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
 

Making Plastic Washers using my Lathe

I like to use plastic washers between wood parts that rotate relative to each other.  There are many available to purchase, but sometimes a thinner one or odd size is needed that isn't available.  For those times I use this strategy to make my own from plastic scraps easily found in most homes.  Plastic milk jugs, plastic CD or DVD cases, or other plastic packaging can be used. 

For my current needs I have roughly 1/32" (0.03125") of space between parts. I found a DVD case with a soft plastic cover that measured 0.0355" thick. This comes close and should work.  

First step was to make holes for the bolts.  Drilling into thin plastic sheets is problematic.  In this case I used a 1/4"d hole punch to make the center holes. 

First Punched Hole

To mark where to punch I put a strip of masking tape on the plastic, and marked out where I wanted each hole to be.

Row of  Holes

Second step was to cut the sheet into squares with a hole in the middle of each.  My rather dull kitchen scissors made quick work of this task. 

Squares with Holes

A threaded bolt, two hex nuts, and two steel washers with the plastic squares clamped between is all that is needed.  

Between two Nuts/Washers

Then a trip to my hobby lathe. 

On my Lathe

A drill chuck to hold the shaft of the bolt, and a few seconds to turn the plastic stack into round washers. 

Lathe Done

Once done on the lathe, the washers were removed from the bolt and tape was peeled off. 

Plastic Washers

I only needed four on my current project, but it only took a few seconds more to make eight.  That leaves four more I know I'll use up eventually on a future project. 

If you have a drill press but not a lathe, the drill press can also be used to spin and trim the squares down to nice round washers. 

I've used this strategy several times in the past, for my projects as well as for student projects. The secret is to make sure the center holes are snug on the bolt shaft, and that they are clamped tight together between metal washers and nuts on both sides.   

4D 

Replacement Trim made with my CNC

 

Pine Trim

A friend need a little trim to replace some that had rotted on her house. She sent a photo which got me close to the profile shape, but an actual section of the trim finalized the vector shape needed to cut it out using my CNC.  

End View 

The angled top and bottom edges I cut using my table saw after the CNC was done with the curved face on the right side.

She could find no commercial source that wanted to make such a small amount of what is apparently a no-longer made trim shape.  I had a pine board with fairly straight grain that was thick enough to cut the trim from. I cut the two strip shapes on one board, then separated them using my table saw.  

A quick job.  It was fairly easy to make the needed vector outline.  The CNC using a file created with the Moulding toolpath in Aspire had no trouble cutting the extruded shapes. 

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 
 

T-Slot Wood Clamps for my CNC

Four clamps conspiring

This is not a new design of mine.  I've been using these wood clamps for several years.  They are sacrificial though and many have encountered spinning router bits during their lives. 

A few of the scrap wood blocks in my collection have hinted that they'd like to be clamps. As such this post is about granting that desire and replacing some previous clamps that are near death. 

My previous clamps were cut from larger boards,  A few were cut as two halves that I glued together.  A few were cut from thicker boards, then turned 90 degrees so I could cut the slot for the bolt in them.  

The length of these clamps is not critical to their usefulness and can vary. 

The first one (upper right)  I made from a dense white oak scrap.  It suffered a few broke out chips when the bottom edge was flush cut after the CNC was done. It works despite those missing bits. 

The second clamp I cut from a scrap of birch (lower left).  It also gave me some grief as I made a mistake when clamping the scrap block down. I stopped the CNC after the first pass when I realized that mistake.  It works but has a few scars from my bandsaw, drum sander, and disk sander.

The last two clamps were cut from a 5/8" thick scrap of walnut. Room enough for 4 halves that when glued together made two clamps. I added an alignment hole for a 3/4" long section of 1/4"diameter wood dowel to make it easier to clamp the halves together and aligned. 

One Scrap, Four clamp halves

Making them in halves is the most reliable method. Especially if you don't have an easy way to cut the slot after cutting out the clamp profile from the side. 

Here are two made from one block of white ash.  Both cut out as one piece, then turned sideways to cut the slots in them. 

Short Ash Clamp

Long Ash Clamp

These clamps hold the work down and also prevent it from moving sideways.  Made from wood you don't have to worry if a spinning router bit accidently encounters one. Should one or more  be ruined from such encounters making replacements is easy. 

4D 

Updated Wrench Handle for my Bench Vise

New handle.  Teak Oil Finish.

While there is nothing fundamentally wrong with the plywood handle I made for my garage bench vise, there are a couple of changes that could make it more useful. 

Plywood Handle

The first issue it that the handle extends above the top of the vise when vertical, and has occasionally been limited in use by objects I wants to clamp down that hang over the edge. The second issue is that it doesn't slip off easily.  If it did I could easily overcome the first issue by sliding it off and rotating it 60 or 120 degrees before slipping it back on.   I do this with the wrench handle I made for my CNC low profile vise. 

First thing needed was a CNC file and a piece of wood to make the new handle from.

Render from my Aspire software.

The wood used was a heavy and dense block of white oak.  The nut pocket, shaft hole, end hole, rounded off edges, and perimeter outline were all cut using my CNC.  The bottom side details were finished on my trim router table.  Holes for the pivot pin were drilled out on my drill press. 

When flat the new handle is the same length as the old one. The hinge allows folding the new one out to clear anything hanging over the edge of the vise.

Handle folds out.

This handle was sealed with teak oil as show in the first photo above, to protect the wood. It slides on and slips off easily but stays in place otherwise. 

Iteration is always a worthwhile endeavor.  The initial wrench handle worked, but use of it revealed the flaws that needed fixing.  Should the new handle reveal any new insufficiency a 3rd iteration may be needed.   Time will tell. 

4D

Compartmented Box for M6 Screw Assortment

I needed some flat head M6 screws for a project, and they came in a cheap subdivided plastic box. Sizes vary from 6mm to 22mm long.  The shiny stainless steel screws looked to me like they deserved a nicer box. This compartmented walnut box was made to hold them. 

Compartmented Box

The lid for the box slips onto the box easy and wedges down securely with a 3 degree tapered edge.  While I do have another piece of walnut that I could use for the top, a scrap of salvaged weathered wood with more interesting grain challenged that presumption. It was thick enough that a second use was cut into the top of it. 

Lid from a Weathered Wood Scrap

It now is a shallow tray to coral whatever small parts my current project may need. 

Parts Tray

A simple project.  Pocket toolpaths for the inner compartments. A profile toolpath for the perimeter. Another pocket for the rabbet edge on the underside of the lid.  Another profile toolpath for the outer shape of the lid.  Then the lid was flipped over to pocket cut the recess center of the tray, and round the inner edge of the recess using a profile on-the-line with a 3/8"d ball end bit.  

Comments encouraged!

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