Question about mA Meter on Chinese Laser (With Video)

[Brian Leavitt]

I just installed a mA meter on my Chinese laser, but I'm not getting much of a reading from it. It's all explained in the video. If I fire the laser at 20-29%, it'll register up to 5mA, but only when the tube makes this high pitched, faint squealing noise. No noise, no reading. Also, if I fire at 30% and up, no reading. The laser fires and engraves as low as 20%. If I go below 20% on power, it's will fire, but it is extremely faint. I get a movement of the mA meter as low as 13% power. I feel like the issue is the tube itself, but I wanted to get the opinion of you guys who are more familiar with the Chinese machines.

Here's the video - Yes the garage is a mess:

https://youtu.be/R-0g9givv4k

[Scott Marquez]

There is a piece of engraved wood inside the machine, did that machine do it?
Was your machine engraving before you installed the meter?
If your machine works but doesn't give a reading, do you think you have it wired backwards?
Scott

[Brian Leavitt]

Yeah, the machine engraved the wood. It's been engraving OK, but it's not very good with cutting. I struggle to cut through 1/8" plywood with it. I don't know if that's because of the tube or the super cheap optics, though.

I don't *think* the meter is wired backwards. I've read that if it were wired backwards, the needle would move down instead of up when the laser fires.

[Bert Kemp]

you say its hard to cut 1/8 plywood.several things could cause this
1. is it a true 50 watt laser and not a 40 or 35 watt with a max zap of 50.what the length of your tube?
2. Exact focus for good cutting
3. what lens are you using 1.5",,2.0 ect4
4. clean lens and mirrors very important to get the best cutting.
5 what speed and power settings are you using.you have to go slow with almost full power. remember the ply has glue and plugs in it, makes it difficult to cut sometime.

[Brian Leavitt]

you say its hard to cut 1/8 plywood.several things could cause this
1. is it a true 50 watt laser and not a 40 or 35 watt with a max zap of 50.what the length of your tube?
It's a 50. It's 1050mm long - advertised as a 60 watt.
2. Exact focus for good cutting
I've tried different focus levels to make sure focus isn't the issue.
3. what lens are you using 1.5",,2.0 ect4
2.0"
4. clean lens and mirrors very important to get the best cutting.
The mirrors and lens are all spotless, but the mirrors are the low quality silver ones.
5 what speed and power settings are you using.you have to go slow with almost full power. remember the ply has glue and plugs in it, makes it difficult to cut sometime.
I've been running the power at 85 to avoid overdriving the tube. For speed - I've gone as low as 2mm/sec. At that speed, it just chars the cut and never gets all the way through. To get it to cut all the way through, I have to set the power to 85, speed to 10mm/sec, and go over it about 20 times. Even then it doesn't always cut all the way through. It doesn't even cut through 1/8" cork sheeting. It just cuts about 3/4 of the way through cork and burns it to death. But at the same time, I can get good depth when engraving so I don't know that it's necessarily an overall power issue for cutting. Seems almost like a beam profile issue. I'm upgrading the optics sometime soon either way.

[Bert Kemp]

Looks like it then.

[Gary Hair]

I've tried different focus levels to make sure focus isn't the issue.

Have you tried a ramp test to see where your focus should be or are you using a shotgun approach?

[Bill George]

I did not watch the entire too long video, is your mA meter in the negative lead of the tube?

If you set your power level to 90% what does the mA meter read? If its not 20 +/- 3 or so that is one problem. You should be able to cut 1/8 plywood , with a 40 watt tube.

1050 mm tube is more than likely a 40 watt peak tube when it was new. No such thing as a 50 watt tube either 40 or 60 and a 60 is 1200 mm long.
Cheap optics and dirty mirrors can be a issue but right now you have power problems.

[Brian Leavitt]

Have you tried a ramp test to see where your focus should be or are you using a shotgun approach?
Yeah I've done the ramp test, the results of which I use for typical engraving and cutting. I've tried closre and farther focal distances recently to make sure focus isn't the issue.

