Question: Air assist for milling metals

I see people on youtube with flexible hoses that push air to move chips out of the way. Is there a simple solution that people are using that is either home made or inexpensive commercial / hobby solutions? I’ve searched a bit but didn’t see any topics on this.

Thank you in advance!

Fish tank air “bubbler” compressor works OK, small tool air compressor with a regulator is better, dust deputy with a short SMOOTH hose seems to work best. Just make sure there are no wood chips in the dust deputy!

This is great. Thank you very much @RickW. I’ll check into these solutions.

I have a cyclonic separator already that I am using for media extraction with the Mk1 w/ shoe. Are you saying to tap off this to get pressure from the bucket to push back at the work piece? I was thinking of also of 3D printing a air “collector” for the output of the vacuum.

I don’t have a tank air compressor (for air tools) or anything like that. I am sure I can pick up something cheap at Harbor Freight. Either that or 3D print a 12v fan to run and step down to those funky hoses.

No, don’t need the funky hoses if you use a cyclone, just a regular dust shoe or use a shopvac tool on the end of a hose-into the cyclone, the chips are vacuumed up but the plastic cyclone and hoses wear out fast with metal chips. Also have to clean it ALL out when you are done with metal and switching back to wood (or 3d print a new one just for wood). Funky hoses just blow it all over the place unless you direct it to a cyclone… or a corner you clean up once in a while-messy and not safe for dogs or little people.

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@Lutraphobia I have no experience using an air assist then milling metal. However, I do have incendiary experience sucking metal chips into a dust collector containing wood chips and saw dust. By the time we realized where the smell was coming from the lower bag on the dust collector was burned through. We were very lucky that we were there.

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Glad you are OK, @alanan and your shop didn’t burn down. Yikes.

That TOTALLY makes sense. Something I didn’t think about. Hot metal and dust collection isn’t copasetic!

Thanks for those words of wisdom friends.

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@alanan yep, smells bad. Glad you got it in time. Dedicated metal or dedicated wood is safest!

@Lutraphobia @RickW I was in the shop at the time that this happened. I can tell you that there were some tense moments. Fire in a woodworking shop is a SCARY thing.

Just to add to Al’s post, he was cutting aluminum with a chop saw, so the chips were likely bigger than our Mills would generate and hotter, too. That said, when I mill aluminum with my LM in my basement shop, I do not use dust collection. I prefer to put up with the mess on the spoilboard. FWIW


@gwilki yes, metal shops and wood shops should be a different area.

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So is it safer to blow the chips into a corner or suck them up?

@RickW If you are asking me, I do neither. I see no need to blow the out of the way and I will not suck them up. I let them cool after the job is done and then use my shop vac to clean the spoil board.

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@gwilki Yes, asking and trying to wrap my brain around this. Didn’t start a fire yet! Re-cutting chips makes a funny sound that makes me nervous. I just suck em up. Aluminum dust is known to cause stuff in cali

Double cutting aluminum chips will tend to dull your cutters quicker.

If aluminium chips made by the LM are hot enough to start a fire in the dust bag, you should get a new endmill and maybe start cooling the workpiece.

For the latter, I recommend ethanol in a spray bottle to cool the entire workpiece by evaporation.

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Great discussion for sure. Love the ideas being expressed here. I started using a b7nch of that high octane rubbing alcohol my wife set aside for hand sanitizer back right at the beginning of covid . Remember that? Wow.

Evaporates quickly and doesn’t leave a mess on my spoil board. Keeps the piece and bit cool, keeps chips from flying all over the place. Then I just vacuum them up as needed.

I do notice though that my main gantry where the router is, is coming loose in the X axis. The whole carriage on the right side rotates up and a couple mm.

I ordered new eccentric nuts and wheels. Replaced them all and tightened them down. But they still come loose.

Gonna use some lock tight (blue) on them to see if that solves it. Anyone else have that issue?

While milling aluminum, it’s caused the bit to wobble enough to catch and break (1/8th" 3 fluted flat). Using the spetool off amazon. My speeds are low (500mmpm) and i get decent chips at the lowest setting of the makita router.

Frustrating. Any ideas?

Haven’t had any issue like this, but also haven’t milled that much aluminium by now on the LM.

Did not completely get, which bolts you mean, but I instantly thought of using locking-nuts with nylon rings… maybe they can help.

Another thing: I just wondered about the speed settings… if they work for you, they are fine, but… they seem to be very slow for 3 flutes and 1/8" diameter… maybe the settings cause more vibrations than needed. Could you post all values?

Happy to do so @JHahn. I am talking about the top two nuts / bolts that hold the wheels on the aluminum channels. The right one seems to keep coming loose creating a slight up / down “slop” to the whole gantry. That translates to X axis back and forth movement of the bit in the material.

From: X-Axis Rail :straight_ruler: - LongMill CNC (

Here are my settings for the bit from Aspire 11.


My first suggestion would be threadlocker blue for baby threads. May have to torch it to adjust later but it will never come loose. I put that stuff on everything…

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Quick update. I received the newly purchased wheels and eccentric a while ago. I also purchased thicker 5mm washers, compared to the ones that come with it. That made a world of difference. Of course, I put them on all 4 wheels on the Z gantry because it would fall out of trim if I used thicker washers just on the top two bolts. I used some blue thread locker on the outside of the eccentric nuts as well. This is keeping it pretty locked in place now. I don’t seem to have the “slop” I did last time. I’ve put a lot of time on a few projects since then and it seems to be pretty rock solid. Probably going to have to purchase another set of wheels just in case.

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@Lutraphobia Glad you got it fixed but bummer you had to.

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