Bowl help please

[John Fricke]

I'm making my first attempts at turning green wood and it is causing me fits. I can't keep the pieces on the lathe. Here is my process.
I cut the blank to round in my bandsaw. I drill a hole and thread the little threaded mandrel thingy in. This is where my problems start. I have a 12" lathe but I can only put about a 8" blank in cause there isn't room for my toolrest after I bring my tail support up to the blank. I made an extended rod to help hold the tail from an old pen mandrel but this is far from ideal. IF I can get this setup to hold together long enough to make my tennon I then turn the blank around and attempt to do all the turning with the blank clamped by the tennon. BUT here is my major problem....I can't keep the tennon clamped in the jaws. I've tried 2 different sets of jaws and my head and arm are rather bruised. Sometimes it just pops out..others the tennon breaks off in the jaws. I'm trying to make my tennons nice and square about 5/16-3/8 deep. Any and all suggestions be greatly appreciated.

[Gordon Seto]

John,


See whether this helps?
http://www.youtube.com/watch?v=uqPuDFtz_-Y

"Turned bowl made easy" by Bill Grumbine is a very good bowl turning 101 DVD.

Join a Club to get some hands-on help.
AAW Local Chapter Listing - The American Association of Woodturners (http://www.woodturner.org/community/chapters/members.pl?submit=Chapter+List)

Gordon

[Steve Schlumpf]

I agree with Gordon but also suggest you get ahold of Pete Jordan and have him go through the process with you.

[Allen Neighbors]

John, what chuck are you using to clamp the tenon? Which Jaws do you have? Are you saying that your tailstock won't advance enough to reach across the Toolrest Mount? What is the little "Mandrel" thingy you mentioned. If it's one of those Screw Chuck/Drive things, it's close to worthless in Green Wood.
For bowls, I mount my green wood using either a faceplate, or a faceplate ring for my SuperNova2 Chuck. Then I shape the outside, and form the tenon. Then I turn the piece around, mount the tenon in the chuck and hollow the inside.
You don't want to form a tenon in the bark or sapwood. And you don't want the tenon to be on a piece that can separate along a grain line. When you form the tenon don't make it so long that it touches the bottom of your jaws. The outside lip of your jaws should rest against the outside of the tenon, against the bottom of the bowl, where the tenon joins the bowl. Once you clamp onto the tenon, you do need to bring up the tailstock at least until you get the some of the hollowing done on a bowl. The green wood is a lot heavier than dry wood, and any out of balance will be more harmful to the tenon on green wood.
Don't know much more to tell you, just now. Might be able to give better advice if I knew the answers to the above questions. Another turner could probably help you out if there's one that lives close.
I can sense your frustration right now... but it's probably not too hard to solve... just have to find the right equation. Once you do, you'll be flyin'. :)

[Ben Gastfriend]

I'll add a piece of novice advice here:


Make sure where your tenon meets the bowl is a perfect square corner (a "shoulder"). Remember- the chuck doesn't just clamp onto the tenon, it clamps onto the tenon and rests on that square corner when the tailstock is brought up. And be sure the tenon doesn't "bottom out" in the chuck. It doesn't need to be very long at all.

[Ron Erickson]

Turning green wood is fun, but to really help you some picture of your set up would help. Ron

[John Fricke]

I have a nova 4 jaw (not sure of model). I have used the serrated jaws and the ones with a ridge along the outer lip. If I attempt to turn a larger bowl that doesn't allow the tool rest holder to sit under the bowl I cannot advance the tailstock to the bowl. I wil get some pics today. I was using the screw you were talking about. I will try a faceplate today. I'm convinced that my inability to solve my tailstock issue is a major contributor to my problems.

[Dale Gregory]

John, if the tool rest base is getting in your way, or you are using a larger diameter piece of wood that would contact the tool rest base, move it to the extreme right or left sides when mounting the blank. Then move it as necessary as you begin to shape the bowl and remove wood. It's kind of a pain to do, but it will allow you to turn the pieces the full swing of your lathe.

Dale

[Reed Gray]

The depth of your tenon sounds about right, how wide is it? For an 8 inch bowl, you need a tenon of at least 3 inches wide. Other wise because of leverage, there isn't enough wood, and it will fail, especially if you have a catch. You can also over tighten. Get it good and snug, but not as tight as you possibly can. Another thing, is grain orientation. You have end grain on 2 sides of the tenon, and flat or side grain on the other 2 sides. You don't want the chuck jaws to be clamped on the end and side grain. Rotate it about 45 degrees and clamp. End grain compresse differently than side grain, and if you rotate your blank, this will help a lot.
robo hippy

[Richard A. Rivera, M.D.]

John, I also have the Nove chuck and use the worm screw to turn green bowls. All the advise above great, but I might add that you use a drill bit about 1/16 smaller to drill the guide hole than the one you use when using the screw on dry wood, also make sure that you are in the sap or heart wood and not in the bark. I will sometimes use a 2 1/2 in Forster type bit on the bark to give a good flat area for the screw to bring the blank in tight against the front of the jaws.

Try to keep the banjo between the headstock and your blank or between the blank and your tail stock and angle the tool rest to get maximim blank diameter and as said above, adjust s you go.

Turning green wood is a lot of fun...especially when he ribbons of wood go flying over your shoulder. don't give it up yet.

Dr, R.

[Hal Taylor]

I've not seen this in the responses, but I use the tailstock whenever possible, even when using a chuck. Also, to begin initial shaping and forming a tenon, I always do it between centers, that is, using a spur in the headstock and of course the tailstock. I find this faster and easier than using a faceplate.

I don't use the screw chuck except for turning platters or plates - items which are fairly thin to start with. I think you are asking for trouble (I guess you know what I mean) trying to use a screw chuck on something long and heavy and especially in endgrain.

