WA8LMF Ham Page | RF Survey System | Updated 8 Jan 2007 

No-Holes "Gravity Mount" Mobile Office Table Installation. 

NEW! Second Generation Table Design For 2006 Jetta Here

This table was designed to support a laptop computer for convenient operation in the car without drilling holes or permanently altering the car.  The table top  is a piece of 1/4" plywood. The foot is a 12"x14" steel plate 3/4" thick carpeted on top, and covered with black rubber ribbed industrial matting on the bottom.    The supporting mast is a 24" piece of standard 1" waterpipe threaded into standard pipe flanges on the top and bottom pieces.  The entire assembly stands on the car's floor in front of the passenger seat.    The 60-pound mass of the bottom plate compared to the 6-to-9 pound laptop on the top plate creates a very low center of gravity, making the table very stable.  The rubber matting grips the car's carpeting powerfully. This installation is purely "gravity mount". Even without being bolted down, the table stays put by virtue of the sheer weight and non-skid treatment of the bottom plate.  The assembly, with the laptop on the top plate, is very stable and doesn't budge, even with very aggressive cornering or acceleration. 

The laptop is secured to the upper plate with "homosexual" Velcro. Instead of mating the normal hook and fuzzy halves of Velcro, I have covered both the bottom of the laptop,  and the top of the table, with the Velcro hook half only.  The result is that you can effortlessly lift the laptop straight up, without the usual massive struggle to separate large areas of Velcro.  However, it absolutely won't budge horizontally. Try this -- it really works!

The pipe screws rather stiffly into the flanges but can still move if you apply a fair amount of force, allowing the top plate can be rotated.  The top plate and it's laptop can be turned to either face the passenger or the driver.  The cantilevered design, with the mast at the extreme left of the passenger seat, supports the table from the left edge instead of the center. The passenger's legs are completely unobstructed getting in or out of the right seat. If necessary, the table can be rotated until it is hanging entirely over the driver's seat while a passenger enters or exits. 

The table was designed to be used in various different vehicles. The bottom plate has a series of holes drilled in it to allow the mast to be positioned at different points fore or aft on the plate.  This accommodates variations in the way the dashboard overhangs the floor pan in different vehicles.   The mast itself is just standard 1" galvanized steel water pipe. One can easily get pieces cut to any desired length and threaded on both ends, at almost any hardware store or home center. 

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Table Outside of Car View of table removed from car showing the cantilevered design. This shot shows the plywood top plate.
LATEST IMPROVEMENT TO TABLE.   During the summer, I had major problems with the laptop overheating and locking up in the extreme heat of Nevada and Arizona, if the car air conditioning was shut down for even a few minutes.  I modified the table for forced air cooling of the computer.  I cut a 4-inch square hole in the plywood top and forced in a 4" 24-VDC surplus brushless fan. The fan runs at reduced speed at 12-14 volts. It is completely noiseless while still moving a large volume of air. It only draws 25 mA so I leave it on 24/7. The PC is now mounted on double layers of Velcro that hold it about 3/16" (approx 8mm) above the table surface. The fan forces a constant flow of air upward against vents in the bottom of the computer. The excess air flow "squirts" out sideways in all directions.  This arrangement has dramatically reduced the overheat and lockup problem.  The double layers of Velcro also act as vibration isolators, helping to protect the laptop from the constant vibration of the diesel engine in my VW Passat TDI. 
Link to Table in Car View of table mounted in car.  The bottom plate is covered with a floor mat in this shot.
Link to Animated Picture of Table in Car Animated GIF showing how the table assembly, supported from only the left side, swings to face either the driver or passenger. ( Warning! 180K GIF file download )
View of Table Parts Table assembly parts shown upside down.  The black plate is the bottom; the silver one is the top.   Note the range of holes in the plate to allow flexibility in positioning the mast in different cars.  This shot shows an alternative aluminum top plate.
Another View of Table Parts This view, also upside down,  shows the anti-skid rubber matting peeled away to show the counter-sunk machine screws underneath. The pipe flanges are secured to the plates with 1/4"-20 flathead machine screws and wingnuts.  The entire assembly can be dismantled in less than a minute, without tools.





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