[Brian Leavitt]

is your mA meter in the negative lead of the tube?
Yes

If you set your power level to 90% what does the mA meter read? If its not 20 +/- 3 or so that is one problem. You should be able to cut 1/8 plywood , with a 40 watt tube.
Barely moves at all - pretty much stays at zero. The only time I get an actual reading is when I run it at 29% power or less AND the tube makes a high pitched squealing noise. It engraves and cuts whether I get a reading on the mA meter or not, and whether it makes the noise or not.

[Scott Marquez]

It sounds like you may have a tube or power supply problem, since you are showing very little current "flow". You should check all electrical connections (using appropriate precautions).
You might also check to see if you have a Max power setting in the software that is set too low.??
Scott

[Jerome Stanek]

I think you have the leads backwards on the meter

[Bill George]

And this is your new eBay laser? Hmmm well check your power supply, find a You Tube video and plan on either/or new tube and PS? Meter backwards the needle would move backward, something to try.

[Brian Leavitt]

I've had it probably 15 months or so. I knew when I bought it the tube and/or power supply probably wouldn't last long, so it wouldn't surprise me if either were dying. I don't have a way to test the output voltage of the power supply.

I'll reverse the wires on the meter and pulse it at low power to see what happens. Wouldn't hurt anyways.

[Jeff Body]

Dude quick messing around

Trouble shooting Logic 101.
Remove the mA meter and return the laser to stock.

Do you still have a problem? Yes or No

And go from there.

[Brian Leavitt]

Jeff,
Nothing changed operationally with the laser after adding the mA meter. If it had, I would already have removed it. It still engraves and cuts exactly how it did before the meter was there. My main question was just why does the meter only register if the power is at 29% or less and the tube whines.

[Kev Williams]

The tube shouldn't make no noise... I seem to remember from reading a few threads, that a whining tube is indicative of it arcing somewhere. I think someone even posted a video of his tube doing this...

anyway, the fact your meter isn't reading much is also indicative of an arc. Did it whine before the meter?

[Brian Leavitt]

The tube shouldn't make no noise... I seem to remember from reading a few threads, that a whining tube is indicative of it arcing somewhere. I think someone even posted a video of his tube doing this...

anyway, the fact your meter isn't reading much is also indicative of an arc. Did it whine before the meter?
Yes it did the whining before the meter as well. It only does that at 29% power and less, though.
I was trying to find a photo of a glass laser tube while firing at the output end, but I didn't come up with anything. I'd like to know what it should look like within the last 4 inches before the output lens while firing.

[Scott Marquez]

Jeff,
Nothing changed operationally with the laser after adding the mA meter. If it had, I would already have removed it. It still engraves and cuts exactly how it did before the meter was there. My main question was just why does the meter only register if the power is at 29% or less and the tube whines.
The meter is showing you "current flow", so use what it is telling you for trouble shooting, my guess is that you should be seeing over 15ma. After checking all of your electrical connections, including your ground, you might start playing with your software output levels
If all else fails, purchase a new power supply and 60 or 80 watt tube and enjoy.
Scott

[Brian Leavitt]

I'm looking at a replacement tube options right now. It has a power supply for up to a 60 watt tube in it already and I'd be looking to get a 60 watt tube. The vast majority of my laser knowledge relates to american-made lasers so this Chinese machine is a different kind of beast. If I can get away with just replacing the tube, I'd rather do that than replace the tube and power supply. This laser is not a money maker for me. I have better ones for that, but I do enjoy using it and want to keep it going. I'm going to go over the electrical connections tonight, if I have time. I'm also going to buy another mA meter for testing since they're cheap. I've read of others having problems getting a proper reading on these types of cheapie lasers.

I did some more brief testing last night. I can cut through 1/8" plexiglass at 85% power and 6mm/sec speed. Pretty slow, but it cuts through clean and actually makes a very nice edge. In the short term, I'm going to just run it as-is until it actually dies. After that, it's upgrade time. Better laser source, better optics, and beam combiner for a red dot laser are in the future plans. Maybe some day I'll actually try to make some money with it.

[Brian Leavitt]

I just had a thought. I wonder if my cooling liquid has something to do with the behavior of the laser tube. I've been running RV antifreeze in it because it's in my unheated, uninsulated garage. I'm going to try some distilled water and see if anything changes.

