Bowl problem

[onedash]

Ok. Made my first bowl out of bubinga. Its my second try. I left it thicker so it wouldnt explode. Nothin fancy. Well I put friction finish on it and it turned out nasty. Guess I should resand and use poly.
But heres the problem. I still have my little tennon left from where I held it in the chuck. How you supposed to get rid of that? Do I have to buy the big thing to hold the bowl upside down? Or I guess make something out of scrap with a slot to jam it in right?

It looks more like a lid to a cookie jar or something...

[bigsteel15]

Looks to me like you have some tool chatter inside (top left corner of picture?) that messed up your finish. Hard to see that until you apply a finish because sanding makes it look OK.
If I'm seeing things I apologize, but just trying to help. I had exactly that just last night. Then I blew the bottom out of the bowl...OOPS!
As far as the tenon I'm in the same boat with a bowl of the style you've got there, awaiting a reply from others.

[DonHo]

Well, I'm pretty much a beginner myself but I'll give you what little I know. If you go with a tennon on the bottom for the chuck you pretty much have to either have the jumbo jaws or make some sort of jam chuck and turn off the tennon. It's too late now but another way is to turn a rebate in the bottom (the jaws fit inside the rebate instead of around the tennon) and finish the outside of the bowl before you turn it around and remount it for hollowing. I have a chuck with jaws that will hold a bowl up to 8" but use the second method most of the time. I mount the blank to the face plate with screws turn and finish the outside with the rebate in the bottom then turn the blank around and hollow and finish the inside.
Good luck,
DonHo

[onedash]

Looks to me like you have some tool chatter inside (top left corner of picture?) .

Does that mean my tools are to dull?
It was like it was not perfectly round. like when you start to round it but obviuosly no where near that bad.
There is a spot on the outside like that too. I sanded forever too...I need a bigger gouge and a scraper. The bigger gouge to hollow it out faster( i think) and a bowl scraper would make it smoother (I think)

[Ken Massingale]

Looks good for the second bowl.
I go with what Don said, throw together a jam chuck and turn the nub off. Make the bottom concave so the bowl will set flat on the rim. If you had a rough spot or two, try using a round nose scraper with a real light touch. Now you have a reason/excuse to get another couple of chisels!
ken

[RayintheUK]

Well I put friction finish on it and it turned out nasty. Guess I should resand and use poly.
But heres the problem. I still have my little tennon left from where I held it in the chuck. How you supposed to get rid of that? Do I have to buy the big thing to hold the bowl upside down? Or I guess make something out of scrap with a slot to jam it in right?

Friction finishes can be a real disaster on bowls, as they can build ridges and dry patchy - yuck! Re-sand and oil or wax it would be my solution.

I tend to use a dovetail recess to reverse my bowls. Here's an example from a very large holm oak bowl:



The chuck jaws expand inside the recess and offer good gripping. You'll hear some tales of bowls breaking apart under this internal pressure, but I'd guess that's mostly caused by other factors as well - never happened to me (yet!).

Cutting a spigot can never suffer from such problems, of course, but you then have to turn it off. If you're not prepared to part it most of the way, then knock it off and pare the nub, the only way is a jam chuck or a set of Cole jaws. You can make your own Cole jaws fairly easily - there are several plans out on the Internet if you have a poke around. Here's one set for you.

I bought a large set of Cole jaws with my lathe, but rarely use them because I use the dovetail recess. When I do use them, though, I'm careful not to run them too fast and get the turning done as swiftly as possible to prevent any scuffing to the inside finish.

Ray.

[Tom Miller]

Another option is to cut a circular groove into the bottom, after you've trued the bottom, and made it slightly concave. Make the groove wide enough so that the chuck jaws fit, then either grasp the spigot, or expand the jaws to hold the outer recess. If you're going to do the latter, be sure to leave enough stock out there, as the chuck can break the wood. DAMHIKT.

I think the preferred method, aesthetically speaking, is to grasp the bowl rim with, e.g. cole jaws, and turn off all signs of chucking. Luckily for me, though, you don't have to do that until you're good.

