Struggling getting started w/ Bowls
#11
  
I'm struggling getting started turning bowls.

I've tried turning green wood into rough blanks.  Within a week they are all cracked horribly. 

I've tried gluing up boards into a solid block to turn a bowl.  It works to some extent, but I can't get a clean surface, and I can't seem to get the thickness of the bowl down thin enough, the bowls I have made are more shallow and thick walled.  When I try to go thin I get bad things happening, vibration and catches, such that I'm afraid the chuck won't hold.

I've tried glueing together plywood like I see on youtube just to try to turn a bowl.  Things were going find but when I got to hollowing the bowl, again the vibration was so bad the mortise blew out on the bottom and the bowl went across the shop...


If this is relevant, my equipment is a jet 14-42 lathe, I currently use a grinder with norton stones and wolverine jig to sharpen.  I "think" i'm getting the tools "sharp".  I have a standard set of tools that are HSS, and I have a square carbide cutter tool, have a oneway talon chuck.  

I know the problem is with my technique, and workholding methods, and possibly sharpening.  I am self taught, obviously not very well, through various youtube video's.

I can turn spindles fine and have made dozens of socket chisel handles and such.  

But I want to turn bowls.  What do I need to do, what will make the biggest difference to get me started successfully?
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#12
  Re: Struggling getting started w/ Bowls by Strokes77 (I'm struggling getti...)
For drying green wood, how thin are you turning the walls? and how are you drying them? uniform thickness and a thicker wall is better, although they will dry more slowly. I don't turn green to any less than 1", even on smaller bowls. What kind of wood are you using, and are you getting rid of the heartwood? Some wood is more prone to checks than others. There are lots of methods that are used to dry green bowls. I've had the most success with putting the green bowl in a paper bag, covering it with the shavings I just took off it and waiting about 6 months with the bowl stored in a cool dry place.


For hollowing the bowl, you may be getting vibration because you are turning the wall too thin too soon. I turn the outside to round and to the finished shape. For the inside, I start at the rim, I turn the first 1" or so down to where I want it. Then I turn the next 1" or so down. I step it down until I get to the bottom of the bowl. This way there's still mass to support the thin rim.
Janus was a disaster, coming or going - K. L, McReynolds 07/01/2015

My blog: http://wcwoodworking.blogspot.com/
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#13
  Re: Struggling getting started w/ Bowls by Strokes77 (I'm struggling getti...)
Do you have a bowl gouge? Diiferent angle and shape than a regular gouge. Just a question, because you didn't list what tools you have. A bowl gouge is not usually included if you bought a set. I also use the same lath as you. Works great. It certainly is not the lathe I would really like, but at the price I paid about 10 years ago it has served well.
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#14
  Re: Struggling getting started w/ Bowls by Strokes77 (I'm struggling getti...)
(12-20-2018, 01:29 PM)Strokes77 Wrote: I'm struggling getting started turning bowls.

I've tried turning green wood into rough blanks.  Within a week they are all cracked horribly. 
Well, let's start there.  Best advice is not to have the walls vertical, but angle or curve them in toward the mount at the base to redirect drying stress.  The long grain walls on a heart up cut will drop as they dry, and the short grain ends will be subjected to differential mechanical stress by the shrinkage of the spring wood.  By tapering or rounding you split the stress, shortening the shrinkable by tapering the design.  
Uniform thickness is nothing you need worry about, as long as contour properly.  Cut the walls ~3/4" thick, bottom can be heavier, especially if your design wants to use its weight rather than breadth to stabilize the final bowl.  At that thickness,  it takes about six-eight weeks to EMC in my basement at ~50RH.  I set on the concrete for the first ten days or so, then move up into the 50%.  You'll lose some diameter from the droop, but that's ok.  

   

I'm a coward, so I start, and try to keep the bowl between centers for as long as possible.  I use a pin chuck or pin jaws and the tailstock, and leave a pillar inside so after drying I can remount on the same centers.  Then I use the length of my arms and the tool to keep my body out of the zone of thrown water and perhaps undiscovered loose parts of the turning.  Pillar parts out when the turning is at best balance and lightest weight. 

   

   

   

As to gouges, helps to have a deep flute type to plunge in hollowing.  Matters not outside, of course.  Keep the toolrest tight up, cut above center outside, below inside, and ALWAYS downhill to eliminate the chatter and rattle you mention.  Means from bottom to rim when turning the outside (tail to head), and rim to bottom when inside. For shaving the final piece, I recommend broad sweep gouges, as they have long sweet spots which can take a tapered shaving, leaving nothing but slick.
Better to follow the leader than the pack. Less to step in.
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#15
  Re: Struggling getting started w/ Bowls by Strokes77 (I'm struggling getti...)
Alot to digest in these posts already.