[Jerome Stanek]

I have been running RV antifreeze in mine for 3 years without any problems

[Brian Leavitt]

Are you running 100% antifreeze or are you diluting it, Jerome?

I've read that antifreeze can potentially cause internal arcing of the tube, but I don't know which type of antifreeze that is referring to.

[Jerome Stanek]

I run the stuff that Walmart sells straight

[Bill George]

I have ran both when I had my glass tube laser, but mA meters don't lie. Changing anti freeze will not help, sorry.

[Bert Kemp]

If the problem is arcing? and I don't know that it is, but putting in distilled water might help. When that tube fires it looks funny. and he says it makes a noise.


I have ran both when I had my glass tube laser, but mA meters don't lie. Changing anti freeze will not help, sorry.

[Doug Fisher]

I wouldn't buy a tube until you confirmed everything else is working correctly. Are you sure the whining isn't coming from the power supply itself? Have you done any testing/confirmation to make sure your mA meter is actually functioning correctly?

[Brian Leavitt]

The noise is coming from inside the tube, and I can also hear it at the point where the laser beam hits the substrate it's engraving. It sounds like an RF laser making a cut at a lower Hz setting, which is what makes me think there's arcing in the tube.

I have not tested the mA meter. I'm buying another one to swap in for testing. The laser fires so the mA meter is not giving me the whole story. I'm going to try distilled water just to see what happens. It's a cheap and easy test.

[Brian Leavitt]

Replaced the antifreeze with distilled water. Interestingly, it still makes the noise, but only at 19 power and below. Also, the visible beam inside the tube is more consistent and stable at the output end now. Still no reading on the mA meter, but I have another one on the way. We'll see...

I did go ahead and order three new mirrors, new focus lens, and a beam combiner setup. My mirrors look more like dull pieces of steel than mirrors so I know I'm losing a lot of power and beam quality. Looking forward to getting them replaced. The focus lens on the machine looks OK, but it has a convex side and a slightly concave side. I've never seen this in a lens before. I decided to replace it so all of the optics will be new and much, much higher quality.

I'm not going to be replacing the tube for now. I'd like a higher quality tube, but since the one I have is still kicking I'd feel like I was wasting it. Gonna wait 'til it dies to replace it, whether or not I can ever get a mA reading off it.

[Bill George]

mA meters don't lie. The tube is made of glass, glass is a insulator, unless the tube has a flaw or you have a bad ground connection it should never try to arc.

[Matt McCoy]

You likely need a new power supply and tube. Lens, mirrors, and distilled water are not the remedy to your symptoms.

[Brian Leavitt]

mA meters don't lie. The tube is made of glass, glass is a insulator, unless the tube has a flaw or you have a bad ground connection it should never try to arc.
I think arcing is the wrong term. That's just what I've seen it called. My mA meter is "lying", though. Well not really, but I just found out today that I had purchased an AC mA meter and not a DC mA meter. Whoops...
DC meter is on order.

[Brian Leavitt]

You likely need a new power supply and tube. Lens, mirrors, and distilled water are not the remedy to your symptoms.
Switching to distilled water most definitely had a positive effect on the tube - noticeably more stable. The readings of my current mA meter are a moot point since I found that I accidentally got the wrong one. Other that that, poor cutting performance is the only real issue I had so new mirrors are going to help tremendously in that department. I'd put up a photo of the current mirrors, but I don't feel like taking it apart right now. There is no visible reflection off these things and they get quite hot after running the laser. I don't know how the beam was making it to the lens.

I'm aware that the tube and power supply are of similar quality to any other part of this machine, but at this time I don't think they are the problem. If I'm wrong, I already have a tube lined up for purchase. I've been trying to find an extension piece for the side of the laser cabinet, to cover the future 60W tube. So far no luck, but the search continues.

[Bert Kemp]

Call Rabbit in Ohio they might have an extension case they had one for mine. In any event should not be to hard to make one if need be, any sheet metal shop could do it.


