Took 10 minutes to run this through the drum sander. Smooth both sides.

Last pass to remove all the glue and level the sections left it exactly 7/8" thick.

Trimmed the ends using my radial arm saw.   Still a bit longer and wider than the final dimensions needed. Now to rip some more cherry for the legs and stretchers.

4D

Raw material on the way to becoming 2 stretchers for the cherry table. 

3/4" thick slices.  5.375" wide total should be enough for a 3" and a 2" wide stretcher both 5/8" thick. Need to fish out a longer board to cut the inner and outer legs from. 

4D

Crosscut 31" of 6/4 cherry.  Ripped three 1" slices, tipped them 90 degree and glued them up.  I'll plane/drum sand them to a uniform 7/8" thick, then rip four 7/8" wide slices out of it to make the 4 legs for the table.  

Best way to get different thickness parts from uniformly thick 6/4" material is to rip and tip. I rip the slices 1/8" wider than needed to account for slippage of the slices when glued up.  So far that system has worked reliably.  A little dicey when the glued up plank gets wider such as the top of the table. 

The board previously glued up for the stretchers has already been through the drum sander to clean up and reduce to a perfect 5/8" thick blank. 

Had good luck so far today.  So far of the 3 glued up panels I've cut the stretchers to width and length, and cut the legs to width. Just barely enough width in the glued up panel to get four 7/8" wide strips plus 3 saw kerfs for the legs. Had 1/32" left on the 3" wide stretch and took off that 1/32" on my little jointer. I've got one stretcher clamped up in my CNC ready for a tenon in the end, but I'm going to park this project until tomorrow.   What is left is careful measurement and layout for mortises and slot and holes.  Everything mirrored perfectly on the other side. Give recent mistakes I've made I'll leave that for a fresh mind on a new day. 

4D

Tenon on the menu this morning.

Clamped vertically in my CNC.  2" upper and 3" wide lower stretcher.  Before and after. Clockwise climb cuts keep the shoulders clean with no tear-out. 

 

Neighborhood has woken up so I went to my router table, changed out the bit to my 5/16" round over bit and took care of all the edges on the two tenons.   Took longer to change and set up the fence for the round over bit than it did to run the boards through it. Worth it to get the bit curve level with the table and bearing flush with the fence edge.

Next will be to cut the inner legs to length, then layout where the mortises for these tenons will be on them. 

4D

Got the mortises cut on the inner legs. Tenons slip fit with a little room for glue.  More to do on the legs before gluing the leg frame together. Pivot holes and whatever is needed for the tension straps.

Pondering how I might round the leg ends. 

Also thinking about how I might keep the pivot bolts from unscrewing when the frame folds/unfolds. Lock tight I have, but I'd rather use a mechanical option.  I can visualize pressing the bolts in until you hear/feel a click which then keeps them from coming out but lets them rotate in place.   Challenge is to provide a way to release them as well. 

4D

Guess I have another mockup to make.  When I was a student I got fascinated with conical springs and used them to make push button releases on a few of my projects. Same idea as a push button depth stop for a drill press but adapted for different project needs.  I already have some conical springs. Going to see if I can make push button retainer/release to keep the pivot bolts in rather than screwing them in.  Have to see if I can mill a 1/16" wide section of a 1/4" bolt down to 3/16" diameter.   Rough drawing of the keyhole in a 7/16" diameter "button" that would release the bolt when pushed in, but keep it in place with a conical spring behind it pushing out. 

 

4D

A simpler approach, and will retain the bolt but not let it spin would be to intersect it with a binding screw.

Already have the binding screws. Already have extra long bolts with no threads on the first 1.5" that I can cut off and use to mock this up.  Just need to see if I can cove/notch the side of the bolt.  The detail of a centered binding screw head is already established on the legs.  They are what I use to hold the strap ends in their slots.  Much as I'm a fan of push buttons this solution should be far easier to implement and still be removable. 

4D

Edited March 18, 20242 yr by 4DThinker

Quick test.  Should work, but I need to find a better way to cut the groove in the bolt.  

With a little wax on the bold head underside and shaft, and a nylon washer between the legs the legs spin easily. Bolt was easy to cut the threads off using the metal cutting bandsaw blade on my small bandsaw. Thought I could make the holes through the two board, then put the bolt in place and drill through the intersecting hole to cove the side out.  Ended up egging out the wood hole.  Used a small round file to clean up the cove in the bolt until the parts fit.  Need a better more reliable method.  Might have a 3/16"d ball end milling bit that I could use on my CNC mill for my next try.

4D 

the more, special hardware that you specify, the harder it will be to manufacture these in large quantities.  keep it simple.  think repairs down the road, lost parts.

Thanks for the reply, DAB.   Realized with no nut/threads to screw into I could start with a regular threaded bolt rather than cutting down a long bolt to have a straight shaft.  Just made a new bolt already the right length, used my milling machine in manual mode to cut a groove in the side of it. 30 seconds it took.  Had to open it up a bit with a small round file, but If I'd used the CNC control I could have had the bit take care of that.   

My first design job out of college was for a furniture company who focused on metal and glass and occasionally plastic parts for their furniture.  They wouldn't mass produce designs until they had a minimum order for 10,000 or more.  If a design required a unique hardware piece they had a specialist who would make a machine dedicated to producing those parts efficiently and usually automatically. 

