Having reflected overnight and in the absence of any further comments, I am going to do the following. I did intend to buy the MSWlaser because it offers a higher power rating and has ample good reviews but based on where I am I will buy the Cloudray for the following reasons and having read some excellent detailed Amazon reviews:
It is probably equivalent in rating to my current tube, but the reviews suggest it works much better than the stock tube.
It looks like a professional piece of kit.
It should be compatible with the new Cloudray LPS.
It has the cathode and anode connections fitted but the red cover is not a high-tension connector so I will order one to connect to the LPS so removing any possible connectivity issues.
The dimensions (length and diameter) are slightly over the stock tube, so I need to be careful fitting to current mounts or buy new ones.
My concerns are any damage on delivery, but reviews suggest it is well packed. I would not buy from anyone other than Amazon which has a good warranty and returns policy.
I am in the last chance saloon. If this does not work, I will be returning both items and will reflect on what to do next. I consider myself a practical person used to solving problems and I have had my share with 3D printing, CNC machining and diode laser engraving, so although I did expect issues hence my decision to buy second-hand and the fact that it did work well for around 2 weeks, I must admit that I am bitterly disappointed in the situation I find myself in so if you have any final comments or words of encouragement now is the time. It should arrive on Saturday so I will update after fitting. Many thanks for all your advice so far and I will see you on the other side.
Sorry that I entered this discussion late been on vaca again.
Usually, when the anode arcs itās because the LPS is unloaded. I have seen arcs of 1-3 inches on an unloaded LPS. This usually means the tube is bad.
Most of the time in these situations the LPS is still good although arcing can damage the LPS.
Both the Laser tube and the LPS are consumable meaning they will both eventually fail. So you have not really wasted any $$ buying a supply it means you are ahead of the game with a spare supply.
There is no good way to test a bench supply other than to let it arch or to measure the output with a HV meter. I have found both methods to be unsafe, expensive, and sometimes inconclusive.
So hang on to the old supply as a backup itās likely still good and you will be able to tell when you install it in the machine.
Good to have your comments, I agree that I may as well put in the effort and cost now, that upgrading the LPS alongside the tube is the right solution and I am learning so much from having to do it. I did view a couple of your early videos on the subject and one which showed using a ceramic resistor to test the LPS: Laser tube problem or Laser powersupply problem - YouTube but I donāt intend to try this. Although I feel comfortable about changing the tube which arrives on Monday, what is going through my mind is what does it mean if it does not work? Is there something I have missed? And second, I would expect to have a long life from these two new consumables as I believe I can control all the parameters that might shorten their lives. I will also produce a new graph of IN vs tube current.
@donkjr I am expecting the new tube to arrive in the next few hours. Forgive my paranoia but can you comment on my take-off checks. I guess the first tube change is always the most worrying one:
The new LPS is Cloudray. I have only fired it a couple of times to check the existing tube and there was still arcing from the anode at that time.
The new tube is Cloudray ā 35-45w, diameter: 50mm, Length:720mm.
I am hoping I have no problem in fitting it on the existing mounts but will not force it if it is tight. I appreciate I may need to fully re-align but simply ensuring it is working is my current preoccupation.
I have taken off the top mount brackets in preparation and are nicely padded. They were quite slack. I noted the nuts are not retained in the lower mounts so I have no idea how I get the nut on the inside of the cabinet to stay in place whilst screwing in the bolt.
I understand it might be a tad longer but as long as it fits into the cabinet it can slide accordingly along the mounts. The current tube is around 25mm from the fixed mirror. Presumably I would aim for a similar distance?
The anode will come with a cable attached and I am using the Cloudray splicing kit and I have seen how to do this
The cathode will come with a cable attached. I have confirmed the existing black cable does go to one terminal of the machine milliammeter and that the other wire goes to the leftmost pin of the LPS. Both wires are embedded in cabelforms so would it be easier if I cut the black cable in the tube enclosure and splice it to the new tube cathode by twisting wires both ways from the middle as I have seen described and then insulating the joint using say two layers of shrink-wrap tubing?
From the checks before I noted a poor earth to the case which I have now corrected
I hope there are no leaks from connecting up the water as I currently have no leaks, and I am loath to put clips or cable ties around the glass posts.
I need to ensure there are no bubbles in the tube. I have not had a problem with my existing tube. How long do you suggest I keep the water circulating before embarking on the testing?
I should have switched off the chiller last night as the water is currently too cold so the pump is currently warming it up. What is the minimum temperature I should embark on testing? I thought it was 15C but am I right in saying it is 18C with a maximum of 20C?
I presume I will know if it works as soon as the voltage reaches the threshold and that I continue to run to a maximum of 15mA for now if all goes well? Thanks in advance for any other checks or comments you may have.
You will be pleased to hear that I seem to have a fully working laser again . There were no real problems following the concerns I had. Even alignment is pretty close but I can finalize that tomorrow and carry out some cutting test comparisons.
I plotted an IN voltage vs tube current which is different from last time although still roughly linear. Not sure how to interpret it:
V ---- mA
0.5 ā 4
1.0 ā 5
1.5 ā 6
2.0 ā 8
2.5 ā 10
3.0 ā 12
3.5 ----14
4.0 ā 16
4.5 ā 18 (estimated)
5.0 ā 20 (estimated)
Iāll keep this post open until I am fully satisfied I am back in business. Many thanks for your support
The table is the characteristic curve for your new tube + LPS.
