Coolant or lubrication?

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aarvidsson
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Coolant or lubrication?

Post by aarvidsson » Fri May 08, 2015 5:34 pm

When cutting aluminium - should I use coolant in the form of methylated spirits or a lubricant in the form of WD-40?
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Hans
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Re: Coolant or lubrication?

Post by Hans » Fri May 08, 2015 6:05 pm

Just lubricant. You won't achieve useful cooling from your liquid without a flood coolant or air blast setup. Lubricant reduces heat by reducing friction and improves cutting performance by reducing cutting force.

You could look into a Kool-Mist or Fogbuster type unit, which uses a cooling air blast to lubricate and evacuate chips. You would only want to use one of these with an enclosure for mess and oily air issues, but they would get the most out of a Shapeoko.
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Hans
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Re: Coolant or lubrication?

Post by Hans » Fri May 08, 2015 7:52 pm

I want to add: in my experience, WD-40 works best for machining when you paint it on, instead of spraying it and getting it everywhere. I always used a gallon can of WD-40 and had a little in the bottom of a cup (formerly packaging for almonds) and applied it with a paintbrush. It keeps the mess down, uses less WD-40, and you can paint it right onto the moving endmill or drill if you have to without damaging the paintbrush.
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MeanderBolt
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Re: Coolant or lubrication?

Post by MeanderBolt » Fri May 08, 2015 9:10 pm

I know that this is a coke vs. pepsi, or tastes great / less filling argument... but with the right speeds and depths, you can cut without either. I have had a lot of success milling at 500mm with .15mm - 2mm passes. This is with a 30K rpm DeWalt spindle.
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aarvidsson
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Re: Coolant or lubrication?

Post by aarvidsson » Sat May 09, 2015 10:04 am

Yes, *can* being the pivotal word here :) Does that mean that it doesn't matter either way, or does it mean that I *should* use WD40?
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Xaracen
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Re: Coolant or lubrication?

Post by Xaracen » Wed May 13, 2015 7:28 am

@Hans, your use of a paintbrush to apply WD40 is exactly how I have been doing my copper engraving. My only issue has been keeping the WD40 from creeping under the copper and softening the double-sided sticky tape I use to hold down the copper, so I ended up using strips of duct tape to seal the edges of the copper to the milling bed. If I didn't do this, especially for longer jobs, I would find that the copper would begin to move slightly under the bit as it cut across the top of the copper, thus spoiling the position accuracy. The larger the copper piece, the less of an issue this was and the more secure it would be, but small pieces could be a nightmare to hold properly, and in those cases I would mill out a small pit shaped to the copper in a small block of wood or HDPE, so the copper was fitted snugly into it.
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Re: Coolant or lubrication?

Post by WillAdams » Wed Dec 14, 2016 2:00 pm

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JeromyReno
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Re: Coolant or lubrication?

Post by JeromyReno » Thu Dec 15, 2016 2:54 am

i have gotten the best results with blowing compressed air on the bit to remove chips from the groove while cooling the bit and lubricant. cutting oil has worked exponentially better than wd40. it doesnt burn off as fast and leaves a nice finish. adding oil to the air spray is probably the most consistent way i have found. re cutting old chips is the fastest way to melt aluminum to the cutter and not melting aluminum is the hardest part of cutting aluminum. and chip build up on steel will break the bit off in a heart beat. i have cut hundreds of aluminum, plastic and quite a few steel/stainless parts and those are my personal findings.

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