Technique for re-turning roughed out bowls

[Jack Gaskins]

I would like if you guys can give me your sequence for how you re-turn your bowl roughouts. I find I am not able to use a bowl gouge on mine due to the bowl being oval and the bowl gouge just bounces all over the place. The only other tool I know to use is my homemade easyrougher with the carbide round tip. This tool works but it seems to open up the end grain and I have to spend a lot of time with the scraper.

[David E Keller]

I generally mount the bowl between centers and true up the tenon. I turn the bowl around at that point and mount it in the chuck. I then true up the outside using a bowl gouge(roughing cuts following by finishing cuts). Next, I true up the inside and turn to final thickness. I sand inside and out, and then I reverse on a jam chuck to clean up the bottom of the bowl and remove the tenon. I hand sand the bottom and then finish. I don't see why you couldn't use the Easy Wood tools, but I've always done it with a bowl gouge(I use 1/2 inch but I don't think it matters)

[Mark Levitski]

Jack,

It's just like starting to turn a blank, which can be out of round also. A blank can be even more out of round if it is merely "stop signed" with the chain saw when first mounted on the lathe. If you can get through that with a gouge, you can surely do the rough-out after it has warped dry.

It is also like turning a truly round piece with a gap. For example, the gap can be from an up-and-down shaped rim as in a natural-edged bowl. The technique is to act as though there is no change in the surface for the tool. Hold the cutting edge out there firmly and steadily in space as if you were still cutting wood. Pretend you don't feel anything different with the gouge and blot out any off the abnormal sounds that you hear as the gouge goes in and out of the cut, from wood to space to wood. Relax but hold it all firmly. Proceed with the cut as you visualize your gouge advancing through the curve.

Once you get it back into round you will be able to make your finish cuts in a clean way. Just make sure you rough out enough thickness to accomodate the eventual warp and yet leave enough room to get to a finished target thickness.

Mark

[Mark Levitski]

P.S.--David's right: I forgot that you also have to true the tenon (if that's what you chose for mounting), and I also treat it as a blank and put it between centers again to do that. Then into the chuck for continuing on from my previous post. Make sure that you leave a large enough tenon so that when it is trued it still fits the jaws that you are using, both when roughing out and when re-turning to round.

A good suggestion I see a lot on this forum: maybe a basic DVD or two, or alternately a visit with a local turner or a club demo is in order. I learned everything form DVD and trial and error (lots of trials and lots of errors).

[Scott Hackler]

Also, proper tool angle and a real sharp gouge are a must. I re-turn (to round) with a 1/2" Sorby bowl gouge taking slight cuts at a bevel angle type cut. But before starting I hone a razor sharp edge on the tool. The handle is held low. If you raise the handle of the gouge, your treating the gouge like a scraper or skew held flat. Thats a very rough and difficult cut and there is a lot of stress on the wood when every rotation there is only two contact points, until round again.

[Bernie Weishapl]

When I re-turn a bowl I open the jaws of my chuck and put the inside of the bowl up against it and then bring the tailstock up to the mark that the tailstock made on the bottom of the tenon when I roughed it. I make the tenon round and then reverse the bowl to chuck it up. From there I finish turning the outside then move to the inside.

[Sean Hughto]

I turn my roughs with a tenon. Here are some coated with AnchorSeal and drying:

http://farm5.static.flickr.com/4098/4874286392_5bf732fe4d_z.jpg

When dry enough, I use the backside of my donut chuck - a plywood disk with thin foam on the front and a faceplate on the back - and the tailstock with a live center to return the tenon to round first.

http://farm5.static.flickr.com/4022/4207689140_94d3c9100a_z.jpg?zz=1

I then mount the bowl in a oneway scroll chuck (Talon or Stronghold). You can then return the outside and inside. There is not much bounce, but rather just the feel that happens when there is cutting then air, then cutting, etc. until you get to round again.

[Thomas Canfield]

I agree with most of Bernie's and use the expanded chuck inside and live center on outside to true up tenon. I will then work on truing up outside around the bottom as a minimum to clean up area aroung the chuck mounting when reverse. Then reverse and work outside and then inside. I have found occasions where the internal stresses make the outside go oval when working the inside and that needs to be checked before turning inside down to finish cuts. The big thing for me is to make small cuts with sharp tool until a concentric surface can be made and provide a flat for riding the bevel when continuing over the elongated surface. A little practice helps one develop his own technique and skill.

[Dennis Ford]

All of the above is good advise, one thing that was not mentioned is speed. Even though the rough-out has warped, it should be pretty close to balanced. Turning up the speed will help a lot when trying to clean up the oval shape.

