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As The Lathe Turns #38: How NOT To Turn A Bowl

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Blog entry by William posted 06-27-2013 12:01 AM 1344 reads 1 time favorited 14 comments Add to Favorites Watch
« Part 37: Solving Some Problems Part 38 of As The Lathe Turns series Part 39: Time To Back Up A Bit »


In the last entry, I had left the first bowl to ever be pressed in the bowl pressed drying for today. Well I unclamped it today and am glad to report that the press applied plenty enough pressure and I am very happy with it.

So I went to chucking it up on the lathe and went at it. I love turning bowls. You may notice it is a little shorter than what was shown clamped up in the press yesterday. I turned about an inch off the top when I messed up. That’s one of the luxuries of turning bowls. If you make too big a mistake, you don’t ruin the top part of the bowl. You just wind up with a shorter bowl.
I was happy with the way things were going. With the new bowl thickness calipers, I was able to get a more accurate measurement of the side walls and was much more comfortable about going thinner than I have in the past. Maybe I was a little too comfortable. If you read the title of this entry, you already know that a huge mistake is about to be told.

As I was getting near the bottom, I slipped with the gouge and made a nasty tear out section in the bottom of the bowl. So with some careful measuring, I figure I could go at least another sixteenth to an eighth inch deeper with no problems. I started doing that and quickly realized maybe that a sixteenth of an inch was about a sixteenth of an inch too much.
You see, when I thought back to see where I made the mistake at, I realized something. I did have enough material to go deeper about an inch and a half from the side where I measured at. However, since I, for some odd reason, like to cut a concave profile on the bottom of my bowls so they are sure to sit flat on a table, that meant I had less material than that closer to the center. Apparently, I had less than a sixteenth of an inch.
This is what happens when you turn clean through the bottom of a bowl. This is how NOT to turn a bowl. It doesn’t hold things too well with a large hole in the bottom.

.

I also ran into another problem today. Well actually it is an ongoing problem that I am constantly learning to deal with. My lathe is actually underpowered for turning a bowl this large. It doesn’t matter how light I make my passes, the lathe is under a stain turning this kind of mass. I feel there has to be a way around this problem, since there is no way I’ll be able to afford a more substantial lathe anytime in the foreseeable future. So I am, as I’m able, working on a few ideas on that front. I am determined to be able to turn bowls.
I changed the grind on my gouge today to a steeper angle. That seemed to help a tiny bit, but I also plan on trying a ring, or hook cutter, sometimes in the future.
I’m also playing with speed on my lathe. It turned smoother at high speeds, but also seems to bog down easier. So I’m thinking of turning slower until the final passes to clean up rough areas.
I’m also thinking of ways to take some of the work load off of the lathe. If I remove the middle of the rings I glue up for blanks, that would eliminate the need for the lathe to have to turn that much weight in the beginning while I’m roughing everything out. This still would not help me if I’m turning a bowl from a fallen tree though. So that one is still a concept in the works.
I’ve done some research. The best answer would be to get a larger lathe with more horsepower that can handle that kind of mass. The thing is, when I look at the prices of such lathes, all I can think of is the fact that my kids need something called food more than I need a bigger lathe. So I don’t see that happening.
So where does all this lead? Well, in the past, I’ve built my own tools when I couldn’t afford large enough to do what I needed to do. It’ll take some time. I’ve been looking for parts. The largest obstacle will be finding a large enough motor. I do see sometime in the future though that I want to build a heavier duty lathe than my wallet would ever allow me to purchase from a name brand supplier.
One day.

-- http://wddsrfinewoodworks.blogspot.com/



14 comments so far

View Nate Meadows's profile

Nate Meadows

1077 posts in 950 days


#1 posted 06-27-2013 12:20 AM

I really do like your bowl glueing jig! That is a bummer about the bottom of your bowl. But, at least you can save it. Cut a bit of and glue a new section on, then take it back to the lathe. I am also sorry to hear about your new lathe bogging down. That is frustrating. Seems like you cannot catch a break, between bent spindles and weak motors. But at least you are not letting it get you down! That is inspiring and awesome! Keep it up!!!!

Nate

-- "With a little bit of faith, and some imagination, you can build anything!" Nate

View DIYaholic's profile

DIYaholic

14494 posts in 1419 days


#2 posted 06-27-2013 12:26 AM

William,
I don’t see no problem with that funnel!!! ;^)

Could you glue on another ring and have another go at it???
edit: Nate beat me to it!!!

Bigger is (almost) always better!!!

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View William's profile

William

9263 posts in 1586 days


#3 posted 06-27-2013 12:52 AM

I have fixed this exact same problem before by gluing a plug in. Unfortunately, since this one became too thin over the entire bottom, I think I’m going to leave it alone. Besides, I’ve already given it to the kids. They wanted it for something they’re creating for their marbles. So the bowl may be more valuable to their creativity than it ever would be to me as a bowl.

Nate, I will eventually figure out something. I was thinking today that I actually love this particulat lathe if the motor was just more powerful. So, after the warranty is gone on it, and if the motor bites the dust then, it would be a good donor for a larger motor.
That brings me to Randy’s comment about bigger is better. I’m glad you included almost, because that plays right into what I want to say.
Another issue with getting another lathe, if I could afford one, is what would I be getting? I’ve learned that, even if I could afford to go out and buy some high priced fancy lathe, it doesn’t always mean you’re getting anything better than what is already sitting on the shop floor. The only way I’d shell out big money for another lathe, if I had it, would be if I could find a great older lathe with a proven track record. These days you’re just about always better off building up yourself than you are wasting money on something new. You just never know what you’re going to get.

