Aluminum Chip Control

[jeffreymcgrew]

Hey all. Thanks to all the great info on this here site, we just did our first aluminum cutting job (1/4" thick 6160 sheet) and it went (mostly) great.

Now, thing is, I can't run our dust skirt and dust collector when we cut aluminum, for I then can't mist the bit as it cuts and keep a close eye on it as it cuts.

So... what do y'all here that do a lot of aluminum cutting do to keep the chips from going everywhere? They are really, really sharp and no fun to clean up. I think when we re-do our shopbot table here soon I'll put in more of a 'tub' kind of thing, with enclosed sides and such, to try to keep the mess at least within the table itself. But I'd love to hear more ideas, for I'm pretty new to this whole thing, and I' sure there is something smarter that we could be doing...

[Brady Watson]

Jeffrey,
Why not modify the dust skirt to house the coolant nozzle? You will lose the luxury of being able to clearly see what is going on with the bit/material, but not have to deal with the chips.

-Brady

[jeffreymcgrew]

But then don't you get 'wet chips' stuck in your dust collection tubes? And isn't aluminum dust and/or chips a pretty flammable thing? Just wondering. So y'all suck them up without worry?

Sorry if it sounds like a dumb question!

[wcsg]

I cut quite a bunch of aluminum and have never worried about it, goin on two years now. MDF and alum chips. 20 ft. of hose before they enter the collector.

[Brady Watson]

I know at least 5 other ShopBot operators production cutting AL using compressed air only with excellent results. I would re-evaluate your coolant setup and see if the liquid is necessary.

-Brady

[frank_hav]

A "Cold Air Gun" MSC work great. They are a little pricey but I've used them for 10+ years. FYI: Misting or coolant in general if not applied properly are not good for carbide bits. Carbide likes constant temps. Cold-warm-Hot, but consistant. Micro cracks are caused in carbide by incosistant temps.

PS. I was a strong "D" english student so excuse the spelling.

Frank

[Brady Watson]

Frank...Yes they do...and yes they are pricey! All of the Bots I have seen (incl my own) run straight compressed air blowing on the bit @ 15 to 40 PSI. No vortex/cold air unit necessary.

I have in the past thought of using an automatic oiler unit filled with denatured or even isopropyl to get temps down. A very fine atomozed mist (practially dry by the time it reaches the bit) will darn near freeze it!

-Brady

[jeffreymcgrew]

cool. so it looks like if we do more aluminum work we should just rig up a compressed air jet to cool the bit, and use the dust collector we've got. That's very good to know.

This first run was a favor to a friend and to teach us how to do this, now that we know how we should get a better setup in place. Hence using a hand-held squirt bottle to keep the bit cool. Good tip about the constant temps on the carbide, that makes total sense to me.

Hey, one more thought: we're researching blowers to put together a vacuum hold-down table. If we got a 'real' blower, and not just a shop vac, would there be enough pressure on both ends of the thing to use the suction for hold-down and the output for cooling the bit? Or would the hold-down not produce enough pressure, and we should use an air compressor instead? Just wondering for we currently don't have a compressor, and it would be great to get something that could do both (our shop is small).

[Brady Watson]

Jeff,
Exhaust from a vac is hot and low PSI. The action of the air moving past the bit with the dust collection system will help, but compressed air may be needed if it is not enough. I would experiement with your setup.

-Brady

[paco]

Benefit of compress air jet is that it clear the kerf which improve cut... mostly with deep cut/thick material.

If you get the tip of the jet very close, it'll keep the bit quite cool. On some soft AL, I still cannot avoid using lubs (I use WD40; cutting oil cost a lot more and doesn't do any better) to keep the top edge from burring.

Brady, in your idea about misting denatured or even isopropyl, have you considered the odor!? It sure would keep the bit cold though.

[Brady Watson]

Paco,
I live in NJ...air quality can only get BETTER! Seriously...yes it is both a fume & fire hazzard if you want to get technical...but if you figure on 5 or so drops of liquid per minute, it is not substantial.

