Strong acrylic smell on small rastor and vector?

[Keith Upton]

Hello everyone,

My first post here but I've gained a lot of information from everyone posting their experiences... so thank you!

I just picked up my Epilog Mini 24 (60w) a couple of weeks ago and start cutting and engraving various materials. One of them is clear acrylic. Whenever I engrave or cut this, I get a pretty strong odor in the office. Enough to have to vent the air out the window with a three head window fan. My laser is exhausted separately with an inline 6" 440CFM fan and 4" silicon ducting with about 5 feet total run. My question is, should I be getting that much of a smell from engraving and cutting a 4.25 inch circle (screen shot of the item attached)? I'm thinking I should not be. If that is the case, is it that I don't have enough air moving through the exhaust system to pull it out of the laser fast enough? I'm pretty sure the odor is coming from the 6 laser tube cooling fans on top of the Epilog. I know it's not coming from any leaks in my exhaust system.


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Thank you for any help or advice,

Keith

[Mark Sipes]

I had a problem with my exhaust going into my neighbors place of business 50 ft away. Could not figure how the odor ( burning walnut) was making it that far and still being so strong. My laser vents to the outside via an inline fan with a 4 ft run so the smoke was venting out of my business out the dryer flap vent. Well the smoke was shooting straight down to the ground into a crawl space access and over to the neighbors business heater/ac fan unit........a simple cover deflected the down draft and problem solved.........

I would buy a can of smoke ( smoke detector tester) and power up the laser and fans at normal and track the smoke and see where the air is flowing.....might be surprised to see where the leaks are.....
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[Dan Hintz]

Where is the fan in relation to the output?

It should be:
Laser --> Duct --> Fan|Outside

You should be pulling air into the outside environment, never pushing... and your fan itself could be leaking, so check that.

[Jerome Stanek]

Where are you exhausting the laser through the wall or out a window. If you put the fan right at the exhaust point and draw the smoke and odor it would be better

[Mike Lassiter]

You also need to consider where the air that you are exhausting out of the room or house is being drawn back in from. If you have air going out it must be replaced somewhere. Is it possible air is leaking around a window by the exhaust outlet and being sucked back into the room or building?

[Keith Upton]

Thanks for the replies everyone. My exhaust is set up like this:

Laser --> Duct --> Fan --> Duct -->|Outside via window

I know that is not ideal at all, and I have some parts on order that will allow me to set it up as Dan suggests (Laser --> Duct --> Fan|Outside via window).

I've leak tested everything on the output side of the fan (soapy water method) and there are no leaks there. I also sealed the fan itself. Right out of the box it was not air tight at all. I exhaust out the window that is next to the laser. I put a 3/4 board with a 4" hole in the window and sealed it with weather stripping. I have to compress/force the sides and bottom down into the window opening, so no leak back there. The window just closes down on top of the board, so there could possibly be some leak back there of odor, but I don't think it's that.

When I smell around the window, before the smell gets strong in the room, I don't smell anything there. I do smell the odor right away when I smell at the laser tube fans on top of the machine.

My return air is just coming from the house in general. I don't have another window in the office that I open up while my lasering... as the only other one is right next to the exhaust window and I did not want to pull that air back into the room. Sometimes I close the one office door to help keep the smell out of the rest of the house, but perhaps that is adding to the odor problem by not allowing enough return air into the room?

I have borrowed my friend's anemometer and measured the CFMs coming from the fan alone and at the end of my exhaust run. I'm losing just over half my CFMs with the current run (one of the reasons I've ordered new exhaust parts to let me remove pretty much all of the silicone flex hose). I plan on running two 90° coming out of the laser into the fan, then straight out the window (fan reducer will connect directly to the opening in the window).

When I laser other smokey materials, I can see the smoke being pulled out of the laser chamber, but I would not say it's getting removed super fast.

So, barring any exhaust leaks or the bad air getting pulled back in the room as part of the flow cycle (both of which I will test and address again), would higher exhaust flow reduce odor around the laser? I mean, you guys that have yours setup and running production stuff, can you smell strong odors while you are cutting?

[Keith Upton]

I would buy a can of smoke (smoke detector tester) and power up the laser and fans at normal and track the smoke and see where the air is flowing.....might be surprised to see where the leaks are.....
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Mark, where can you find those cans of smoke? I did not see them listed on Lowe's or the HD websites.

[Mike Lassiter]

Another thought - you said you are loosing 1/2 of fans rated cfm if I understood right. Maybe need to consider air tightness of building and fan trying to pull more out than building leakage letting back in. I know this may sound odd but try cracking a window to allow air in. If air cannot enter building the fan is effectively starved for air. For fan to remove 400 cfm for several minutes of running time that much air must be available for it to move. Think of your car or lawnmower with stopped up air filter.

[Joe Pelonio]

I have a similar setup with about 4'duct, then fan, then 3' duct and out, with no fume problems.
My fan is 800 cfm and I always crack a window to allow it to come in to replace what goes out.
Another thing that helps is leave the fan running and wait 10-30 seconds before opening the top to remove the items to ensure that the last of the fumes have been extracted.

[Keith Upton]

Thanks Mike and Joe. I'll try opening a window in an adjacent room and see if that helps with the flow (I'll measure it with the anemometer to see the difference). I also try and wait a few seconds to let all the fumes get pulled out before opening up the laser.

[Dan Hintz]

Another thing that helps is leave the fan running and wait 10-30 seconds before opening the top to remove the items to ensure that the last of the fumes have been extracted.

That was going to be my next suggestion... annoying when you're trying to crank through a number of items, but if you want to cut down on smell, you gotta do what you gotta do.

[Keith Upton]

Well, looks like MLK day is going to delay my exhaust parts another day

[Joe Hillmann]

Does it start to smell when you are cutting or once you open the laser and take the parts out. There are many materials that will hang on to the smokey smell after they are taken out of the laser and will stink the place up from a few hours to even days after it is engraved.

[Keith Upton]

Does it start to smell when you are cutting or once you open the laser and take the parts out. There are many materials that will hang on to the smokey smell after they are taken out of the laser and will stink the place up from a few hours to even days after it is engraved.

During the cutting and engraving of that small 4.25 inch round product posted above.

[Chuck Stone]

Another thought - you said you are loosing 1/2 of fans rated cfm if I understood right.

You can lose that just by using flexible duct. 90° turns, blast gates, dryer vent flaps.. they
all suck down the cfm, probably more than anyone realizes.