The patent drawings don't show any solution for stopping the design from collapsing in either position.  Just the raw views that show it in all three positions from standard orthographic view points.  My experimentation isn't to provide a specific solution for some manufacturer.  Just mostly to keep myself entertained in my retirement.  The two prototypes I've already made work perfectly well and used off-the-shelf hardware.  I like to consider designs imagining a scenario of use for them. How could they be made to cause less stress over their complete life of use?  The push button idea would be the hardest to implement and require a very unique button and a unique bolt.  The intersecting pin idea only needs a cove cut in the side of a bolt to work, otherwise everything is off the shelf. The additional hole for the binding screw is a small additional cost.  For that effort the bolts holding the legs to the top and each other will never need tightening up. Bolts will never fall out/get loose or lost.  There is no action on the binding pins that might tend to make them loosen up. Both can be found at Amazon.  A larger city than my own may have a store that keeps them in stock.

i had to repair a part for a friend last year, some Ikea piece that one part broke.  duplicated it.  drilled all sorts of matching holes....but he was missing one bolt.  not commonly carried at homey depot.  had to improvise to get it to work.  of course, the original was metric!

 

we live in a "when it breaks, i'll toss it and buy a new thing" society.  but i build my stuff to last and to be able to easily fix if needed down the road.

 

if you built it right, it wouldn't break!

Yep. Ikea, and most other "quick assembly" furniture is generally not even intended or designed to be moved from place to place. Furniture built from particle board vinyl wrapped core boards IMO should be banned from existence.  It sells because it can be flat packed and shipped very efficiently and most folks can put it together with the included 4mm allen wrench or a phillips screwdriver.  So far none of my work has come back broken or in need of repair. Only one customer that wanted to know how to fix/remove makeup stains on a desk top. 

4D 

I know that the binding bolt trick does work keeping the pivot bolt from coming out.  What I don't like about it after playing with my mock-up is that the head and shaft in the outer piece rotate with the inner piece.  This adds wear to the wood in that outer leg.  I'd rather have a solution that keeps the bolt head and shaft still relative to the outer leg and only rotate inside the inner leg. Only solution I can think of tonight is to make the groove shallower, but encircle the bolt. This won't guarantee the bolt head won't rotate, but it should let the bolt shaft rotate in the inner leg while pinned in place.  Sleep tonight may come up with a "better" solution.   

Only vision I had was to move the binding pin to the other side and use an embedded nut on the inner leg.  Pivot bolt screws into the nut, then the binding pin locks it in place so it can't back out.  Minor problem is that the screw will still be turning in the nut when the frame and legs pivot. The legs never rotate more than 60 degrees, so with 1/4-20 threads that means they'll move in/out 1/120th of an inch. The top flips over 270 degrees the flat side to the slanted side to folded flat. roughly 1/27th of an inch moving in/out through that rotation.  A noticeable amount. 

I ordered 7/16" aluminum rod for the push button idea.  It should show up today or tomorrow.  I think I can cut a 1/16" wide groove around a bolt using a hack saw with the bolt chucked up in my little variable speed lathe.  I can make the push button with some tedious steps on my CNC milling machine. So I may yet mock up the push button release idea. 

4D 

Edited March 19, 20242 yr by 4DThinker

Got distracted for a moment about using knife hinges instead of a pivot bolt between the legs. Problem with them is that it seems since most are designed to trap a cabinet door between them that they come apart.  A pin on one side slips into a hole on the other.   Then I saw that Rocker sells a bulky pivot hinge.   Too big, ugly, and expensive for my application.  Something that hides in between the two legs and gives them a pivot point does sound intriguing. Might be an excuse to dust off an warm up a 3D printer. 

Addendum to the above...  The binding bolts are close to 5mm diameter.  I ordered a few 5mm ID bearings to see if they are a good fit around the bolts. Thinking about a cover plate to hold the bearing in on each inner side, with the binding pin serving as the axle between the legs. Plate would be wide enough to screw down when the legs are 90 degrees apart. Embedded flush into the wood.  A nylon washer still between the legs, around the binding bolt.  Drawing to follow in a few days after I receive the bearings. 

Quick drawing done in Aspire. 

I don't yet have the bearings, but this is the idea.  Actual dimensions may change.  Pivot would be hidden between the legs and between the outer leg and top.  No bolt heads visible on the outside. Cover plate shape will be slightly different at the top connection between leg and table top. Cover plate is 1/2" wide, 1/16" thick, and recessed flush into the wood. I can make a precise pocket  for the assembly using my CNC. I'd make the bearing a snug press-in fit. Clearance for the head of the binding bolt axle to spin freely. Not sure how good the metal of the binding bolts is.  Time will tell. 

4D

While I wait for materials to try the pivot joint idea above, I've been playing with how I might dress up the cherry top a bit.  It has to look the same, or at least have a detail that flows nice between top and bottom edge.  One option below, with a stretched french ogee on the front.  The top cove wrapping down the sides to meet a simpler ogee/bullnose on the back edge. Face of the sides is mostly flat. 

Rendering from Aspire. Not ideal for 2 sided projects, but should get the idea across.  Opinions welcomed. Does this look fancier, as if it might cost more than one with a simpler bull nosed edge?    The little cove might look good and relate around the outside edge of the outside legs. 

4D

Edited March 20, 20242 yr by 4DThinker