A serious question for those attending the DWR

[davidwalser]

A serious question for those attending the DWR

Like many of you, I have a short list of "dream lathes". High on my personal list is the Serious Wood Lathe. I wrote about my love affair in this post on Sawmill Creek: http://www.sawmillcreek.org/showthre...ous+wood+lathe

Well, because I had gushed about the lathe in that post, the good folks at Serious Toolworks asked if I might be interested in buying the lathe if they were to bring one to the upcoming DWR (next February 18, 19, & 20, here in Mesa, Arizona). Unfortunately, I'd need to greatly expand my shop before I could consider such an acquisition. So, they've asked me to pass along the following question to those who will be attending the DWR: Would any of you consider buying the lathe and taking delivery of it after the DWR if you could get it for about $1,400 less than the normal delivered cost? If so, drop me a PM and I'll give Serious Toolworks a head count of potential purchasers. (I won't share anyone's name or contact information. If you want to, feel free to contact the company directly.) If the company thinks there is a decent shot at selling the lathe at the DWR, they will ship it to Mesa so all of us can get a chance to see it in person. Otherwise, they might not.

I don't have any financial interest in Serious Toolworks or in the potential sale of the lathe. I'm doing this because I think a lot of turners would like a chance to see the lathe in person.

 

[Odie]

A serious consideration:

It seems to me there is some point of diminishing returns by simply adding weight to a lathe. There is no question that weight is a good thing....however. Weight is not the catch-all solution for the problems we face with turning wood. Adding more, and more weight, while it seems to make sense on the surface, is not going to provide the results it did when upgrading from a small and cheap lathe.......to one in the 500-750lb range.

Isn't the only real benefit to a 1500lb lathe, realized by those who specialize in finished projects that end up being significantly out of balance? It seems that way to me. For most of us, 95 percent of any out of balance condition is eliminated in the initial roughing stage of the process. During this roughing-out step, we are dealing with vibration that originates from the unequal distribution of weight of the object being turned.

With that in mind, this initial source of vibration is entirely different than vibrations we deal with when bringing our turnings to a final shape. These latter vibrations originate from structural inadequacies of a bowl being brought to the final shape, and improper use of speed, tools and related equipment......not a balance issue at all. Here, admittedly, the weight of the lathe is an important consideration......but less important than it was while bringing the turned object to a general shape in the roughing stage. What's important is proper speed, shape and species, defects, wall thickness, sharpness of tools, proper use/selection of tools, rests, steadies, etc.

Knowing how things work on these forums.....there isn't much I can relate of my own observations and findings about lathe turning that someone isn't going to dispute. But, can we agree there are two sources of vibrations? One is caused by the unequal distribution of the weight of an object being turned, it's relationship to speed, and is remedied by weight and stability of the lathe itself......while the other source of vibrations is caused by things that are not remedied by adding weight to the lathe?

One other point that was brought up in the discussion, is cast iron's superior ability to absorb vibration. I'm giving my opinion that this is a complete myth. I can't prove that I'm right about this, but it seems like the only way to know for sure, would be to have two lathes of the exact same configuration, one w/cast iron components, and one without. Experiment by running the same object on both of these lathes in exactly the same way......then measure the vibrations. To my knowledge, such an experiment has never been done. There is one thing that is better about cast iron that I'm aware of, though.........and this is it's ability to remain rigid and unaffected by temperature variations. For this reason, I'd much prefer cast iron for the basic construction of just about any full sized machine tool that depends upon precision performance.


ooc

 

[Bill Blasic]

I am a cast iron fan, I've turned on the steel bed lathes and I know that I prefer cast iron. I have turned on the Serious Lathe and I'll tell you it is one solid piece of equipment and if I could afford it I would have one in a second. It was a very comfortable lathe to turn on.
Bill

 

[john lucas]

Odie You've been thinking too hard again. 🙂 You do bring up a good point. a retake on an old joke goes like this. Mass isn't everything but it's way ahead of whatever is in second place.

I have a powermatic 3520A and I though 700lbs would be rock solid. Well it is to a point but when you spin an out of balance piece at 1800 rpm you get vibration. I added 300lbs of weight and still get vibration unless I carefully adjust the feet so that each one is taking the same weight. ( do this by feel with a wrench, not the most accurate way but it seems to work)

When I turn vessels with holes in the sides I like to spin them fast and that is the problem.

