Cold Air Gun

[Kenny_BTFP]

We need a cooling method for our aluminum work. We have a vacuum hold down system installed on our shopbot. I was told that I shouldn't use any kind of lubricant or cooling fluid because it can ruin the vacuum system.

I have started looking into cold air guns, but i am not sure what the difference is between them. Also, we have an 80 Gallon 2 stage air compressor for our air drill, but will it also be able to handle the cold air gun at the same time?

[Brady Watson]

Tooling selection is paramount. You want a tool designed for CNC routing of AL, which should be of the O-flute variety sold by Onsrud, Behlin or Harvey Tool.

Second, if cooling IS required, start with a less demanding cheaper option like a football inflator nipple pointing at the bit. It will use about 4 CFM @ 25psi. Dust collection definitely moves enough air for most AL cooling with the right bit.

Cold air guns are nice & do work. They are not always required. I've never used one and have cut a decent amount of AL. You'll have to get CFM ratings from the manufacturer & compare that with your compressor output and the air drill CFM, which I think is advertised around 5 or 6 CFM, but I find it is closer to 10 if you are drilling a lot of holes.

-B

[Kenny_BTFP]

For the football inflator nipple, are you just running the air hose to the machine, or are you using a flex tube like loc-line?

[Brady Watson]

Kenny,
Yes. You can make a setup for around $25. Get a Home Depot/Husky blogun kit with the inflator in it. Then buy 2 90 degree threaded brass elbows and a close nipple to connect them together. A long brass nipple can be used as a vertical support as well as a way to connect your air source. Make a donut with a little V in it out of 3/4" material. The inside part of the donut should be the diameter of the lower bearing housing on your router or spindle. Then use mini bungee cords to fasten it to the router so that it holds it up. A large hose clamp will hold the long nipple in the V notch around the outside of the donut.

Tighten or adjust the 2 elbows so that the inflator (which comes with an adapter for the brass fittings) is pointing right at the bit. Take care to avoid collisions. Dust collection is out unless you clearance for it.

That's just how I did it using local parts. I see absolutely no reason why you couldn't just use a loc-line, which is probably a lot easier to adjust.

-B

[Kenny_BTFP]

Brady,

Thanks! Im going to look into that. Also, my PM came to me with a different air compressor model from what we were going to get and isnt sure why one over the other. Could you give me your opinion?

This one: http://www.aircompressorsdirect.com/Campbell-Hausfeld-TQ3104-Air-Compressor/p7630.html

Compared to this one: http://www.aircompressorsdirect.com/Ingersoll-Rand-2475N7.5-Air-Compressor/p707.html#reviews

[Brady Watson]

The Ingersoll is a superior machine. I know it is more money, but it puts out 24CFM compared to the CH @ 16 CFM. If you want air to spare, get the Ingersoll. It also generates 40 more max PSI than the CH - although my mac valve shuts it off around 152 psi. It may go higher when it breaks in fully.

Also, that model is available with two optional packages that extends the warranty. The startup kit comes with cork/rubber vibration pads, redhead anchor bolts, premium lubrication and air filter. There is also the 'full kit' version of this compressor that includes an automatic purge valve to get rid of condensed water in the tank, an aftercooler to cool the compressed air and a low oil switch that shuts the motor down if it gets too low on oil. I think this adds $500 to the price, but it is worth it.

I've got the same Ingersoll with all the goodies & starter kit. I didn't want another band-aid compressor so I went with one that would probably last as long as I will! Yes, it is more money...but you get what you pay for. It's got enough air to sand blast with, if you need to...

-B

[donchandler]

I have had one of the IR compressors like this for nearly 25 years. Had to replace a capacitor on the motor a couple of times. I seem to recall putting new valves in it once, but I am not sure about that. I have sandblasted with it many times, where it ran hard all day long. Great compressor!

[bleeth]

I have the 10HP version of the IR and it is a great machine. Well worth the difference.
IMHO Campbell-Hausfeld is an ok compressor for the occasional user but not a true production environment. According to several compressor people I have spoken with the CH, like virtually all of the value priced AC's use a different rating system to determine HP output and so not only have lower HP when compared to the likes of IR or Curtiss are just plain not as reliable when worked regularly. Note that IR does make a lower priced line that is not the same as their better built cousins.

[genek]

If i was running a vacum system. I think i would have a filter system for my lines going to the vacum pump... This could be made out of 6 inch pvc pipe... With a tee and a diverter plate to allow all debree to fall to the bottom.. This could be large enough to keep the water out of your vacum pump ect.