I received an email a couple days ago from a student at the University of Michigan that goes like this:
I just discovered your blog – very nice.
I was impressed by your parametric Mission Table. Especially how you handled the parametric mortise and tenon joints. I’ve been able to make parametric tenons no problem – but I don’t know how to make the mortises auto-update when the tenon changes. Does your model do that? If so – any way you can share it – or a part of it – so I can see how you accomplished that?
Again, thanks for your blog.
Sincerely, Mark Meier
The short answer was no.
Generally mortise and tenon joints are sized to the available tooling, and are based on the particulars of the design at hand. In my case, I use a Powermatic 719A Mortiser (shown to the right) and have ¼”, ⅜”, ½”, ⅝” and ¾” hollow chisels. While designing a piece, I pick one of the chisel sizes based on the strength (or other factors) needed for the furniture item in question. A ¾” thick stretcher on an end table usually gets a ¼” tenon, and the leg gets a ¼” mortise to match.
But in the case of work being sent to a CNC router (or template routing by hand), there is a bit more flexibility as to joint size. You may want to tweak a tenon size up a bit when switching from white oak to pine for instance.
There is some pretty slick stuff coming down the pike in this Inventor Tutorial series including web configured components and a eco starter home with a designed-in upgrade path.
But for now, back to the Mission Table. The skeletal stuff is now complete, and all that’s left is to make components of the whole mess (47 solids). The image to the right shows the outcome … but for now, we have what you see below…
Just the corner bracing, top, and some square pins left to model, then it’s mostly patterning from there on in … and a bit of chamfering to finish things off.
The highlighted geometry you can see in the image to the right is the projected sketch that was used to create the corner brace. The lines seen stabbing into the aprons are representations of the screw holes that will come shortly. One of these same lines was also used to create the plane that the screw and bolt sketches were laid out on.
The hole layout sketch is mostly constrained to projected geometry, with only the two dimensions shown below added to the equation. There are Equal constraints, Coincident constraints to projected points, along with Horizontal and Vertical constraints to create a fully constrained sketch. As per usual, here is no geometry projected from solids…
Today’s parts and the top are the last of the major components that need to be directly modeled. Most he rest of this piece is patterned from here…
If you’ve read the previous articles in this series, you know that whenever possible I create my new sketch planes on sketch geometry that resides on the Layout (plan view) or other skeletal geometry, and this part of the model is no exception.
The side stretcher below was, again, created from a sketch that is shared with the tenon. In the image, the tenon is shown being extruded, and if enlarged, you can see that the Extents is set to ‘To’, and a point where the front apron’s tenon and the side apron’s tenon meet is being selected as the stopping point. Continue reading →
As stated in an earlier post, when modeling a multi-sold layout part, it is a best practice to reference only the skeletal geometry wherever possible.
.As you may be able to see in the image below, the yellow shelf plane was created via the line and point method at a point on the main elevation sketch that represents the top face of the shelf. The shelf boards were laid out early in the design process on the Layout sketch down at the bottom of the image. I always lay out all of the boards when designing Mission Furniture because generally the boards are book matched and often have butterfly splines between them. The boards in this case are book matched, but have no butterfly splines.
The modeling process for the first shelf board, as shown below, is simply to create a sketch on the plane that was just created, project the geometry that describes the board up to the sketch, and finally, extrude the shelf downwards to the point on the elevation sketch that describes the bottom of the shelf.That point on the image below is the next intersection down from the plane shown… Continue reading →
The slats are one of the defining elements of the Arts & Crafts style as designed by the likes of Stickley and Frank Lloyd Wright. This is how I modeled them…
If you can’t quite see in the image to the right, click for the bigger one. What the image shows is the creation of a sketch plane using the line and point method, utilizing the Elevation 01 sketch to get a plane at the top of the stretcher. Again, it is very important to not begin sketches by clicking on a face, especially with multi-solid bodied layout parts such as this.
The slat is created in a similar manor to the stretcher and apron, albeit with less complexity. It is just a square stick with tenons on either end, and uses geometry projected from the same sketch that was used to create the slat mortises in the previous post: Mission Table Design: Modeling the Apron —as you can see in the image below…