Wood Lath Question

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What makes a lath "good" or "bad" ?? This looks like a pretty straight forward tool to me, meaning there are not a lot of adjustable compound angles like a table saw or jointer. Is it just the tolerances that the bed and spindle heads are held to in manufacturing ? The design of the tools looks like they are all clones. I am pretty sure I am missing something but I don't know what. Are there specifically a class of tool or specific tools to avoid. Like many tools the prices vary from a table top model at < 200 to as much as the budget can bear. If I had one it would mostly keep the other tools in the garage company, but like all tools when you need it it is the one you need. I would like to hear from the wood turning crowd on this.
Thanks, Charlie
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I just finished a wood lathe course. The guy had ten machines. Variable speed is better than changing the belt on the pulleys. He had General, Delta, Mastercraft. To me, the General was best. Mind you, all were older machines, but I felt that given the Generals were around a long time and still going strong that's the one I'd opt for. The instructor said the small (midi??) lathes were ok but if you were serious about wood turning the bigger one is the way to go.
Now - a few days ago my neighbour, who teaches industrial arts, had a lathe in the back of his truck. Turns out he was bringing it from one school to another..Anyway, I asked him about it. It was a Rockwell-Delta and sold for about $3,500. He said it was an "Industrial quality lathe" and from his experience, if he had the moola would buy no other. Oh yes - It was variable speed.
Salmo
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Charlie H. wrote:

First off, a lath is a piece of wood.
A lathe is a machine.
Someone who doesn't know the difference shouldn't be using either.
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To "Gus"...
Picky - picky - picky....???
If your comment was meant to be funny, then it's ok. If it wasn't, then read my answer and you will see that it was correctly spelled lathe, as it was meant it to be in the post title. Spell-check doesn't pick up the difference if the word is spelled correctly, no matter what was implied.
Salmo
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Take a chill pill Sal,
He's picking on the OP.

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Stephen M proclaimed:
<<It's "LATHE" BTW.
I assume your question boils down to why should I spend more for a "better" lathe and what will I get for my money?
Try posting to Rec.woodturning for more. >>
I am sure he appreciated your spelling lesson. Let he without typos post critical remarks.
"Rec.woodturning". An unusual spelling there, too. I am unaware of the significance of the capital "R". Maybe you could explain.
Then if you would (you know, while we are correcting one another's posts), correct your own post. It is rec.crafts.woodturning, not "Rec.woodturning".
Robert
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paul_bilodeau1 wrote:
<<I'm not a pro woodturner but I have been trying to learn all I can so I can build or buy one myself.>>
*SNIP*
A good post with a lot of constructive thinking except for that first part. I am just givnig a respectful warning about building a lathe, and if may be something you have your heart set on doing. If that is the case, do it!
But I have known and talked to a few on the net that have tried to make their own lathes. As for making a general lathe (for spindle and bowl), none would do it again. It was too hard, too long a process and required too much work. They were never completely happy with their efforts, they felt like it took too long (they wanted to be spinning wood, not metal working) and at the end of the process they felt like they had actually tried to reinvent the wheel.
I think a much better way to go (my opinon) for a general use lathe is to find some old iron and restore. The old machines were simple, and made to be rebuilt. You can get great variable speed motors and drives at places like surplus equipment dealers, surplus electrical motor dealers and a ton of others. It is faster and you have a well balanced machine designed and made for the purpose of general turning.
That being said, I have visited shops where bowl turners have made their own BOWL turning lathes and like them. Since their are no ways to align and worry about, no headstock/tailstock alignment issues, and no worries about axial twisting from under engineering, etc., they had a pretty easy build.
Essentially, one guy I visited took pieces of 6 inch angle iron and made himself a box about 40 inches tall, and about 30 inches square. He filled it with concrete, and welded a cap on it to which he welded a receiver to hold his pillow blocks. He put a 2 horse variable speed motor next to the table top, inserted a shaft he had threaded (1 1/4"X8 so he could buy faceplates), belted up, and welded a homemade affair to hold his toolrest. The toolrest assembly is one of those outrigging affairs like Nova makes.
After experimenting with some huge pieces, he decided to bolt it to the floor as he had a little wobble when roughing out the big stuff (which is why he built it). He loved his setup, and I must say it was as steady as a boulder. He routinely turned 24-30" platters for sale in an artist community north of here. It took him about a month to build and finish, and at the end of the project he had about $1000 bucks in a lathe the would have cost him about $4000 were the to buy something comparable. Not as elegant, but certainly as usable.
But for any kind of spindle work, he had an old Rockwell in the back that he used. Knowing the engineering and the precision he would have to observe, he never even tried to make a spindle turning lathe.
Come on over to rec.crafts.woodturning, another usenet group, or read WoodCentral.com's turning forum. Both have excellent archives where you will get lots of hands on info on turning, sharpening, techniques, lathe buying advice, and there is even some here and there on lathe building.
Robert
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It's "LATHE" BTW.
I assume your question boils down to why should I spend more for a "better" lathe and what will I get for my money?
Try posting to Rec.woodturning for more.
For spindle turning and smaller work, a top-quality lathe is not really necessary. I had a cheap Crapsman, an it did OK for spindles but the general build quality was weak and ease of use of all the lockdowns was marginal. For a few extra $ you can get better fit /finish/ergonomics and to some degree capacity (Distance between centers, Swing, HP).
Quality (and by quality I mean price point) really matters when you get into bowls. With bowls, and out of blance workpiece (when you first mount it) will pick up your lathe and throw it around the room. This is because the (off) center of gravity is much further from the center of rotation.
The following things can be incorporated into the lathe design to combat this problem, all of them cost $$$:
1. Add weight (more cast iron and lot's of it) 2. Heavier weight shafts and bearings are required to handle those forces. 3. The bottom speed of most mechanical drive systems is around 500rpm. That translates to a pretty fast linear surface speed with a 12" diameter workpiece. To get really slow rpms you need to either rig your own drive system or invest in electronic variable speed motors (most EVS-equipped lathes start around $1500)
Hope that help shed some light.
Steve
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You make better spindles on a smoother lathe. Better bearings, rigid construction are what you want.

