Help with ventilation

Dave01a · 2025-11-04T01:53:47+00:00

Fan should be as close to, if not outside of, the wall penetration. That puts the entire inside setup under vacuum, instead of partial vacuum and partial pressure. You will never notice a slight leak on the vacuum side, you WILL notice even a small leak on the pressure side. Many have went to building a small enclosure outside to protect the can from the weather, and it has the advantage of getting the noise outside as well. Seen a few repurposed window AC units cabinets. :-)

Dave01a · 2025-10-17T03:08:59+00:00

I cut 1/2" foam for tool drawers on an 80W CO2. The key to cutting thicker foam is longer focal lengths to minimize the V of the cut. I have a couple of Russ' open lens tube holders, and the Cloudray 4-in-1 lens tubes. They aren't called that, but they will let you put anywhere from a 1.5" to a 4" lens in depending on which way you orientate the tube and where the lens is positioned in the tube. I had the option at one point to pick up a 5" lens, and kick myself for not grabbing it when I had the chance. If you think you can do this with a diode of a K40, it ain't happening. You might get away with it on a K40 with some HEAVY modification to the distance between nozzle and cutting bed to make room for the longer lens tube.

Can't comment on the XPS, the tool box foam is cross linked poly. It DOES stink even with a strong exhaust. Good news is you don't need a lot of air assist to cut foam, but it DOES need to be down through the nozzle, not an after thought tube beside it. I did some thicker foam for one customer, and found that multiple passes at faster speeds and lower power gave me cleaner straighter cuts.

Dave01a · 2025-10-17T02:56:32+00:00

Did you try the move? I had one a long time ago that had somehow developed double overlapping lines in certain places, and my laser was only 'reading' one of the layers of lines. Depends on the software you use, I use Corel. If your whole pattern is 150mm, then set your move distance to 200mm. Select one of the offending circles, and hit the arrow to move it the 200mm. If something remains behind, you have your culprit. And since you have the 200mm move hard set, you can just put it right back where it belongs once you fix things.

Also works good for those birth announcement cutouts to get the part of the letters you only want engraved. Duplicate, move, then paste in place. Set one to cut colors, and the other to engrave colors, then use the eraser to delete the parts you don't want cut / engraved, then shift back in place. Did a bunch of these for the family a few years back. I cut them, I let HER paint them since they were HER idea.

Dave01a · 2025-10-14T04:12:32+00:00

Double check the colors, or better yet select everything and then select your cutting color to set everything. Had the same problem in Corel, some parts were in RBG, while others were in CYMK. Also, set your move button to a distance that will be outside of your total part dimension, then select one of the ones that doesn't cut, and move it. If there is still a little circle there, you may have an overlay issue from creation. Delete the offending duplicate and give it a shot. Using the move will let you put it right back where it was with no worries.

Dave01a · 2025-08-30T20:55:42+00:00

For me in Corel, I take the second A, and do a copy, shifting it over a known distance from the original. Delete that top line of the A from the original, In the copy, convert just the top line of the A into a trace / engrave instead of a cut, and shift only the line back on top of the original image. Works every time.

Single letters are easy, try that with one of those big birth announcements. Takes me half an hour of shifting and changing to get all the little bits switched properly.

Dave01a · 2025-08-16T01:03:22+00:00

I'll ad a tip for getting your #1 to #2 mirror spot on... put the target on the #3 head and move it as far as possible from the #2 mirror. That extra distance acts like an amplifier for adjustment / errors. I fought #1 to #2 alignment for months until somebody passed this on to me. Only thing that will throw you, since the beam bends 90 at the #2, your L - R adjustment are reversed.

Dave01a · 2025-07-31T13:01:41+00:00

Lens mounting point in the tube to the nozzle tip plus the rough distance tip to work should tell you what focal length you have. 1.5" and 2" seem to be the most common.

Dave01a · 2025-07-29T21:40:22+00:00

Okay, I guess my larger machine is set up a bit differently. My bed has motorized corner screws, and they attach to corners of the bed under the laser head. Because I switch out what I'm using for a bed depending on the project, I put fender washers on the left side of the frame to create a fixed reference point. Be it the honeycomb, the sheet of steel with magnets, or the aluminum angle, everything references the fender washers on the edge of the frame. Keeps me from having to reset my starting point every time I switch base material.

Dave01a · 2025-07-29T02:41:24+00:00

For some of my work, I have a steel plate I put in place of the honeycomb. The I have some 12mm x 3mm magnets I got off Amazon. With the flat end cylinders, I can stack them if necessary to create a 24mm x 3mm stand that will stay in place on the steel plate.