[Jim Becker]

Put the whole blank between centers...you don't need the "worm" screw if it's not working for you. What you do need is for the blank to be held securely while you true it and put your tenon on. Use a drive center in the spindle and a live center in the tailstock. Put your intended "bottom" of the piece toward your tailstock and use pull cuts (assuming you have a side-grind gouge) to define the piece's bottom and rough the tenon area. You can use your parting tool to true and finalize the tenon and don't forget to leave a shoulder for the top of your chuck jaws to rest on. This is critical! And your tenon should never bottom out in the chuck, too.

Worm Screw chucks are quite useful because you can leave your chuck on the lathe, but you still need to use a live center in the tailstock...the screw chuck will hold the piece "on center", but it will not keep it on the lathe if you have any kind of catch. That's what the tailstock is for. The bottom of your tenon doesn't have to be pretty as you'll remove it later, so having the live center in place doesn't matter.

[Reed Gray]

For me, rather than a face plate or turning between centers, I use a forstner bit to drill a recess on the top of the bowl/platter blank, then use the chuck to expand into that. I turn the outside, and a recess, then reverse, core, and finish turn the inside. No screws, no screw center, just the chuck in the same position, and it never comes off the lathe. I also don't use the tailstock. This did take some experimenting to find out what it takes to get a good grip on the blank. If you try this method, take it easy until you learn what works for you. Don't try this method, or any other by turning at full speed. A 3/8 inch deep recess, for turning the bottom (the sides are straight because a drill bit won't cut a dove tail shape), and minimum 1/8 deep for the recess on the bottom, just like you use for the tenon (1/4 inch deep for 18 inch bowls). The last thing you want to happen is for your blank to come off while you are turning, because of a catch, or any other reason. You can use the tailstock for security purposes.
robo hippy

[Richard A. Rivera, M.D.]

John,
In my response above, I want to clear up some things.
I use the screw bit that fits into my SuperNova2 and ALWAYS use the tailstock. I have a large cone live center and use it when ever possible. I shape and balance the blank between the centers as much as possible before I cut the tenon, and everyone above is right, the tenon should not bottom out on your chuck and the shoulders shoud be true.
Once I have the tenon turned, I just open the chuck, unscrew the worm and but the now turned tenon back into the chuck and keep turning. I still keep it beteen the centers for as long as I can, and the large cone live tailstoock lets me get a start on the hollowing out of the bowl untill the weight is down and the blank in good balance and I can then increase the speed of the lathe.

I am new to the Vortex...just joined the other night, although I have been circling the edge for a while before I decied to jump in...thanks for all the past advice.

don't give up yet...Dr.R.

[John Fricke]

I've been trying your suggestions. Mounting directly to the face plate worked well as did drilling a hole with a forstner bit. Still having problems holding onto a tennon. I've finally got some pics to show my setup.

http://i263.photobucket.com/albums/ii128/roadymi/DSCN0032.jpg

This wide gap I feel is what causes me problems

http://i263.photobucket.com/albums/ii128/roadymi/DSCN0033.jpg

Not enough clearance to advance the tailstock

http://i263.photobucket.com/albums/ii128/roadymi/DSCN0031.jpg

I've somewhat solved this by tapering the edge of the blank on the bandsaw.

[John Fricke]

This is the bowl I had chucked in the lathe on previous post, rough turned and ready to soal in DNA

http://i263.photobucket.com/albums/ii128/roadymi/DSCN0034-1.jpg

Same bowl top view

http://i263.photobucket.com/albums/ii128/roadymi/DSCN0035-1.jpg

Rest of my meager collection soaked and in drying process

http://i263.photobucket.com/albums/ii128/roadymi/DSCN0036.jpg

Thanks for all of your help

[Maylon Harvey]

John,
Please don't take this wrong, just don't want to see you get hurt but I couldn't hep but notice your "T" handle wrench still in your chuck. This is not a good practice as any machinist will tell you. If you forget it is there and turn on the lathe it's going to go flying. Don' ask me how I know that.

[Reed Gray]

John,
In the bowl at the top here, it is end grain oriented, which means you are cutting down into the center of the tree. This isn't normal orientation, and is harder to cut. Most of the time, you would cut a length of log in half up and down the tree, then the center of the tree becomes the top of the bowl, and the outside of the tree becomes the bottom. With end grain orientation, when turning the outside, you work your way from the rim of the bowl to the base. On the inside, you start in the center, and work your way up to the rim. This is just the opposite of regular or face grain turning. Your tenon is close to proper size, but could be bigger. Also having a bigger set of jaws would get you a better grip. If your jaws close to 2 inches, then you want a tenot that is about 2 1/4 inches. If you have a 4 inch tenon, then only the points of the jaws are in contact with the wood so you don't get a good grip. Another thing, you have the pith or center of the log in the bowl. They will almost always crack off of the pith, if it isn't already cracked to begin with. It can be done, but usually takes super glue and saw dust to fill the cracks. I would recomend finding the closest club. The best learning experiences I have had in my 10 years of turning. If no club is close enough, then get some DVDs, in particular, Bill Grumbines first DVD. You can look him up. That will answer a lot or questions.

robo hippy

[Kevin Cole]

My lathe is similar to yours and the live center should be able to extend 1 1/2"-2" out this might give you more room for you tool rest to maneuver.

[John Fricke]

Reed...I totally understand what you are saying. I have done it as you described on all of my other attempts. Fot this bowl I wanted to try one larger and deeper than the wood I had on hand would allow for cross cutting. I did cut the log at about 30 degree angle to make my blank, not sure if this will make a difference.

Kevin....My tailstock was modified and welded on before I got it. It doesn't have any adjustment.

Thanks again for all of the advice