Holy grail of aluminium cutting?

So I stumbled upon this totally by accident. My MPCNC was struggling to cut aluminium, but it could do it passably as long as I took it slow, used adaptive clearing, and made sure to periodically give it a healthy squirt of WD-40.

Today I couldn’t find my WD-40, and I was in a rush to finish this very large cut of a 2ft X 4ft sheet of 1/4in aluminium that I’d spent a good 18 hours or so on already (not including figuring out the settings and breaking more than a few endmills).

Figuring that any lubricant was better than no lubricant, I grabbed a bottle of 10w-40 motor oil I had lying around, poured a little in the track and went to town.

The difference was night and day. I was easily able to bump my feed rate up to 300% of the original 450mm/min. I’m sure acceleration/deceleration made it a little less than 3 times the original speed, but it was easily doing a good 1000mm/m rock solid.

In hindsight, I think that the heavier oil worked so much better because the DW660 spins at a much higher RPM than most mills - so it might make sense that the lighter WD-40 was just getting blown away or otherwise not able to keep up with the speed. Motor oil, on the other hand, is designed to operate at very high speeds without a problem.

Curious to see if anyone else can replicate this - the difference was immediately apparent on my machine, so if it’s not just some weird fluke of my build this could be an awesome discovery.

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Great find! I’m still in the process of buying parts for my first MPCNC and will definitely give this a go with aluminium. How do WD40 and water compare?

Never tried water, can’t say

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How do you keep the lubricant from making a mess of your whole setup? I’ve spoiled many a spoil board trying to use cutting oil as a lubricant.

I would imagine the problem with water would be rust - rust on your rails, rust on your tools, rust on your spindle, and swelling wood on your table and spoil board. If you have an all metal setup and it’s sealed somehow then I’m sure it would work fine so long as there was a steady stream of it during the cutting operation, though this is more of a guess than anything else.

I have some friends that use the big expensive HAAS machines in their shop and they use what I have to assume is a water based cutting lubricant (coolant really) but it looks to have a lot of additives in it.

My understanding is that there’s no water in it. Water would cause the part you’re cutting to flash rust as after you cut in to it for some materials. It’s a cutting fluid that’s captured, filtered, and re-used by the machine.

Well, that’s what I get for making an ass out of umption XD

I was working retail and a customer asked me a question. I said, “I assume…something”.

He said, “Do you know what we say about assumptions in the marines?”

“It makes an ass out of you and me?” :slight_smile:

“No. It is the mother of all F—ups” :neutral_face:

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I bought some water based cutting fluid for when I someday return to steel cutting. It has additives to inhibit rust as well as god knows what for lubrication, and I think the cooling action is just the water.

When you buy it you just buy the magic additives and add your own water at like 10:1 or so.

I’m not sure if my setup will be able to have an acceptable mess. I have a concept to try to contain it but I can’t be sure that it won’t splash everywhere.

As for WD 40 my guess would be that evaporation could have some cooling action but WD 40 is about the worst lubricant there is.

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As for WD 40 my guess would be that evaporation could have some cooling action but WD 40 is about the worst lubricant there is.

It works fine in a jam so long as you keep it flowing but lets face it - cutting oil is going to be better than most any other product that’s easily available to the average consumer. I have a friend in the UK that swears by paraffin (aka kerosene in the US) for keeping his cutter cool - he’s a pro and owns his own shop so I trust him when he says that it works. That being said, it’s unlikely that I’d ever try to use that with my setup. All the wood around my rig would soak that stuff up and be a house fire waiting to happen.

I use 3in1 on my drill press. I have never used anything else.

Funny you ask, I accidentally knocked the bottle of oil over partway through and spilled a bunch on the particleboard that the MDF spoilboard was fastened to. Just wiped it up.

There’s definitely oil on the spoilboard and the particleboard base that looks kinda ugly if you care about that sort of thing (I don’t) but I don’t think it really messed anything up structurally speaking. I can check when I get back, at a conference in Vegas for the rest of the week.

I have heard that WD 40 is essentially kerosene with a tiny bit of other stuff for water displacement.

Edit: looked it up and this is false.

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I used gun oil the other day. For some reason it was in closer reach than anything else.

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Mental note never sneak up on David…

I need to do some tests I guess. The first few videos I ever made with this thing was milling with water,on a plastic shelf, with a tape duct tapped as a catch. I honestly have not used any fluids since then, not sure why not. I even bought real cutting fluid but have not used it. I wonder if that will drastically increase speeds for me as well. This could be fun, thanks for the post!!!

Tap Magic for aluminum is “magical”. 3-in-1 works well also. I can see how 10W-30 would be effective also, but probably messier. I only use wd40 as a solvent to remove heavier oils/grease and prevent rust on tools. NOT a lubricant but likely has some cooling effect.

Regular tap magic worked great on cutting stainless steel with a 1/8" carbide bit for a wood lathe diamond insert.

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I sprayed some water on my aluminum just to cool it off. We get great evaporation out here.

I’ve used a solid lube developed by Boeing and manufactured/distributed by The Orelube Corp. for drilling/tapping aluminum and like it a lot. They make a paste having milling as one of its intended uses that may be worth a try.

https://orelube.com/about-boelube-products/pastes/

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I have seen videos with and without lubricant for aluminum and I am not sure what I am going to do. From what I read it is important that you don’t scrape around in it but really try to shave off a good bit at least and that you should not buy aluminum that is too soft, like most of the aluminum you get in stores.

It definitely has water in it. The additives prevent rust, and try to limit biological growth.