Wet Bowl turning problem

[Rob Holcomb]

I finally finished my flat work project and tried to rough out my first green bowl. I took a hunk of Cherry and cut it as I'm supposed to with a chain saw and then cut the piece octagonal on my band saw. Then I secured it to the 3" face plate that came with my Delta lathe making sure it was mounted as close to center as it could be to minimize vibration. I began turning the outside of the bowl to shape and after an hour or so, I was able to get something that resembled a very rough, out of round exterior. It was close, but not round by any means. On to the inside. I removed the bowl from the faceplate and mounted the reversible Nova chuck that also came with my Delta lathe deal and inserted the tenon I had turned. Making sure it was tightened down good, I started to gouge out the inside of the bowl. Eyeballing the bowl size, I would say it's about 8" in diameter and 4" (excluding the tenon size) in depth. As I was gouging out the inside, I had many catches. I thought my new Benjamin's Best 5/8" bowl gouge may be a little dull, so I stopped and sharpened it. I went back to work and the gouge was sill catching. I was making sure I wasn't taking too much wood, barely touching the wood at all but there was one area that was giving me fits, catching every two to three seconds. I continued on and as a result of all of the catches, I thought the tenon must have come loose from the chuck because the bowl came off the lathe and rolled across the floor. The bowl itself survived but after closer inspection, the tenon didn't come loose, it actually broke. I was left with a tenon that is ragged and maybe 3/8" in length. Although the piece was still thicker than the norm for soaking in DNA, by this point, I just wanted to stop. I know enough to know that once you get frustrated, back away from power tools and tackle them another day. It's just safer that way. I put the bowl into the DNA and called it an evening. Anyway, my questions are, what mistakes am I making and with a tenon that's now short and a bowl that isn't quite round and still an inch thick, should I toss this blank and start with a new piece or is there a way to save this piece and chuck it up another way for final turning once it's dry? Keep in mind that I don't have any fancy jigs for my lathe nor do I have a donut chuck. Thanks in advance for any thoughts you have. Rob

[GLENN THOMAS]

It would really help us help you if you could post some pictures of the blank and the tools you are using. It would also be helpful if you could post some pictures of how you are using the tools and how you are presenting them to the wood.


GT

[Steve Schlumpf]

Rob - photos would help.

Also, if your tenon broke off and you were still left with a 3/8" stub - then the tenon was too long.

Best advise would be to join a local turning club and have someone fluent in bowl turning show you the basics. Next best thing is to get Bill Grumbine's DVD - Turned Bowls Made Easy. Everything you need to know about bowls is in that one DVD!

[Rob Holcomb]

I will take some pictures of the bowl, faceplate and nova chuck a little later today and post them but I don't think I'll be able to get it mounted again to show you my technique or lack thereof. Basically what I did was set the tool rest at about the mid height and then angled my gouge to a comfortable place and began.

Steve, the tennon was maybe an inch long before I mounted it. I chose that length based on some pictures I'd seen of bowls with tenons as a visual guide. There are no turner clubs in my area that I'm aware of so I'm taking your advise and getting the videos. I'm more of a hands on, learn as I go type of person but I think you're right in this case. Without a class to take or a club to join, I'll have to use video's from a master and trial and error.

[Steve Schlumpf]

Rob - most of us are self-taught and do what we can to answer each others questions. Do some SMC searches and ask lots of questions.

Normally, tenons are 1/4" to 3/8" in length, depending on the size of the blank you are turning. A 1" tenon allowed the mass of the bowl to act as a lever. You also have to understand how the tenon fits properly in a chuck and also how to properly cut the tenon to fit within the jaws you are using.

[Steve Schlumpf]

Rob - check out the PDf in this thread: http://www.sawmillcreek.org/showthre...ighlight=tenon

[Chris Zeigler]

Rob,
The Bill Grumbine DVD is well worth the price. I am sure it would help you tremendously. I found it very useful even after I had turned a couple of bowls.

Good luck.

Chris

Rob - photos would help.

