Is that adjusted at the final mirror mount, the lense, ??? I’ve not run into this before.
Yes ans no.
Getting your beam parallel in Z is done via the #3 mirror, getting it centered in the lens tube is done via physically moving the head and / or the #2 mirror.
Just like getting your beam parallel, in Y and X, notice I did NOT say centered, you also need to have your beam parallel in Z. As in down the lens tube. Once you have it parallel in Z, then you make the physical adjustments to get it in the center of the lens tube, that correlates to center of the lens. And the incoming hole into the #3 mirror if you have that type, is in no way shape or form connected to center of the lens tube. It usually is in Y, but with my old head I had to hit the hole 2.5mm high in Z to be centered in the lens tube.
If you haven’t seen them, Russ has some great videos on the CO2 lasers and several on alignment. Personally I think his #192 & #193 are about the best on alignment and the reasoning behind what you are doing. The first 30 minuets of the #192 is on mod progressions over the years, so you can fast forward through that if it doesn’t interest you.
Found one of my post-it notes. His #119 about 30 minutes in is another good one on getting your Z set up properly.
Thanks a million for the info. I’m working 12 hour night shifts all this week so unfortunately I won’t be able to mess around with it until Saturday. This covid crap has me helping fill in the gaps of missing persons due to illness or quarantine so I’m stuck on long night shifts doing other people’s jobs this week…7pm to 7am.
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Well, I went through the entire alignment process and found everything is good up to the last mirror. When I remove the lower cone and lense, the laser appears to be square to the bed. Putting the cone and lense back on appears to shift the beam back and left. Im going to try to verify this somehow .
Appears to be? So you haven’t actually checked your Z for parallel?
Burn a test spot, lower your bed as far as you can, and do a second burn just like you did for Y and X, just a shorter distance. I like to do a test after reinstalling the lens to verify what I think is a parallel Z. Same procedure. test close, then move away and do a second test.
Yup…did that. From the bed in the high position to the low position, it only moves a little bit. I reinstall the lense and it moves back and left quite a bit.
It moves when you put the lens in… So after you had Z parallel, you verified it was centered in the lens tube. An off center beam will kick as it goes through the lens.
Centering is done via physical movements, not the mirror adjusting screws.
If it’s not done using the mirror screws, how is it accomplished? I watched some vids on adjusting the beam and it shows moving the mirror…
Once it’s parallel in any axis, you don’t touch the adjustment screws. You physically move the mirror or head to ‘catch’ the beam in the correct spot. The exact how depends on your physical set up. Usually you will have one axis adjustment on the #2 mount, and the other on the #3 mount. If you are lucky, some will have two axis adjustment on the #3 mount.
I’ll start this from scratch just to be sure I don’t miss anything. You align #1 to #2 to get it PARALLEL using the adjustment screws. Then you physically move the #2 to get it close to center. You adjust the #2 to #3 to get it parallel. The you adjust the #3 to get Z parallel.
Then comes the fun part. You will adjust the #2 front to back to move the beam front to back in the lens tube. You will raise and lower the #3 head to move the beam left to right in the lens tube.
Check out Russ’ #192 & 193 for a good tutorial. The first 30 minutes or so of 192 is progress in design, so you can skip through that if you want.
When I check #1 to #2 it was parallel and centered perfectly…same with #2 to #3. I think i made a mistake somewhere after that. I’m going to restart the process in the morning and this time having the video playing as I go. I really appreciate all your help…I will have an update tomorrow morning. Thanks again!
One thing to remember, the incoming hole into the #3 mirror head is in no way shape or form associated with center of the lens tube out the bottom. Usually you have to hit the hole a few mm high of center to even get close. That’s the up and down that is hopefully built into your head mount. If not it’s time to start shimming.
It’s the nature of the beast. The Chinese read from right to left. I had no problem setting my machine up to start on the top left, but it still homes to the top right during start up. Completely normal me thinks.
It should home to your homing switches. You can pick any corner to mount the switches, and then set the software in the controller to home to that corner.
Now if you are talking the 0,0 in design software, yeah, that can be a PITA. My 80W red & black physically homes in the top right, the machine has a 0,0, in the top right, but the software that came with the controller has a 0,0 in the top left… even though when I installed the software it asked my home position and I gave it top right.
Success! I actually had to loosen the brackets and move mirror assembly #2, the head, and adjust mirror #2 and #3, then go through the alignment process again, but it cuts perpendicular to the bed now. I also found out that my focal length was way off from what the included shim calls for. I had to raise the bed over 1/16 of an inch for a good clean cut. Thanks again for all the help…I would have fought it for hours without the good advice.
Yeah, engraving wants a nice precise focal point and a short focus lens. Drop a different tube in set up for a long focal length lens for cutting and the focus point becomes a lot less significant. You usually want to set your focal point one or two mm into the surface for cutting.
Where is the best place to get a "cutting " tube?
Lens tube, and it’s actually a combination of the tube and nozzle. Primarily the nozzle to have the proper air flow, but also the lens tube to let you put longer focal length lens up into the lens tube.
Example: I have anything from a 1.5" to a 4" lens, yet my nozzle tip to work surface distance only varies by a few mm at around 8mm.
A cutting nozzle has unrestricted air flow through a small opening directly down into and close to the cut. Where as an engraving nozzle will have a restricted air flow through a much larger opening and holds the lens so the nozzle tip is up around 20mm from the surface.
For engraving, your exhaust fan is doing the heavy lifting, the air assist is just keeping the lens clean. In cutting, the strong air assist is functioning a lot like a cutting torch, keeping all the out gasses clear of the laser beam.
My best analogy to date, is cutting with an engraving configuration is like driving at night in heavy fog with your high beams on. Clear the fog of out gasses with good air assist and everybody is happy.
Without knowing what you have for a head configuration, I can’t say if making the change to a cutting set up would be simple or involve a complete head change. If you want to see the resulting physical difference, check out my Google Mod Page and look at Air Assist 04.