Switching to distilled water most definitely had a positive effect on the tube - noticeably more stable. The readings of my current mA meter are a moot point since I found that I accidentally got the wrong one. Other that that, poor cutting performance is the only real issue I had so new mirrors are going to help tremendously in that department. I'd put up a photo of the current mirrors, but I don't feel like taking it apart right now. There is no visible reflection off these things and they get quite hot after running the laser. I don't know how the beam was making it to the lens.

I'm aware that the tube and power supply are of similar quality to any other part of this machine, but at this time I don't think they are the problem. If I'm wrong, I already have a tube lined up for purchase. I've been trying to find an extension piece for the side of the laser cabinet, to cover the future 60W tube. So far no luck, but the search continues.

[Dave Sheldrake]

Using a conductive coolant on a glass tube most certainly does affect power, to demonstrate this stick a 50/50 mix in your machine then fire it up, power will drop like a rock.

The latest 1050mm tubes are indeed 50 watt but are very low quality, a year is doing well, any more than that is amazing.

Make an extension on the machine but make sure to add a decent copper bonding strap that runs from the machine body down the inside of the extension. They don't need to be metal, they just need to have a path to earth

Mo mirrors are very good but they will corrode or tarnish so have to be kept clean on a daily basis

[Dave Sheldrake]

Using a conductive coolant on a glass tube most certainly does affect power, to demonstrate this stick a 50/50 mix in your machine then fire it up, power will drop like a rock.

The latest 1050mm tubes are indeed 50 watt but are very low quality, a year is doing well, any more than that is amazing.

Make an extension on the machine but make sure to add a decent copper bonding strap that runs from the machine body down the inside of the extension. They don't need to be metal, they just need to have a path to earth

Mo mirrors are very good but they will corrode or tarnish so have to be kept clean on a daily basis

[Brian Leavitt]

Call Rabbit in Ohio they might have an extension case they had one for mine. In any event should not be to hard to make one if need be, any sheet metal shop could do it.

Thanks for the tip. I'll give it a try.

[Brian Leavitt]

Using a conductive coolant on a glass tube most certainly does affect power, to demonstrate this stick a 50/50 mix in your machine then fire it up, power will drop like a rock.

The latest 1050mm tubes are indeed 50 watt but are very low quality, a year is doing well, any more than that is amazing.

Make an extension on the machine but make sure to add a decent copper bonding strap that runs from the machine body down the inside of the extension. They don't need to be metal, they just need to have a path to earth

Mo mirrors are very good but they will corrode or tarnish so have to be kept clean on a daily basis
I'm going to see how much time I can get out of this tube before it dies. It is a year and a half old now.

I thought about making an extension out of plexi. That is what I will probably do if I can't find a cheap one pre-made.

[Jerome Stanek]

you could have a sheet metal shop throw one together pretty quick. heating and cooling companies

[Kev Williams]

The latest 1050mm tubes are indeed 50 watt but are very low quality, a year is doing well, any more than that is amazing.

I just love(hate) the planned obsolescence build ethic these days: Build it to break down at 1.2x the warrantee period so we can sell replacements...

Not that this is new thing...

[Matt McCoy]

Switching to distilled water most definitely had a positive effect on the tube - noticeably more stable. The readings of my current mA meter are a moot point since I found that I accidentally got the wrong one. Other that that, poor cutting performance is the only real issue I had so new mirrors are going to help tremendously in that department. I'd put up a photo of the current mirrors, but I don't feel like taking it apart right now. There is no visible reflection off these things and they get quite hot after running the laser. I don't know how the beam was making it to the lens.

I'm aware that the tube and power supply are of similar quality to any other part of this machine, but at this time I don't think they are the problem. If I'm wrong, I already have a tube lined up for purchase. I've been trying to find an extension piece for the side of the laser cabinet, to cover the future 60W tube. So far no luck, but the search continues.


Using a conductive coolant on a glass tube most certainly does affect power, to demonstrate this stick a 50/50 mix in your machine then fire it up, power will drop like a rock.

The latest 1050mm tubes are indeed 50 watt but are very low quality, a year is doing well, any more than that is amazing.

