@Steven_Whitecoff@Nedman cooling water does not contact the electrodes, that would really be bad :(.
Heh, I chase down technical mysteries because knowing how things work enable you to know why they don’t. Also the engineer in me wants to make things better and I love to solve unsolved problems.
Right now I am trying to find why LPS fail so often, this may be one reason but even then I cannot fully explain it so I am not done. It could be that the supply is find its the coolant that’t the culprit.
This thread is a good example. I took it at face value that RV antifreeze was ok just cause it was less conductive. I also thought that distilled water was nice to have.
Now that we know how this fails and generally why, we almost know what to avoid.
Use of antifreeze is recommended across the web and our data suggests that they are ALL wrong and putting their machines at long term risk.
BTW these discussions and thoughts are good cause we can help each other learn.
@Nedman I thought it was the fly-back that was internally arcing, they are infamous for HV break down followed by self destruction.
Two things did not make sense though. No visible arc, current did not change, and the plasma acted weird right at the anode during the screeching.
My hypothesis is that the conductive water causes an arc inside the tube at the anode. It finds a path through the epoxy and current flows through the water and out the cathode (@TwelveFoot idea), though the meter and to gnd.
If it wasnt for the tube making noise you wouldn’t even notice the problem other than a loss of optical power.
Short answer: the screeching was the arc inside the tube at the anode, nothing in the electronics. That’s my story (theory) and I am sticking with it … until proven wrong
Just thought i would wade in here and confirm that standard water and antifreeze isn’t the way to go i recently changed my water due to algae build up in the tank and i usually use dehumidifier water, but I’m short on supply of that as its winter… I put tap water and antifreeze in it last week, only done a few jobs since then but been experiencing the same issues. Didn’t put two and two together until i read this.
I’m getting the screeching and also some fluctuation in the readings on my ammeter, as well as noticeable dips in cutting / engraving performance… hopefully i have not done any long term damage to anything, ill be flushing the system again when my Distilled water gets delivered in a day or two.
Do you guys use an anti algae treatment for the water or do you go with a biocide?
@1981therealfury I would recommend an aquarium type algaecide, I think Alex Krause mentioned one above. You can also prevent algae from forming by protecting your reservoir from not only direct sunlight, but indirect sunlight as well.
@donkjr as far as I can tell looking at my laser tube, there is no epoxy interface between the gas side and the liquid side. It’s interesting that the screaching is coming from the tube rather than the transformer. Would that imply some kind of resonating harmonic?
Also depending on the electric susceptibility of the glass you could get a strong polarization of the glass which could lead to a polarization of the ions in the cooling water creating a secondary electric field. Not sure how strong the field would be and what effect that would have though. Just throwing a few thoughts out there.
Also I looked at the ingredients for auto antifreeze and they seem to typically include a buffering salt like sodium tetraborate to make the solution slightly basic, which is the corrosion inhibiting part, and accounts for the higher conductivity.
I confirm, switching to fresh distilled water stopped the screeching for me. For those who dont read the whole thread, I used Redline auto water “wetter”. Im pretty sure it did not screech at first but after a week it sure was. Probably not meaningful but my DVM said my Redline water was .5meg ohm and the distilled read 1.5 meg ohm, I’ll be checking that from time to time to see if it will change with time.
On a slightly different topic, I am also switching to 3/8" vinyl tubing, it will help flow even with the tube fittings being smaller and since the supplied tubing instantly adsorbed dye from the Redline I’m not thinking its the best material. To use the vinyl 3/8" tubing I’m using silicon sealant and a tie wrap on the connections since there is only the one barb on the tube.
@donkjr True, but you typically don’t need to add much algaecide and, as long as you stay away from the copper based stuff, it shouldn’t add much if anything to the conductivity of the solution. But definitely a data point to collect.
This looks interesting, i’m building my closed loop system at the moment and have an arduino controlled safety system monitoring flowrate and temps. I know this probe isn’t accurate like a proper meter but i should be able to calibrate it to only enable my laser when the voltage is within acceptable levels.
I imagine this code will only run once as part of the boot, i’ll have a DPDT relay trigger once its ran to remove any connectivity from the probe tips to anything electrical.
@John_Sturgess I have built a similar one, it´s pretty accurate to a “real” meter, enough for our usage atleast
I did the same thing, added the code to the arduino that already controls the security, water leaks, mirrors temps and stuff on my machine. It gives a hint anyway when the water needs to be changed.
@John_Sturgess adding a meter to the water as a constant measurement is a great idea. I wonder if its left in the water it will corrode, although it is using nichrome wires.
We could connect this and other readings to bluetooth or push it up through the cloud as an IFTT alert :)
One challenge is that we do not know what would be a good set-point other than the broad set of readings we have above.
Thanks for sharing …
Damn, I don’t need another idea to add to my K40 project list :).
I had the same problem with the laser cutter screeching a few weeks ago when using distilled water mixed with 20 percent car anti freeze, switched to new distilled water without the car fluid and the screeching is gone! It looked like the screeching was coming from the psu, but I am not sure about it. Unfortunately I could not measures the resistance of the water well, because I don’t have a suitable measuring device. My multimeter was not suitable for that job.
Some more data:
Additives:
Vinegar: 137 uS
Clorox: won’t measure, causes my meter to freak out. That can’t be good ? Not a chemist so I do not know what that means. Likely something to do with how IONS act in Clorox?
So at full concentration I would guess its a conductor or something else IONIC going on.
Practical use of chlorine:
Did some simple tests at 10% concentration. Meter is now reads something.
@10% concentration = 565uS.
…
Rule of thumb for adding Clorox
So assuming this is linear (which it not) then a 5% concentration of a 5 gallon bucket is about 32 oz and that would raise the conductivity 120uS. So the conductivity would increase about 4uS per oz of Clorox?
@donkjr Normal Clorox is a solution of sodium hypochlorite (NaClO) which in solution yields the ions Na+ and ClO- (hypochlorite). I imagine the meter freaked out because the ClO- ion is such a strong oxidizer. Were you testing it straight or diluted?
Also vinegar is a dilute solution of acetic acid which is a relatively weak acid. In general, weak acids have a lower conductivity than stronger acids because they dissociate into ions less. That is, at equilibrium there will be portion of the acetic acid that is not dissociated into ions. So there is an acid dissociation constant (Ka) which is the ratio of dissociated to undissociated concentration. This chemical equilibrium constant is therefore also affected by temp. The higher the temp the more dissociation and therefore more ions. So ideally you want to be comparing things at about the same temp.
@Nedman I expected there are errors in these measurements due to temp but my meter is supposed to adjust for that ??? I don’t think it will be a problem as we are playing with a 2 order of magnitude problem and I doubt that error is that big.
Note: I updated the post above after you read it and did some measurements at lower Clorox concentrations as you suggested.
From GoogleIT research and sloppy (averaging) math I concluded that an oz of Clorox in 5 gallons would kill algae and only raise the conductivity by 4uS.
I am going to drain my current tank and start from there.
Your meter will adjust for a type of temp related error but will not account for temp dependence of dissociation constants. That being said, I did some calcs and it looks like at the most you would get about a 5% difference for acetic acid between 25 and 40c.
Ok I’ll bite, why is antifreeze needed? Are you guys run this in an unheated garage? Is this not ok to run in the house with ventilation to the window while running?
i recently changed my water due to algae build up in the tank and i usually use dehumidifier water, but I’m short on supply of that as its winter… I put tap water and antifreeze in it last week, only done a few jobs since then but been experiencing the same issues. Didn’t put two and two together until i read this.