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| 18 Inches Tall |
This coffee table raises and lowers. The height adjusts from 14.25" to 18". The table is 16" wide and 42" long. The top of leg frames move in and out. The bottom edges simply rotate in place. An intersecting panel maintains support of the top as it moves up or down.
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| 14.25 Inches Tall |
A hand crank raises or lowers the table height. The top of the leg frames remain attached to the underside of the table top as they slide. A HDPE slide in a T-slot connects to a barrel nut embedded into the top of the leg frames does that job.
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| HDPE sliders |
Inserts that pivot with an embedded square nut on one side, and two lock collars for the other side hold the ends of the hand crank shaft. 3/8-16 threaded rod.
I haven't yet made or found a hand crank. I may make a nice one from hardwood. The threaded rod stays registered through one leg, and threads through the other leg. Spinning the shaft clockwise pulls them together lowering the table top. I used lock collars on either side of a pivoting insert.
To allow the pivot panel to pivot I made four blocks like the block below. Twin tapered tenons wedge tight even without glue. Adding some glue prevents them from ever dropping out. A nylock nut embedded in the pivot block keeps the screw from rotating/unscrewing as the leg rotates around it.
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| Twin tapered tenons |
In place and set back from the top sides this pivot bracket discretely does the job. |
| In place |
Square blocks with 5mm pins inserted into their sides pivot in the leg panels as the 3/8-16 threaded shaft pulls them together or spreads them apart. Lock collars keep the shaft in place on the crank end.
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| Nut Pocket Revision |
With the nut dropping in from the top of the block, it can't come out if the threaded shaft it running through it. I made a plug to glue in over the nut, and another plug to fill the square hole in the other block.  |
| Test Pocket for Pivot Block |
Two small blocks with a hole for the pivot pins, inset next to the hole. They are 5/8" deep with the pin hole centered 3/8" down from the top:
Pivot pins are trapped in place.
Thin plastic washers were needed to keep wood from rubbing on wood. I had to make my own as I couldn't find any the right thickness this size.
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| Plastic Washers |
I needed a link between the sliding slots to synchronize the movement of the leg panels. I drew up and outline of the needed link plate and sent a DXF file to SendCutSend.com. They sent me 2 copies of the stainless steel link plate I designed. Just under 1/16" thick. The plate won't scratch the wood as it pivots as Teflon tape has been applied to the side between the plate and the underside of the table top
I chamfered the edges of the leg panels. I 3D printed end stops so the slides won't pop out. Simple 1/2" diameter cylinders with a chamfered hole for a 1/2" long wood screw.
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| 3D Printed End Stop |
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| Installed into the slot. |
There remains a small danger potential. Over-cranking past limits may stress and break something. I need to work on a way to indicate when to stop. If the shaft was motor powered I could install limit switches. Adding a motor and Up/Down switches was considered.
The table was stood up and the top edges were profiled using a ball end bit and a roundover bit.  |
| 15.5" tall. |
The table can be set to any height including and between 14.25" and 18". I don't anticipate changing the height frequently. This table was more about solving the engineering to make it work than contemplating how it would be used. I leave that for the eventual owner to figure out.
4D