Roughing a piece should not be used as a test of the lathe. If the turners has sense, they will get the piece into best balance possible prior to roughing. Many don't but they deserve what they get.

Nope, learn the physics of turning, build a rigid stand with proper geometry to take the thrust of the turning and put a little bit of weight close to the floor behind it to keep it from lifting.

Once again, be smarter than the lathe, and balance your turnings. Good bearings and rigidity are your friends.

Mechanical and electrical options are available for obtaining slower speeds. A constant-speed motor with mechanical changes (pulleys) cools itself best and provides good torque to the piece at slow speeds. As the energy available to eat your tools or throw a chunk varies with the square of the velocity, you want slower speeds for starting, and just enough to pull a shaving afterward. Don't read all that baloney about higher speeds being necessary. They're for people who bought crummy lathes instead of good, rigid ones with heavy bearings. What they do is try to substitute inertia for torque and stability.
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I agree. But, I said "not really necessary". I stand by that.

Let me restate my point: Out of balance situations happen (before or after roughing). They are bigger problem at a a higher diameter. A sturdier lathe will handle/dampen/withstand the resilting forces better.

That addresses the forces associated with the mass of the workpiece contacting the tool. An out of balance piece will attempt to move in the direction tangent to the heavy spot, which is well....rotating.

I try.

Yup we said that (OK I didn't use the word "ridgid")

Agreed. However, I have not personally seen a pully system capable of <100 rpm that comes with a mainstream (delta/jet/oneway/vicmark/nova etc.), but I could be wrong.. I have only heard of home made jack shaft systems. Hense, "rig your own drive stystem"
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Well, since you like to pick nits, no. The kinetic energy depends more on the speed than the diameter. The moment of inertia may not be at the rim, either. You'll want to review your angular velocity concepts.

You _really_ want to review your physics. Try this site for some good, easily understandable information. http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html The heavy spot begins to accelerate at 12:00. achieves maximum moment at 9:00 when rotating counterclockwise, but maximum energy somewhere around eight o clock. Has nothing to do with the tool, which contacts the piece, if you are any kind of a lathesman, at an oblique angle so the wood slides down the edge, severing cleanly. If you're a good lathesman, shavings fall, they don't fly.