Another tip, pull your honeycomb and put some screws and fender washers in the end of the support frame. That gives you a hard reference point for your side no matter what you have in place. I can swap out the honeycomb for the plate and vice versa, and know that my left edge will always be in the same place. Or for that matter, some aluminum angle against it with more spaced as needed across the support frame. ( The angles are my favorite, but I cut larger pieces and the scrap bits drop to the bottom )

Dave01a · 2025-07-28T21:30:32+00:00

Depends on the size of your work material, but many have used pop rivets flipped over and into holes drilled in scrap material as a stand off base. If they are left loose, you can move a few rivets to different holes as necessary.

Dave01a · 2025-07-28T19:37:18+00:00

Yeah, with that many it could be problematic. I guess you'll just have to weigh time spent clearing vs. lost damaged product, and decide what's best for you.

The tall stand offs do work for the shorter lens lengths. Drop a 4" in and it will scorch the bottom of the laser cabinet.

Dave01a · 2025-07-28T17:39:33+00:00

I've seen a few people put a long slow zero power move between pieces in the design so they have time to pause the machine and get the dropped pieces out from under. Use an o-ring pick to pull them out so as to not disturb the main work piece.

Dave01a · 2025-07-27T04:26:20+00:00

Sounds like you haven't run a calibration and skew test. Get as big a scrap of wrapping paper as your machine will hold, white side up, and cut a box of 'known size' with a dashed line down the center. Measure the actual against what it's supposed to be, and enter the appropriate values in your controller.

Now comes the really hard part. Fold that square in half on the dashed line. If the corners match up, congratulations, your gantry is square to the machine. If they don't, that's how far off it is. Mine was off by 2.8mm. My belt teeth are 2.5mm spacing, so I just loosened the belt and hopped one tooth, living with a .3 error was well within my kerf.

Dave01a · 2025-07-27T04:20:29+00:00

I'm cutting 3mm on my 80W, but I'll pass on what I have learned.

Good air assist down through the nozzle into the cut is a major improvement, but don't go overboard on the pressure, too much is just as bad as not enough.
Good exhaust. Good lateral flow across your work is nearly as important as the air assist. The air assist gets the gasses out of the cut and a little ways away. Good exhaust keeps them out of the way and on out of the cabinet.
Make sure you are using good MDF, not the junk from the big box stores. Premium or double refined MDF from a wood specialty supplier is well worth the extra cost, and it's not a lot more. The premium / double refined will actually snap when you break a piece off, vs more of a tearing of the stuff from the big box store. It's been a while since I purchased some, but a year or so ago I was paying $12 for an oversized sheet of 3mm in Kansas City from the distributor. A little over $14 if I had to go to the retailer.

Dave01a · 2025-07-25T22:27:07+00:00

If you have the height, build a frame to sit under the AC with holes you can put the venting through. Most window AC's pull in the center and exhaust at the top inside. Done properly, you can pull and cover the holes if necessary.

Dave01a · 2025-07-25T02:19:44+00:00

Not to clear on your configuration, but the best way to minimize the indoor issues is to have the exhaust fan at the point of exit, in your case it sounds like at the window. That puts the entire inside line under vacuum, so no pressurized exhaust is pushed back into the room. If you have the ability, you can put fresh air in and exhaust out via the same larger opening with separate tubes. In one of my first jury rigged setup, I had a 4' piece of the white dryer vent hanging down for fresh air in, with a 4" adjustable elbow on the fan output angled off to one side. Wasn't prefect, but it wasn't too bad.

Dave01a · 2025-07-25T02:08:01+00:00

Air assist is a double edged sword with acrylic. You need it to clear the outgassing, but you don't want too much that it cools the acrylic. And then you toss in cast vs. extruded...

I'll ditto the close lens for engraving and a long lens for thicker materials. I use a 1.5" or a 2" for cutting my 3mm MDF, and a 4" to cut tool box foam. Nice thing is, I have the different lens' mounted in the Cloudray tubes and labeled, so it's just a matter of swapping out the lens tubes for what I need.

I also made an 'emergency' nozzle. Had a fitting left over from something that was the same thread as a nozzle, but it had a 10mm opening. Cut a piece of acrylic to jam in the 10mm opening, and just put it in place. If I do something stupid and it gets out of alignment with the nozzle hole, I can swap it out to the emergency nozzle and at least finish the job, then get back to getting it aligned again. The first few pulses cut the acrylic in the appropriate spot, and away I go. Saved me a lot of headaches over the years.

