Using metal working tools and techniques on wood

[Jim Barstow]

I'm just finished the first class in a 10 week beginning machinist course. I thought I'd learn some useful new skills plus I've got some ideas for mixing metal details into my wood furniture. After doing my first metal turning where we measured down to 1/1000", it got me wondering why woodturning tools and techniques are so imprecise. Yes, the material is much more dynamic but it seems that the precision design of a metal lathe could be applied to woodturning. Why not have a lead screw and tool carriage? In fact, why not just use a metal lathe?

[Allen Grenz]

Price for one, a large metal working lathe is not chump change not to mention fixtures. Second would be why? Does a table leg need to be turned to within 1/1000"?

[Keith Weber]

I think that the biggest thing is that wood is not nearly as stable as metal. It is very susceptible to humidity changes, so why strive for 0.001", when your panel will shift more than that overnight? It's also more compressible, so it's easy to deform (by feed rollers, etc.) while machining. It likes to bounce back to it's comfort shape once free of the pressures deforming it. That flex also works to our advantage sometimes, however, when it comes to squaring during a glue-up.

Having said that, there are plenty of people around here that seem to get their panties in a knot if their bandsaw table has a .002" dish in across its 24" width.

Having a lead screw/tool carriage on a wood lathe would probably take a lot of the fun and craftsmanship out of it. Plus, it would be slow and difficult cutting something with a lot of curves.

[Brian W Smith]

Some people do...........pool cues and musical instruments to name a cpl.

['Jacques Malan']

The right tool for the job.

I've done woodturning on a metal lathe out of need.

I am now using a milling machine to bore holes in wood.

It works. But not really very well.

For a start, wood dust and oil isn't a good combination. And the highest possible speeds of the machines isn't fast enough to get a good finish.

[pat warner]

Working upside down, I use the woodworking tools and methods to work metal (http://patwarner.com/images/tswebb4759.jpg), plastic, and wood to .001". So it is possible to apply hybrid metal working methods with woodworking tools.

[Richard Coers]

Patternmakers lathes do have that cross slide so they can turn cylinders and tapers. These cross slides rely on an oil film on the bed, not a good mix with dust. But most woodturning involves beads and coves. Not easy by turning two cranks to do that. Also rpm is lower on metal lathes, tough to grind tooling to get the extreme shear angle you can get with a skew, most low end metal lathes don't have the length to do table legs, limited diameter capacity, etc............

[Mark Bolton]

I'm just finished the first class in a 10 week beginning machinist course. I thought I'd learn some useful new skills plus I've got some ideas for mixing metal details into my wood furniture. After doing my first metal turning where we measured down to 1/1000", it got me wondering why woodturning tools and techniques are so imprecise. Yes, the material is much more dynamic but it seems that the precision design of a metal lathe could be applied to woodturning. Why not have a lead screw and tool carriage? In fact, why not just use a metal lathe?

In addition to the other replies, if your talking about using a metal lathe in its conventional configuration, they are simply not conducive to qucik forming of sweeping curves, beads, and so on. Of course you could fit a tool rest which I have seen many times.

They each have their purpose and while if you only had space for one the metal lathe with work arounds for working wood would be the only option. Having both would be best especially when you start running a metal lathe in a wood shop with oil/coolant mist and spray. Not a good mix for a wood shop. We do quite a bit of metal fabrication in the shop and some tools we have in duplicate are used for metal only but without the luxury of two completely separate shops your always wondering about the cutting oil thats flying off the metal shavings and what piece of wood/work its landing on only to rear its ugly head when you start spraying finish.

[Art Mann]

If you are really interested in doing high precision woodworking on a lathe, check out the Legacy Ornamental Mill. I have only seen videos of this machine in action but it looks like it would do precision work almost to machine shop tolerances. This machine also appears to be incredibly versatile. I would actually like to hear from someone who owns one.

[Rod Sheridan]

Jim, that's a good idea for turning cylinders, however most turning has details that would be hard to do with a coumpound driven tool unless it was CNC.

It's amazing how good your eye/hand is a blending or repeating curves on a wood lathe.

Regards, Rod.

[Peter Kelly]

Some industries typically use metalworking equipment on certain hardwoods eg: wind instruments made from African Blackwood are often machined on a CNC lathe.


https://www.youtube.com/watch?v=31KR46tCucI

[Tai Fu]

I asked the same question to a machinist years ago. He said he doesn't allow wood in his shop because he said the wood dust is bad for machines. You can always add a tool rest on a metal lathe to allow you to turn wood without having to use a tool post, if you wanted a dual purpose machine. You would probably have to find a way to increase the RPM though.

In a manufacturing setting they use CNC lathes because it gives much more consistency than to have someone manually turn it on a manual wood lathe. It also saves time and labor as well as not having to find someone with the skill to turn parts on a wood lathe with acceptable dimensional accuracy. Though I suspect in the old days, or certain individual builders still turn them by hand. .001" accuracy is possible on wood initially but with the added difficulty of making sure the wood is stable so it doesn't move. Luthiery is complicated because you need good accuracy (often without the aid of CNC) and you still have to deal with wood movement.

[Myk Rian]

I bought a cross-slide for my Delta 11" wood lathe. Works fine for small metal turning, which is all I would ever do on it.
Heck, I have more in tooling than the lathe cost.