The first column is the control voltage into the LPS (the IN pin).
The second column is the current that the tube draws for that control voltage.
For example:
With a control voltage of 2.5 your tube fires and draws 10ma.
You will find that as the system is used these values change. For the same control voltage, the tube will draw less current. You would need to adjust accordingly.
you should have a label on your new tube which states what the max current is and you should know that these new tubes are way better than the stock tubes shipped in K40 machines which were basically closer to 30-35W tubes which was why weād run them no harder than 18mA.
You should get much better output and life from the new tube as they usually test a 40W tube at 50W and sell them as 40W expecting youād want to run them at 100%.
The reason I did the new chart is because these were the results from the chart for the old LPS/Tube to asked me to carry out.
V ------ mA
0.5 ----- 4
1.0 ----- 8
1.5 ----- 11
2.0 ----- 14
2.5 ----- 16
3.0 ----- 19
3.5 ----- 22
4.0 ----- 24
4.5 ----- 26 (estimated)
5.0 ----- 28 (estimated)
So for the old LPS/tube I needed around 1.5V to draw 10mA. I would have expected a lower voltage versus current for the this new LPS/tube so is this reverse logic. I was just seeking reassurance from these new results.
So with a rating of 35-45W do I still run it at maximum 18mA or can I safely run it harder, I will do comparison cutting tests later today so I will see any actual performance improvement then.
Although the difference is a little surprising, I do not think you can compare one tube with another especially if they are different designs.
Consider that these values do not tell you light output only how much the tube draws at a certain setting. The chart is not intended to compare different tubes but rather one tube over its life.
My guess is that at a lower current, this new tube puts out more light. Itās possible but unlikely the new tube is less efficient than your old one but your cutting test will tell you.
Many thanks. When I was deciding which tube to buy, many of the detailed Amazon reviews said that this tube was better than expected and certainly better than the stock tube so I am very hopeful when I carry out comparison cutting tests later today
As predicted this new LPS/tube combination cuts better than the stock tube. In a 2 hour session yesterday, it cut both 3mm hardware shop ply and MDF at 10mm/s with one pass at 15mA and 2 passes at 8mA and that is before I have fully re-aligned my mirrors. For the longest tube life is it better to do one pass at 15mA or two passes at 8mA - erm. Anyway, I can close this one down. Again many thanks for your reassurance at what was a tense time.
I donāt think we have a good answer for this as we donāt have a good handle on a model for laser and LPS failure modes. My intuition suggests the shortest running time while staying within the current limits of the tube.
Yes I would tend to agree. So rule of thumb says we are talking about maximum of 15mA and fastest speed to cut in one pass. I have created a new post where I have found a more efficient way of carrying out multiple passes.
Worse than @donkjr I donāt get notified and I miss a number of theseā¦ I did read through the previous posts here.
What I wanted to point out, is that most good tube manufacturers will placard or at least advise you of the rated current and maximum current.
These are better referred to as working current and maximum current.
In theory you should be able to run working current most of the timeā¦ it will be the maximum load you should put through the tube. Wonāt give you maximum life, necessarily, but should give you close to the rated hours between failure.
Anything above working current and up to the maximum current is detrimental to the tubes gasses and will shorten itās life. You can use it up there, if need be, but know there will be a penalty for doing so.
Sometimes itās worth the penalty.
Tube manufacturers create lots of tubes. These are really technical to get the mirrors exactly aligned dealing with molten glassā¦ Not every one produced will be able to perform as well as those that are in spec, so to speak.
They do not throw these away, they are sold to vendors who re-sell them. I watched a video on a 80W RECI, they got it new for a better price than Cloud Rayā¦
Upon receipt, it was actually marked 75W from the RECI testingā¦ So he got a grade B tubeā¦ not the 80W RECI. Most of these donāt put in them what is advertised.
My 50W China Blue from OMTech measured a little over 40W with a Mahoney meterā¦ Itās only 880mm in length ā¦ 50W if I used it like a flash bulbā¦
As you can see from the label above on this Cloudray tube it is rated at 35W with a peak power of 45W but has no current rating and this is the only documentation I received. I am not sure how useful it is to say that 15mA is 3.8v, tracks linearly and has not changed in the short time I have had it. Having completed my cutting tests on various materials it will cut 3mm Ply in a single pass so pretty happy to stick to this limit at the moment but it is interesting to note the manufacturing grading process.
I stick with the above graphic on length and current as have others with good resultsā¦ My OMTech tube had a placard for maximum current, not maximum working currentā¦
Iād have to have someone explain how to set the pot on a k40 to me. I looked through @donkjr blog and canāt find it.
With most of these, when the pwm goes high, it will lase at whatever the pot is set toā¦ So the question is how do you actually change the current (power) levels in the software between layers since the current control is the value set manually with the potā¦?
. There were no real problems following the concerns I had. Even alignment is pretty close but I can finalize that tomorrow and carry out some cutting test comparisons.