Make an extension on the machine but make sure to add a decent copper bonding strap that runs from the machine body down the inside of the extension. They don't need to be metal, they just need to have a path to earth

Mo mirrors are very good but they will corrode or tarnish so have to be kept clean on a daily basis

Dave: Brian originally stated that his tube was squealing and did not have enough power to cut even 1/8" material. The meter he installed indicated that there was an issue as well. It looks like Brian installed the incorrect meter, which explains the goofy reading, but will distilled water address the squeal and poor cutting so dramatically. Brian?

Thanks.

[Bill George]

Its interesting that I ran RV anti freeze, then 50/50 automotive anti freeze and all with just tap water. No squealing and no reduction in power. Perhaps some sort of capacitor effect on the electrons inside the tube happening, but not conductive in a normal glass tube, not defective. Unless someone removed the ground from the tube or it was faulty, then the voltage inside might try to seek another path.

[Brian Leavitt]

Dave: Brian originally stated that his tube was squealing and did not have enough power to cut even 1/8" material. The meter he installed indicated that there was an issue as well. It looks like Brian installed the incorrect meter, which explains the goofy reading, but will distilled water address the squeal and poor cutting so dramatically. Brian?

Thanks.
The noise is still present at about 20% power and below. Above that it's silent. I'm sure the tube and/or power supply is not in tip top shape, but it fires and engraves OK. I haven't actually run anything on it since swapping coolants so I can't say whether performance has been affected. All I can attest to is that visually, the tube is more stable, and the noise it made at 29% power now only occurs at 20% or less. I just started taking everything apart in preparation for my new optics which should arrive Friday. Maybe I'll put it back together and make a test cut, if I have time.

What I find interesting is that by installing the wrong mA meter, I got some unintended information. It seems to me as though AC voltage is present at these lower power levels. It still registers about 3 or 4 mA at <20% power. This tube has always been useless at that power level and I only really run it at 50% power and up, so it never made much difference to me. I'm certainly not an electrical guru, so I don't know if there are other phenomena that would make an AC mA meter register like that.

[Brian Leavitt]

So I could previously cut through 1/8" plexi at 85% power and 6mm speed. Now I can cut through it at 85% power and 9mm speed. Same piece of plexiglass. I have done nothing since the first cut except for changing the cooling liquid.

[Bert Kemp]

So this would back the previous statements that the RV coolant robs some power and conducts some electricity.
By changing to distilled water the tube seem more stable (less arching) and you have a bit more power.:)


So I could previously cut through 1/8" plexi at 85% power and 6mm speed. Now I can cut through it at 85% power and 9mm speed. Same piece of plexiglass. I have done nothing since the first cut except for changing the cooling liquid.

[Matt McCoy]

So I could previously cut through 1/8" plexi at 85% power and 6mm speed. Now I can cut through it at 85% power and 9mm speed. Same piece of plexiglass. I have done nothing since the first cut except for changing the cooling liquid.

That is dramatic. How confident are you that you're conducting this test under the same exact conditions? You mention that you're in an unheated/unconditioned space. For instance, was the original test in the summer after some time messing around on the laser and then your current test was first thing in the morning when it's cool? Did you align or clean your mirrors/lens? Were your numbers really dialed-in? Appreciate you sharing.


So this would back the previous statements that the RV coolant robs some power and conducts some electricity.
By changing to distilled water the tube seem more stable (less arching) and you have a bit more power.:)

But unfortunately doesn't coincide with the previous two statements by Jerome and Bill. :(

[Brian Leavitt]

That is dramatic. How confident are you that you're conducting this test under the same exact conditions? You mention that you're in an unheated/unconditioned space. For instance, was the original test in the summer after some time messing around on the laser and then your current test was first thing in the morning when it's cool? Did you align or clean your mirrors/lens? Were your numbers really dialed-in? Appreciate you sharing.
I didn't do anything with the mirrors or lens other than remove one mirror and the lens, measure them, and put them back in.

Both tests were done immediately after turning on the machine for the first time that day and the temperature in my garage at the time of testing was was in the 50's both days. Test one was the night of December 1st. Test two was the night of December 7th. For both tests I cut two 1" x 1" squares out of plexi at each speed setting until it cut all the way through, starting at 10mm/sec and lowering by 1mm/sec for each test. Both times the testing was done around 8:30pm, which is when I usually have a short window of time to get out to the garage.

