Lathe strobe

[Gedeon Spilett]

What you need is a DC light (i.e. a car headlight with battery to keep things simple and cheap) chopped at the same frequency of the lathe. It can be a mechanical shutter like in a movies projector connected with the lathe spindle.

 

[Rocketcaver]

Ok, I'll chime in here.
Get a few of those real bright white LED's.
Fasten a magnet to the lathe chuck, or somewhere else out of the way.
Use a reed switch or hall effect sensor to turn the LED array on when it "sees" the magnet.
This will give you a pulse of bright light on every revolution of the work. If your LED array is bright enough (you can get some VERY bright LED's these days), you will have your strobe effect.
A regular car headlight does not turn on and off fast enough due to the relatively slow heating and cooling of the bulb filament, but the LED array is essentially instant on and instant off.

Later...

Oops! I see that MuellerNick has already made basically the same suggestion. That circuit would be pretty easy to duplicate, and would do exactly what you want.

 

[MuellerNick]

Initially, I thought a reed switch would not be fast enough. But they go up to 300 Hz. That would be 18000 RPM.
So a reed switch is the simples way, together with the LED strobe I linked to.


Nick

 

[GailInNM]

For safety reasons I would like to see this thread die at this time. As it does not violate any rules I am not locking it.

Our hobby is dangerous by it's nature. Any time we do something that makes it more dangerous should be balanced by additional safety measures and an examination to make sure that any additional hazard is necessary to accomplish the task.

Gail in NM

 

[MuellerNick]

That's what you get under professional conditions. Certainly done with a intense flash in a dark room.

[ame="http://www.youtube.com/watch?v=78XYpr2Vnvg"]YouTube[/ame]


Nick

 

[skyline1]

GailInNM

I agree with you entirely and as for car tacho strobes not being dangerous. They are, for just this reason. There are bold warnings printed on them to this effect.(mine certainly has).

Regards Mark

 

[MuellerNick]

There are bold warnings printed on them to this effect.(mine certainly has).

My US-made lathe has about 2 square meters of warning stickers on it with blood and body parts splashing around.
But I still can stick my head between the running chuck and bed if I prefer.


Nick

 

[skyline1]

Hi Nick

Yes quite true, This modern Health and Safety Obsession does go a bit far sometimes. Most manuals for anything the slightest bit technical seem to be 50% safety warnings and 50% operating instructions. And some of them are obvious to the point of being silly Who is likely to immerse their T.V. in water for example but the warning is still there. A strobe device like this that can make a rotating part appear stationary does carry an additional risk though and a very real one.

Regards Mark

 

[lampy]

I'm missing something What is the benefit of the strobe other than making a cool video to market your cutting tools?

 

[ELM6061]

I'm missing something What is the benefit of the strobe other than making a cool video to market your cutting tools?

Using a metal lathe, you know the dimensions of your raw material and also the dimensions of the material you are going to remove. You then control your sight/cuts using your dial indicators, specially if they are internal cuts.

Using a wood lathe and specially true if your raw material is tree burls or logs, you have no idea of actual dimensions and all your cuts are by freehand and by sight. Using a wood lathe, you have no dial indicators and if you make a cut to deep or the edge of your chisel catches on an edge of your work piece, the consequences can be catastrophic. As shown in the video with an internal cut and with an incursion to the work piece, having a strobe that fires with each revolution can actually be seen as having a safety feature, as it shows you exactly where you are cutting and how much material you have left.

I have seen one made using a reed switch, but sorry have no idea of the wiring diagram. Shouldn't be to hard to make up though.

Eddie

 

[lampy]

Thanks for the explanation. So it is more of a wood lathe application that could also be used on a metal lathe.

 

[ELM6061]

Thanks for the explanation. So it is more of a wood lathe application that could also be used on a metal lathe.

I am not an experianced machinist in either application (wood, metal), though I have watched a strobe being used on a wood lathe several times and that was the explanation/reasoning I was given.
As for this application and the reason this thread was started, yes it is for a wood lathe.