No, you didn't, and rigid is absolutely the key here _not_ weight. The best lathe, as with the best stand, is rigid. It does not allow any flex which can lead to paradoxical motion between the rest and the work. Further, it should have positive locks throughout which will not allow the components to move relative to one another even in adjustment directions unless the operator chooses it.
I have not personally seen a pully system capable of <100

Your straw man. I don't turn that low because I concentrate on balancing the piece and use the tailstock. Those, plus a properly constructed stand allow a 16" piece to rough at 360 with no real complication. 12" pieces had to begin at >600 on my old one, which was a great encouragement to rapidly reducing an off-balance piece. If I go lower on my mechanical system, I have to shave before the same point comes 'round again.
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George wrote:

I think you are assuming that all turned pieces end up balanced. That's very often not the case especially with more whimsical effects, or even if you are just making a nice mallet (remembering a recent post about an old mallet with off-center turning requirements.)
er
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No, that's what you are assuming. I'll wager I've turned more weird chunks than you have in the past 25 years, but I got them "as balanced as possible" prior to working them, and I understand the physics of turning. Quick example. I'm sure you can see that this could never have been in balance. It was merely controlled properly.
http://photobucket.com/albums/d160/GoodOnesGone/?action=view&current=ShellacLongSide.jpg
Would you believe there are actually experienced turners who won't nibble the ends off of a standard half-log mount on the bandsaw prior to spinning it on the lathe? They are the ones who complain about dismounts and broken toolrests and such, of course.
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George wrote:

Oh I'm sure you have, I've turned wood but I'm not by any stretch of the imagination a wood turner.
BTW, from where in your previous post, to which I responded, did you clip the quote "as balanced as possible"?

http://photobucket.com/albums/d160/GoodOnesGone/?action=view&current=ShellacLongSide.jpg
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Sorry, actual is "into best balance possible."
Followed by "balance your turnings" later in the post.

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Stephen M wote and replied:

Certainly not postively necessary. I have seen some beautiful work turned out by turners (some now nationally recognized) on old Sears monotubes. Small spindle shafts, tiny bears, and the monotube..... ouch. We have some in our club that just love theirs though, and they turn all manner of nice work.

Hmmm.... WTF do they deserve? Sounds ominous. I agree with Stephen completely on this aspect, and it has CERTAINLY been my experience. With some pieces, they refuse to be mounted in perfect balance, and some wont come close. You can trim then with your chainsaw while mounted, shift the attachment points... anything else. If you don't have enough mass on the lathe to handle a large piece until you can get it as balanced as you want, you are up against it.

Well, again I am with Stephen on this one. I don't know how you could design a lathe stand to cover all aspects of length, diameter, and the things that make woodturning interesting like voids or hollow spots. Or large, heavy swirly areas. Rotted or hollow areas you can't see that you simply cannot plan for and don't know about until hollowing. Or a green piece of wood with really rotted half. I am thinking of a piece of green persimmon that I just turned; it was 8-9" in diameter and about 12" in length. Down the length it about half was fully dried and just beginning to rot and was very dry. The other side was healthy, and green as grass. It was quite lively the whole time I turned it as it was always out of round as it dried more, and it was always out of balance from the start.
A well designed stand with cleverly placed supports "built with the proper geometry" without sufficient weight would have done a voodoo dance, hopping all over the shop. I may still struggle with the physics of turning (well... probably not) but I don't see how that would help a severely out of balance piece that was mounted to the best of my ability behave while I got it where I wanted it. After rounding (I was looking for a half and half contrast of dark grey to white wood here - striking in appearance) that piece was still completely out of balance.
Even in concentricity, no geometry lesson or clever support placement would ever make this 23 lb block of spinning wood so. Sigh.

I try too, but it is hard. I turn a lot of things off center. A lot. Off center is interesting and develops a whole different skill set of woodturning. However, sadly, the geometry alone is evident to my lathe (our constant battle of IQs aside) that off center means almost by definition in woodturning (as opposed to speed balancing a tire) well off balance.
My lathe and I will make a concerted, mutual effort to work this out, though I am not encouraged by his response. We both feel (I am speaking for both of us here) that if the piece is centered, rounded on the lathe, and still out of balance the only way we can overcome the problem it presents is to add more mass to the lathe to combat the motion caused by spinning the out of balance piece while holding it between two centers.
And since we don't have the proper equipment (he is thinking an MRI machine here, but I don't know) to determine exactly where on every single piece of wood we mount it is out of balance, hollow, rotted, dried, or has a hidden inclusion, regardless of diameter or length (length is his pet peeve on the out of balance biz) we are truly "up against it".
Sure, we could turn smaller items out of perfectly dried or perfectly green wood, or use wood that has no defects. We could turn only perfectly symmetric shapes, balanced in profile and dimension out of nice pieces of wood with good straight grain. Could even add in a little curly stuff here and there to make up for the boredom. Sadly, I am not really interested much in that anymore. Years ago, sure. Now, not usually interested unless I have a really pretty piece of wood and I don't want to detract from the wood with design work.
I still intend to battle with that spinning know it all and turn natural edge bowls, leaning mushrooms, spoons, spatulas, natural edge vases, and off center ornaments no matter how off center or out of balance they turn out to be in the final form. It won't be easy, though. His head(stock) is really hard... almost like it was made of iron.
Robert
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Once again, you're ignoring physics and the easy way to counter the situation - a proper stand. Wastes the effort of the piece in trying to compress the incompressable versus limiting the lift on a strictly inertial basis.
What do they deserve? They deserve the poor outcome of the lousy technique which they continue to follow. Rather than applying their noggins to turning, they apply the turnings to their noggins. Simple things like not nibbling the ends, or my particular favorite, starting between centers with the spur center driving are easily avoided.

