Variable Height Coffee Table

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. 

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. 

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. 

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. 

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.

Plastic Washers

The steps needed to make the washers I've documented here: Making 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.   

3D Printed End Stop

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
 

A Wood Mallet made from Wood Scraps

I've made a few wrenches from wood scraps.  Time now to see if I can make a wood version of a heavy steel mallet I have. Basically a small sledge hammer. 

I had a nice block of dense white oak for the head, and a section of hex shaped oak that was going to be the handle for a tool chest that made a good handle for the mallet. 

Using the CNC to cut the top details took some contemplation and experimentation. The hardest part was the chamfer around the edges. The easy parts were the top curved surface and the center hole for the handle. That hole was first drilled out at my drill press,  The CNC flared the top of the hole anticipating the wedge that will spread the tenon and trap the handle in place. 

White Oak Mallet Head

The old steel mallet is blessed with a nice patina and grace from being used and cared for over 5 decades since I inherited it from an Uncle. I'm sure he got good use of it over the time he had it. 

Old and New

Wood sealed

For a finish I applied tung oil on the red oak handle, and Danish oil on the white oak head.

Perhaps with time and use this wood version will acquire similar qualities. Time will tell.

4D 
 

A Coin/Key Cup , Lathe or Rotary Axis CNC Project

Key Cup  

When I taught furniture design we would have our first year students each make a coin/key cup on the lathe to learn the tools and procedures needed.  A simple project.  a 3" diameter 1" deep bowl on the face.  A 1/2" outside curve on the top, and a 1/4 x 1/4 bevel on the bottom edge were required.  The edge profile between was up to the student to design.  

Profile done on the Rotary Axis

This red oak version I cut using my CNC.  The top bowl I cut with the block standing up using a moulding toolpath. The bottom bevel, top round over, and the profile between the two were all done on my rotary axis.  This project is intended to be set on your dresser or any shelf near your entrance to throw your keys or pocket change or jewelry into.

A cherry stain was added to warm up the cup.  

Cherry stain applied

To avoid screw holes in the bottom we glued the starting block to a plywood scrap with notebook paper in between.  After the project was done on the lathe the faceplate was unscrewed and removed, and then the plywood was relatively easy to split off the bottom with a broad chisel and a few taps of a mallet. The bevel cut on the bottom made it easy to place the chisel on the paper seam. 

Plywood back split off.

 Once split what was left of the paper and glue was easy to sand off the bottom.  

Bottom sanded clean and smooth.. 

The bottom was then stained and finished. A felt self-adhesive 3.25" diameter disk was stuck to the bottom. A bit of cushion and a shadow line for effect. As pocket change isn't as common as it used to be this cup can still be useful. I park my car keys in mine. An official spot where they can rest in style between car trips when not needed. 

Questions and comments are appreciated.  Please no ad or self serving links otherwise they will be deleted.

4D

A Simple CNC Rotary Axis Project. A Lathe Tool Handle.

Oak handle for a parting tool

This handle design is a close copy of one I made while in my first college furniture design class.  All students were given a tool with no handle, and challenged to design and make their own handles for them.  Mine was a parting tool.  This project is also for a parting tool.

Handle and Blade

All projects made from wood require some prep work, and this was no exception. First came finding some wood scraps long enough and wide enough.  Job done.  Next came gluing them together to get close to the final thickness I was after.  Job done. Scrape off any dried glue that oozed out, then joint one side square to the front and back faces.  Jobs done.  Next to my table saw to rip the block to just a bit wider than 1.5".   To mount it on my rotary axis I glued a 1.5" diameter circle of plywood to one end with some paper between the plywood and board end. The center was carefully marked on the other end.  Then a 1/8" hole, 1/8" deep was drilled in the center.  This for the tailstock to pierce.   

First step after mounting it on my radial axis was to turn the square block into a cylinder. That was done with a pocket toolpath at 0 depth, spanning across the surface. As the rotary axis spun this toolpath trimmed off the high corners, leaving a nice straight cylinder. 

The ferrule end was done with a pocket toolpath.  The contoured surface was done with a moulding toolpath and a ball nosed bit. 

Done with the initial slope.

Over the hump and almost done.

CNC is done.

Once the CNC was done with its work, I took the block out to my mini lathe to sand smooth and trim off the back end. 

Handle and the tool it will hold.

A 12mm hole was needed in the tip for the tool blade. Done on my drill press. 

I'll put some Danish oil or Tung oil on the handle to finish it, and I may v-carve my initials in the back end.   I'll update this post with final finished beauty photos when that is done.

The End.

4D
 

Variations of a TV Tray Table

Iteration is the secret to the best solutions. A patent was granted for my folding tray table design. It was about the geometry that allows it to be horizontal in one position or slanted down in another.  This is a variation using the same geometry but with different details.

