Lathe speeds

[DUANE POLING]

I am not new to wood turning but I am new to my 3520 lathe. I have turned on my old lathe for 30 yrs but always at the same speed, 875. All tasks were accomplished at that speed and I just got use to it. I know there are speeds better suited for different tasks. Can I get input as to what speed ranges would be best for different stages such as rough out, shaping, finish cuts, sanding?
Thanks in advance

 

[hockenbery]

Dwayne,

Just use the speed control knob and don't worry about the actual speed.

When I'm roughing I put the belt in a lower max speed range this gives you finer control of speed,
turn the speed all the way down with the lathe off
mount the blank,
balance it for weight so it isn't real heavy on any side,
Turn the lathe on and dial up the speed to where there is acceptable vibration.

As I turn the speed up there will be a point where vibration begins or the blank looks good and I start roughing.
If the vibration begins a lower speed I will try a little higher speed looking for one with less vibration.
As the speed increases you have a vibration point, worse vibration, and sometimes a speed 50-100 rpm faster with less vibration.

For sanding I turn the speed low. If I'm not getting a steady dust stream with a good disc I slow the speed to where the dust stream appears.

For work with interrupted cuts - natural edge bowls, multi center spindles a higher relative speed gives a smoother cut.

My suggestion would be to never turn REALLY FAST.
Speed is frequently a factor in injury.
Any piece of wood prone to come apart is more likely to do so at a higher speed.
There are lots of blocks of wood out there that look really solid until a few cuts reveal a defect.

Work safe!

 

[DUANE POLING]

Thanks for the comment. that is what I have been doing, just increasing or reducing speed according to the piece and how it feels. I was just curious if there was an advantage to cutting at a higher or slower speed. I get it on pieces with voids or air turning at higher speeds to keep from falling in the hole, wasn't sure if smoother cuts would be achieved at higher speeds. Since I havn't had the higher speeds avaliable in the past I will just have to try it with safety first in mind.
Thanks

 

[Mike Peace]

There is a speed guide table in the manual that came with your lathe. If you do not have the manual you can download it from the Powermatic website. As Nor Abram says, "Before we use any power tools, let's take a moment to talk about shop safety. Be sure to read, understand, and follow all the safety rules that come with your power tools. Knowing how to use your power tools properly will greatly reduce the risk of personal injury. And remember this: there is no more important safety rule than to wear these — safety glasses." Substitute face shield for safety glasses : )

 

[Hu Lowery]

FPS and material

Duane,

Probably telling you what you already know but might be a good time for a reminder with your new speed capabilities. We talk RPM but without also considering diameter RPM is almost meaningless. What really matters is how fast the material is going past your cutting edge, feet per second. Coming from a machine background I am very aware of this and have found that sometimes my wood likes to be turned slower than the usual advice to turn as fast as possible without excess vibration. Some dry wood that is creating a lot of dust and not much else starts making nice shavings at slower speeds for example. Very hard wood can get contrary when getting close to centerline because the feet per second have gotten very slow. The tool is a little duller too but unless the tool is badly dulled often a speed increase will clean up the cut so a pass can be completed before stopping to sharpen.

With your experience I think you will quickly find that there is a best speed for the piece you are turning and what you are doing at the moment. The charts get you started but they can't and don't cover the fluid nature of turning the things we often turn now. Once you are in the right neighborhood, adjust up and down on RPM by feel and you will soon find yourself doing so almost automatically as you turn. The 3520 is a spindle turning lathe too of course and the high RPM capabilities are most likely there for semi-production turning small spindles. I doubt you see that high RPM very often.

I will talk a little about sanding. Again no numbers because FPS is what matters. While sanding RPM is lower than turning RPM, hand sanding RPM is considerably faster than best RPM for power sanding to get maximum effect, or so I am finding. Being able to fine tune hand sanding RPM is a major plus of variable speed.

You have a new feature with easily adjustable speed Unfortunately, no hard and fast answers about RPM. I would look at the chart and consider that the recommended maximum for sound wood with no voids or flaws. Roughing and less sound wood calls for adjustments.

Just what I have found in the little time I have been trying to do traditional wood turning. Speed thrills but I'm finding that slowing down often results in a few less thrills and better results.