Also, if your tenon broke off and you were still left with a 3/8" stub - then the tenon was too long.

Best advise would be to join a local turning club and have someone fluent in bowl turning show you the basics. Next best thing is to get Bill Grumbine's DVD - Turned Bowls Made Easy. Everything you need to know about bowls is in that one DVD!

[Tony De Masi]

I'll agree with Steve that the tenon was too long to begin with. I'll also agree with Glenn is saying that with as many catches as you were getting then the tool presentation must be looked at.

I will also highly recommend the Grumbine video as well. Make sure you get the first one titled Turned Bowls Made Easy. I just recently took some lessons from Bill and he was a superb teacher in person as well as on video.

Tony

[Rob Holcomb]

Here are the pictures of my faceplate, chuck and what I have left for a bowl. I took it out of the DNA and have it wrapped in newspaper for now. Forgive the large pictures. I didn't know how to post as thumbnails on here.

[Rob Holcomb]

Forgot to mention that I ordered the Bill Grumbine videos, "Turned Bowls Made Easy DVD! From the Tree to the Table and Everything in Between!" and "Beyond the Basic Bowl: Advanced bowl turning DVD" from Amazon. Should be here on Monday.

[Scott Hackler]

I will also agree that the tenon was way to long. The face of the chuck jaws should "seat" on the bottom of the bowl blank. As far as your catches, it doesnt sound like a dull tool... it sounds like tool presentation. That video should help a bunch. I spent a ton of time on youtube watching videos and then a ton of time practicing before I figured out what I was doing wrong, when first starting.

[Wally Dickerman]

Rob, do yourself a big favor and find a good instructor and take one or more turning lessons. You won't believe what one day's instruction from a good teacher will do to improve your turning. Watching someone else turn is a big help but there is nothing like hands-on instruction to quickly improve your knowledge and tool handling techniques in turning.

If there is a Woodcraft store in your area, they have classes available.

Wally

[Dave Ogren]

Ron,

I know how you feel. I was in the same place a year ago. The problem is tool presentation, the way it looks to me, because of the gouges. I hate to see you loose your first bowl. I would fasten a board to the top of the bowl then mount the face plate as best as you can in the center, remount on the lathe return the outside....Then, now maybe you can then use the tennion to finish the inside.
I have never used a tennion. I always use a recess, 100 ++ bowls and never lost one or even had one come loose and I am an agressive turner.

Another big help would go back and read Leo Van Der Loo's and Reed Grey's postings, they were a big help to me.

Good luck and the best turning to you. Remember to save the first one, so in a year you can look back and smile.

Dave

[Reed Gray]

A long tenon is actually weaker than a shorter one. As to your catches, I would imagine that you have the flutes of your gouge straight up. You want them rolled away from the cut/side of the bowl. On the outside, you want them at 9 to 11 o'clock, and on the inside, from 1 to 3 o'clock. If you have them too straight up, the up hill wing/side of the gouge catches on the bowl. I don't know what kind of lathe you have, but if you have variable speed, set the speed way down and experiment with rolling the gouge sideways away from the cut. Takes us all a few times to figure this one out. The selection of DVDs you got is good.

robo hippy

[Dick Strauss]

Rob,
As Steve said and others confirmed, you want the tenon to match the chuck but not bottom. So, if the chuck has jaws that are 1/2" tall, you want your tenon no longer than 3/8" so that the chuck grabs it with the jaws and holds it against the shoulder of the chuck. The shoulder interface really gives you much more holding power. You also need to turn a dovetail shape to match if your jaws have a dovetail profile. You also have the best holding power when you are say 1/4" to 1/2" larger than the inside diameter when the jaws are fully closed (this extra 1/4" will allow for a little room to true the tenon after the bowl dries and the tenon goes out of round).

Make sure that you are in solid wood for your tenon. If it still includes bark (or maybe even the first layer or two of sapwood), you are asking for tenon failure.

Join a club or find a local mentor before you hurt yourself!

Good luck,
Dick