Cast iron vs steel. Well I don't know about that one but I have never seen a steel metal lathe. Vibration is an absolute no no for metal lathes and accuracy. All I've ever seen are cast iron (and heavy)

Of course weight is not the total answer. I looked at the the lathe pretty hard in Hartford. If you go through the specs the Serious lathe has a 1 1/2" spindle (bigger than most lathes) It uses #3 morse tapers (bigger and stronger than #2) The tailstock is about as heavy as any I've seen. That's a concern for me because I remove the tailstock for many projects and that thing would hurt you if you pick it up wrong. The lathe comes with a 3 horse motor and I would assume that if they are designing this thing to be that strong they they probably designed in better bearings. How else would you put it but this is a "serious" lathe.
http://www.serioustoolworks.com/wood-lathes.php

 

[Odie]

Odie You've been thinking too hard again. 🙂 You do bring up a good point. a retake on an old joke goes like this. Mass isn't everything but it's way ahead of whatever is in second place.

I have a powermatic 3520A and I though 700lbs would be rock solid. Well it is to a point but when you spin an out of balance piece at 1800 rpm you get vibration. I added 300lbs of weight and still get vibration unless I carefully adjust the feet so that each one is taking the same weight. ( do this by feel with a wrench, not the most accurate way but it seems to work)

When I turn vessels with holes in the sides I like to spin them fast and that is the problem.

Cast iron vs steel. Well I don't know about that one but I have never seen a steel metal lathe. Vibration is an absolute no no for metal lathes and accuracy. All I've ever seen are cast iron (and heavy)

Of course weight is not the total answer. I looked at the the lathe pretty hard in Hartford. If you go through the specs the Serious lathe has a 1 1/2" spindle (bigger than most lathes) It uses #3 morse tapers (bigger and stronger than #2) The tailstock is about as heavy as any I've seen. That's a concern for me because I remove the tailstock for many projects and that thing would hurt you if you pick it up wrong. The lathe comes with a 3 horse motor and I would assume that if they are designing this thing to be that strong they they probably designed in better bearings. How else would you put it but this is a "serious" lathe.
http://www.serioustoolworks.com/wood-lathes.php

My comments below are intended to address the following portion of your post:

I have a powermatic 3520A and I though 700lbs would be rock solid. Well it is to a point but when you spin an out of balance piece at 1800 rpm you get vibration. I added 300lbs of weight and still get vibration unless I carefully adjust the feet so that each one is taking the same weight. ( do this by feel with a wrench, not the most accurate way but it seems to work)

When I turn vessels with holes in the sides I like to spin them fast and that is the problem.

Good morning John......

You don't disappoint......😉

OK, so you've added 300lbs of weight, and your out of balance hasn't improved without adjusting the feet of your lathe. You should have figured this out, my friend. The feet should have been in adjustment all along! Unless you removed the 300lbs, and took that same turning back to the original set-up, but with adjusted feet.......then how would you know the added weight alone helped with that particular turning? 🙄

Actually the Powermatic lathe is more like 550 or 600lbs, because the listed weight is a shipping weight......this includes the pallet, crate, packing, tools supplied, etc. My Australian Woodfast is close to 500lbs, but I can handle an out of balance condition on it that would compare to a lathe that is double the weight.....because it's firmly bolted to the concrete slab floor. Maybe you should give that a try.....you'll have positive results with it.

I do understand there are those who wish their lathe to remain mobile, and bolting it to the floor isn't an option........

A lightweight object that is previously hollowed, isn't comparable to a heavy solid block of wood that's out of balance. The forces aren't nearly the same. With the heavy block of wood, it's an uneven application of centrifugal forces that cause the vibration........while the much lighter hollowed form will exhibit vibrations from completely different sources. Basically, it's a structural response to the tooling and speed adjustments. Some of these things are mentioned in my original post.

In the shop where I work, we have about a dozen metal working lathes.....the biggest is massive, probably close to 5, or 7,000lbs! (Although we have CNC controlled screw machines that are similar to a lathe, these lathes are mostly just digital readout......but, very precision.) I operate a precision grinding machine where I maintain tolerances of a couple ten thousandths of an inch, but have access to and use the lathes myself. They are all cast iron for the base components. For the reasons I mentioned, I'd also prefer cast iron. There is one significant difference between metal lathes and wood lathes........the common turning speeds are much lower, than with wood lathes. It's very common to have heavy out of balance pieces being turned, but it isn't the problem at several hundred rpm, than it is at one, or two thousand rpm. I suspect the cast iron in these metal lathes has everything to do with maintaining accuracy, rather than dealing with vibration absorption.......which is what is being claimed with the "Serious" lathe. As I said, I can't confirm one way or another.......so, my opinion on this is worth exactly what you paid for it!