There was one difference besides the coolant being used that I just thought about. The temperature of the water was probably different. For test one, the RV antifreeze would have been close to the temperature of the garage, so maybe around 55 degrees. For test two the water was probably closer to 65. I don't know if that makes a different or not, but it's the only other variable I can think of.

[David Somers]

Brian....if you are looking for a quick check on the accuracy of your mA meter, do you have a multimeter handy? That will do the same thing for comparison purposes.

[Matt McCoy]

I didn't do anything with the mirrors or lens other than remove one mirror and the lens, measure them, and put them back in.

Both tests were done immediately after turning on the machine for the first time that day and the temperature in my garage at the time of testing was was in the 50's both days. Test one was the night of December 1st. Test two was the night of December 7th. For both tests I cut two 1" x 1" squares out of plexi at each speed setting until it cut all the way through, starting at 10mm/sec and lowering by 1mm/sec for each test. Both times the testing was done around 8:30pm, which is when I usually have a short window of time to get out to the garage.

There was one difference besides the coolant being used that I just thought about. The temperature of the water was probably different. For test one, the RV antifreeze would have been close to the temperature of the garage, so maybe around 55 degrees. For test two the water was probably closer to 65. I don't know if that makes a different or not, but it's the only other variable I can think of.

Cool. Water temp definitely affects cutting on a laser. How much and to what degree it might have had with you, in addition to switching to distilled water, I'll have to defer to someone like Sheldrake, when he swings by. Thanks for the info.

[Kev Williams]

There was one difference besides the coolant being used that I just thought about. The temperature of the water was probably different. For test one, the RV antifreeze would have been close to the temperature of the garage, so maybe around 55 degrees. For test two the water was probably closer to 65. I don't know if that makes a different or not, but it's the only other variable I can think of.

Big fat YES! I'm running an 80w machine with 3000 'radiator' cooler, which means I can watch the temp go up pretty quickly when cutting. With only a 5 degree temp rise, what was a 2 pass cut in 1/8" plastic will require a 3rd pass. I run into this mid-job all the time, where the beginning cuts are great but the ending cuts are .030" light...

you had a 10 degree swing, so that likely had some to do with your testing... :)

[Brian Leavitt]

OK then I'll do a third test tonight and see what happens. It'll probably be about 10 degrees colder in the garage than it was for either of the other tests. It's 38 degrees outside now and has been that cold or colder since the sun went down yesterday. I'll get a water temp before I start. What is the optimal temperature for the incoming tube water anyways? I see the active chiller on LightObject is supposed to keep it between 64.4 and 86. That seems like a big swing if temperature makes that big of a difference.

If 65 degree water resulted in more power than 55 degree antifreeze, then 45 degree water should be even worse than the first test. I will report back with whatever happens.

[Bill George]

OK then I'll do a third test tonight and see what happens. It'll probably be about 10 degrees colder in the garage than it was for either of the other tests. It's 38 degrees outside now and has been that cold or colder since the sun went down yesterday. I'll get a water temp before I start. What is the optimal temperature for the incoming tube water anyways? I see the active chiller on LightObject is supposed to keep it between 64.4 and 86. That seems like a big swing if temperature makes that big of a difference.

If 65 degree water resulted in more power than 55 degree antifreeze, then 45 degree water should be even worse than the first test. I will report back with whatever happens.

I think you have it backwards. The cooler the water (within limits) the more effective the laser tube operation. Unless your tube has defective glass as much thinner in one area, I don't see how tap water vs distilled water makes any difference. If the power was being magically drained off, the mA meter would show it.

[Kev Williams]

Thanks for the reminder Bill, I forgot to mention this about rising water temps-
as my water temp goes up, my mA meters also read lower. At 70% power and 20c water my mA meter is usually just under 28, but at 25c it's usually at 26. I'm assuming the warm water creates some sort of resistance which shows up on the meter as well as the work--?

