Adding tachometer to lathe

[Michael Anderson]

Has everyone,

Has anyone here added a tach to their lathe? I have a vicmarc vl300 from the late 90s. It works great, but doesn't have an rpm readout. It's not totally necessary for me to know how fast I'm spinning, but for some things it would be nice. I think I have the general process down pat, but am not sure on the gear. There are a lot of tach systems available online, and I have experience with 0 of them. Any recommendations? Or alternatively, any problems to look out for?

 

[Randy Anderson]

Michael, I added this simple setup to my first harbor freight lathe a number of years ago. Seems still available on Amazon and there are likely others like it. The hardest part of the process was adding a small flywheel on the back side of the headstock and a way to locate the sensor, magnet, etc. Took some fiddling around but eventually got it right. No idea how your lathe is setup so not sure it would even work. Net, the device was reliable and worked. The installation took some serious DIY.

https://www.amazon.com/gp/product/B01FQMI18Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[Michael Anderson]

Thanks Randy, I saw that option. Seems fairly straightforward on paper. How did you secure the magnet? Epoxy?

 

[Randy Anderson]

I think so but I can go check tomorrow. It's out in my storage shed. I'm sure I'll look at it now and think to myself "what was I thinking, there's an easier way to do this". My memory is a small flywheel in between the handle and the headstock with the magnet secured with epoxy. Getting the sensor on an arm that sticks out just close enough without hitting was tricky.

 

[Mike Drake]

I bought two of those since I have both a reeves drive and vfd on my P90. As Randy stated, you will need some creativity to mount the sensor and forethought on where to mount the magnet. I have a few ideas but I am still in the forethoughting stage.

 

[JeffSmith]

I, too, added a similar sensor to my Robust AB when I first got it. Bent a bracket from sheet metal to hold it, added a small rare earth magnet to the spindle with CA glue and attached the readout in a small project box to the control pendant. It worked very well. I thought I needed to know how fast I was going - all the lathes I had used up til then had a lovely read out…turns out that I really didn’t bother to use it after about a month. It came off shortly thereafter and I haven’t missed it in the last 12 years or so.

 

[Kevin Jenness]

Do you really need it? If(?) the scale on the potentiometer is linear you should be able to estimate the speed pretty closely based on that plus the pulley steps in use, e.g. full speed in second gear 2000 rpm, speed control setting 5, rpms 1000. If you can do tenths calculations in your head it's easy enough.

 

[Kirk Amidon]

Second the question of do you need it. IMO a tach is a device that measures reality. Reality being how fast the piece is spinning. Trying to match an RPM that "should" be used for a particular piece is folly. Your experience is different than all other turners, and just because turner 'x' turns at a specific RPM does not mean it is appropriate for you, or I for that matter. Same is true for two different chunks of wood - you might turn the first one at 'x' rpm, but the second one will not be balanced at that same setting.

It can be a nice thing to know after the fact, but too much emphasis is placed on this one measure.

FWIW - my first lathe was a reeves drive with a VFD and my current is a 3520A with no tach. I really don't see a need for it.

 

[hockenbery]

Thread chasing is one operation where dialing in to 300 rpm would be useful
Alan Batty gave a good lesson in an AAW trade show.
he said watch the threads on the spindle turn the lathe speed up to highest you can see the threads.
turns it that speed is 300+- and easy enough to dial in watching the spindle threads.

later I discovered it could cut threads on a minI lathe lowest speed 500. i was making little acorn boxes with threaded tops at a club demo booth. i Could get good threads because I could adjust to the higher speed. I was not able to successfully coach a club member to get threads at that speed.

that said I use the read out when available in just about every demo I do because an audience member will ask.

 

[Michael Anderson]

Thanks for the comments everyone. For the record, I agree that a readout is not necessary, and every situation is unique. Trust me, I'm an overthinker, and am generally safety conscious and not chasing speed numbers at all. And, for the price I'm willing to pay, I'd likely just get an rpm approximation anyway. I just thought it would be a fun addition to have, and was hoping for the kind of feedback I'm getting--a la, "is the juice worth the squeeze". It's fun to customize/modify things in relatively non-invasive ways.

