How I finish bowl bottoms that are too big for my cole jaws

[Kathy Marshall]

I've seen a few posts recently asking how to reverse a bowl to turn off the tenon and finish the bottom. So last night I started turning a big mesquite bowl, got about 1/2 way hollowing the inside before I called it a night. When I started back up tonight, I decided to take some pics showing how I hold a bowl too large for my cole jaws to finish the bottom.

This is my "big bowl" jam chuck. It's what was left of a piece of dry mesquite that I turned some bangles from. Since it's mesquite and since it's dry, I never have to true it up. It runs true every time. The face is covered with double sided tape. It's Duck brand that I got at Walmart and it's got more holding power than the double sided turners tape I got from Woodcraft.

The face is about 4" across and the bowl I'm turning is about 10 1/2" diameter.
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I use the live center of my tailstock in the divet left from roughing between centers, to line the bowl up and get it centered.
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I turn off most of the tenon, then turn the bowl bottom slightly concave.
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With just a nub left under the live center, I sand the bottom through all of the grits.
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Once the sanding is finished, I turn the nub down until I can slice right through it without tearing the grain. In this pic the nub has been cut completely through, it just looks like it's still attached.
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Here I've turned the quill back a little so you can see the separation.
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I used my small detail gouge to clean up the tiny dot that remained, and then a quick touch up with 320 and 400 grit and the bottom is done.
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Continued.......

[Kathy Marshall]

When I pull the bowl off the jam chuck (it can take a little persuasion to get it to let loose), I usually hit the inside bottom with some fine grit sandpaper (whichever grit I finished with) to remove any adhesive from the tape.

I use the nearly the same technique for finishing the bottoms of my hollow forms. The difference being, I don't use the tape (it can get stuck to the inside bottom of the piece, DAMHIK) and the jamb chuck needs to be a little longer than the depth of the form. I want the form to bottom out on the end of the jamb chuck and I turn the base of the jamb chuck to as close to the same diameter as the opening as I can get without the fit being too snug. That will help to center the piece and will also give a little bit of hold for when/if I cut all the way through the nub. Since I don't use the tape, I only take the nub down as small as I can get it without it separating. Then with the lathe off, I turn the spindle by hand and use my skew to slice completely through it. Then I clean it up off the lathe with a small chisel then hand sand it. Here's the finished bowl.

Mesquite, 10 1/2" x 3 1/4", finished with Mahoney's Walnut Oil. This is the beginning of another salad bowl set.
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And here it is next to the Mesquite bowl I turned a couple days ago. Just to show how much the color can vary. The wood was from 2 different trees, but they are both Chilean mesquite. Just hope I have some smaller pieces from the same tree so the serving bowls will match.
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Thanks for looking!
Comments and critiques are welcome.

[Doug W Swanson]

Great idea. I haven't seen that one before.

Nice looking bowls, too!

[Faust M. Ruggiero]

Kathy,
Great method for turning off the tenon safely. I am fortunate enough to have a vacuum chuck but I wanted to comment on the quality of your work. The lines you choose are true and fair and your centering perfect. You always make a nice finish and you find ways to make the wonderful woods you work with look their best. I'm really happy to get to see them.
faust

[Bill Hensley]

Thanks for the tip on the double sided tape. I hadn't considered it for that purpose.

The bowls are just beautiful. Love the Mesquite. The only Mesquite around here is the chips you buy in a bag for grilling...

[Nate Davey]

Great tip Cathy thanks for taking the time to put this together.

[Roger Chandler]

Pretty much the same as I do Kathy, with the exception of the double stick tape. I also use my vacuum chuck when it is a good candidate for the form in a bowl or platter..........for hollow forms, I like a long jam chuck that is longer than the form as well...........makes getting the bottom nib off real easy........one just has to remember to stop and do the final sanding first like you showed.

Very nice "how to" thread..........should really help newer turners who think they have to have every new gadget on the market...:eek:......like I did at first! :o:D

[Tom Winship]

Thanks, Kathy. This is something I wrestle with on every bowl. Have to try your method. Can't believe you get the "nub" so small without it breaking.

[Jamie Donaldson]

Jam chucks are very versatile and priced right! I have been using them for many years, and turners build a collection of shapes that fit many varieties of turnings, including hollow vessels. Be careful to round over the sharp profile edges at the outer diameter of the chucks, so as not to compress a ring in your bowls. All sorts of padding can be used, from carpet padding to mouse pads, and I often cut circles from some old non-skid router pads left over from my flat working days.

[Kevin Lucas]

I really like the idea of double stick tape. I just used a small round jam chuck and the tail stock to take the tenon off of a natural edged bowl. It needed some scraping and sanding as well. It was off center so one wing was high and the other was really low towards the bottom. I was a little leery even though I knew the tailstock would hold it. That tape idea sounds like a good bit of extra insurance )

[Tom Winship]

Kathy, you are my hero again. I went to Wally World before a meeting today and picked up two rolls of the double sided tape. I was a little concerned when it was blue. (Of course, you peel off the blue and the color matches you pic.) Wasn't able to use it on your mesquite bowl till a few minutes ago. The nib disintegrated before I had machined everything away, so I continued to turn and the tape held.

Who needs a vacuum chuck????

This is the best bowl bottom I have turned yet. Will post pics tomorrow.

[Donny Lawson]

Thats pretty much my method without the tape. I have quite a few sizes to put into my chuck and slide the bowl over and bring up the tailstock and turn the bottom.