Hu

 

[Bill Boehme]

Thanks for the comment. that is what I have been doing, just increasing or reducing speed according to the piece and how it feels. I was just curious if there was an advantage to cutting at a higher or slower speed. I get it on pieces with voids or air turning at higher speeds to keep from falling in the hole, wasn't sure if smoother cuts would be achieved at higher speeds. Since I havn't had the higher speeds avaliable in the past I will just have to try it with safety first in mind.
Thanks

If the tool falls in a hole that means you are pushing it and it is probably dull. For interrupted cuts, a speed high enough to see a shadow or outline works best. Think about the tool position relative to this shadow so that the tool is barely touching it and concentrate on NOT pushing the tool into the wood. Pay attention to the bevel and its relationship to the imaginary semi-transparent wood being cut.

 

[hockenbery]

Thanks for the comment. that is what I have been doing, just increasing or reducing speed according to the piece and how it feels. I was just curious if there was an advantage to cutting at a higher or slower speed. I get it on pieces with voids or air turning at higher speeds to keep from falling in the hole, wasn't sure if smoother cuts would be achieved at higher speeds. Since I havn't had the higher speeds avaliable in the past I will just have to try it with safety first in mind. Thanks

High speed is a frequent component of lathe accidents. And higher speed usually makes an accident worse.
You have gotten a lot of similar advice.

A piece with a lot of voids particularly those created by bark inclusions is more hazardous at high speeds.
Higher speed does yield a cleaner cut.

The most straight forward advice is to not exceed your skills.
You now have a machine that can spin a huge block dangerously fast.
as one safety feature turn all blanks over 12" in diameter on the low speed pulley.

Al

 

[DUANE POLING]

I appreciate all the comments. I am very safety aware working wood shop machinery for 30+ years, but reminders are always needed and appreciated. I agree with working at your skill level and comfort level and that is my plan. Just as I learned at a slower speed I will adjust as I get familiar with the new machine. The sanding advice is where I had my most questions and I had found even at the 875 speed, certain woods would burnish at higher grits rather than cut, but without options what can you do? I plan on taking my time in this learning curve and only moving up as my comfort increases.
Thanks for a great site.

 

[odie]

I appreciate all the comments. I am very safety aware working wood shop machinery for 30+ years, but reminders are always needed and appreciated. I agree with working at your skill level and comfort level and that is my plan. Just as I learned at a slower speed I will adjust as I get familiar with the new machine. The sanding advice is where I had my most questions and I had found even at the 875 speed, certain woods would burnish at higher grits rather than cut, but without options what can you do? I plan on taking my time in this learning curve and only moving up as my comfort increases.
Thanks for a great site.

Duane......I've found that 300rpm, or close to it, is about optimum for all phases of hand and powered sanding.....with the exception of random orbital. If you burnish, or burn at that rpm, then you're either pushing too hard, or have gone prematurely to a higher grit.......try it.

ooc

 

[DUANE POLING]

Using the 300 mark for sanding is right on the money. The paper cuts much faster and scratches disappear quicker. That gives me more time to get back to the fun part of making little curls!!!
Thanks guys

 

[odie]

Using the 300 mark for sanding is right on the money. The paper cuts much faster and scratches disappear quicker. That gives me more time to get back to the fun part of making little curls!!!
Thanks guys

You got that right, Duane!.......

The diameter of the piece, species, and grain orientation will effect the best rpm, too......but, there is a best rpm for the job at hand. 300rpm is a good place to start.

One thing that was very difficult for me to overcome, is to throw away sandpaper long before every last little bit of usable grit is used. I usually look for unused places on the sandpaper, until about 95% of it is used....then toss it. There is nothing like always using fresh grit, and I used to waste a lot of time and effort by being way too frugal! :mad: You know, I believe it was input by members of this forum that finally broke that bad habit of mine!



ooc

 

[Bill Boehme]

?.. I usually look for unused places on the sandpaper, until about 95% of it is used....then toss it.

I'm not saying that I'm phrugal, but are you saying that you tossed perfectly good paper that still had 5% goodie remaining?

