"scooping out" a chair seat

[edcoleman]

I've got a customer who is asking to have some windsor chair seats "scooped" out. I was figuring on probing his original and then just running with a ball end mill - pretty simple stuff. This method will surely work OK, but I was wondering if anyone had a better machining strategy.

[chris_booth]

Ed,

I would be tempted to only probe half of it and then mirror it to make the complete object - just to save time and to guarantee the symettry.

If the data is going to result in a CAD model, then it is normally possible to analyze the shape (typically with the use of section views at different depths through it) to find out where you could send a bigger cutter than the ball end mill to do some roughing.

If you'll be using a 3D CAD it's also possible to model up the shape that should result from the roughing operation based on your planned toolpath, and plonk this right on top of your model of the Windsor chair seat.

If your roughing model completely covers the finished model, you should be okay. And if you can look at section views through both models you can see how much margin for error you may have for e.g. possible inaccuracies in Z changing from the roughing cutter to the ball end mill.

I guess my suggestion is only relevant if you're planning to use a CAD system with the capabilities I've outlined. And it's probably only worth it if it's quite a "deep" Windsor chair seat.

[stickman]

Ed,

Now these is a file I would love to see shared on project wizard or for a bank of files:

Bar Stool seats
Chair seats

I am looking to build barstools, I haven't really decided on a design yet, but I know that I need to get them built, cause what is a bar without barstools.

I would be interested in seeing what others have built for barstools. You can e-mail me the pictures instead of posting them. mailto:stickmanwood@hotmail.com

[jsfrost]

I presently rough a rocking chair seat using a 1 inch ball end bit, area clearing concentric oval shapes at multiple depths. It's primative, but gets surprisingly good results using only PW.

My first seat was shaped using a 30 grit wheel on an angle grinder using drilled pilot holes to gage depth, and took about an hour. The bot does 95% of the job in less than 10 minuites. The steps need cleanup, but the Bot made seat requires far less sanding than the angle grinder version. If interested in making rocking chairs see www.haltaylor.com.
Jim