I believe I've seen some of your work with holes in the sides. Was it on youtube? Anyway, beyond using proper sharp tools with the right accessories, there really isn't much you can do to eliminate vibration that doesn't originate from a source less powerful than can move your lathe at 1800rpm. Adding weight to your lathe isn't going to do it, because if it's a light object, which I suspect it is, then adding weight to an already stable lathe (with adjusted feet) isn't going to help. In a situation like that, adjusting the variable speed control is your best way to deal with that kind of vibration. (Yes, I understand you wish to have high speed, so it's a dilemma you will find your own solutions to.......I wish you well with it.)

ooc

 

[robo hippy]

After looking at it and the Robust, I took the Robust. In part because of a preference for the sliding headstock.

robo hippy

 

[davidwalser]

Guys,

Thanks for the interesting discussion. As has been pointed out, there are different sources of vibration and different types of vibration. Sometimes the spinning wood flexes as it spins. No lathe design can eliminate that source of vibration. But some lathes are better than others at preventing vibrations from being transmitted to the tool rest. I'm not an engineer and designing industrial equipment is not my field. I don't know whether cast iron is better than steel at controlling vibration. I do know I was very impressed with the Serious Wood Lathe's ability to dampen vibration. They had a large out-of-balance block of wood mounted onto the lathe by a face plate. The lathe was spinning at turning speed. Stacked on the headstock were lettered blocks spelling out "SERIOUS". I rested my hand on the ways of the lathe by the tailstock. I could not feel any vibration. If I did not see the block spinning, I wouldn't have known the lathe was on. I was seriously impressed.

Would a Robust, Oneway, or other dream lathe have done as well? I don't know. All of those lathes have their fans. Some lathes fit different turning styles better than others. Robo Hippy has his lathe in a corner in his shop, so he cannot turn outboard. In addition, he finds turning on a short bed more comfortable. For these reasons, a sliding headstock is a must have feature -- so a Serious Wood Lathe is not for him. Another turner might have the space and might prefer turning outboard. For that turner, a Serious Wood Lathe or a Oneway might be a better option than a Robust.

 

[Dave Ogren]

Bolting the lathe to the floor

Odie,

I think that you and I are almost the only ones that have the lathe bolted to the floor. Everyone complains about vibration but no body bolts them donw.

Dave

 

[john lucas]

Thanks for the thought provoking essay Odie. I have to move my lather periodically so bolting it down is not an option. I do adjust the legs whenever I move the lathe but I think really get it right you would probably need some sort of electronic device to measure the weight or stress at each leg.
I've tried leveling it front to back and left to right and it seems to help but my method of putting a wrench on the levelers and then trying to make the "feel" of pulling the wrench the same on all 4 legs seems to work just as well.
My lathe does weight pretty close to 700 lbs without the gravel. I had to disassemble it to move it one time so I weighed each part. With the bags of Pea Gravel it's right at 1000lbs.
I was turning an offcenter platter the other day. It is about 8" square and 1 1/4" thick. I mounted it to a 19" round disc and glued it down so just the corner was on center. I was able to get up to about 800 rpm before vibration started. I was able to crank it up to about 1600 rpm before the vibration settled down but was too nervous of the hot glue that I mounted it with to turn it at that speed.

 

[Odie]

Odie,

I think that you and I are almost the only ones that have the lathe bolted to the floor. Everyone complains about vibration but no body bolts them donw.

Dave

Very true, Dave.......