Several years ago, Bruce Hoover did a program at our club. You might not think that a program about sanding could be interesting enough to entice people to make a special trip on a Saturday to spend several hours hearing about sanding -- but they were and and they were glad that they did. He is very knowledgeable about the technical aspects and is a very entertaining speaker. His motto is, "worn out 120 is not 220". I know that I still use sandpaper a bit too long, but it is hard to overcome being cheap. Maybe there's a 12 step program for sandpaper abusers.

 

[Hu Lowery]

nuther sandpaper trick or two

Sandpaper tends to have a few big grains or grains of grit that have stuck on top of others. If using a power tool, touch it to an old piece of scrap for a couple seconds before sanding the piece. Hand sanding, a quick brush or two across that same scrap before sanding on your piece. Nine times out of ten(statistic made up on the spot!) those nasty scratches that look several grits coarser and take a long time to get out of the wood happened in the first couple seconds of contact from one of those high points sticking up.

I also strongly suggest avoiding cheapest available sandpaper. Paying a little more for quality is saving time and money. Loaded sandpaper isn't the same as dull sandpaper and a quick lick with a wire brush or running a disk under power against a wire brush and then a touch with the crepe block can bring the sandpaper pretty close to like new, once or twice. Time to toss it then but depending on the quality of sandpaper and what you are sanding it is often far from dull the first time it is loaded up.

Hu

 

[odie]

I'm not saying that I'm phrugal, but are you saying that you tossed perfectly good paper that still had 5% goodie remaining?

Several years ago, Bruce Hoover did a program at our club. You might not think that a program about sanding could be interesting enough to entice people to make a special trip on a Saturday to spend several hours hearing about sanding -- but they were and and they were glad that they did. He is very knowledgeable about the technical aspects and is a very entertaining speaker. His motto is, "worn out 120 is not 220". I know that I still use sandpaper a bit too long, but it is hard to overcome being cheap. Maybe there's a 12 step program for sandpaper abusers.

Good tip from Hu about using quality sandpaper.....I concur with that. I've used nothing but Norton 3x and the Japanese Finkat for the last dozen years. These are quality papers. Of course, there are other quality sanding alternatives, but these two are good choices.

You bet, Bill.....toss that paper out! In the end, it's not what the paper looks like......it's the results you are getting that determines the decision making process! Once you get a handle on what's important, then it makes throwing out that sandpaper a much easier thing to do!

ooc

 

[Steve Worcester]

....
My suggestion would be to never turn REALLY FAST.
Speed is frequently a factor in injury.
Any piece of wood prone to come apart is more likely to do so at a higher speed.
There are lots of blocks of wood out there that look really solid until a few cuts reveal a defect.

Work safe!

That kind of is a key message. I teach lower speed turning as bad stuff happens quicker at high speeds. The only difference between high and low speed (for an uninterrupted surface) is the feed rate of the tool. Sure, too low on a balanced piece is going to be frustratingly slow and the gouge kind of flops around instead of cutting.

Probably the number one question asked during a demo is "what speed are you turning at?". Eliminating the dangling participle, the answer has more to do with the wood, the balance and the confidence level (that it isn't going to grenade).

 

[Steve Worcester]

I'm not saying that I'm phrugal, but are you saying that you tossed perfectly good paper that still had 5% goodie remaining?
......
Maybe there's a 12 step program for sandpaper abusers.

Do you need a sponsor?

 

[Steve Worcester]

...Loaded sandpaper isn't the same as dull sandpaper and a quick lick with a wire brush or running a disk under power against a wire brush and then a touch with the crepe block can bring the sandpaper pretty close to like new, once or twice. Time to toss it then but depending on the quality of sandpaper and what you are sanding it is often far from dull the first time it is loaded up.

Hu

Using a wire brush will kind of work if you ares sanding oily or wet wood, but it can impregnate brush shards in the paper and you end up with worse scratches (or rusting material with a water based finish). Crepe is the way to go, just have to do it more often in the aforementioned situations.

 

[Shawn Pachlhofer]

I'm not saying that I'm phrugal, but are you saying that you tossed perfectly good paper that still had 5% goodie remaining?

