China is cheap, we all know that.
China also doesn’t know what quality control is.
Well, they know, they just don’t perform that kind of process in most of their cheap production. So, what can happen if you buy a cheap china laser tube and power supply? Well, mostly two things (three, if you count absolute failure, four if you also count pieces falling off.):
- Power supply doesn’t work well for engraving because of massive power “ringing”:
(yeah, in this particular case it produces a beaitiful 3D effect, but that’s beside the point)
- Beam shape is not a roundish circle but dual kidney shaped, having 0 power in the center of the cut:
So, what did happen when I bought the cheapass laser and supply? Obviously, all of the above.
The interesting part is that the original tube the machine came with (alongside the
almost absolutely crap moshiboard) worked fine and had no ringing. I had grown into engraving reliably when the happening, so when I found I could no longer do it…it was a bit of a let down.
Since the beam had virtually zero power in the beam’s center, I was forced to pump it up so it could get through, wich meant it would more readily charr/melt the edges and also slowed down cutting speed to a crawl (I think at the end of it, I was doing like 125mm/min at full military overpower to cut 2mm MDF, and it couldn’t even handle 4mm…yeah)
This is a laser tube on steroids and no water filter in the circuit.
As the tube aged, it required more oomph, and once I went over the laser rating, performance cascaded downhill. (laser rating was 15mA normal, 17mA Max. and I was pushing about 23mA through it. I got away with that because a beer chilling unit, I could freeze the tube if I wanted. BTW, if you do freeze the tube, from 18 to 8ºC the power goes down noticeably, then goes back up @ 0ºC XD! )
Finally I decided it was time to change the tube, and the supply…and since I was at it, maybe upgrade a bit.
First step: Make a hole in the box. It was square but as an afterthought, it should had been round and lower.
You can see previous mods there:
3 power output connectors with a relay board controller, air assist input, with solenoid valve. And oh, yes, also a ginormous laser tube wich doesn’t really fit as much as protrude…
Oh, hai, bro.
The original tube was (chinese) rated at 40W but sources say that’s peak power for a 55/750mm tube, and it’s really 35W. Working as it was, I probably had an effective power of 20-25W at best . The new one tough is a Lightobject 45W rated, 50W peak power laser.
- Power: 45W (50W peak)
- Triggering Voltage: 20KV
- Operating Voltage: 15KV
- Current: 18mA
- Life Span: 1500~1800 hrs
- Length: 1000mm/ 39.4″
- Diameter: 55mm/ 2.2″
- Water Cooling required
- Water temperature: 20~25’C(68-77F)
I also bought a matching (more on that later) power supply:
Fun thing is that since the tube was 45W, the power supply had to be their 40/60W one. What with that? Well, the 60W tube is just longer (1250mm instead of 1m) so, sometime in the future, I could just make a longer cover and change the tube…half a meter long cover, tough…that’s a bit of an overhang, ain’t it?
Anyhow, here are some more shots:
I was going to make the cover in metal, that’s the reason behind the squarish hole, but I didn’t had the bending press at hand, nor was going to buy one, yet. While I was shopping for supplies, I saw a PVC tube in the shop, and just ran with it (not literally, of course
for the 7 dwarf lords to hold the cover. I would have preferred a bit more margin in there, but the square deed was already done.
Almost everything has sleeves, especially around power cabling.
The laser in the workshop. Yes, I have lost a bit of table…but it will be worth.
I have some bits to wire up, but all the important parts are in place.
Next installment: Controls, wiring, cutting performance.