Dennis,

I run my lathe dry and use WD40 from the can if wanting a good finish cut.

Having spent years covered in coolant off various machines and the smell when cleaning down said machines…..I didn't want my garage to get that dirty.

Trevor

Hi Dennis,

Like Trevor and Andy I don't use a flood coolant, For a nice finish I too apply coolant with a brush or similar. If you use emulsion as coolant you should clean the lathe afterwards and oil it. My experioence with emulsion is that if you leave it you get stains on slideways.

Thor

Hi Dennis

Welcome

I tend to cut dry & only use WD40 on aluminium, I don't do a lot of machining at the moment..well not yet any way, & then only been small stuff & then only generally use my tangential tool for 90% of any turning,the other 10% I use insert tip tools, so applying neat cutting oil with a brush tends to suffice for my needs.

George.

For the home workshop mystic is just not worth it, the emulsion inevitably goes sour, smells foul and all needs to be cleaned out and replaced . Also its not required for machining cast iron , brasses, ally , just for steel. I think Alan.204 has the right idea, a slow drip feed.

I use a soluble oil for coolant, Biokool14 from Hallett Oils. It seems quite happy sitting for months, or years, without going sour.

I use coolant on my machines as follows, with the proviso that brass and cast iron are normally cut dry:

Lathe: I mostly use insert carbide tooling and cut all materials dry; coolant is only used with HSS tools, mostly drills

Repetition lathe: I always use coolant, mainly to wash away swarf, although all tooling is HSS

Vertical mill: Carbide cutters run dry, for HSS I use coolant if it involves heavy cuts

Horizontal mill: Mostly HSS cutters, so I use coolant

CNC mill: I always use coolant, irrespective of cutter type, to wash away swarf, escept for cast iron

Cylindrical grinding: I always use coolant

All my machines use flood coolant, I just can't see the point of the occassional 'dab' of coolant. Think about the numbers. Let's assume we have a 3/4hp motor on the lathe and we're running a decent depth of cut and feedrate. So we might be consuming about 500W of electrical power, let's say 450W of useful power allowing for losses in the headstock. Most of the 450W is going to end up as heat, ideally mostly in the swarf, but some in the tool and workpiece. Now 450W is equivalent to 450J/sec. So each second we need to get rid of 450 joules. The specific heat of water is about 4.2 joules per gram per degree. Let's assume we want to keep the coolant temperature rise to 30°C, we don't want to boil it away. That means we need 3.57 grams of water per second or 214 grams per minute. One litre of water weighs about 1kg. So 214 grams is 214 millilitres, or about 0.38 pints. That's a lot of dabbing!

Regards,

Andrew

One of the benefits of WD40 apart from its (relatively) limited cooling effect is to lubricate the tool and its cutting edge. In many cases the surface finish is visibly improved, so you might reasonably deduce that the action at the cutting edge is being affected for the good and the power consumption / heat generation is being reduced.

Obviously this would only hold true when the tool and workpiece are below the temperature at which WD40 ceases to be – but for many of the operations described, that's probably valid..

For larger and longer duration jobs, I use the coolant in the certain knowledge that if I don't, the tools will soon lose their edge and need to be replaced or resharpened before the work is completed.

Muzzer

I use soluble cutting oil in a 250 ml squeeze bottle, it was a bottle of PVA wood glue. Ian S C

Rik. The fact you're getting smoke suggests the coolant in contact with the cutting edge is getting too hot and burning. You're only going to fix that by generating less heat, or throwing more coolant at it to keep the temperature down. I notice that neatcut stuff is advertised as a neat cutting oil, not a machining coolant.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=171063504655&ssPageName=ADME:L:OC:GB:3160

No connection to the seller, and presumably the high price means he is out of stock, but I use this stuff. It dilutes down with water, turning into an emulsion. You can make plenty up from a 5L tub. Lasts a long time, doesnt stink too bad and stops your machine rusting if you spray it everywhere (not good if you want to keep your machine nice and clean though…. My lathe is one of the dirtiest places known to man due to a combination of coolant everywhere and the occasional spraying of cast iron dust/swarf)

Yesterday I was taking 60 thou cuts on my C6B on mild steel flooding with coolant and wasn't getting any smoke whatsoever. I do have full guarding in place over the chuck so I can really chuck coolant at it and it doesn't go everywhere. If i was going to make the same cut and just dab some neat cutting oil on from a squeeze bottle or low feed from a coolant system, then I'd expect alot of smoke too. I'm probably applying in the region of 1 litre of coolant every 30 seconds when I properly flood coolant. How does that compare with the rate coming from your system?

Like Andrew said above. When you're generating alot of heat, you need a lot of fluid to take that heat away. A small amount of fluid is just going to burn and ultimately give you smoke.

I see that Neatcut oil is used neat and not mixed down with water.

Hope this helps

Graham

Castrol Ilocut 486. This is non soluble cutting oil. I have done quite a lot of work in stainless and I have found that this is excellent.

A 20 litre container can be had at fairly reasonable cost. My coolant sump is full of it. I bought the 20 litre container over two years ago and it is still 2/3 full.

For hand tapping etc I tend to use Rocol RTD. I would agree that dabbing on coolant is rather pointless. If you need it then it has to be flood.

As for WD40…Some time ago I was closing my workshop up whilst I went away for my job. I sprayed WD40 on my machine surfaces, rotary table etc to try to discourage corrosion (my old workshop was in an unheated outbuilding). On my return after 6 weeks, corrosion had occurred but only where the WD40 had been sitting. I now don't use WD40 either in my home workshop or at work. If I want a water dispersant I use GT40 which is silicon based.

I think a lot depends on whether we are talking about cooling or lubrication. A flood of coolant will obviously do both. Sometimes a small amount of lubricant, as can be provided by a brush or squeezy bottle application, can be very beneficial, and is what is required as opposed to a coolant. This afternoon I was parting an aluminium bar and used a quantity of Ilocut 486 in this way. It made a big difference.

Edited By Carl Wilson 4 on 10/01/2014 18:13:00

I will investigate this Castrol Ilocut as I have only three litres of Rotabroach left. Should really have bought more when I was offered it as it worked out at £3 a litre!

With regard to the WD40. As a newcomer here I didn't think i was really in a position to tell people what to do regarding WD40 but you have discovered something that I have known for a long time. WD40 is anhydrous, it attracts water, moisture. I would rather use cooking fat than use this as a rust preventer.

If you must use a protective surfaceant THIS is the stuff I recommend it is T9 Beoshield developed by Boeing for their aircraft. Not cheap though.

graham.

Jason,

I'm sure there's someone who would have bid for it on ebay – collection only

Neil