 

[Doug Freeman]

While many dont see a need for a tach, I’m on the other side. Perhaps a permanent tach is not necessary but at least a hand held to verify speed with marks on a dial. I used one of the to verify the preset speeds on my HF reeves drive lathe, then made a speed chart vs attempting to remember.

I didnt look for a permanent mount laser/optical type. The reflector tape may get covered in dust needing occasional cleaning.


https://a.co/d/0yOaRqj

 

[Brian Gustin]

While many dont see a need for a tach, I’m on the other side. Perhaps a permanent tach is not necessary but at least a hand held to verify speed with marks on a dial. I used one of the to verify the preset speeds on my HF reeves drive lathe, then made a speed chart vs attempting to remember.

I didnt look for a permanent mount laser/optical type. The reflector tape may get covered in dust needing occasional cleaning.


https://a.co/d/0yOaRqj

Ditto.

 

[Michael Anderson]

Thanks for the link, Doug. That might be a better option. I hadn't considered a handheld tach, as I assumed the price would be out of my budget. Apparently not.

 

[Nathan Roper]

I had looked into this as well since my Vic is from 2005 and without a tach and had found a couple options. I don't know if either one would be better than whats already mentioned. The first is a big DIY option to build it from parts. It could be fun if you like to tinker. The second is a pre built unit from the little machine shop.

After taking a 101 class in February I was really intent on getting a tach set up. I felt like I had done enough bowls that I was okay on that front but wanted one for the other items we had turned and that I wanted to practice on. I haven't felt like spending the money on one so I've made do.

I'm intrigued by the handheld tach though that Doug linked. For the price and ease of use, it could do the trick while I learn my lathe and understand what speed corresponds to what setting on my speed dial.

 

[Randy Anderson]

Here are a few pics from my early setup. I don't use the lathe any more but it did work well enough. The lathe came with an AC motor and a belt system for changing speeds. I soon changed to a variable speed DC motor so the tach was somewhat helpful although the torque was not great. Note that the magnet is turned 90 degrees to the sensor. I found this worked better. The opening under the display was for a 9V battery. Good initial plan but battery life was not good.

 

[Dean Center]

In reality, there are only 5 speeds on a lathe and after 6 months of turning, you can judge them adequately without a tach. In order from lowest to fastest, they are:

Reed sanding-->too slow-->comfortable fast-->scary fast-->Jimmy Clewes

 

[Michael Anderson]

Dean, hahahaha tht made me laugh. I’ve watched some Jimmy Clewes videos, and was always amazed at how he could remove so much material so quickly from big platters. Turns out, the solution is MORE RPMS kidding..

 

[Michael Anderson]

Thanks for the images Randy, I really appreciate the effort. Good to know about the magnet position and the battery.

Nathan, Vicmarc club! Thanks for the information. I think I’m also leaning toward the handheld method.

 

[JeffSmith]

Michael - I, too appreciate the joy of modifying my tools - that's why I added the readout to my lathe when it was new. I found myself with a piece of equipment that I was not familiar with. After years on a smaller lathe I had grown accustomed to the sounds it made at different speeds and I really didn't rely on the readout very much as it happened. With the new lathe my rationale for adding it was two-fold - it would provide data and look very cool attached to the pendant.
In practice, I adapted quite easily to the new sounds and it wasn't cool enough to keep in the long run (my opinion only).

I took it all off and laminated a copy of the speed chart the size of a business card and attached that to the cable for the pendant. I consult that on the rare ocaision that I'm curious about the speed.

I do have one the hand-held tachs - I use it on my drill press when needed, otherwise it sits in a drawer.

 

[Michael Anderson]

Thanks Jeff, I appreciate the comment and deep explanation. And you’re right—part of the joy of modification is the “this would be cool to have” factor, regardless of the benefit.

 

[Marc Banka]

It’s a data point, and a great one at that. Speed is one of the most important aspects when considering our work, and making it a guessing game (when it feels right) doesn’t make sense to me. Feels right to whom? The 30 year veteran or the folks just starting, which would be the safety part.

Maybe it doesn’t matter much to some of you, but I really like data points. They give me security. Things I like to know when I’m in the shop:
The time (lots of good reasons)
The weather (especially if I plan chainsaw work) ( know what clothes to wear)
Species of wood I’m working
Size of wood
Weight of wood
Which gouge, at which angle
Toolrest height
etc., etc.
RPM of spinning wood (why not?)