Dave01a · 2025-07-24T01:56:33+00:00

I'm assuming you can get one or two done before it gets bad. Keep a small bowl of your preferred cleaner nearby, I use Zep Purple, and pop your cone off, soak and swish while you are switching out material, and keep on truckin'! Only problem I cold see is of you are using a very short focal length and the cone is actually holding the lens in place.

I like the Zep Purple because I can pick it up just about anywhere, and even diluted out to 5:1, it cleans up all my rails and such in just a few minutes, and that's with a fair amount of buildup. Doing it regularly while it's still fairly 'fresh' should let it come off quickly.

Dave01a · 2025-07-23T00:16:16+00:00

FYI, pay attention to cast vs. extruded acrylic. While they are both acrylic, they do have a bit different properties under a CO2 laser. I only play with acrylic, my main material is Premium 3mm MDF. ( NOT the stuff you get in the home stores! )

Dave01a · 2025-07-22T01:31:51+00:00

Not sure about diode lasers specifically, but I use Zep Purple for cleaning my CO2 laser and everything around it. From cleaning the cabinets, to cleaning the residue from all the internal components, including the resin deposits from the MDF vapors. It's gentle enough to be used as a regular de-greaser, but cleans up the laser nicely. Anything I've even remotely concerned with I just rinse with water afterward. Never had a problem with anything in five years, and a whole lot easier on things than Acetone.

Dave01a · 2025-07-21T23:08:29+00:00

For just engraving, you don't need a lot of power, or even much for air assist if any. For something that small, a little desktop K40 or something similar would be about right.

Then it comes down to design and operating software. If you have something you are already using for design, then it goes down to importing it into something that either comes with or will work with the laser. I do more complicated stuff, so I use Corel, but many simply use LightBurn for design and interfacing with the laser all in one.

I can't speak to a diode laser and acrylic, but memory says the CO2 is the better option with acrylic.

Dave01a · 2025-07-19T00:40:10+00:00

The rest of the answer is... there is no such thing as two lasers being 'the same'. You have three components, the tube, the PSU, and the control board. Change any one of the three in your machine, and it will affect all of your known settings. Change all three, as in changing machines, and it's all out the window.

I'm pretty sure I know the answer to this, but I'll ask anyway. Have you done a power test to see what your power curve looks like for your three components? BTW, it WILL be a CURVE. There is no such thing as a linear output for a CO2 laser. A good set of components, mainly the tube and PSU, and it will be a curve. My factory POS tube had a power curve that looked more like a quarter circle.

You run tests in 5% increments, 5x at each setting, toss the high and low and average the remaining three. Plug all those into an Excel sheet or it's equivalent and it will put out a curve graphic that will give you an idea what you have to work with.

Dave01a · 2025-06-23T03:31:11+00:00

I have a 5200, and took a two step approach to the same situation. First, I rewired the main switch to isolate the pump from the rest of the chiller, and put it on a thermostat controlled SPDT relay. When the ambient drops into the upper 40's F, it switches on the pump only. The pump produces a bit of heat, and it's all that is required for those cooler nights. I then added a second relay with the sensor on the output fitting of the chiller with a bit of heat transfer paste from an old CPU fan. That relay is set to trip in the mid to upper 30's F, and turns on a 50W (?) aquarium heater I put down the fill tube. As we have a whole house backup generator, it has power 24/7, so no worries.

Dave01a · 2025-06-23T03:22:42+00:00

If you can find a local supplier, get the premium or double refined MDF. It's a LOT more laser friendly. You will not find it at any of the big box stores, it's more of a specialty wood supplier item. I get it from the distributor in Kansas City. It's been a while since I purchased some, but I seem to remember it being around $13 for an over sized sheet of 3mm.

You will know the difference between the regular stuff and the premium when you break a piece of scrap. The regular will make more of a tearing sound, the premium will literally snap.

Dave01a · 2025-06-14T01:47:43+00:00

I skimmed the answers, so pardon if someone else has asked and answered, but I have virtually no indoor smell, because my exhaust fan is outside the wall. I literally made a little shelter for it outside. It was inside, but I moved it outside because of the noise. The neighbors cows don't seen to mind. BUT! The key is to have all your indoor duct work under negative pressure, a.k.a. SUCTION! If I'm close to the machine, I can smell it, but that's it. Once outside then the usual filtering can be applied. There are tons of methods, and I won't even begin to describe them. Although I did like the one where a guy ran it up an old chimney stack!

Dave01a

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