables and some grow lamps can run on one 15 amp circuit.

The toppers are then draped in plastic. Water from the saturated sand condenses on the plastic and "rains" back down on the plants, reducing the need for hand watering.

Each heated table weighs over 400 kg! This would not be possible with conventional table legs, but there is no sign of strain with the pedestal design.

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