Transferability is huge, right? I can share my speed to anyone, anywhere in the world, in any language, and can store and recall that data point.

Data is good, information is good, tachometer is good.

 

[Michael Anderson]

Thanks Marc. That’s a good perspective.

 

[JeffSmith]

I guess. It’s all relative - if I know that #2 on the speed pot is 75 rpm, does. It really matter if a readout would indicate that 1/32” past the #2 is actually 79 rpm? I know from the speed chart about how fast I’m turning…

 

[Kent Jaffrey]

My last lathe didn’t have a tach so I got one similar to what Doug linked above and made a note of the rpm’s at the different knob positions and it worked really well. My new lathe has a tach so I use it as a double check, but am finding I am staring to use knob position as a default anyway. So for most things the knob and the readout are a toss up.

One exception is that I do like to keep an eye on the readout during coring. It is much easier to see if I am starting to bog the machine down by watching the rpm rather than to hear it, so that is one plus for a display.

 

[Earl McLain]

While many dont see a need for a tach, I’m on the other side. Perhaps a permanent tach is not necessary but at least a hand held to verify speed with marks on a dial. I used one of the to verify the preset speeds on my HF reeves drive lathe, then made a speed chart vs attempting to remember.

I didnt look for a permanent mount laser/optical type. The reflector tape may get covered in dust needing occasional cleaning.


https://a.co/d/0yOaRqj

I have the same one, use it on a Sweet 16. Put some of the tape on my little Rikon and it seems to match the Rikon's readout within 10-15 rpms. I rarely use it, as noted by others i mostly use it for feel. Don't know if that would be close enough for the threading that Mr. Hockenbery mentioned, but i also don't know whether the discrepancy with the Rikon is because the Rikon or the handheld is more accurate. Or if they are both equally off the mark.
earl

 

[Steven Forrest]

I have an older Stubby, no read out. I bought a cheap tach on Amazon - used it once, mapped the speeds, made a little chart, laminated it, keep it by the headstock. I hardly use it, but I have it if necessary.

 

[Mike Selser]

I have an older Stubby, no read out. I bought a cheap tach on Amazon - used it once, mapped the speeds, made a little chart, laminated it, keep it by the headstock. I hardly use it, but I have it if necessary.

Did the same thing when I first got my Stubby except I used a free tachometer app on my iPhone.

 

[Michael Brown]

I put a tac on my jet1015 using a hall effect setup from China. I ended up sacrificing one index point of the pulley on the spindle. I 3d printed a mount to fit into the space under the pulley between the belt paths. It works perfectly.

 

[Michael Anderson]

Nice setup Michael!

 

[robo hippy]

Oh no, another overthinker in the group...... My newer lathes all have read outs on them. My older lathes do not. I learned without a read out, and still don't use them, even when available. I always start slower, and work my way up till it 'feels' right. Having attended the last Oregon Woodturning Symposium, I found that people were always asking what RPM the demonstrator was using. Most had to stop and look. I haven't tried hand chasing threads yet, but will keep that image of 'till you can't see the threads' in mind. I do have a stash of box wood....

robo hippy

 

[Michael Anderson]

Oh no, another overthinker in the group......

Ha! To be fair, I've never actually used a lathe with a readout before. Seems handy. Like Marc said, I too like data, even if I don't always prioritize the "knowing".

BUT, based on the feedback here, I think I'm going to buy the hand tach, and create a little laminated readout a la @Steven Forrest

 

[odie]

What is the point of knowing the speed? Is it to know the exact rpm, or is it to have the ability to start and stop the lathe, while returning to a specific rpm?

For me, it's the latter, and the reason is the specific rpm I want to maintain, is that which I've determined is the best rpm with the least inherent vibration. This is the rpm that allows you to get the best possible cut with your tools. (considering everything else in the equation is otpimal)

My solution is very simple. I have a pointer that attaches to the center of the potentiometer dial with a magnet. When I find that perfect rpm, I adjust the pointer to point straight up. When starting up, I simply bring the rpm up until the pointer is straight up.....no problem, but I never know exactly what that rpm is. All I know is it's the best rpm for one specific spinning piece of wood.

