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/showthread.php?t=134525&highlight=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.

http://www.robholcomb.com/bowl/1.jpghttp://www.robholcomb.com/bowl/2.jpghttp://www.robholcomb.com/bowl/3.jpghttp://robholcomb.com/bowl/4.jpg

[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

[Thom Sturgill]

Grumbine's DVDs are great. I also suggest Mike Mahoney's Bowl Basics video. It has the best info on creating a tenon that I've seen. He also discusses tool grinds as he uses a different grind than most.

[Michael E. Thompson]

Rob, I agree with Scott that your problem likely is tool position. Me personally, on a bowl that size I would use a smaller bowl gouge more like 1/2". Nothing wrong with using a 5/8", just seems to be a bit overkill to me. You can take a lot of wood off with a tool that size. What kind of grind are you using on the gouge? If its a swept back grind, you may be using the long edge to make all your roughing cuts. That is a lot of cutting area against the bowl. Catches can easily happen. You will see in the videos Bill will have you present the tool with more of the tip rather than the side, as well as "rubbing the bevel". Keep in mind you are not actually cutting with the tip, but right next to it. The video will describe tool presentation much better than I can.

The other thing I noticed from the picture is your tenon is a bit cone shaped. Make sure the tenon has the same profile of the jaws on the chuck. Its hard to tell on the chuck, but it looks like it has a dovetail shape. The chuck will hold the bowl very well with the correct profile, and as other have said, shorter tenon.

Just my opinion.

Hope I didn't confuse you. You will enjoy the videos, I learned a lot from them.

Mike

[GLENN THOMAS]

Rob,

Looks like you got some good advise from everyone. On thing I noticed and it was hard to tell from the picture but it looks like the bottom of you bowl curved right into the tenon. In addition to cutting you tenon in a dove tail you should also leave a small portion on the bowl bottom flat where it intersects the tenon. The angle between the tenon and the bottom of the bowl should be 90 degrees and this flat area only needs to a half inch at most. This will allow the bottom of the bowl to sit squarely on the end of the jaws and that makes it a little harder to knock the bowl out of the chuck. For me it is very difficult to explain in words how to present the cutting edge of a tool to a piece of wood. There is a very fine line between having you flute too far either way, there is a very small sweet spot. The video you ordered will be the next best thing to having some one show you what to do. In addition to Bill Grumbine videos I would also recommend watching Jimmy Clewes videos if you get the opportunity.

GT

[Richard Madison]

Rob, If your 5/8 BB gouge is like mine, it is a deep V. I found it very difficult to control (a few years ago) and never use it. As mentioned, use a smaller gouge if you have one, simply because it will be easier to control. It appears that you were indeed struggling with tool control/presentation and the Grumbine videos should be very helpful.

[Dennis Ford]

You have gotten lots of good advise, I hope this is also useful. Keep that bowl! It can most likely be salvaged after it drys and you have a little more experience. I would wrap it up in some brown paper and put it out of the way. It looks rough now but a "rough-out" does not have to look pretty.

[Mark Levitski]

Hi Rob. I agree, great advice, valuable forum.

Yes, salvage the roughout. Looks just like any other.

Your chuck is the same as one of mine and also the jaws. I have turned many bowls with tenons longer than 1/4 to 3/8" w/ no problems with these jaws. Just as was said, just don't let the tenon bottom out against the inside back of the jaws. If it broke leaving 3/8", I would think it was not from the leverage of a long tenon--the remaining shorter tenon should have held the piece. The key, as mentioned, is to keep a flat face for the jaws to seat against, as well as a slight dovetail to match those jaws (they do have a dovetail). For the tenon diameter, I would highly recommend leaving more than a 1/4" over the fully-closed jaw diameter when you do your roughouts. Only 1/4" would mean turning off only 1/8" off each side of the "ovalness", and in my experience, 'taint enough. (What do you others say re: this?) Most bigger bowls will go oval more than that when drying and you will have to resort to not only truing up the tenon but turning a smaller one for totally different jaws on the chuck, or doing a glue block--more work than necessary. Been there, done that, learned how to accomodate this. Did you true the tenon after the bowl dried?

Good luck and keep at it. Beyond all the advice, it mostly takes doing over and over.

[Thomas Canfield]

It sounds like there are multiple things going against you.

I agree that the tenon is too long and needs to be short enough to allow the back side to seat against the face of the chuck.

The tool marks on your "green" bowl look like your presentation of the cutting edge is not correct to rub the bevel or tool dull. What speed were you using? Higher speed will give you a smoother cut within reason but you still need to keep the speed within the normal turning speeds recommended. Unbalanced rough wood needs to start out slower until the removed wood improves balance and allows higher speed.

Shallow bowls or saucers are easier to work on at first. Trying to go deeper or steeper cuts are more prone to catches, especially trying to work the bottom.

Another vote for the Bill Grumbine dvds. I watched them and it helped me a lot. Today, I turned 6 green Bradford Pear bowls from 11" down to 8" diam, sap slinging all the while. Once you get the hang of it, the shavings seem to flow off effortless. I did notice that I had to sharpen (or change tools) during each exterior, but could do at least 3 interiors per tool. Sharp tools make the difference. It took about 15 - 20 minutes to turn the exterior and tenon, and 5 - 10 minutes to turn the interior. I use the screw in my Oneway Stronnghold chuck and had rounded up the blanks with bandsaw circle cutting jig and turned at about 650 rpm on my Powermatic 3520.

All that said, I will admit to having one catch on the exterior of one blank and twisted out the threads for the drive screw being too agressive. That blank will now have to be done with a faceplate tomorrow. There was a dry limb section on the green wood that really grabbed the heavy cut being done on the green wood.

[Maylon Harvey]

Rob,
Where in Western NY? How close are you to me?

[Rob Holcomb]

I want to thank everyone for their input and advise. Believe it or not, the Grumbine videos will be here tomorrow. I'll spend the weekend watching them and then put the teachings to work and practice practice practice! Maylon, it looks like we live 3 hours apart from one another. I'm in the Southwest corner of NY in Jamestown. Since there aren't any clubs or classes closer than 2 hours away, I'll have to stick to the videos and offerings by all of you. There's a Woodcraft in Buffalo that has classes from what I've been told and I plan on checking into the dates/times they are held. Unfortunately, work, wife, kids and my flat work makes it difficult to take off for a day but I think it would be in my best interest to make room in my schedule to do that.

[Bill Blasic]

Ron,
If you feel like traveling to the Erie PA area I'll fix you up with a lesson. We have a member or two from Jamestown in our club the Presque Isle Woodturners.
Bill

[Rich Aldrich]

I agree that getting some lessons really helps. Steve Schlumpf showed me how to rough out a bowl. His help was excellent. I have since roughed out two bowls without much trouble.

The biggest thing for me was the process and tool presentation. The DVDs help reenforce the things that Steve taught me.

He also loaned a couple of DVDs to me and they are very helpful. One is the Bill Grumbine and the other is Richard Raffan - Turning Wood.

I will probably end up buying these two. I also have been looking at videos on using a skew.