Slat Back Steam Bending Form (Laying Out Grid Lines from Plans)

[John Morris]

Project

I was able to get in the shop today and play a little, I made a Slat Back Steam Bending Form for a series of shaker chairs I want to make. The style of chair that has peaked my interest lately is the New Lebanon and Union Village style shaker chairs. I love these chairs, especially when you put a pair of rockers on the legs.

 

The form I made today is the bending form for the back slates, I am using Kerry Pierce's book "Chair Making Simplified". I have also contacted Kerry with some questions and he was readily available and wiling to help a fellow chair builder. It's amazing the work, time, planning and text and photographs that are in Kerry's book "Chair Making Simplified" and the book is very reasonable in cost as well. 
 

Unrelated to the bending form but related to the chair making process is the jig below. This is the first jig my son and I made, the "Side Rung Mortising Jig", it is used to drill the rung holes in the legs at the correct angle. The image below is my son putting the final touches on our Side Rung Mortising Jig.

 

The next image below is a picture of chair maker Kerry Pierce using the Side Rung Mortising Jig. 

 

The Slat Form

I had already milled and glued the 8/4 ash and produced a blank for the bending form and used Kerry's book to come up with the exact bend for the back slats. Here is a case where I need plans, this is out of my knowledge base, and a bit beyond my mental skill level, to be able to come up with the exact bend to join the rear mortised legs would of taken me a ton of trial by error. Sure, I could have done a take off from a rocker, but again, it would have taken material, and funds I don't have, to make a bunch of firewood. So, going back to another discussion in our communty about plans, I use plans, especially when they can broaden my horizons.

This book is chalk full of information, you can see on the right hand page, there are some diagrams for form jigs.

 

I drew some lines on the ash blank 1" apart. The grids on the diagram of Kerry's book represent 1" grids. This makes it simple for a guy like me to reproduce lines on a piece of wood, I don't like it when writers get smart, and set down some grids like 1 1/2 grid is equal to 1". I have seen it!

 

Here is a close up of the grids laid down by Kerry Pierce, I am using the "Slat Bending Form" information.

 

You'll see the first intersecting line is about 1/2" up from the edge. I set my pencil on the line so you can see which grid intersection I am laying out. 

 

I used my trusty Sawnson tri-square, I love this little tool, I've had it for about 15 years, it's always with me when I am in the shop. So I set my tri square to 1/2" and set my intersection on the first line, as shown in the layout diagram above.

 

For photography sake I am moving my pencil below each layout line so you can see what line I am on next, at this point, I am going to layout the second line from the right. I am only eyeballing some of these, it's not a precise art, so we can't get hung up on the little things. I am going to say this next intersection needs to be laid out at 1 1/16" up from the edge at the second line. You may have a different opinion but I bet we all can arrive at about the same measurement on this.

 

Setting my ruler up at 1 1/16" I laid out the intersection for the second line.

 

Skipping to the fourth line for expediency sake in this topic, you'll see my pencil sitting below the fourth line. This is the next one to be laid out. This is an easy one, the intersection is at exactly 2" above the edge.

 

You'll see I have set my ruler at 2" as seen in Kerry's layout diagram above and made the intersection. 

 

While laying out the right side, I was also sliding my ruler over to the left and marking the intersections while I had my ruler set. Now we can see a curve materializing.

 

The dots are connected and we have something that looks similar to what the layout should be. I used my string bow curve to lay this out, you can see my string bow at My Big Ash Mallet topic. 

 

It's time to cut the curve now, I am using a 3/4" [4 teeth per inch] re-saw blade to cut the ash block into my bending form. The re-saw blade was perfect for this operation, it sliced right through the hard and thick block of ash.

 

The cut is complete.

 

The bending form.

 

I cleaned up the ridges with a scraper (not shown below), I did not have too, the form will work fine and the band-saw ridges will not make a difference at all in the finished bent slats. But it's always fun to break out the hand tools when possible. This form is meant to go into a bench vise, the slats are steamed, then stacked, and all the slats for the chair are inserted between the forms, and the vise is closed, and the slats are left in the form and vise for a week.

 

I know this is a really basic process here, nothing dramatic nor extravagant, but I thought for our woodworkers who may never have laid out a design based on grids from plans, well now you may have a better understanding how it's done!

Thanks for reading along!

[lew]

I think we mentioned on the site before- here's an alternative to laying out the graphs on the wood.

http://www.printfreegraphpaper.com/

[John Morris]

Now that is way cool Lew, thanks for the resource!

[Stick486]

thanks John...

very well done...

[Chips N Dust]

Very nice!