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Digital RPM readout......do you use it?

odie

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I see the digital rpm readout on nearly every new lathe being made these days. I can only assume this is something that's there because of consumer demand. Well, I've turned for 35 years now, and never have had digital rpm readout......and, I don't feel handicapped at all. I know the rpm at the top of the range for that pulley, and easily estimate the rpm by how much percentage of full use of that speed I'm using on my potentiometer. If my belt is on the 1200rpm range and I'm using about 75% full throttle.....I'm doing approximately 900rpm. To my thinking, it matters not if it's not exactly 900rpm......so, why is it important to know the exact speed?

So, what am I missing here?

Note: Every single time I'm using turning tools at the higher speeds, I'm adjusting the speed for the least amount of vibration I can detect though feel, and other indicators on my headstock.......so, rpm is secondary to the vibration at that rpm. (Of course, this is not necessary for sanding speeds.)

ko
 
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I have never had one either. Can't see a need for one since I learned by feel rather than by numbers. Even when I demo on a lathe, I don't use the read out.

robo hippy
 
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I thought it would be really cool and useful when I got my new lathe. Not so; I still just turn up the speed until I get scared and then back it down a bit.
 
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i have a digital readout.....yes the vibration is the most important criteria. mostly I look at it when first starting roughing out of balance and out of round blanks......once I get blank fairly balance can increase speed, usually to 500/600 rpms to shape and 800/850 for finishing cuts, for hollowing about the same.....but if any vibration lower speed unless already at low speed, sometimes if only going 200/300 and fairly round you can increase thru the vibration .....must be very carful at that point......called harmonic vibration??????? I like route signs on highways also........most turners that demonstrate turn at higher speed than I do, I rarely turn over 1000 rpms where they do most of the turning at those speeds, suppose to get a better cut at higher speeds.......turn at your comfort level
 

john lucas

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No. I've had 2 lathes with digital readout and the only reason I look at it at all is so when someone asks what rpm do you turn this or that I can at least give them a ball park answer. The smart ellick answer that is really quite true is I turn at whatever speed feels comfortable and safe. That usually turns some people off so I try to give some sort of educated quess. I have the older 3520A. The actual readout is meaningless unless you look at the sheet that came with the lathe to interpret.
 

hockenbery

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Few experienced turners use the rpm read outs.
I will use it in a demo if someone asks what the RPM IS.

RPM a use reference point for getting started.

RPM is sort of critical for some thing like thread chasing.
Someone starting to chase threads for the first time can find RPM useful
I was told to slow the lathe until you can see the threads on the spindle.
 
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I have always had one on my lathes. I use it all the time. When I do bottoms of bowls with a vacuum I try to keep the speed around 600, when jam chucking I like to stay below 600. For bowls I find little advantage to speeds over 1200. I have always had one so I use it. I have been turning 12 or 13 years don't really remember which.
 

odie

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Yep......that's kinda what I figured! :D

Probably 90% of new lathe sales are from first time buyers. That's probably a key to understanding why so many new lathes have the digital rpm readout. I suspect many new buyers want it, because they think it's important. From the manufacturer's point of view, it doesn't make any difference if it's something a turner needs, or not.......what's important is what makes the person buy their lathe! :rolleyes:

ko
 
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For an experienced turner the digital readout is really not needed, recently I watched several
video's from blind wood turners, I am sure they would not see any value in the feature. We all
know by the sound of the lathe and the balance of the piece if we are in the zone.
 

Bill Boehme

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I can see where a beginner feels lost in this type of woodworking that is unlike any other aspect of woodworking. The cutter is stationary while the wood is a blur as it spins dangerously close. And, occasionally for some inexplicable reason the wood explodes with a loud bang or launches itself into hyperspace. As a result of being shell shocked the beginner decides that they need to exactly emulate every aspect of the way that a demonstrator or mentor turns. So they see the demonstrator turning something sans catches or launching the turning and naturally the precise RPM is probably their key to turning catch-free. One might hope ... after presuming to have exhausted all other theories. :oops:

It doesn't take long before you intuitively know what speed feel right and then a display becomes superfluous. If my lathe had one, I might feel obligated to look at it instead of the piece of wood that I am turning. That might not work out too well for me. :rolleyes:
 

AlanZ

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I don't "need" the tachometer on my cars, but I do use them regularly. I do like, but don't need, the shift indicator on our MINI that displays the current gear and suggests shift points.

All of my lathes are variable speed, only one has a built in tach, and it lets me set specific speed rather than guessing (not that guessing is a bad thing)

I have installed reflective strips on my other lathes so I can use a handheld laser tach to confirm the speed when I am curious.

For example, some time ago, a guy insisted that we should not use magnetic bases on lamps to attach them to the headstock. He said that the magnets causes the lathe to slow down.
So I tested this on each of my lathes, with various magnets and configurations and found no difference in rpm.

Measuring something is only really useful if you want/need to know the information.
 