Regards,
Tom

[bigsteel15]

The nice thing about the dovetail recess like Ray shows is there is a tool for that.
http://www.leevalley.com/wood/page.a...330,49233&ap=1

[SteveR]

Newbie here as well so take this with a grain of salt. I had the same situation as you. But I would hazard a guess the safest way would be a homemade cole jaws like Ray mentioned. I was doing natural edge bowls so could not use the cole jaw method as far as I know anyway. I got my method of getting rid of the tennon by watching the Bill Grumbine video. I assume you turned the tennon with the bottom of the bowl towards the tailstock to begin with and reversed & remounted into chuck to hollow the interior. Remount it this way again and find the original tailstock hole. Make a friction fit chuck out of scrap (do this first obviously) with some padding on it so as not to mess up your finish. It appears the interior of the bottom of your bowl is flat (POS screen at work) so you may need to fuss with this a bit to get it relatively running true again. Tighten everything up and take light cuts....and recheck for tightness of the friction fit. You can get the tennon down to almost nothing after awhile, leaving maybe an 1/8" (scary yes, but it works). This piece can be broken off by hand and then sand. Like another poster stated, be sure the bottom is concave. This will help in the event you can not get the thing running perfectly true......saved my rear by doing this as I was only able to get a couple running fairly true again.
Steve

[onedash]

Well I took a piece of plywood and made a big circle. Took my parting tool and cut a groove (first try was a success) and pushed the bowl into the groove....got rid of the tennon and have a coat of poly on it now.

I thought id make another one out of walnut. I thought hey let me try this screw. After I had already started between centers. well it got pretty wobbly and I made the inside cut instead of a tennon. It stayed pretty wobbly through the entire thing. Then not taking into account the chuck was not much closer I went through the bottom and there was a tiny hole...No big deal until all of the sudden it became a huge hole the size of the inside of the chuck...
So I have one bowl out of three attempts..I guess once you start a piece you shouldnt change the way its mounted huh???
What is the order you do things to use the chuck grabbing on the outside of the jaws?

[RayintheUK]

What is the order you do things to use the chuck grabbing on the outside of the jaws?

I use a helical screw chuck into the top to mount the blank. Bring the blank into balance, then square up the base. Caliper the chuck jaws, cut my dovetail recess (check that the chuck fits!), then shape the outside to taste. Sand and finish the outside completely. Reverse the bowl onto the chuck and hollow out the inside. Use a simple depth gauge to prevent going through the bottom, remembering to include in the calculation the depth of the recess.

Ray.

[DonHo]

"What is the order you do things to use the chuck grabbing on the outside of the jaws?"

First I find the center of the blank(mark the center with an awl) then cut the blank into a circle on the bandsaw. If I'm going to mount the blank on the face plate I mark a circle the same size as the face plate so I can make sure the face plate is centered, then mount the blank on the lathe and use the tailstock for support until I have pretty much shaped the outside of the bowl. Then I move the tailstock back out of the way and using the hole left by the tailstock support (center) to mark a circle the size of the rebate I want to have for my chuck. I then use a parting tool to cut the rebate about 1/4" deep (my chuck needs 3/16ths to grip) I then use a scraper to make the bottom of the bowl slightly concave. As Tom said you need to leave plenty of wood outside the rebate to withstand the pressure of the chuck and I also leave the inside of the rebate but make sure to cut it lower than the rim of the bowl. I often decorate the bottom of the bowl with a few groves then sand and finish the complete outside and bottom of the bowl. Then turn the bowl around and mount the chuck in the rebate. Just remember that the bowl will need to be 1/4" shallower than it would without the rebate. There is nothing like practice to learn how to turn, I've probably made most mistakes that are possible including the "hole in the bottom"
If you can it would help to watch videos by people like Richard Raffan or other pros to get ideas as to how they do things. I think probably most turners have their own way of doing things but they all end up with a good end product.

DonHo

[onedash]

I think what really messed the last one up was going from spindle like turning between centers to using that wood screw in the chuck.
Thanks for all the advice...I hope I dont break any more. at $10-15 a piece if I dont get some bowls out of them my wife will stop letting me buy them I think.
She already said I made enough pens.....gotta sell a few to restock my parts....

[gerti]

As others pointed out there are many ways of reverse-chucking a bowl. On a recent club meeting someone showed home-made jumbo jaws made from plywood mounted on a regular chuck.

Personally I use a home-made Longworth chuck:

http://gerd.knops.org/shopnotes/?p=13