I did recently learn that I have a bowl gouge. I didn't know there was a difference between spindle and bowl gouges.  I bought the lathe and tooling as a package deal used.  So I didn't know what was what.

Recently I have been using the right tool.  I can also admit, that while I was using the bowl gouge, I wasn't using it correctly, I was using it as a "scraper" I guess, as I heard that mentioned in a video I watched, and he was using it how I had been.  I'm trying to learn more about how to "ride the bevel", which I believe is the appropriate way to use the bowl gouge.

I have been using bradford pear.  Cut down from the side of the road.  The first 2 bowls I tried, I didn't know to remove the pith.  The last couple I did.  One I turned too thin I guess, it cracked instantly.  One cracked, but has since closed back up?  

I tell ya, I'm not usually a slow learner, but this is getting the best of me so far.

Next time I go out I'm going to take this post with me to make sure I'm hitting all these points correctly.
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#16
  Re: Struggling getting started w/ Bowls by Strokes77 (I'm struggling getti...)
Is there a turning club in your area? Get connected with a club and I'm sure there will be members happy to mentor you in a hands-on fashion.
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#17
  Re: RE: Struggling getting started w/ Bowls by Strokes77 (Alot to digest in th...)
(12-20-2018, 07:59 PM)Strokes77 Wrote: Recently I have been using the right tool.  I can also admit, that while I was using the bowl gouge, I wasn't using it correctly, I was using it as a "scraper" I guess, as I heard that mentioned in a video I watched, and he was using it how I had been.  I'm trying to learn more about how to "ride the bevel", which I believe is the appropriate way to use the bowl gouge.

I have been using bradford pear.  Cut down from the side of the road.  The first 2 bowls I tried, I didn't know to remove the pith.  The last couple I did.  One I turned too thin I guess, it cracked instantly.  One cracked, but has since closed back up?  


Couple thoughts.  "Riding the bevel" makes things rattle.  If it's not cutting, it's traversing the annual rings soft/hard/soft and as the soft depresses, the hard won't, so you get a rocky road as the wood squirms to adjust.  You have to have a clearance angle to avoid this phenomenon.  Granted, lower pitch angles allow shavings to flow rather than packing pulp, as scraping angles do (especially on wet wood), but don't go too low, or you'll be bumping and burnishing.  Good info on edge and wedge action here: http://homepages.sover.net/~nichael/nlc-.../caop.html  Terminology is as close as we get to universal when communicating what happens when an edge is applied to wood.

Second thought comes from the word "pith" in your post.  I assumed, as is obvious from the photos, that you were turning face, not long grain bowls.  If turning long grain, again the taper helps redirect the mechanical stresses imposed as the wood dries, but you want to set the piece aside to cure so the bottom, which should be thinner than is required on a face grain piece, will dry from both sides more or less equally.  When you put the heart in the piece, heart checks you may not even see may open regardless.  As you've noticed, they are closed when the wet fiber is expanded, so the way I work is to wet the end and see if the water is drawn into cracks which, though invisible to my eye, still draw by capillary action, revealing their presence.  Time to turn thin to win when they are there, and forget final circularity.
Better to follow the leader than the pack. Less to step in.
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#18
  Re: Struggling getting started w/ Bowls by Strokes77 (I'm struggling getti...)
Just a word on the cracking. For green bowls you want to rough turn the bowl and leave the wall thickness around 1 inch and the let the bowl dry. It could take up to a year or more.
Don
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#19
  Re: RE: Struggling getting started w/ Bowls by DFJarvie (Just a word on the c...)
(12-21-2018, 10:47 AM)DFJarvie Wrote: Just a word on the cracking. For green bowls you want to rough turn the bowl and leave the wall thickness around 1 inch and the let the bowl dry. It could take up to a year or more.

At least 2 of the rough bowls I turned, I got thinner than 1"... One got down to 1/2 probably and another 3/4.  

So that is definitely one of my mistakes confirmed.

I'm still processing all of this, and going to get back out in the shop this weekend.

I appreciate everyone's help.
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#20
  Re: Struggling getting started w/ Bowls by Strokes77 (I'm struggling getti...)
Cracking will be more pronounced if the wall thickness is not the same from lip to bottom also, whether thin or thick, if you turn the bottom to 1"+ and the wall near the rim to 1/2-3/4" you'll have issues also.

Might be worth grabbing some DVD's if you don't have a local club, but the value of in person demonstration / instruction is unmatched imo especially early on in turning.

Michael
Every day find time to appreciate life. It is far too short and 'things' happen. 
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