Beginner turner becoming frustrated by bowls

[hu lowery]

Matt,

Here is an hour and a half video on holding wood on a lathe. Using a chuck starts at about the one hour mark but I seem to remember the whole video being worth watching. Been a few years.

One thing that hasn't got much attention is your choice of woods. Some woods are much more inclined to crack and split so just spinning them can be enough to break them. If possible start with plain wood that isn't prone to splitting.

I have used tenons and recesses and don't have a real strong preference. Either will work fine cut properly, either one can cause trouble if they aren't cut properly. Another issue is overtightening the chuck. You may be damaging the wood before you even start trying to hollow.

I did about the same as you sounds like, I broke a lot of blanks off of my lathe when I started out. A combination of a very poor choice of wood and pretty much all the errors you can make chucking. I notice that you are breaking the wood off of the lathe hollowing which usually has you outside the primary line of fire but it is dangerous anytime you have the wood making an unplanned departure from the lathe. Do your homework and very possibly modify the way you are hollowing. A major catch can cause a trainwreck with a perfectly secured bowl.

Sometimes we have to back off and do some homework instead of plunging blindly ahead on the lathe like I did for awhile. I think you are finding out the same thing, therefore this thread. Take some time to regroup, read, and watch video. Wood turning is fairly safe going about it correctly, pretty dangerous when we blunder into it like I did.

Hu

https://www.youtube.com/watch?v=aUXil-5dEeo

[Ron Rutter]

Matt. It is easy to over tighten the geared scroll chuck. You are applying a lot more pressure than you think!! I use both methods, BUT always use the tailstock as long as I can to support the work. As mentioned keep more meat outside the recess. If the comment about length of tenon was confusing it just means it should shoulder on the end of the jaws not the bottom. Ron.

[Reed Gray]

Matt, maybe this will help a bit:

https://www.youtube.com/watch?v=5KHkkws9lWA

I haven't been able to determine any advantage to either method of mounting a bowl blank. I went through a learning curve where a lot of pieces came off the lathe and chuck. Almost never now. Both tenon and recess work excellently, IF THEY ARE MADE CORRECTLY. I do have a bunch of other clips geared mostly to bowl turning.

robo hippy

[Brian Kent]

After watching the Reed Gray video, I have switched to recesses in most of my bowl turning. I always make sure there is plenty of wood on each side of the recess and that the wood is not cracked. I have a 2-1/8" Forstner bit, which perfectly fits the jaws of my chuck. I drill into what I want to be the open top of the bowl. Then I used the caliper to mark a 2-1/8" circle and form the recess on what will be the bottom of the bowl. I have made 60 bowls and plates this way over the summer with no failures. It is the fastest method for me.

[Reed Gray]

Russell,
This is an argument that I haven't been able to understand. The wood is under compression either way. It makes no difference to the wood if the metal is pushing out from the inside (recess) or in from the outside (tenon). Wood is compressed either way.

robo hippy

[Mark Greenbaum]

My limited experiences with recesses and jaws, you need more wood outside of the jaws to support the force of the jaws. Yes, it compresses the wood, but a normal tenon has beef . I've had one small bowl fly off and it was because the rim of what was going to be the foot of the bowl gave way - too much expansion on my part, and too much cutting force trying to pry it away. My 2 cents.

[robert baccus]

If you are using a chuck with dovetail lips, in or out, it helps to contour your recess or tenon to match.

[Lance Mirrer]

All good suggestions regarding either tenon or recess. Both will work, or both will fail, depending on how well they are done.

Second is the sharpness and presentation of tools, and the depth of cut (amount you are taking off).

With the tenon/or recess, they should be tailored to the shape of your chuck, usually straight or dovetail. If watching videos, note the depth & diameter of the recess to get a better grip. Be sure you achieve 90 degree hole for straight chuck. If your recess/tenon are cone shaped, tightening the chuck pushes the bowl away instead of closer.

Is the bowl coming off due to a catch? if so that will speak to the lighter cuts, sharper tools thought.

Last, for as long as possible leave the tailstock in place while hollowing. On small bowls, it's easier to hollow from center. But, if you're having issues, the tailstock can help hold until the bowl is lighter.

Let us know what works!!! if you're still having issues, be more specific when & why the bowls fly so we can be more direct.

Good Luck & keep having fun!

Leo, great advice, but why is the trailer only half full???

[David Delo]

Matt,

If you care to take the time to view the videos, Stuart Batty has some excellent videos with detailed explanations about tenons/recesses. There's 30+ videos listed, just scroll through the titles. Several of them have information you are asking about. Here's the link. https://vimeo.com/woodturning/videos...rmat:thumbnail

[Michael Mills]

1+ on the link above to Stuart Batty's videos; extremely clear and well presented. I believe there are three on chucks, recesses, and tenons.

I typically use a recess but in your case I would use a tenon. My chucks are Nova and they suggest 1" of wood surrounding a recess.
With 50mm jaws your base would be 4" on a 6" bowl. It could be trimmed down on the final cleanup but that is a lot of cleanup; this assumes you would want a base of about 2" or 1/3 the diameter.
My guess with your problem is a combo of not enough wood surrounding the recess and over tightening.

[Eric Schatz]

Check this out. https://www.youtube.com/watch?v=ybQl3WwLnpU

[Mike Goetzke]

When I started turning about a year ago I wanted to make a bowl and kept getting catches. Getting so frustrated I was thinking "this must not be for me." Then I thought many people turn bowls must be something basic. In my case it ended up that I had a terrible grind profile on my gouge. Helpful members here steered me in the right direction and the hobby has not only become enjoyable but addictive.

Good Luck,

Mike

[Russell Neyman]

Dick Raffin pretty much sums it up here.

http://www.finewoodworking.com/woodt...-and-jaws.aspx

[Russell Neyman]

Russell,
This is an argument that I haven't been able to understand. The wood is under compression either way. It makes no difference to the wood if the metal is pushing out from the inside (recess) or in from the outside (tenon). Wood is compressed either way.

robo hippy

Well, Reed, if the jaws are expanding, potentially pushing the grain apart, that wouldn't be compression, would it? Perhaps it's just a matter of semantics.

When I have a questionable piece in my lathe and I've shaped it, I sometimes put 5-6 layers of stretch wrap on the outside to hold it together when I turn it around to turn the inside. In my world, that process of holding the darn thing together is compressing the grains.

[Dave Mount]

To the OP: Lots of good information on tenons, but I would equally emphasis having sharp tools as a few posters mention. Failure of most any type of hold is because the force exerted by the tool exceeds the resistance of the weakest link in your hold. Sharper tools impart less resistance (all other things being equal). Catches are situations where sudden and extreme loads are applied, but just a heavy cut with a dull tool puts a lot of stress on a bowl, and the orientation of that stress is constantly shifting as the bowl's orientation shifts from side grain to end grain.

Regarding compression -- IMHO, the way to think about compression is whether the failure results from the wood crushing. When recess holds fail, it's not generally because wood was crushed, it's because of shearing or cracking along the lines of wood fibers. Yes, one could argue that the wood immediately in contact with the jaws is being compressed, but center of the bowl is in tension because the jaws are pulling it apart -- if you overtighten a chuck in a recess, what happens? Either the rim of the recess shears off, or the center of the bowl splits.

Best,

Dave