[Steve Schlumpf]

I open the jaws of my chuck up as wide as will fit within the bowl, bring the tailstock up and insert the center into the divot left over from roughing out. I then turn the tenon round and finish the outside of the bowl - including sanding. Once the outside is complete - I reverse the bowl and complete the inside.

To remove the tenon - I use either a donut chuck or vacuum chuck - depending on the bowl.

[Jack Gaskins]

Thanks for all the replies. I guess it is as I thought........I should be using my bowl gouge, guess I am presenting it to the cut improperly thus trying to take to much off to get the bowl round again. One other technique I am having issue with is making finishing cuts with the bowl gouge, can't seem to get the bevel to ride against the bowl and make a clean cut. Probably due to lack of sharpness of gouge I suppose.

[Prashun Patel]

I'm in the presence of experts and hope i'm not speaking out of turn...

What is the angle of your bevel? Closer to 90 made it easier for me to ride the bevel on finishing cuts, but harder to hollow.

You can also use the bowl gouge in a shearing cut. I am probably doing this wrong, but basically I turn present the gouge flute-side to the bowl, so I'm cutting with the bottom wing of the gouge. The bowl just barely misses the top wing, which keeps the bottom wing at the right scraping angle w/o letting it dig in. You can get some very fine shavings this way.

Like I said, I'm probably doing it wrong, but this HAS resulted in tiny shavings that leave a pretty smooth surface. Direction seems to matter, if you have any kind of reversing concavity on the outside.

[Jake Helmboldt]

Jack, it is all about how you enter the cut. Here is what I do:

roll the gouge on its side and point the bevel in the direction of the cut and start taking light cuts working progressivley inward. Once past the rim the bowl isn't as warped and after a few passes you'll have a fairly smooth continuous cut.

[Jack Gaskins]

I'll have to check my 3/8ths gouge and see what the angle is. Just bought it from PSI with the intentions of using it just for outside the bowl. I have most of Jimmy Clewes DVDs and he just glides across the outside with his gouge.

[Harvey Ghesser]

Jack...Get Bill Grumbine's DVD....Turned Bowls Made Easy...nuff said.:D

[Ken Fitzgerald]

Jack,

As suggested...Get Bill Grumbine's 1st video "Turned Bowls Made Easy"....


Second, you have to consider some things when you see someone like Clewes or Grumbine....1st they have a lot of experience...2 they are using SHARP tools.

Get the video....make absolutely sure your tools are sharp.....practice riding the bevel.

[Cathy Schaewe]

Just out of curiousity, is it really necessary to re-turn the tenon? I've been roughing a lot of stuff and some of it seems dry now, but the tenon doesn't look particularly deformed. Is it everybody's experience that re-turning the tenon is helpful/important?

[Steve Schlumpf]

Cathy - when returning the tenon - all you do is lightly reshape the tenon so that it is round again. That way you know all 4 jaws of your chuck will grab equally and the blank will be secure.

[Thomas Canfield]

Cathy,

A tenon on green turned bowl can be severely distorted, 1/8" + in diameter, and the seat face also out of square. That would make for a dangerous mount. Yes, the safe thing is to true up all tenons as if there is a distortion problem. Even remounting a dried tenon can have problems unless well marked and you are able to hit all the previous seating deformations (I use a serrated chuck).

[Cathy Schaewe]

Steve and Thomas - That makes sense. I was thinking about it in terms of what it would do to the form, rather than holding on the chuck. And Thomas - I always use a serrated chuck - I think they're safer.

Thanks for the info!

[Leo Van Der Loo]

No tailstock on my outboard turning setup, I normally have a recess rather than a tenon, and a recess will deform to an slight oval normally, the Oneway chuck will hold a oval recess quite well when positioned so all 4 jaws hold.
The next thing is to straighten/flatten the rim and then mound the bowl in the Jumbo jaws to return the recess, and quite often return most of the outside if not all, depending the shape of the piece.
Then I flip the bowl over and hold it in the recess with the chuck again, finish turn the outside if that wasn't all done yet.
Then the inside will be turned round and thinned to whatever I want to for that piece.
Sanding etc. are than done, HTH

[Scott Hackler]

Also, to add to what Steve said, if you re-turn the tenon to a round state... you have the option of rechucking later if you want to remove it from the lathe and work on a different project. An oval tenon is hard to get back to the exact true if you remove it from the chuck and then try to put it back on later.


Just out of curiousity, is it really necessary to re-turn the tenon? I've been roughing a lot of stuff and some of it seems dry now, but the tenon doesn't look particularly deformed. Is it everybody's experience that re-turning the tenon is helpful/important?