Okay I'm back. Sorry for the delay.
After the epoxy has cured overnight your mold is now a big heavy chunk that must be cut into a circular blank. This is not as simple as you might think. It is important to make careful measurements with two separate objectives:
1. You want to make the blank as big as it can be and still fit on the headstock of your lathe. The distance from the center of your spindle to the bed is called "Swing over center". On the Nova DVR machine I used, the swing over center is 9". So the radius of any piece I turn on that machine must be less than 9". Very often people will just eyeball it and put a rough blank up on the lathe. It happens to fit when mounted in one position but as soon as the turner switches the motor on, the out of round chunk of wood acts like a cam and jams against the bed of the lathe. It always pays when working with big wood to make a quick mark of your center and draw a circle with a marker to follow on the band saw.
2. With this particular design and most glued up blanks, your finished piece will greatly benefit from carefully centering the pattern of the glued up assembly. The herringbone zigzag can be deceiving so what I do iscut a disc of cardboard the same size as the desired blank (this time it was 17") and move it around on the glue-up until the pattern is centered under the disk. Then, mark the center of the cardboard disk into the wood glue-up and trace the circle with a marker. Remove the disk and before cutting on the bandsaw, check the pattern for centration. Once satisfied, cut it.
The blank gets mounted to a faceplate. I use a three inch machined steel faceplate and number12 x 1.5" phillips head screws. The screws are going into what will be the top or concave side of the bowl. Here's what it looks like when you have the blank mounted andcleaned up:
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You are now cutting the outside profile and bottom of the bowl. It helps to have Basil with you in the shop.
Once it cleaned up the balance should be very good. That means you can work at 1500 RPM or higher. I usually work at or above 2000 rpm with a 5/8" bowl gauge. The quality of the cut is better but there is alot of heat generated. This is maple and hard plastic with bits of brass. The chips from this baby at two grand can and will make you bleed so it would behoove you to wear a glove on your forward hand. The brass pins come out when they get short enough and of course they are extremely sharp little darts sowear eye protection too. If you start this project with just a T-shirt, after taking one or two of those brass darts in the belly or a nipple, you'll be donning a coat or sweater for protection of your upper torso.
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Once up to speed, this thing is like a spin balancer with a car tire mounted. It takes a while to spin down. be sure you have no loose sleeves or scarves or anything hanging off you. You can become one with your work faster than you can imagine. Notice the close proximity between the tool rest and the piece. This is the way it should always be. When you remove enough stock to widen that gap, stop the machine, move the tool rest in so it is just clear of the piece and restart the machine. Never move the tool rest while the machine is running. If that big piece of steel hits the rotating chunk of wood, the steel will win.
Break time for Braddie. I'll be back with more of the exciting world of chip production.