[Brian Leavitt]

I know the performance of the tube is reduced if the water gets too warm, but I had warmer water in test two than test one and cutting performance increased, and it was suggested that the water temperature affected the power between the two tests, so from that I deduced that water that is colder than optimal will also reduce power. If that is not true, then the change to distilled water, from antifreeze, is what affected performance.

[Brian Leavitt]

44 degree water and still cut at 9mm/sec and 85% power. It actually cut through at 10mm/sec, but not clean so I don't count it. Changing my optics now.

[Brian Leavitt]

Got the new mirrors and lens installed. Not 100% aligned yet but I was impatient so I ran another test. This time I was able to cut through the same piece of acrylic at 85% power and 21mm/sec speed. :) As I said - I still need to finish alignment, and I also need to find the optimal focal point (I used the focus "tool" that came with the machine for this test), but I'm happier than a pig in slop. I also made an order from Macken for their 100 watt power probe. This is mostly because I think my X2-600 is losing power, but also to monitor the health of all the laser tubes.

Photo of old mirror vs new mirror. The old lens didn't look too bad, but I don't think it was focusing very well. Couldn't get a very small spot size with it.

[Scott Marquez]

I also made an order from Macken for their 100 watt power probe.
A power meter is worth the money for tracking your tube health, and will also be useful on your other lasers.
I made an acrylic bracket to hold mine in the different parts of the laser path.
http://www.sawmillcreek.org/showthread.php?243119-Options-for-laser-power-meters/page4
Keep us informed of your future findings.
Scott

[Brian Leavitt]

Yeah I've been wanting one for a while. I just never pulled the trigger. In the past I have rented one before, but I decided that's just a waste. If I had bought one in the first place, it would have paid for itself by now, avoiding the rental fees. Should be in Friday. Then I'll get a measure on all the machines.

[Dave Sheldrake]

It's not the loss of current that conductive coolant causes, it's destabilisation of the actual plasma it causes leading to a loss of power. It's something I looked into in great depth about 5 years ago when I decided to fill a tube with UV reactive coolant just for giggles and stuck a UV light in the cabinet, it dropped 30% power and the beam profile when measured on a decent quality profiler went all sorts of insane.

[Bill George]

I was thinking it was more like a capacitance effect instead of current flow or voltage arcing. In my Chinese glass tube laser I could not see any difference, RV , automotive anti freeze or plain tap water.

[Brian Leavitt]

A power meter is worth the money for tracking your tube health, and will also be useful on your other lasers.
I made an acrylic bracket to hold mine in the different parts of the laser path.
http://www.sawmillcreek.org/showthread.php?243119-Options-for-laser-power-meters/page4
Keep us informed of your future findings.
Scott

At 85% power, my Chinese machine is measuring at 48 watts. My new (correct type) mA meter is due in tomorrow so I'll get to see what kind if current that power correlates to then.

The Epilog measured only 53 watts, 600 measured only 42 watts, and 660 measured 62 watts. I'm going to rerun the tests on the Fusion and the 600 tomorrow, as I don't believe they are really that low.

[Bill George]

Is that the one that looks like a large dial thermometer with a chunk of dark colored aluminum on one end? Paid about a $100 or a little more for? Very difficult to get a good, repeatable reading from, too many variables. I sent mine
back for a refund.

[Brian Leavitt]

Yes it is an analog meter, but it's not the cheaper one. The one I got it is the Macken P100C - runs about $350 and comes with a certificate of calibration. It also doesn't require a wrench to zero the dial. I've been able to run repeat tests on the Chinese Special and the X-660 and the reading has been within 1 watt every time. The aluminum chunk on this one is pretty light in color. It's meant only for CO2 lasers. I've seen probes elsewhere that say they are for CO2 and YAG, but I felt one specifically for CO2 only would be likely to be more accurate for my application.

I'll get a better read on this probe tomorrow when I get back to the shop and repeat some tests, but so far it seems accurate (based on the X-660 readings) and results are certainly repeatable. I'm not confident with the results on the Fusion and X2-600 because of factors other than the meter itself, mostly being in a hurry because I had a mountain of Hydroflasks to run.

[Bill George]

Sounds like you got the good one and that should help in your troubleshooting.