-B

[dingwall]

Brady are you dry cutting 6061?

[Brady Watson]

Sheldon,
Yes. AL doesn't need lube. Compressed air helps both cool the bit to prevent chip welding and clear out the kerf.

OSG makes some excellent tooling for cutting AL. If you are cutting block AL (billet) you will want to use a rougher 1st, then a finsher. They have end mills with polished flutes and anti-stick coatings that really help.

-Brady

[jeffreymcgrew]

Wow, so we bought a used air compressor off of craig's list and rigged it up and it's made a huge difference. No more liquid, which is wonderful! However I think we might be able to do better, so I've got two questions:

1. Where do you position your air nossle? Do you use only one, or two? We had ours close to the bit and cutting spot, however it was more sideways than vertical. Is vertical better? Seems like it would be. I'd love to see some pics of other's air setups to learn more about this.

2. Back to the first question. Ok, so in the mean time, we've been having such a problem with the dust that we went and bought ourselves a cyclone dust collector. We got ourselves a Clearvue, mostly because they had a smaller model now that we could hang from the wall in our small shop. It's made of super-tough plastic. When I asked them about using it for aluminum, they forwarded me to the OSHA page that more or less states that it's a real bad idea to use anything not rated for aluminum clean up for such things. Some of y'all were saying that you run your dust collectors when cutting aluminum, any of you got a cyclone-style sepirator? We'd like to do more aluminum, but it just makes such a mess when we can't run it with the dust collector...

[Brady Watson]

Jeff,
If you run dust collection & have a high volume unit, you most likely do not need a nozzle pointing on the bit. The amount of air that flows over the bit via the dust collector is usually adequate. I just setup a machine for a customer cutting .063 & .120 AL sheet & the DC was all the cooling that was needed.

-B

[jeffreymcgrew]

brady, thanks for the tip. It's a pretty high-volume unit, so I was hoping for some cooling action there. I think I'll still use the compressed air when doing thick or aluminum deep stuff.

[Brady Watson]

Yeah...the DC foot might obstruct thicker pieces & cause problems.

-B

[paco]

I've been considering rigging a vacuum inlet just as the air jet; at the bit/collet assembly. Any Shop-Vac would do the trick, the only concern I would have right now would be the length of the hose...

Loc-line has this vacuum line of products that would be just what's need for such task. Maybe the 3/4" would do nicely too...? Check it out at WWW.LOC-LINE.COM (http://WWW.LOC-LINE.COM)
I use the 1/4" for the air jet with the 1/16" tip.


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[Brady Watson]

I just pieced this setup together from spare parts and a blow gun from HD with football inflator pin. It works really well. The white plate attached to the bearing case on the Colombo & is retained by a piece of allthread + 90° bracket. The air line is just a couple of brass fittings + the football inflator + quick connects and capillary tube with an air coupling on the other end. I run @ 20-25 psi and it seems to be doing the trick. In case you were wondering the AL on the table is .750" thick...aside from a some 'bit walk' when tightening up some of the corners, the 1st half of the part came out great. Still have to do the other half...more when I get it done. (I'll let you know what it is and the story about it when done...)



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Sorry for the beat pics...had to resize & reduce colors to get them on here...Wondering if new 7 Meg camera has something to do with this...Never seemed to have a problem on my old 2.0M camera.

-B

[gerald_d]

Mail me the pics and I'll try and doctor them for you. gdpost@gmail.com (mailto:gdpost@gmail.com)

[Brady Watson]

Thanks...but I'd rather learn how to scale them myself so that I can do it again later...I had to resort to a gif (which I never use) rather than a jpg to get the size down. This only occured after I reduced the colors in the pics.

-B

[mikek]

Brady I have used this free picture resizer for years to get large pictures down to sizes that will comply with limited space on forums like this. It is real easy to use.
http://bluefive.pair.com/pixresizer.htm

[Brady Watson]

Thanks Mike, I'll check it out!

-B