Never had a problem with the extenders as long as they are sized for the bit properly. I've never had any excessive wobble, vibration, router bit problems. Never had problems. Make sure you route in the proper direction on the inside. I found it easy to ease the top with a small round over bit on my router table, but you could also sand it, your choice. I also us a slightly bigger round over on the bottom and gave it an edge.
I have made many bowls and find that laminating them is easy and works better than trying to use one (chunk) piece of wood and waste most of it. Here is what I did.
1. Decide what shape you want your bowl to be i.e. oval, ellipse, round... any shape you choose.
2. Make a pattern from MDF, plywood, hardboard, just make sure the bearing will ride on pattern until you're deep enough to use the side of the bowl as a guide.
3. Decide how deep your bowl will be and gather enough wood to laminate to give you needed depth, and how thick you want the walls to be, around 1/4-3/8 is good.
4. As you cut the lamination's to over size lay the pattern over it draw the pattern on the wood and cut out the material with a jig saw. ( Don't saw out the bottom lamination)
Save this and make a slightly dished out tray for your dresser to put change in. Do this for each lamination and give to friends after finishing them.
5.Glue up lamination's, when dry, attach pattern to the bowl with drywall screws, use a pattern bit for the inside's and dish/bowl bit for bottom. Remove pattern and with a compass scribe wall thickness and trim excess wood with band saw or jig saw, or sand and finish. Use food grade oil for food or what ever finish you like.
I made one with Birch and 1/2" Paduk middle and top and did the same with roasted walnut on the bottom and rim, oiled it and finished it with lacquer. Mine were about 3" high, 5-6" wide and 11-12" long. I also made round ones, ellipses and ovals, varying wood and size. Great fun and you get to be the designer.
A big plus... by cutting out the centers and then gluing, you really have very little waste, as opposed to throwing away the whole center.
Good luck, they are a great project for Christmas presents. You're only limited by your imagination.
Last edited by PAD3; 07-15-2014 at 06:45 PM.