-----odie-----

 

[Doug Freeman]

What is the point of knowing the speed? Is it to know the exact rpm, or is it to have the ability to start and stop the lathe, while returning to a specific rpm?

For me, it's the latter, and the reason is the specific rpm I want to maintain, is that which I've determined is the best rpm with the least inherent vibration. This is the rpm that allows you to get the best possible cut with your tools. (considering everything else in the equation is otpimal)

My solution is very simple. I have a pointer that attaches to the center of the potentiometer dial with a magnet. When I find that perfect rpm, I adjust the pointer to point straight up. When starting up, I simply bring the rpm up until the pointer is straight up.....no problem, but I never know exactly what that rpm is. All I know is it's the best rpm for one specific spinning piece of wood.

-----odie-----

Great question. IMO it depends on the experience level. Obviously for those that learned w/o it, learned to “feel” what they liked and worked. For the newer turner its important to know rpm, ~10%, of what a demonstrator is running, to help get a “feel” for what speeds to use for various cuts.

I use rpm to refer to my surface speed chart to give a starting point for the dia and cut/tool. I used the hand held to build an rpm/surface speed chart when the machine didnt have one. Potentiometers age and can get touchy, 500 rpm changes with just a nudge. I want to know if its spinning 2000 or 2500.

 

[odie]

Potentiometers age and can get touchy, 500 rpm changes with just a nudge. I want to know if its spinning 2000 or 2500.

That would be true, Doug. My Minarik potentiometer has been in constant daily use for more than a decade, and it still works smoothly throughout the range for me. Some lesser quality ones may be different, I'd presume....

-----odie-----

 

[Doug Freeman]

That would be true, Doug. My Minarik potentiometer has been in constant daily use for more than a decade, and it still works smoothly throughout the range for me. Some lesser quality ones may be different, I'd presume....

-----odie-----

You presume correctly, I’ve experienced the worn ones.

 

[Randy Anderson]

It is an interesting thing. Do I like have a tach on my lathe? Yes. Do I look at it. Seldom. About the only time I pay attention to it is when roughing a big out of round blank and knowing I can get it up to 350 for when I stop to check it often during the process then creep up a bit. Different point but, I've wondered about how folks turn with headphones and music playing. I can't. Sounds of the cuts and vibrations vs whatever speed that might be give me very good feedback that I rely on. I feel "disconnected" from the process when I can't hear it clearly. Now for sanding, that's different. Headphones on, noise reduction and my podcasts playing.

 

[Neil S]

Having stated turning twenty years before the first variable speed lathes came along (Reeves pulley models may have been earlier), I'm with those that don't feel the need to see a number to know I have the lathe spinning at the revs I need. Never had a lathe that showed RPM numbers or felt the need for that. However, pulley range selection has always been important for safety.

Since acquiring my first variable speed lathe my practice has been to start off every new blank at minimum speed for the selected pulley setting and, while standing out of the firing line, dial up the revs with the other hand on top of the headstock to detect the start of any isolations and back off a tad if and when that happens. The revs at which any isolations will happen varies from one bit of wood to another and as the turning progresses.

 

[Tyler Pierce]

It is funny how much a tachometer helps. The more info the better.

 

[Vincent Vogel]

My old lathe didn't have a tach just four different speeds by changing the belt on a pulley. I made a cheat sheet with the speeds of each pulley on it and eventually I learned which pulley to use for which operation. My new lathe has a tach. It's a nice feature, but I don't get too excited about dialing it into an exact rpm. I like the potentiometer to adjust the speed vs the pulley system. I do as most have said, I just turn the knob faster or slower as needed for whatever operation I'm doing. Only thing I get fussy about a certain speed is when I use the spiraling attachment or when I've tried to chase threads.

 

[R Henrickson]

All I know is it's the best rpm for one specific spinning piece of wood.

-----odie-----

Amen. I had lathes with rpm readout for years. I haven't had one for 7 years now and don't miss it. As Odie said, the best rpm varies from piece to piece. I adjust speed to minimize vibration. Optimum can even vary spindle to spindle. When it involves something where a relatively specific rpm may be preferable, I have learned to judge it visually. When I teach in classrooms where lathes have readouts, I set by eye and may check. I'm close enough. It's more important to optimize for vibration and safety than to set precisely, e.g., 400 rpm.