[curtis rosche]

Jim, using a metal lathe with a carriage would simply take all the fun out of it. Might as well put a scooter motor in your muscle car. All the fun is being able to do exactly what you want with your hands, and doing what they tell you. Not what a carriage can produce. try turning a bowl by hand once and you will understand

[Ray Newman]

For some projects/cuts, I put end mills in my PC routers -

-- I use end mills having ½”, 3/8”, and ¼” shanks.
-- Cutting diameters are available in metric and fractional sizes, as well as 2, 4, or more flutes .

For those like me that have PC routers, PC has a 3/8” collet for its routers. See:

www.portercable.com/Products/AccessoriesDetail.aspx?ProductID=16428

[Tai Fu]

Also you can actually cut aluminum with end mills on a router. You just have to reduce speed (if possible) and take lighter cuts...

[Jeff Erbele]

I'm just finished the first class in a 10 week beginning machinist course. I thought I'd learn some useful new skills plus I've got some ideas for mixing metal details into my wood furniture. After doing my first metal turning where we measured down to 1/1000", it got me wondering why woodturning tools and techniques are so imprecise. Yes, the material is much more dynamic but it seems that the precision design of a metal lathe could be applied to woodturning. Why not have a lead screw and tool carriage? In fact, why not just use a metal lathe?

I am a school trained and career machinist. You have been provided with a lot of good reasons why not. Generally, each lathe is built for a particular application. First is cost; metal turning lathes typically are built for the task, built heavier, more massive, require more horse power and have feed & lead change gearbox, and maybe some other stuff, a chip pan, a coolant system, maybe optional accessories a steady rest, a follower rest, a taper attachment, a tracer attachment (wood lathe could also), and the tailstock is adjustable to remove taper or put a precision taper in the shaft one is making (again some wood lathes could have the same feature.

You mentioned a lead screw. Some metal lathes, those less than full featured, less expensive may have only one screw. In industry that is the exception. Typically there is a feed screw or feed rod for power driving the carriage and cross slide, and on some lathes even the compound, and a lead screw. You could use either the feed screw or the lead screw for driving the carriage, but NEVER both at the same time. The feed screw is used for turning and facing; the lead screw is used with the half-nut and typically only for turning threads. If one used the lead screw for turning, in school you may have a talking to (or should) and on the job, could get fired; because that is not what is intended for, the concern is unnecessary and premature wear.

Another difference is a machine tool has gibs on the carriage and slides; adjustable to compensate for wear and hold precision over time. Gibs are standard on any decent machine tool and add to price.

Turning radius's was mentioned; it's faster to do it free-hand and eye-ball on a wood lathe. Correct.
The fact is with a some practice and the correct tooling, one can get very good (**) at free-handing, manipulating the carriage hand wheel and the cross slide with both hands; or engage the power feed on one and manipulate the other. Just think about and be careful which direction you select the power feed. Default to feeding away from harms way, in case you get flustered at the wrong time and fail to disengage the feed soon enough. e.g. feed away from the chuck or feed away from a shoulder, not towards either one.
** Very good means close, not perfect. Roughing, not precisely finished. That is accomplished with a file, and a radius gauge, or an emery paper covered form, or a tool post grinder, or a form tool for smaller radii, or a radius cutting attachment for larger radii. If you don't have one of those, one can lock the carriage to ways, loosen the compound bolts just enough to swivel the compound, adjust the radius with the compound screws, adjust the depth of cut with the cross slide, and feed the cutting tool by manually swiveling the compound. You want to take light cuts and always maintain control of the compound, even if it means adding leverage with something you fabricated like clamping a long bar in the tool post. It is a non-standard practice, one where you must know what you are doing and eliminate the risks.

Speeds & Feeds - metal lathes could be challenged on the slow side. They may not have the upper RPM range to achieve the proper cutting speed. Like wise on the feed; but so what if time is not important. Overall so what. The fact is in industry, unless one has a variable speed capabilities, one has step pulleys, gears to change or a quick change gear box, then, almost never does the machine offer the theoretical correct speed or feed. You do a quick calculation in your head, on your calculator, or glance at a reference chart, find your speed, find the closest speed the machine offers and set/shift the gear box. Take a trial cut; if you have chatter, down shift. if you don't, try the next higher speed.

Precision. Salad & nut bowls, table legs and handrail spindles don't need .001" or .0005" tolerances. Making them that way is wasting time and humidity will change it.
Traditional wood turning tools and techniques are precise enough.
Early on in machine shop training, our Journeyman Instructor made a big point of we would always be working with tolerances; a given size plus or minus something, or minus nothing/plus something, or minus something/plus nothing. His point was once you meet that tolerance, you are done, it is good enough, move on, time is production, production is money and profit. e.g. if your task is to make broom handles 5' +/- 1/8" and after one cut is 5' 1/16" long; you are in tolerance, do not bother with the 1/16". The handle meets customer specs and will work just fine.

Cost, speed, maybe capacity are all good reasons not to buy a metal lathe for wood turning and you do not need the precision, features and usually the strength provided by the construction and mass. But if you have a metal lathe and need to or want to turn out a wood project you could. Protect your wood from machine oil, and protect your machine from wood dust by covering the ways.

[Tai Fu]

I can't say covering the ways is enough to protect machines from wood dust, perhaps from wood chips. Those wood dust float EVERYWHERE and anything within 20 meter of the machine gets coated in wood dust, inside and out (wherever drafts could carry sub-micron particles to).

I still think a metal lathe is useful for making custom parts, bushing, etc. for maintenance of woodworking machines...