You begin by listening and not whining and picking nits. It is not that a piece is out of balance. It's _always_ out of balance. What you do is the best you can to control the effect of the conditions. For example - if you read and think, you realize that the closer to center the imbalance is, the less significant it is, and the difference is geometric. Trim what won't be there in the resultant piece prior to mounting to gain an advantage . As you thank Sir Isaac for reminding you about mechanical moment, you check on his angular momentum equations and realize that the worst thing you can do is speed up the lathe, as some, believe it or not recommend, to counter a resonant condition. Turning as slow as you can stand to is really a great idea.
Oh yes, did I mention that you buy a lathe and build or buy a rigid stand which does not allow elastic collisions to exacerbate out-of-balance conditions? It doesn't have to be heavy. You've got the whole earth as your counter if you want it.
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Lathes are unlike other power tools. A turner really becomes one with a lathe, much more so than other tools. Holding the cutting edges in your hands, moving your entire body to make a smooth flowing cut, watching (out of the corner of your eye :) ribbons of wood arcing through the air, having more fun than normally allowed. The lathe is the only tool on which you can mount a chunk of tree and take off a fully-finished piece.
What makes one lathe better than another? Lack of vibration, stiffness smooth transfer of power, ease of reach to power switches, smooth and precise adjustments that are always within reach. All of these come from lots of cast iron, precise machining and attention to detail, and all cost money. The mini lathes (Jet and Delta most notably) are outstanding value, given their size limitations. Small things can be turned (more easily) on a big lathe but large items cannot be turned on small lathes... hence the ever-present desire to get bigger lathes. Getting what you pay for applies to lathes, as it does to most things in life.
Turning is a glorious addiction. Most dedicated turners I know used to be well-rounded woodworkers before discovering the uniquely satisfying and fascinating world of turning. Enter at your own risk. :)
Michael Latcha - at home in Redford, MI

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Charlie,
I'm not a pro woodturner but I have been trying to learn all I can so I can build or buy one myself. Here is what I have learned so far....
First, variable speed (as mentioned before) is a very helpful feature that can be attained in a few different ways like stepped pulleys and electronic controls. Price will bear on this. If you are happy changing belts, you can save a few dollars.
Next, you may want to think about the option of bowl turning. The term "Swing over bed" means "how big of a piece will turn on the headstock without hitting the ways". The ways are the rail-like things that hold the tailstock securely. If you want to turn bowls, you may want to be able to attach a faceplate to the outside end of the headstock, OR be able to turn the headstock 180 degrees. Again, prices will vary.
Next, you may want to look closely at the size on the headstock shaft. The cheaper lathes will use a smaller diameter shaft. A larger diameter shaft will tend to vibrate less when you are turning a larger piece or at higher speeds.
Another feature to look for is the construction of the ways. The cheap lathes will sometimes use thin wall pipes or stamped steel ways for attaching the tailstock. These will also tend to give you more vibration in use. Generally, I have found that "the heavier the better" seems to run true. The large cast iron ways hold up better and help to keep the lathe more stable.
Yet another thing to consider is the attachment of headstock accessories. Some lathes use a threaded shaft only, some have external threads and a No. 1 Morse taper on the inside, while others have threads and a No. 2 Morse taper. Morse tapered accessories are quick and easy to change.
Last of all, how long of a piece do you want to make? Do you need to make canopy bed posts 6' long, or table legs, or pen blanks? Length of bed also translates into price.
As you can see, there are a few facts to consider to make sure that you get the right tool for the job.
Hope this helps,
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Pay a little extra and get an e.
:) xxxooo Notal Kyder
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