-- http://wddsrfinewoodworks.blogspot.com/

View clieb91's profile

clieb91

3306 posts in 2679 days


#4 posted 06-27-2013 02:06 AM

William, Glad to hear the kids have a use for the bowl. Looks like the press works really well.
As to the lathe, I hear what you are saying about getting more or not? My lathe is pretty old but I got it at a good price. It can handle everything I have thrown at it so far and even though my wife is interested in turning a couple of bowls I do not see us doing anything huge. Even though the guys at Woodcraft needle me about the #1 Morris Taper and when I am going to upgrade the cost is too much. Plus as you mentioned for that cost you are still not really sure if you are going to get a good quality tool these days.

Look forward to seeing some of your future solutions.

CtL

-- Chris L. "Don't Dream it, Be it."- PortablePastimes.com (Purveyors of Portable Fun and Fidgets)

View William's profile

William

9263 posts in 1586 days


#5 posted 06-27-2013 02:38 AM

It may be a while Chris. I have to wait till I can find everything.
I’ve been looking online tonight though at some home made lathes. It seems very doable to make a decent lathe yourself. The biggest hurdle is going to be a motor. From what I’m reading, I need at least a two horsepower. I have a 220 outlet near where the current lathe resides. So that won’t be a problem. New motors that strong aren’t cheap though. I’ll have to keep my eyes peeled for a good used one.

-- http://wddsrfinewoodworks.blogspot.com/

View gfadvm's profile

gfadvm

11478 posts in 1434 days


#6 posted 06-27-2013 03:10 AM

Now if you could just rig a flywheel on the Blazer like the old John Deere’s had. 400 HP lathe!

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View William's profile

William

9263 posts in 1586 days


#7 posted 06-27-2013 03:37 AM

I think you’re joking Andy, but less than an hour ago I read an article about turning a bowl that was over eight feet in diameter. They rigged a chuck to the axle of a chevy rearend. That was driven through a gearbox that was chain driven from a tractor PTO.
Now, in all seriousness about my own situation. I keep talking about the motor I need, but I haven’t said anything at all about how I’m going to transfer the power of said motor to a spindle shaft. I’m thinking of using a Ford transmission I have tucked away at the back of the shop. This will give me extra torque for large heavy bowls. Also, it’ll add even more mass to the contraption to keep it stable.
Of course, all this is purely speculation at this point, but I have been putting some thought into this. It may be a year or two before I can have everything together, but I will eventually build a lathe that’ll handle anything I could possibly throw at it.

-- http://wddsrfinewoodworks.blogspot.com/

View Jamie Speirs's profile

Jamie Speirs

4163 posts in 1600 days


#8 posted 06-27-2013 08:35 AM

William that is a first class lamp shade :)

Jamie

-- Who is the happiest of men? He who values the merits of others, and in their pleasure takes joy, even as though 'twere his own. --Johann Wolfgang von Goethe

View stefang's profile

stefang

13623 posts in 2078 days


#9 posted 06-27-2013 09:43 AM

The press looks great and it sure did the job. As for turning through the bottom, you can avoid that by drilling a hole in the the center of your workpiece after you get it rounded and squared up at the ends. Just measure the depth you want and use a piece of tape on a long drill bit to mark the depth (I use the kind of drill bit designed for electricians that is about 5/8” diam. and 15” or so long. I use a vise grip as a handle and I just drill to depth using the slowest speed on the lathe, and I pull the bit out as I go to clear the swarf to avoid freezing the bit in the hole. When your hole disappears you are at the correct depth.

-- Mike, an American living in Norway.

View William's profile

William

9263 posts in 1586 days


#10 posted 06-27-2013 12:42 PM

Thqanks Jamie. I’ll go with that story next time.

Mike, thanks. I have used the hole method a couple of times in the past. I have a drill bit made up with a handle on it just for that purpose. I thought I could do it with my new measuring tools this time. I guess the drill bit is still a better option in this case though.

-- http://wddsrfinewoodworks.blogspot.com/

View Roger's profile

Roger

15261 posts in 1548 days


#11 posted 06-27-2013 02:01 PM

I’m thinkin, funnel. :) You could just glue a new bottom in it…?

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View William's profile

William

9263 posts in 1586 days


#12 posted 06-27-2013 10:36 PM

Thanks Roger, but the kids have it now.

The kids told me it was supposed to be part of a marble contraption. While going up in front of the shop for coffee today though, I noticed it on the floor. They have sawed a square out of the side of it, turned it upside down, and are using it as a Hot Wheel garage. Hey, at least they got some use out of it.

-- http://wddsrfinewoodworks.blogspot.com/

View lew's profile

lew

10151 posts in 2499 days


#13 posted 06-30-2013 12:47 AM

William,
I think we all have days like this, at least I know I do.
About that bottom, an LJ buddy of mine, Darryl, has a neat way to do the bottom of a vessel. Here’s a link to one of his projects. The last comment explains a little about what he does- http://lumberjocks.com/projects/70070

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View William's profile

William

9263 posts in 1586 days


#14 posted 06-30-2013 01:30 AM

Thanks Lew. I’ll be sure to check it out. As you know, it’ll be no surprise if this happens again.

-- http://wddsrfinewoodworks.blogspot.com/

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