Laser Tube Bad?

[wctx1977]

By the way, it would be nice if you can make another video when you run more tests to help others to understand this problems better. Thank you very much.

[nlucomputers]

ok, another update,
today i realigned all the mirrors, runs better, but same problem. today i ran till it quit again (about 5 minutes) and i put a peice of paper in front of the tube (before first mirror) and nothing. it will engrave, but not cut.
i also bypassed the meter to make sure that the resistor in it did not go bad (same thing).

EJ

[Tech_Marco]

EJ:

Let's do an experminet. Put some ice in the bucket to cool water to about 18~20'C (65~68'F) and run a few test.
Remember that the 100X100mm square box test that I asked to try this afternoon. With about full power it couldn't finish 3/4 cutting and the last part fade out.

Now do it again but with ice-water. I want to confirm something as I consulted with two Pro and received two answeres. I want to find out which one is correct


Marco

[waltfl]

HI
like I said the result looks like that the focal distance changes you can see this how the line gets wider and finally gets totally out of focus.
I had this with some guys who I tutor they have aligned the beam but still could not cut a area. the reason was that the material was not plan or the table was sloping a bit.
I mean the cooling water for cutting should always be between 65 and 68 F the hotter it gest the less cutting power there is, but it will not totally cut of until the water temperature gets over the max 86F this will destroy the tube.
I always use 18 to 20 F. I also set the frequency to 16000 for cutting and I cut up to 6mm with 1 run and 50% power 3mm/s, even oak wood.
greetings
waltfl

EJ:

Let's do an experminet. Put some ice in the bucket to cool water to about 18~20'C (65~68'F) and run a few test.
Remember that the 100X100mm square box test that I asked to try this afternoon. With about full power it couldn't finish 3/4 cutting and the last part fade out.

Now do it again but with ice-water. I want to confirm something as I consulted with two Pro and received two answeres. I want to find out which one is correct


Marco

[Tech_Marco]

But he put a piece of paper in the front of the "lit" laser and still not being able to burn it. That is a sign of bad tube. The cause could be "leaking gas" or "bad mirror". Since it fire the first few minute and I'm thinking that it was caused by miss alignment of the internal mirror. It shift position once the tube get over-heated. That's why I need him to run the tube by adding 'ice' to cool of the water. If the fire last longer, then it is caused by mirror alignment.

Marco

[waltfl]

hi marco
that's exactly what would happen if the cooling water was getting to hot.
like I said before the most guys don't measure the temperature they "eye-ball" or finger check it where they can not define the
difference between 28C and 40C which would destroy the tube. you can see on the picture from the tube that it was already
overheated the silicon is brown what would never happen with normal temperature.
if you would take the silicone off you probably can see that the mirror is already not tight attached and the gas could go out.
I got two thermometer on it one for in and one for out.
greetings
waltfl

But he put a piece of paper in the front of the "lit" laser and still not being able to burn it. That is a sign of bad tube. The cause could be "leaking gas" or "bad mirror". Since it fire the first few minute and I'm thinking that it was caused by miss alignment of the internal mirror. It shift position once the tube get over-heated. That's why I need him to run the tube by adding 'ice' to cool of the water. If the fire last longer, then it is caused by mirror alignment.

Marco

[Tech_Marco]

He is using a 3 gallon water tank to cool off the tube. For a few minutes of testing, it shouldn't affect that much. Plus, it shouldn't cause the missing firing power. I'm thinking that this tube is defective to some extend. It works when it is cool down but beam reflected when heated up.

To my conclusion: I believe that the mirrors/lens installed inside of the tube was not well align by the tube installer so it shift a little bit (even a 1' degree shift can cause cause big trouble!) when it is getting hotter . When the light beam was not able to bounce out, it reflect back to the tube intentionally. That's why the still showing "grow".

