I bought a K40 laser recently, only to discover today that the water cooling jacket for the output mirror of the tube has broken off. Rather annoying as this is a relatively new tube and from what I have read is not really fixable.
So I need to get a new tube, but due to supply issues I can only find 40W tubes priced at pretty ridiculous prices. However VEVOR despite not having any 40W tubes in stock, has plenty of 50W tubes at a decent price. Currently I can buy a 50W VEVOR laser tube with a VEVOR 50W PSU for less than I can find a 40W laser tube for sale for anywhere else.
Would swapping the 40W laser tube and 40W PSU that comes with the standard K40 be a straight swap for the 50W tube and 50W PSU? The terminals are exactly the same on the 50W and 40W PSUs.
From the specifications on the PSU I can see no difference other than wattage:
40W: VEVOR VEVOR 40W CO2 Laser Power Supply for CO2 Laser Device Laser Engraver Machine | VEVOR UK
50W: VEVOR VEVOR Switch Laser Power Supply 50W for CO2 Laser Tube Engraving Cutting Machine | VEVOR UK
As for the tube I understand that the length would required an extension on the case, as well as being slightly larger in diameter (50mm vs 55mm).
Outside of this I cant see any other differences, so I was wondering if anyone else attempted this and If so am I missing anything that would need to be considered and/or upgraded in the K40 to facilitate this?
it can be done and you will have a far far more powerful machine than you would have had with the stock tube. The K40s are so cheap partly because they install low grade tubes. Tube which degrade quickly if you even get close to driving them at full power and so MANY sites recommend to run the stock K40 tube at no more than 18ma( ~30-35W ). With a good 50W tube which allows you to run at 50W power without unusual tube wear you’ll have quite a nice little desktop machine.
There are guys here who know these Laser Power Supplies(LPS) very well and can steer you through the migration.
Looks like you have done your homework!
You do want a metal extension tube. We have instructions here in #k40:intro on how to safely splice the high voltage wire to the laser.
If the machine is new, contact the seller and ask for a new tube or a partial refund.
The two water cooling rings are just glued on and you can glue them back on if they come off. Just be super careful not to get any glue on the center of the output mirror and it will probably be okay. But definitely contact the seller first. They may ask for a bunch of pictures or demand that you smash the tube.
Unfortunately I bought this K40 second hand and the tube broke during transit from the sellers house to mine, so technically its my fault so I cant really demand a refund.
One thing I have just noticed is that the trigger voltage of the 50W tube is 24KV, whilst the Maximum Output Voltage of the 50W PSU is 22KV. I assume that would be issue?
I have never seen an incompatibility due to trigger voltage especially from supply and tube from the same vendor.
Therefore I do not think that this would be a problem, my guess is that these values vary 8-10% anyway.
Having said that, I would try to contact Vevor and see what they say.
I submitted such a question on the Vevor site.
BTW I would definitely try gluing the water jacket back on, you have nothing to loose…
These are kind of notorious for major arching when the tube fails as the voltage seems to really climb high.
My 50 watt tube is 880mm and puts out 44 watts. A ‘real’ 50 watt is closer to 1 meter in length.
Length is less of a problem than tube diameter when swapping out, in my view. A change of diameter adds a little more complexity to the change over.
I replaced my tube/mirror holder and it has the ability to handle some variations in diameter, also required a extension on the case.
Good luck, have fun
Here is the vendors response, looks like you are good to go!