Several years ago, Bruce Hoover did a program at our club. You might not think that a program about sanding could be interesting enough to entice people to make a special trip on a Saturday to spend several hours hearing about sanding -- but they were and and they were glad that they did. He is very knowledgeable about the technical aspects and is a very entertaining speaker. His motto is, "worn out 120 is not 220". I know that I still use sandpaper a bit too long, but it is hard to overcome being cheap. Maybe there's a 12 step program for sandpaper abusers.

my motto: "Use sandpaper like someone else is buying it"

 

[odie]

my motto: "Use sandpaper like someone else is buying it"

Yep.......that is a terrific motto!

I've heard that before, and it's one of the things that helped me to understand. Sandpaper is cheap, and if tool control/sharpening produces a surface devoid of needing to do much sanding......the light bulb that hovers over your head is twice, or even three times as bright! When that mental light is turned on.......there is a whole new concept about what is, and what isn't a worn out piece of sandpaper!

ooc

 

[Bill Boehme]

I don't know if John Jordan originated the clever expression, "use sandpaper like somebody else is paying for it", but he is the one who is usually credited.

Steve, I probably do need a sponsor. I try to be good, but when nobody is watching, I just squeeze out that last drop of goodie that ought not go to waste. Did you know that really badly worn out 80 grit can be used for 400. This is a really great discovery because it means that when one grit is completely worn out, it still isn't time to toss it. No sir, it gets promoted up to the next grade ... Ready to begin life anew. And, it's not just a social promotion. OK, maybe I'm seriously ready for that 12 step program. (pssssst! As my sponsor, will you you be paying for my sandpaper? Doesn't hurt to ask. You are interested in my recovery. )

 

[Sean Boyle]

admitted a fellow sand paper abuser here.

I think I need a sponsor to

Step 1 get off the forums and go to shop and throw out all of the multiple boxes and used sand paper that I still think I will one day use. the down side is once it is all gone I will have to rethink the expansion to the shop that officially stared today.

What's step 2

 

[DUANE POLING]

One other thing that many may not relized, if you fold sand paper over so the grit is touching grit, you are basicly sanding your sand paper and what you think is a fresh side is already used. I always cut my paper down so I am using only a small piece and it is always paper on the back. It is also easier to use all the grit on a small piece and then be able to throw it away and grab another. Seems like the paper goes further this way. I also have several small pieces of leather from old gloves or boot tounges to use as a backing when hand sanding. Old cabinet shop trick. Saves the fingers from getting raw.

 

[Bill Boehme]

I tear a sheet into quarters and then fold each of those into thirds. Works great.

 

[odie]

One other thing that many may not relized, if you fold sand paper over so the grit is touching grit, you are basicly sanding your sand paper and what you think is a fresh side is already used.

The problem________^

I tear a sheet into quarters and then fold each of those into thirds. Works great.

The solution________^



I've been folding in thirds for a long time, and I don't remember off hand, who it was that mentioned this. Pretty sure it was in one of the old VHS videos I watched about 25 years ago. I think it may have been Richard Raffan, but can't remember for sure. Anyway, if you fold in thirds, the grit will always be facing the paper backing.

ooc

 

[odie]

admitted a fellow sand paper abuser here.

I think I need a sponsor to

Step 1 get off the forums and go to shop and throw out all of the multiple boxes and used sand paper that I still think I will one day use. the down side is once it is all gone I will have to rethink the expansion to the shop that officially stared today.

What's step 2

LOL....... .....Did make me laugh!

step #2 is to not throw them all out. You know darn well you'll be needing some used paper for that odd job on metal....or some such thing! I save some of my used sanding discs for the same reason. If you throw them all out, that just increases the odds that you'll be using good sandpaper for something you'd rather not!

ooc

 

[Bill Boehme]

.... I've been folding in thirds for a long time...

The advantage of folding in thirds is that you have a better grip on the paper. If I was trying to hang onto the smooth back of a piece of sandpaper, I think that it would be easy for it to slip out of my hand. Then there is also the possibility when trying to hold onto the smooth backing of pressing harder on the paper to keep it from slipping. Anyway, I think that I have been folding the paper in thirds most of my life. I think that my dad taught me to do it that way.