I'll bet there are a few more than that who do bolt their lathes down, but it does seem to be a common theme that many do not because of the mobility issues. There is no right or wrong in this, but those who choose not to bolt their lathes down have to understand that it's something that's easy to do and can be done in an hour with a rental or owned hammer drill and drop in anchors......and it represents an easy improvement to any lathe's stability.

ooc

 

[Odie]

Guys,

Thanks for the interesting discussion. As has been pointed out, there are different sources of vibration and different types of vibration. Sometimes the spinning wood flexes as it spins. No lathe design can eliminate that source of vibration. But some lathes are better than others at preventing vibrations from being transmitted to the tool rest. I'm not an engineer and designing industrial equipment is not my field. I don't know whether cast iron is better than steel at controlling vibration. I do know I was very impressed with the Serious Wood Lathe's ability to dampen vibration. They had a large out-of-balance block of wood mounted onto the lathe by a face plate. The lathe was spinning at turning speed. Stacked on the headstock were lettered blocks spelling out "SERIOUS". I rested my hand on the ways of the lathe by the tailstock. I could not feel any vibration. If I did not see the block spinning, I wouldn't have known the lathe was on. I was seriously impressed.

Would a Robust, Oneway, or other dream lathe have done as well? I don't know. All of those lathes have their fans. Some lathes fit different turning styles better than others. Robo Hippy has his lathe in a corner in his shop, so he cannot turn outboard. In addition, he finds turning on a short bed more comfortable. For these reasons, a sliding headstock is a must have feature -- so a Serious Wood Lathe is not for him. Another turner might have the space and might prefer turning outboard. For that turner, a Serious Wood Lathe or a Oneway might be a better option than a Robust.

Hello Dave.......

See bold in your post above.

My general thought is other less heavy lathes would not have done as well as the Serious Lathe (all other things being equal), if we're strictly speaking of vibration related to a basic unturned block of wood. I'd suspect the same if discussing final finish turning of a project that is significantly off center.

For most turning, that block of wood quickly becomes a roughed turning, ready for seasoning. Once it's brought to round, and centrifugal weight issues aren't as problematic, the turning becomes much easier to handle.......and, final finish turning is 90 percent of where our needs are, as turners.

I don't want to seem too negative about the Serious Lathe......it has a purpose, but most turners just won't have a need for the kind of advantages it offers.......which is large out of round and off center turning with significant weight considerations. For most of us, we can accomplish these things with our regular lathes, but we will be limited to just how much size and off center weight we can handle........

If that's the right lathe for you, then get it.......just don't subscribe to the notion that it's what everyone needs, or even wishes to have.

ooc

 

[Bill Boehme]

.... I don't know whether cast iron is better than steel at controlling vibration. ......

There is some marketing half-truth in that story about cast iron vs. steel vibration. In actuality, the higher vibration damping in gray cast iron (not ductile cast iron) refers to the type of vibration that we think of when we hear the ringing from a bell or tuning fork. If something the size of the Liberty Bell were made of gray cast iron, it would be more likely to "clunk" rather than ring while steel would probably have a bit more of a pleasant ring to it.

However ---- this does not have much at all to do with the type of vibration that woodturners are concerned about which would be structural vibration that occurs at a far lower frequency than the ringing of the structure. An out of balance load can shake a machine and excite structural vibration modes, but those structural modes are related to the geometry and overall stiffness of the machine and not much to do with whether it is steel or gray cast iron. One potential advantage of cast iron is that the fabrication cost is probably less because it is easier to have a casting with all of the necessary webbing for stiffness as opposed to welding up a steel structure. On the other hand, cast iron also has some long-term disadvantages that might offset its initial cost of fabrication advantage. Cast iron is often overly heavy in order to overcome warping and other casting issues. Cast iron is likely to have built-in stresses due to uneven cooling which can eventually lead to stress cracking. Repairing a stress crack in cast iron is all but impossible. Welding is almost certain to exacerbate stress cracks. Woodturning lathe beds are rather simple structures so I would not envision that the cast iron vs. steel question would matter much either way, but I do not care for advertising malarkey.

...... I do adjust the legs whenever I move the lathe but I think really get it right you would probably need some sort of electronic device to measure the weight or stress at each leg.
I've tried leveling it front to back and left to right and it seems to help but my method of putting a wrench on the levelers and then trying to make the "feel" of pulling the wrench the same on all 4 legs seems to work just as well.

Actually, John, the way that you are doing it is about the best and simplest way of going about it. It is pretty easy to gauge how much torque you are applying to the wrench simply by judging finger pressure. I would make a final pass at all four feet to verify that they are still all about the same.

 

[john lucas]

Bill Maybe I could attach a spring to the wrench and pull it with that. Then I could attach a ruler to the spring and measure the length as I pull. I could then adjust each leg so it took the same number of inches of stretch in the spring. Does that make sense?