Now that I have the new laser fairly dialed in I am trying to optimize my cuts even more by trying to improve my air assist. I have the standard chinese 70L/m pump. I do plan to either get a larger pump or tie in my compressor in the future but for now I am looking at what I can do right now to gain just a little bit more cutting power at higher speeds.
In Russ’s RDWorks Lab #87 video he dissects the air assist paths and finds where they can be improved. In his tests he determined that the elbow where the air assist goes into the nozzle is restricting about 50-60% of the air flow. Once he drilled that out he was able to increase his speed by a couple mm/s. He also made a slip on nozzle extension that has a 1mm smaller hole than the nozzle to help concentrate the air more. He was able to gain a little more speed with this change. That last thing he did was to replace the pump with one double the size. This was also helpful.
I have drilled out the elbow as he did but I have not seen any improvements in my cuts. I have given this a lot of thought and I think I may know why. Watching his video his nozzle is only about 5-6mm above workpiece. Mine is 16.5mm. So I am wondering if I were to move the lens further UP the lens tube (away from the work piece), could I shorten the distance from the nozzle to the workpiece allowing the air to be more concentrated in the cut?
I borrowed this image (altered it) from a post back in 2019 from @Stroonzo. In his post he was wanting to do the opposite of what I am thinking of doing but the image is a perfect example of how my lens/tube is setup. The distances are exaggerated in this image but should be easy to understand. The image on the left is basically how mine is now with the lens mounted low in the tube and a 16.5mm distance to the work piece. The one on the right the lens is higher in the tube and the distance to the work piece is much smaller. Would this improve the cutting ability and possibly allow me to increase my speeds which would help reduce residue on my cuts?
The only concern I have, if this is a doable option, is that the factory position of the lens there is a hard stop that the lens is tightened against. If I were to move the lens up then the position would not be as set/repeatable. I guess I could 3D print a inner spacer/sleeve that would help. Hmmm
In order to cut wood you need to burn it. In order to burn it you need fire and air. More air is always better because you will never blow out the fire (laser beam). So without driving the nozzle into the wood, a nozzle held closer is better. You might need a shorter focal lens on the right.
I’m sure cutting non combustible materials works differently.
I will have to look for those. That would make things a lot easier.
By looking at the different nozzles in the image, I am thinking that my machine came with a 2" lens tube and a 2-1/2" lens. When I first setup the machine I could not get it to focus using the settings/procedures the seller told to me use. He told me many times that it came with a 2" lens. But after doing a ramp test I realized that the focal point is between 16 & 17mm from the nozzle instead of 5-6mm like he kept telling me. I have heard how Chinese factories will use whatever parts they have around to finish a product and get it out the door. So it does not surprise me that it is not the lens it was supposed to be.
With that said, I am thinking that maybe I just need to buy a lens tube for a 2-1/2" lens (or Russ’s setup if I can find it).
If my comment above is true and I have the wrong lens/tube combination, then I think getting the correct size tube should work. And from what I can tell in the image, the nozzle appears to be the same for the 2" & 2-1/2" lenses. I am just trying to get it down to about 5mm which seems to be the sweet spot for a lot of these lasers.
Hey do you know where I can purchase these? I cannot find a link.
Also I have been trying to access the RDWorks forums for a few weeks now but it looks like it is dead. Do you know if it will be back or did he shut it down?
The most simple way is to do a ramp test and measure from the best focus to the approximate lens location within the tube. That is probably the best judge of focal length. It’s got to be closer than the 1/2" you are varying between.
Don’t know what to tell you about RDWorks site. Some of their requirements are too strict for me. They require you post quite often, so I ended up being kicked off since I didn’t post enough. It’s got lots of information, it’s sad they came up with something that makes the site seem like more trouble than it’s worth.
I got mine from Russ Sadler in the UK. You should email him and ask. He’s really a nice guy.
Most of these are Chinese, don’t know about your machine. Need to know the bearing type to get the proper head mount. So make sure you add that information when you email him… The way it’s mounted and the size of the bearing.
Most of the mass of the X axes has been removed. The machines acceleration is set to 45,000mm/s^2. It pays off in just overscan time. Even though it will run 1650mm/s, that’s a purely academic benefit.
My best guess is that it is right about 63.5mm. My machine came with a 52mm square piece of polycarbonate. The lens sits right around 10-11mm (+/- 1mm) higher than that.
While researching new lens tubes I came across this adapter/spacer. I am thinking that this is another way to move the lens further away from the work piece.
That’s what I thought. What sucks is I just found the forums and joined right when I got my machine setup. The next day I went to start researching and it was gone
Russ charged me 40 quid ($51.86) for mine when I ordered it in late Sept of this year. He also included lots of extra goodies; it was almost like Christmas.
Russ also chastised me for delaying his much-deserved retirement . I installed mine on an OMTECH ZF2028-60. In my case I have 15mm top mounted liner rails. I ordered the adjustable head mount from Cloudray (along with a bunch of other bits and bobs) and everything bolted together quite nicely. I can’t tell from the picture if you have a side mount or a top mount.
Well I have a feeling that he will have a hard time retiring as popular as he is in the laser world. LOL
I don’t know enough yet about my machine/setup to know what I need to replace and with what. Other than this air assist/nozzle height issue, I am pleased with it so far. Hey I do have a question though. I do not understand or know the difference between the Cloudray C series and E series? And is this designation a Cloudray only designation? Or is it an industry designation? When I try to search for C series parts only Cloudray comes up. So I am thinking it is just Cloudray but I could be wrong.
They are different… These are the links, but it looks like a very similar photo… These have the specifications. At one time I was told they were different machines, but I don’t know.
He was retired when he started this stuff…
Although I learned a lot doing this, if I’d been smart, I’d have purchased one of the Russ Spec lasers in the first place.
So I think I found the difference between the Cloudray C & E series lens tubes. I cannot believe I didn’t see the difference before when I was going through the specs but the C series has a 24mm outside diameter and the E series has a 25mm diameter. So now I know mine is a C series.
I received my Cloudray lens tube today and installed it using the 63.5mm side. I ran a ramp test and the sweet spot was right around 1mm. This was obviously too close to the nozzle so I removed the lens and screwed one of the extra lens locking rings inside and then installed the lens up against that. I reran the ramp test and it came out at 5.5mm from the nozzle. I think this is about right. When cutting 5mm material it leaves about 3mm from the nozzle. It definitely brought the air flow right down to the material.
The strange thing is that I do not really notice any improvement in cutting ability. I was hoping that doing this would allow me to increase my speed a little at lower power settings but this did not appear to happen. But I do think that the cut edges are cleaner with less residue so I guess that is a plus. I do plan to hookup my compressor to the air assist in the future so hopefully that will help improve my cutting.
If you have the “C” series lens tube you could pick up some extra nozzles, of different lengths (I have several), and swap them out depending on what you’re doing. Just be mindful of the nozzle exit diameter.
. I installed mine on an OMTECH ZF2028-60. In my case I have 15mm top mounted liner rails. I ordered the adjustable head mount from Cloudray (along with a bunch of other bits and bobs) and everything bolted together quite nicely. I can’t tell from the picture if you have a side mount or a top mount.