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I'm still pretty new to turning and I just automatically look at the RPMs when I adjust the speed of the lathe. Now that you mention it Odie, I'm sure I could get by without a tach though. I'd just watch the piece I'm turning come up to speed and judge by sight and sound when to stop rotating the knob.
 
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AlanZ wrote: "For example, some time ago, a guy insisted that we should not use magnetic bases on lamps to attach them to the headstock. He said that the magnets causes the lathe to slow down. So I tested this on each of my lathes, with various magnets and configurations and found no difference in rpm."

LOL, This reminds me when I wrote a very logical paper explaining why current flows better through black wires... Had to do with black body emissivity as I recall... Helped physics students develop critical thinking...

73, Ely :cool:
 

odie

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Measuring something is only really useful if you want/need to know the information.

Hi Alan.......I guess if anyone "wanted" to know the rpm, that's a good enough reason for that person to have a tachometer. What I don't get is the "need" to know. Is there a particular reason to necessitate a condition of....."need"?

Funny......but, when John mentioned that his car with an automatic transmission had a tachometer, I couldn't, off the top of my head, remember if mine had one, or not! It does......but, I couldn't remember.....until I recalled that on occasion, I might start the engine, and be sidetracked for a moment. These modern engines are so smooth and quite, that the only way I can tell if the engine is running, or not......is to look at the tachometer! o_O

I think most of us on this forum are old enough to remember the days when it was really bad to try and start a car that was already running!......I wince to think of the grinding of gears between the starter and the flywheel! :eek: I've done that with the modern cars, but they have some sort of "override", or something that prevents that awful grinding of gears!

That ain't the way I remember it was in my old '51 Chevy, though! :D

ko
 
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I have a rpm read-out. I like it, but I also like the bicycling analogy. Back in the day when my knees were younger, and I had delusions of athleticism, I got a bike computer with a cadence meter. It's a training aid. The one time I really pay a lot of attention to the rpm readout is when I have the buff on the spindle, and when I have cole jaws or other delicate chucking.
 
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I recall teaching stick shift ,, the wantabe driver did not have any feel for the clutch....What finally clicked for her was to watch the rpm s to ease the clutch out, within 1/2 hour she was vastly improved, and within a week hell on wheels
 
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Ok I am not a professional and have only been turning 11 years so I can still relate to the question "what speed are you using?". Not because it is important , but it can give the beginner a relation to safety. I do not recommend turning at 3000 or on a rough out starting at 1200, but yes speed can give the beginner and some intermediate a starting point. What I like about having it is that most lathes with it (larger lathes) have a variable speed knob to get where you want and for me that makes it worth the trip.
 

Emiliano Achaval

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I dont think that I have even looked at it. But... Since I have been chasing threads, its very important to have the same low speed for consistency, when making boxes I use it all the time now, I'm starting to get pretty good at finding the speed. We have an engineer in the club, he's going to set up one button for the 250 rpm!! Beginners always ask what speed are you at, I never know!
 
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A readout is handy for conversation purposes when explaining turning concepts to newbies and it adds to the "wow" factor when selling and folks have questions. Otherwise, I go by feel. I have a magnetic base light that sets on the headstock. If it's shade is shaking it's time for an adjustment.
 
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None of my lathes have a readout, but I do know what the RPM’s approximate are, and keep that in mind when drilling and sanding especially with the VFD.
When starting a new rough half log or other unequal piece I try to use my experience and start with the speed I expect to be right, however I always step aside starting up, just in case, and have had occasion to cut the power fast :D.
So even if there was a rpm counter, it would not do me any good there, and when balanced I usually turn much slower than most, heck my top speed on my large lathe is 1510 RPM running free.
Most times I will use 550, 790 or 1000 rpm to do my turning with 75 rpm the low speed on there, don’t need no readout for that as these speeds are set manually :D.
 

hockenbery

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My first lathe was not variable speed just five pulley positions. You had to guess which would give tolerable vibration until you roughed out the vibration. Whenever changing pulleys, I always turned the lathe on then off quickly to gauge the vibration. If it was ok turn it on and turn.

With VS i mount the blank, set the speed dial to a few rpm, turn on the lathe, run the speed up until it vibrates too much then back off a little to acceptable. Then I turn the speed up past the bad vibration speed. Usually there is a faster speed with less vibration at maybe 50-200 rpm faster as the harmonics cancel.
Anyway the correct speed for me with that blank mounted using those centers s found through trial and error.
 
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Fascinating replies. I started with a readout and know exactly what speeds to sand and drill for various woods at various diameters, learning these speeds by my senses. Just assists in effective repeatability. I have never written them down, I just know what I’ve learned over the last 8 years of having this tool in front of me.
 
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My lathe as a speed control but no readout so I just guess and adjust when I feel it's too fast or slow. What I feel is great about the Nova DVR's and others like them is the fact that you don't have to change belts. I am relatively new, only turning a little over 2 years, but I like the fact that I can keep the belt on the middle pulley for most turning and control the speed within a wide range of speeds within the mid-range of my lathe's capabilities. Then when I want to go slow, I can move the belt and also operate within a range. The same with the high range. When I upgrade my lathe I will look for a lathe that allows complete control via a speed control rather than via belt movement. It just is less trouble. The readout probably isn't significant except that it would give me a better idea, at this point, if I'm in the range I want to be.
 
