Seat carving process has started and it is going a LOT faster than I thought it would. I was able to get the first seat done in 4 hours and that wasn't overlapping glue drying time. If I do other operations while glue is drying I could easily get that down further but I won't bother timing it because it doesn't really matter.
First step is to select material. I had some nice 10" wide boards from my order of 6/4 Cherry. I figured I'd use 2 pieces to make the seat. In order to do the pre-sculpting though that board gets hacked into parts to be glued back together. Spoiler the grain turned out quite nice despite cutting and gluing back together. I'll be able to spot the glue seams but an average observer probably won't look close enough.
In the picture above the center of the board is missing. The pre-sculpting works best of the center of the seat is a board about 4" wide. This sets up the pommel area, as well as the main seat area. To make the 4" center I took 2" off of each board, jointed and glued them together to make a 4" board.
To start of the pre sculpting and ensure the chairs end up roughly similar, i made a template with index marks to make sure that the profile is accuraly placed on the center board of each chair.
The profile is then cut on the band saw. To set the pomel area I needed to cut an angle. I didn't want to tilt my band saw table to do this as that would be a hassle as I use the glue up time to back out the milling for the next seat. Also this doesn't allow the wood to sit long in a partially milled state which may cause movement I don't want. The angle was achieved by setting my fence at 2_1/8" and using a 1" spacer.
After the center board is pre-sculpted, I align all the boards and draw on the outline of the sculpted area with my template (the picture is old and the template needed to be cut yet.)
Because of the curve on the backside you have to be careful with the profile of the pre-sculpting. It's possible to cut into an area that should be left. The boards just to the sides of center are the main boards that your legs sit over so they are recessed 1/4" from the pomel and sides of the chair. It's kinda hard to see below. The seat area I think is about 5/8" which leaves around 3/4" under your rear.
The outside boards are the most complicated to pre-sculpt. It's not really easy to do it on the band saw as you can't do a through cut so there are some weird compound angles and well it's easier to just do as @Bmac instructs and take the outside pieces to your bench and sculpt them with your sander/grinder. This is a step that Mar doesn't do in his rocker videos and it's immensly helpful as you have more room around the part to maneuver your tool to get the perfect shape.
I also use a very high tech measuring device to set an offset from the outside line. This tells me about where I want the curved side to stop. I remove the bulk inside the line and then setting the grinder on the angle blend from my rule of thumb line to the outside line. This has helped prevent me from trying to make the sides too steep which doesn't work very well and isn't very comfortable.
The outside part after pre-sculpting, next to it is an untoched piece.
After this point the seat is ready to be clued together and shaped. With all the pre-sculpting there isn't a lot to be done. Really it's just even everything up. This is why pre-sculpting seems like the cheat code to do this.
After I use the RAS with 24 grit paper I go over the seat with a goose neck scraper. This is where I deviate from others. I know Bmac uses 50 grit and the moves into the RO90, while I don't have the RO90 and every time i went to buy it I had a really hard time pulling the trigger. I did one of my trials with the goose neck scraper and found it was an excellent way to get between 24 grit and 80 grit with an interface pad.
It may be hard to see in the picture above but after sculpting there are some high spots and some deeper scratches. Trying to level all this out with sanders left a surface that felt like it undulated a lot to me. When i used the scraper I was able to remove those high spots and the surface felt far more uniform. Both were smooth it's more the difference between laser flat and slightly scalloped.
The scraper did not leave a perfectly clean surface though. With the changing grain directions there was some tear out and other issues. Goose neck scrapers and difficult to sharpen and get tuned up well so that doesn't help either. So I started sanding at 80 grit on my 125mm sander with the foam interface pad. This generally goes well. but the sander is VERY under powered so care has to be taken to not stall the RO movement. After 80 grit i jump to 120 grit on my 150mm sander with a foam interface pad. Using the 2 sanders back to back it's very apparent that the 125 ets needs more power. Due to the curved surface the 150 nearly jumped out of my hand numerous times. I ended up turning it down from 6 to 4 as i found it almost unwieldy at full power. After 150 is 180 than 220.
Next up is finishing touches and round over to the seats then finishing and mounting. The end is near. My goal is to eat dinner Friday on one of these chairs fully finished. If I don't meet my goal so be it but it's my goal.