The top on this version has front rounded corners.  

Red Oak.  Slanted top.

The side legs have a slight curve rather than a jog in them to reach the offset bolt connection required so the design folds flat.

Flipped over. Top flat.

This table was my initial crude prototype, and suffered through 3 iterations before appearing here in its best form. Ball chain was what I initially used as the tension member that went between the front and back legs. Ball chain proved to be unpredictable in strength and prone to breaking apart.  One inch wide strapping at the top is my second approach.  First try with the straps found that due to the unique geometry they needed a unique path. The path they took needed to leave the legs the same distance apart in both positions. A new path was found that works. A replacement top stretcher was made. Two straps run between the center of the back edge and the middle of the top stretcher. Binding pins through grommets in the ends of the straps lock them into slots. 

Straps into back edge

The table transposes with the leg frame pulled through and the top flipped over. In the image below you can see the straps running over then into the top stretcher.  When in the flat position the straps run directly into the stretcher.  

Over and into the stretcher side.

Straight into the stretcher side.

The same unique geometry is expressed in this version with different materials, different details, and different tensioning strategies. Iteration.

This version is mostly red oak. My alternative version is here:  Made from Ash wood

This design is patented. For information about licensing the design please contact:

Sarah Nolting
Licensing Associate
Kansas State University Innovation Partners
(785) 532-3910
snolting@ksu.edu
www.k-state.edu/innovation-partners
   

Original CNC-Cut 3-way Interlocking Mitered Corner Joint.

This joinery sample was inspired by several 3-way miter joint solutions posted on YouTube.  A common one you can find is a solution with three unique parts that slide together using normally hand cut tenons into machine or hand cut mortises  Side one tenoning into the second, with the third part using two tenons to lock into the previous two. All the clever cutting hides inside the mitered facades. Optionally a tenon end or two can peek through the outside faces.

My goal was to come up with one unique part I could make three times using the same file on a CNC router.  They have a single tenon protruding inside their miter-cut shell. The core of the joint is a floating cube of wood with three mortises through it. Each of the mitered parts slide into one face of the cube.   The mortises in the cube are cut using the same single tool path file, with the cube rotated to a different face for each of the three cuts.

When assembled no end grain is showing. There is no external clue of what goes on inside this joint. When clamped together all parts bottom out against the cube making it easy to pull together tightly with no slipping of the mitered edges.

The tool path files for this joint can be scaled to any size within range of the router bits available.    This single corner example was done in 6/4 oak with a 1/4" diameter end mill to pocket around tenons and a 1/4" diameter ball nose bit  for the mitered edges.   I've made a 1/4 scale model of an 18" parsons table using this joint.  A 5/16" long 1/16" diameter end mill was all I needed for all the tiny tool paths required.

4D

Improved Light Bracket for my Overhead Camera Rig

My first light bracket design hasn't failed. That I can perceive how they would fail has moved me to come up with a new design that eliminates the weaknesses of the first. This is not an uncommon happening as I work through the design of a thing. 

Making the first prototype is more about being able to discover where an idea might be weak than being done with the design.

This version was cut from the same scrap of red oak as the first two were. I removed much of the initial potential mass in the first design. This version removes only the outer bevel where no forces would pass through. The beveled edge was cut with a 3/16" end mill using the fluting toolpath that is available in Vectric's Aspire software.  The side hole was drilled out with a #7 drill bit then tapped for 1/4-20 threads.

The center cone spreads force from the screw head across the bottom area against the rig post.  The side bolt simply threads into the initial mass for strength.

The lights now do a great job of illuminating whatever I want to make a close-up photograph or  video of.  Next for this camera rig I'm working on an improved camera hanger bracket.   So far I'm not satisfied with my first or second ideas. The second idea is shown in the last photo above. It worked, but not as well as I hoped it would.   That tells me there is a better solution out there.  Now just to find it.

4D

Light Bracket for my Overhead Camera Rig

This was a quick project to allow me to mount my LED lights directly onto the posts of my overhead camera rig.

The LED lights came with a short tripod base, but by unscrewing the lamp module from the base I realized they could be mounted on my camera rig. I just needed a bracket that would allow me to adjust the angle and direction they pointed at.  This is the solution I came up with:

Carved from a scrap of red oak using my CNC.

The center hole is 1/4" diameter for a 1/4" bolt.

The side hole was drilled with a #7 drill bit and tapped for 1/4-20 threads.

Each post was drilled and tapped for 1/4-20 bolts.

Friction between the bracket and post keeps the light from rotating when the bolt is tight.

Angle of the light can be adjusted by loosening the knurled handle.

 I will seal these brackets with tung oil to prolong their lifespan, and slow down any tendency to expand or contract. For the moment they seem strong enough, but the drier the oak becomes the greater chance it may split under the load of the lamp.

4D