Posts tagged #exhaust

Laser Exhaust Complete, First Test Fire

Completed the exhaust system for my FSL 5th gen laser today and did the first test fire! All seems well. First the exhaust, then some nit picks about the setup. As mentioned in the first post about the exhaust, I got the Harbor Freight 1HP dust collector, the router speed control, and this 4" blast gate. To complete the setup I ordered this 4" stay put flexible duct hose, and made a run to Home Depot for the following:

  • 4" x 5' metal rigid vent pipe
  • 4" dryer vent hood
  • two 4" 90 degree adjustable vent pipe elbows
  • 4" x 2ft alum. vent pipe
  • four 8"x8"x16" cinder blocks
  • 3 roofing shingles
  • four 2.5" 5/16 bolts/nuts/washers
  • 2 hinges

With all this and a bunch of spare lumber I had around, I built the exhaust box. I used 2x2 for the corner supports, 3/4" plywood for the side, 3/4" MDF for the base, and some 1/2" chip board for the top. The base is around 16" square, same for the back, front is 13" x 16", sides 16" with angle cut at top to make sloped roof. Basic layout is like so.


The blower is bolted to the MDF with some 2.5" 5/16ths bolts.


I then cut the holes for the intake and exhaust and screwed it all together. There is a notch in the back side of the floor to run the power cable through. Running it out the bottom keeps water from running down the cable into the box, this way it'll just drip off the bottom. Some duct was run between the exhaust and the dryer vent, and a 90 deg elbow for the intake both hose clamped on. I put some hinges on the top so I have access to change motor brushes or clean it out etc.


I threw some shingles on top for rain protection but we'll see how that goes. Also some aluminum tape around the inlet hole to keep water out.


The window insert is 1/2" plywood with a 4 1/4" circle cut into it for the blast gate and a notch for the power cable. The cable comes in the window and plugs into the router speed control with is mounted on the inside. I painted it black and am using cheapo foam pipe insulation as weather stripping and it works great.


The blast gate lets me shut off outside air to keep the tube from freezing in the cold. Pretty simple setup and it's pretty quiet when not running full blast, which I don't foresee doing too often as it's a LOT of air at full speed.


Pretty happy with the setup. Easy to remove if I need to move the laser, and pretty quiet for me. We'll see what the neighbors think.

Setup and Test Fire

Setting up the water pump and air compressor was pretty simple. They forgot to put in an air tube so I had to run to Petco and get a 1/4" OD air tube for $5. The air compressor comes with a splitter which is semi annoying as you have to block all the split ports since you just need one to go to the 1/4" OD air assist input to the printer. This is my ghetto quick rig just to test it. I'll come up with something better.

air pump

The air hose on the inside of the laser that come out of the coupler wasn't seated very well so I had to take the side panel off the laser and reseat it. Otherwise everything seemed well assembled. I threw some thermal paper on the bed and fired the pumps up and did a test fire and the laser looks well aligned. Ready to rock! Just waiting on the iMac to get here that will be used to run the laser so I can run an actual job! Can't wait.

Friggin Lasers
Posted on March 3, 2013 and filed under Laser.

Laser Exhaust

A laser burns/vaporizes to cut material, which means lots of smoke and nastiness coming off the laser bed, which needs to be vented away not only for optical reasons (a laser shooting through smoke gets scattered and loses power) but for health/sanity reasons. Originally I was going to put the laser in the basement workspace but after realizing I'd need to be present during cuts for safety reasons, I decided I'd rather spend that time in my office rather than the freezing ass cold basement. So... how to vent/exhaust a laser out of my office... I found this great "Laser Exhaust Systems Basics" article very helpful.

The FSL 40W 5th gen hobby laser I've ordered has a 4 inch exhaust port on the back, which can be seen in this YouTube video. They offer an exhaust fan for $250 as an accessory. I know I could get one for half that, and even FSL suggests as much mentioning the one from Harbor Freight I'll talk about below. The exhaust will come out of the laser via metal 4" flexible ducting (dryer hose style) and pass through a 4-Inch Blast Gate in a window seal probably made of painted wood. From there I'll probably run metal vent pipe down to the exhaust fan outside of the house in a weatherproof box (doghouse? plastic tub? something like this but much nicer?). This will keep most of the noise outside of the house and the blast gate will allow me to keep the cold air off the laser tube when the system is off and control the airflow when needed to a finer degree than the speed controller. Nice negative pressure system sucking air through the laser bed and venting outside. But what fan to use...?

After reading way to much about exhaust fans on the forums...  I settled on a couple of options.

240 Bilge

This thread on the FSL forums recommends an in-line bilge fan, specifically a Rule 240 Marine Bilge Blower, which is $33 (plus a $17 power adaptor... it's 12V after all). That's cheap! Noise level reports are all over the map. You could easily put a dimmer switch on it to control speed. It's rated at 240 Cubic Feet/Minute (CFM).

1HP dust collector from HF

The other more popular option on all the forums is the 1HP Mini Dust Collector at Harbor Freight, referred to as "the red one". It's $99 (easily $80 with HF coupons) and can be speed controlled with a router speed controller for $20. So supposedly much more powerful but much more expensive. I like the easy speed control that will also allow me to turn the fan on and off remotely. Con is that it uses a brushed motor so the reports are that the brushes have to be replaced fairly often with regular use and that they are hard to find. The other popular option is this "green one" from Harbor Freight, which is brushless so it'll last a lot longer with less maintenance, but it's soft start so it can't be speed controlled. It's supposedly much quieter, though "the red one" is supposedly pretty quiet when not at full power.

So I'm going for the red one with speed controller as of now. (Ordered on 2/20/2013 with blast gate and 9" level from HF)


The whole negative pressure thing could be interesting. As the Exhaust Systems Basics article mentions, a system like this needs "make up air"... or air to replace all that air you are sucking out of your space. A 500 CFM setup will suck all the air out of a 8' x 8' x 8' room in one minute, creating a vacuum. You are also pumping out all of the heat/cool of your room/house depending on the season. So in winter I'm basically blowing all my heat out the window. I'm going to set it up and see how it goes. I might have to set up an outside air feeder system or just end up putting it in the basement workshop where that's not a concern. We shall see...

Posted on February 20, 2013 and filed under Laser.