My brother is a Woodturner (can't convince him to stop using that brown stuff)
He wants to have a strobe synced to his lathe (approx 50 - 2000 rpm).
Would an auto timing light work? If so, what to sync it? Hall effect sensor? How would one hook this up?
I'm at a loss with 'lectrical stuff.
Thanks for any suggestions

 

[dman]

i haven't read the whole thread but i fail to see why the automotive timing light is being discouraged. a timing light uses some kind of clamp sensor, there are a few types but my understanding is that they are all designed to measure current not voltage.

http://en.wikipedia.org/wiki/Clamp_meter

the voltage of the source it's detecting is irrelevant. the energy that the pickup provides is very small and can likely be created with a hall effect sensor, if not directly you can likely step up the signal easily with a transistor and external power source.

a timing light is cheap enough to cut up and the cheaper ones actually work better, the one with digital displays and timing knobs are never as accurate as the non adjustable ones.. you can either do some research and get a better idea of if it works or just cut the pickup off of one, get a 12v transformer and coble up a sensor and try it out.

 

[MuellerNick]

a timing light uses some kind of clamp sensor, there are a few types but my understanding is that they are all designed to measure current not voltage.

A timing light uses capacitive coupling. One side of the capacitor is the clamp, the other the HV wire. If you want to get awake (= get an electrical shock), simply touch the wire coming from the clamp. There should be at least something like 400 V. That's the voltage needed to ignite a xenon bulb (that are used in almost all timing lights).


Nick

 

[dman]

A timing light uses capacitive coupling. One side of the capacitor is the clamp, the other the HV wire. If you want to get awake (= get an electrical shock), simply touch the wire coming from the clamp. There should be at least something like 400 V. That's the voltage needed to ignite a xenon bulb (that are used in almost all timing lights).


Nick

my timing lights have two wires running to a clamp. if it was capacitive it would only need one and if the voltage drove a xenon bulb directly like that it wouldn't need a 12v source only a grounding point. but my lights do need a 12v source, both positive and negative.

maybe the lights they use i europe are different. i'm sure that's how it was here in the old days but all the lights i've handled don't appear to work that way.


edit; as it's been mentioned above, after some searching, capacitive timing lights and inductive timing lights both exist. an inductive timing light may serve the purpose. but not a capacitive light without some extra circuitry.

 

[MuellerNick]

if it was capacitive it would only need one and if the voltage drove a xenon bulb directly

I wrote "ignite". The cheap timing lights take off part of the high voltage and lead that to the ignition contact of the tube. That has nothing to do with the voltage for the bulb that makes the flash. A Xenon tube has 3 contacts, not just two.


Nick

 

[dman]

I wrote "ignite". The cheap timing lights take off part of the high voltage and lead that to the ignition contact of the tube. That has nothing to do with the voltage for the bulb that makes the flash. A Xenon tube has 3 contacts, not just two.


Nick

all i can tell you is that my timing light in fact has an inductive pickup. i just pulled apart the clamp and it contains a u shaped core and is wrapped with a coil that drives the light circuitry. capacitors have two plates separated by a dielectric sometimes a cylinder inside a cylinder seperated with a dielectric (the plug wire casing would be the dielectric in this case). inductors have a permeable core wrapped in a coil. believe me many timing lights do not use capacitive coupling.

i could be wrong but is it some coincidence it says "inductive timing light" down the side?

and just for S's and g's i disconnected the cables from the light and started up my car with the clamp on the number 1 cable to measure the voltage and got a mere 3mv AC. i know that's RMS voltage and I'm not measuring a full sine wave so it's not a clear picture of what the peak voltage is so i then stuck my thumb over the leads and felt absolutely nothing.

I've already admitted there are capacitive lights but I've never seen one for sale in the states. I'm saying that a light with an inductive pickup may work for the purposes of the op.

if i had a scope i could measure the signal voltage and try to trigger the light without the pickup but i don't have the equipment.