Shaker Coffee Table build curved apron question
I’m building a round coffee table, shaker style, out of cherry. The top will be 36″ in diameter, the legs at the top will be 1.5″ square, tapering down. I want to set the apron 2″ in from the edge of the top and have a width of 4″. So there will be 4 sections of apron approximately 25″ in length if my calculations are correct. I would prefer to make this out of a thicker piece of stock and not bend them as I think it would be possible. Without getting into the bend/cut discussion what I want to know is if I cut them how do I figure the arc to use on the bandsaw to make this work? Do I attach the legs first an use a thin piece of scrap to create the arc and trace that? What is the process to figure out the cutting of the mortise/tenon to attach them to the legs? Attached is a picture of what I want to build.
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Get some big paper & draw it full size. Butcher's paper or leftover hoilday wrapping paper works fine. Draw the circles before adding the legs. Make a trammel stick & save it to either make a pattern or draw directly on your parts. Make the curves full 90 degree segments, this way you have the extra length available as you work out your joinery.
Ha! I've trying to do this in Sketchup and one never thinks about paper and pencil anymore. That's a great idea, I'll give it a try. I'm going for a 2"lip btween the edge of the top and the apron, sound about right?
Depends on how far out your legs project from the apron. One nice thing about a pencil is the eraser...
2" would be fine. That would give you a radius of 16" for the outside of the aprons.
Considerations in the bend/saw question:
If you saw, the tenons will be weaker, as the grain will be angling across the tenon.
If you saw, the cherry near the ends of the aprons will look and finish very differently from the middle, where the grain is parallel to the surface. You can get around this by using secondary wood and gluing on a thin resawed layer of cherry.
If you bend, I would glue up thin strips rather than steam bending. All but the outer layer could be an easy bending wood.
I rely on pencil and butcher paper a lot.
I agree with a full scale drawing. I chose to use a thin strip glued to base structure. Older craftsmen would use a bricklayer of solid wood to make the underlying circular structure. Glue it up then shape/sand it to your final.
What I did was use plywood to form the base structure. More stable. I made an outer form of dimensional wood to compress the thin strip to the shaped ply. It was locust and I cranked the beans out of it to get together and wondered if it would hold. No problems after 10 years on the first one I built.
Good article on bricklaying ..
Round Bistro Table
Instead of bent lamination for the curved aprons, try the centuries-old method of making a brick-laid, circular core and veneering it.
Raymond Finan #264-Nov/Dec 2017 Issue
https://www.finewoodworking.com/project-guides/tables-and-desks/round-bistro-table-puts-a-spin-on-brick-laid-curved-aprons
From my reference book :
Do you know if there's n english edition of that book?
I have not seen one, althrough I rarely refer to the text since the drawings are so explicit. https://www.cafr.ebay.ca/itm/194140920059
You posted this 2 days ago, so I hope this isn't a waste of time.
I suggest you do not do it the way you intend. Not only is it a huge waste of lumber, there will be end grain/face grain/end grain and that's going to produce less than optimal result. It will also be subject to movement.
I know you don't want to hear it, but bending is the right way to do this.
Steam bending 3/4" lumber is not that difficult.
Bent laminations are not hard to do but you need a decent bandsaw and resaw capability as well as a planer or preferably a drum sander. If you can't do that, IMO it would be worth finding someone who can and also had a drum sander. and would be my suggested method.
I have done the brick method and is not only easy it is fun. You can cover the face with thick veneer.
Thanks for all the great info. My concern about the brick laying / bendy plywood process was that the veneer would not match the top. I don't know about cutting it thin enough on my bandsaw to then glue it to a substrate. Plus, would not the bottom of the apron look like pine/plywood.
I did find a David Marks video here:
https://youtu.be/4wdzba9OR9k?t=217
And I think I'll try his method of doing the apron. I beleive I can get the veneer strip s thin enough on the band saw in combination with my planer (1/8, maybe 1/16). I started making my forms and should be done with them today.
One question I have is an example of a long open time (24 hours?) glue to use when setting them up to put in the form. Dave mentions "plastic acrylic" I believe, but I'm not familiar with what that is or the best place to get it.
Thank again for all the answers so far.
You need a glue that sets with a hard glue line... no creep. Unibond 800 is one.
Unless you’re worried about people looking under the table you could save yourself some primary wood by using secondary wood for the laminations. Just one primary wood slice for the show side. This would allow you to use a special domestic wood or you could go all secondary laminations and try your hand at applying an exotic veneer.
I think that there is a compromise option here that may work. You can build the same way the greats of woodworking did this 'back in the day' - the old timey way is to make a segmented back for the curved section which includes the joinery and a shop sawn veneer on top.
It is relatively easy to use a cheaper secondary wood circle the appropriate diameter - build it up out of four 1 1/4 inch thick rings with the joints offset. you can make it out of anything - pine is fine, but poplar or whatever is cheap where you live will do. I would build it up glueing the first layer to 6mm MDF, then the next layer offset. Make the last layer (which will be the bottom) from your main species if you like - it can be very thin. Mark the inside diameter, outside diameter, centre, and joinery locations on the MDF INSIDE the circle. You don't even need to be too careful about gaps, though it's best to avoid. You can of course fill them with any method, as no-one will ever see them.
When dry, you can use the MDF to register on a circle cutting jig for your bandsaw, cut round and sand. Separate along the joinery lines (NOT easy) then you can use the remaining radius of MDF to cut the inside radius, or since it need not be precise, you can cut this with hand tools or even freehand - a follower pin for the band saw will get very good results.
The veneer allows you to pick a nice bit of wood and shave off 1/16" or so veneers. You don't need to cover both sides unless being fancy - there is no danger of movement issues as the curve will keep the wood straight, and anyone lying under the coffee table has bigger problems ;-)
You can plane one side of the veneer then the band-sawn face can be lightly sanded with 80 grit to ensure it is close to even and glued directly to the form. It need not be perfect, especially if you use polyurethane glue to attach it.
You can even cut a wee corner and make half-lap joints for the legs so there is no need to cut more formal joinery.
This method seems janky, but it is a perfectly valid way of building a curved section that requires structural strength. It has the advantage of being very strong, not requiring the tools for a curved lamination and allowing all the difficult work to be done on a secondary wood. It was widely used on curved Federal style furniture.