Agreed with me? So, I'm waiting for him to do the test for me. Add some ice to cool off the water once the tube is missing fire. If it bring back the light once ice is in placed, then my 'shifting theory' is established

Marco

[waltfl]

Hi marco
I agree with your theory but just take a tank of water in a normal room with a room temperature of 23C the tube will increase the temperature during cutting for another 4 to 5 degree C and the water will be follow this temperature within about 3 minutes cutting
I did extensive testing about this. 1 gallon of cooling water will reach 30+ C within 3 minutes cutting just with 48% ( 15mA).
you know it is not just the water temperature it is also the max current what will contribute to the internal break down of the tube.
lets see what is happen.
greetings
waltfl

He is using a 3 gallon water tank to cool off the tube. For a few minutes of testing, it shouldn't affect that much. Plus, it shouldn't cause the missing firing power. I'm thinking that this tube is defective to some extend. It works when it is cool down but beam reflected when heated up.

To my conclusion: I believe that the mirrors/lens installed inside of the tube was not well align by the tube installer so it shift a little bit (even a 1' degree shift can cause cause big trouble!) when it is getting hotter . When the light beam was not able to bounce out, it reflect back to the tube intentionally. That's why the still showing "grow".

Agreed with me? So, I'm waiting for him to do the test for me. Add some ice to cool off the water once the tube is missing fire. If it bring back the light once ice is in placed, then my 'shifting theory' is established

Marco

[Tech_Marco]

Walt:

Like me, you like to do hands on experiment. We're learning little by little daily.. I enjoyed reading your post and it is interesting.
If we live closed by each time, we should have a lot of fun. I bet we will make a lot "bet" for beer or pizza when we have topic with "argument"


Marco

[waltfl]

Hi marco
you are damn right and it would be fun. you know I tutor lots of guys from every where and most who start out with laser experience
make the same mistake sometimes I could rip my hair out, because I tell the guys the most important things up front, but they are so eager to start that they forgot this things.
greetings
waltfl

Walt:

Like me, you like to do hands on experiment. We're learning little by little daily.. I enjoyed reading your post and it is interesting.
If we live closed by each time, we should have a lot of fun. I bet we will make a lot "bet" for beer or pizza when we have topic with "argument"


Marco

[nlucomputers]

Marco, did the test
wanted a control test so i started it up and ran the 100mm box at 5mm 60% power it ran through the box twice slowly weakening and quitting completely on the third box first line into it.
I then waited 2hours for everything to cool down/ level out/ whatever.

I dumped 3 trays of ice (all the ice i had) into my water bucket

I ran the water pump for 10 minutes to get the ice melted a little and get the cold water circulating.
I felt the side of the bucket and it was definitely colder than before.

Once again i ran the test, 100mm box 5mm 60% power. once again it ran through the box twice slowly losing power and it quit completely on the third run first leg. Same exact spot.

soooo, what does that tell us?

EJ

[waltfl]

what did your mA meter show???? 60% must be around 19 to 20mA or??
greetings
waltfl

Marco, did the test
wanted a control test so i started it up and ran the 100mm box at 5mm 60% power it ran through the box twice slowly weakening and quitting completely on the third box first line into it.
I then waited 2hours for everything to cool down/ level out/ whatever.

I dumped 3 trays of ice (all the ice i had) into my water bucket

I ran the water pump for 10 minutes to get the ice melted a little and get the cold water circulating.
I felt the side of the bucket and it was definitely colder than before.

Once again i ran the test, 100mm box 5mm 60% power. once again it ran through the box twice slowly losing power and it quit completely on the third run first leg. Same exact spot.

soooo, what does that tell us?

EJ

[Tech_Marco]

EJ:

It seems it is heating issue. And I still think that my theory is right as the heat caused the problem.
By the way, what flot rate is the pump doing? Is it weak or decent? Are you able to measure the temperature of water coming out from the tube?

Anyway, we started doing testing for a new tube and once we completed the prelimary burned in test, we will ship it to you for replacement


Marco

[nlucomputers]

marco,

meter held steady at 17.8ma
i just checked tempatures, ambient in my shop is 72F and two hours after i ran the ice test the water is at 67F. water pump gives it a decent flow.

EJ

[nlucomputers]

marco and walt,
I have a refigerator on the other side of the wall from my laser, would it be worth getting a stronger pump (im assuming because of the distance, its a few more feet) and putting a bucket in the refigerator?
I dont think that will help this problem but for the future?

EJ