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About the only thing I use the readout on my PM3520C for is the digital indexing system.
 
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I use my read out all the time on my Galaxy to set my speed before l turn my lathe on. I consider it a safety feature to know my speed before l start up. I don't find the read out that useful fine tuning my speed.
 

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I see the digital rpm readout on nearly every new lathe being made these days. I can only assume this is something that's there because of consumer demand. Well, I've turned for 35 years now, and never have had digital rpm readout......and, I don't feel handicapped at all. I know the rpm at the top of the range for that pulley, and easily estimate the rpm by how much percentage of full use of that speed I'm using on my potentiometer. If my belt is on the 1200rpm range and I'm using about 75% full throttle.....I'm doing approximately 900rpm. To my thinking, it matters not if it's not exactly 900rpm......so, why is it important to know the exact speed?

So, what am I missing here?

Note: Every single time I'm using turning tools at the higher speeds, I'm adjusting the speed for the least amount of vibration I can detect though feel, and other indicators on my headstock.......so, rpm is secondary to the vibration at that rpm. (Of course, this is not necessary for sanding speeds.)

ko
My digital readout quit working on my Jet 1642 but I don't really miss it. I do a lot of multi-axis turning so I use an RPM just 'short' of the vibration RPM. Having a variable speed control is a big plus!
 

brian horais

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I use my read out all the time on my Galaxy to set my speed before l turn my lathe on. I consider it a safety feature to know my speed before l start up. I don't find the read out that useful fine tuning my speed.
Mike, I always use my speed control to return my RPM to zero before shutting off the lathe. I don't want the lathe to start turning when I switch it on, not until I am ready
 
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I consider myself a beginner to intermediate turner. I recently upgraded from a Jet 1236 to a Jet 1840 which has the DRO. It seems to me that speed is a function of many things - dry vs green, species of wood, method of cut, but most importantly, diameter. After all, isn't it the speed of the wood passing over the cutting surface that's most important? As you move from the center to the outside of a round object, the wood to cutter speed may increase by a factor of many X's while the lathe is at a fixed RPM. I only occasionally look at the DRO mainly out of curiosity. I do like being able to sand at very slow speeds (under 100 RPM) to avoid overheating the paper. I'm not sure the DRO really helps in that respect either.
 
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I don't have a display on my lathe and have never felt as if I needed it. Just like driving the old grain truck during harvest when I was a kid we shifted gears by listening to the engine (the tack was broken), I listen and feel when I'm at the lathe. Actually, now it just seems intuitive on where to set the lathe speed. I did a demonstration a couple months ago and was asked many times what my rpm was, it was only then that I would look at the display.
 
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When I started turning seriously (bought the second lathe), it had a DRO. Got used to looking at the numbers when doing something critical or just something new to me. After about a decade, I bought my last lathe - no DRO (American Beauty). I felt a little lost at first not knowing what the new sounds were telling me and rigged up a DRO right away.
After about a week I wondered why I had bothered. Since it was in a different position - a small box on the side of the control pendant - I found that I wasn’t paying attention to it. A month later I removed it and don’t miss it in the least. I think I just needed to get a feel for the relative sounds the new lathe was making and adjust my brain...
 
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I use the rpm dro on my galaxi for everything I turn. With the exception of an out of balance situation, surface cutting speed determines rpm to start at, then tool type, edge condition, and wood type or condition can move the speed up or down.

As for using sound, the dc is always on when turning and I cant hear the lathe run - the galaxi is very quiet. I can feel and usually hear vibration, and make speed adjustments based on that. With bigger pieces and slower rpm, under a 1000, it easy enough to sense the speed, but with smaller stuff it gets more difficult to tell if its 1500 or 2500 rpm. Once the sound of the lathe at a speed is synced in your brain you can get close. Doesnt work when you cant hear the lathe running. I would be lost without a dro, not to mention I would really miss the speed presets on the Galaxi.
 

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I've never had a lathe with a tachometer installed (my new Robust AB doesn't come with one, or even, I think, offer it as an option). I guess I don't know what I might be missing, but I've never felt the lack. I just look at and listen to the wood and I can pretty much tell how fast it's going (too slow, about right, wicked fast...)

Even if I had one I can't imagine wanting to believe it rather than what the wood and my tool were telling me about my speed.
 
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I turned for perhaps ten years on lathes with DRO (Jet 1642, PM 3520). I referred to it less and less as time went by. My current lathe does not have DRO, and I've never missed it. I set speeds by sight, with adjustments if necessary for vibration or whatever. When I'm using a lathe with DRO, such as in teaching classes or doing a demo, I usually forget that DRO is there and set specific speeds by eye; when I check, I'm usually close to the target.
And, as Roger remarked, what the wood and your tool are telling you is critical. Each case may require slightly different settings.
 
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