What coolant shoud I use?

[Dave_424]

Hello guys, seems like a good community here and I have been lurking around for some time.

I did have a small mini lathe but managed to break pretty much every cheap plastic gear on it. Just not built for what I was asking it to do.

I was searching around on Evilbay and bought a single phase converted Colchester Chipmaster.

Ive used it quite a bit, without a coolant system but now I need one.

It has a full return system and coolant tank and need some suggestions.

Im not sure about coolant pumps, Im 17 years old and don't have bundles of cash so I was going to go with a submersible water fountain pump.

I have seen that there is a bit of a problem with the 'Milky' coolant going off and stinking, is this going to happen? I use the Lathe not that often maybe 3 times a week but when I do, I will do about 6 hours solid.

I have seen on some of the gunsmithing videos they use a true oil, the golden brown kind of oil similar to engine oil.

I have also noticed that in the bottom of my coolant tank, there is the same golden brown oil. Is there a coolant oil that is like regular engine oil? Would this stop me having the problem of stinking oil if I don't use it for long periods?

All opinions appreceated

Dave

 

[Ken Bartlett]

First off welcome to the community. Its good to see those in your age group interested in the hobby. As far as the coolant, to help out with the stinky coolant syndrome that happens when you leave it sitting to long you can add a skimmer to you tank. It consists of a plastic wheel that is rotated slowly in the coolant tank and attratcts the top layer of oil that separates out of the coolant doing use. There is a scrapper that, as the wheel rotates and brings the oil out of the coolant, scrappes off the "tramp oil" and lets it dribble into a container nearby. This will help your skummy coolant. There are also additives you can put into the coolant so it does not as readily get skummy. There are times when I have used regular chlorine bleach in the coolant to kill off the bacteria and such, but take it upon yourself to do this, as they say your mileage may vary. A good water soluble coolant will serve you well.
I dont know what cutting your doing, with what type of cutting tool and what type of material you are cutting. But take it into account, dont be afraid to machine dry with carbide inserted cutters or other cutting tools. Many of todays carbide actually work better dry. Hope this helps a bit.

 

[Dave_424]

Thanks, Ive really been interested in machine tools etc. all my life so I can finally make some stuff

Ive made stuff like Airgun shrouds, Airgun valves, Machined barrels etc.

I work with a multitude of materials, usually aluminium, brass, steel, stainless steel and some plastics. Ive so far used HSS for most of my cutting, but when cutting Stainless steel, it just won't touch it. I bought some inexpensive carbide brazed tools and it will cut it well, but it tends to overheat the seems to harden, taking much more force to get through the hardened part and will cut fine after that. But it tends to chip my tools and I don't have a means of sharpening them.

Im going to buy some Glanze insert tools, If I'm having problems with brazed carbide tools chipping, it is likley that the inserts will chip also.

I really want a coolant system, maybe just because I can say I have it but Im sure it will help, I get really tired of painting on cutting oil.

Dave

 

[rake60]

Welcome to HMEM Dave.

I rarely use coolant in my hobby shop. When I do it is just simple cutting oil applied
with a brush or spritz bottle as you have been doing.

Emulsified coolants work very well, but as you and Ken have noted they can become
nasty very quickly. They will harbor bacteria that can cause a minor scrape or nick to
become a major infection.

I have never heard of chlorine bleach being used to clean up
an emulsified coolant myself, but it may be something to consider.

Thanks for posting that Ken!

Rick

 

[Maryak]

Dave,

Welcome to our forum. wEc1

I have seen on some of the gunsmithing videos they use a true oil, the golden brown kind of oil similar to engine oil.

Yes there are neat, (not mixed with water), cutting oils. They contain additives such as Sulphur and Chlorine. They are for difficult machining operations such as broaching and difficult to machine materials. Their biggest problem is they smoke and give off nasty fumes when used with a flood coolant system. Best left to a production environment with adequate shielding and ventilation of the machine tool.

If you want to use a neat oil in the home workshop use automotive differential oil (SAE 80/90) and apply it with a brush. This oil is readily available in small quantities.

Hope this helps.

Best Regards
Bob

 

[Ken Bartlett]

@rake - the bleach is used to kill off the bacteria more than anything. I have seen it have mixed result here at the machine shop I work at. But anyone using this make sure your careful with and not get it in your eyes. What I do find more useful to keep the skanky coolant from developing to is run the tramp oil skimmer constantly, and to run the coolant system on the machine every other day or so, even if I am not running a production job on it. Keeps it fresher longer, at least in my experience.

 

[Dave_424]

Thanks for the info guys and the warm welcome.

My lathe is pretty dirty, it is old and has seen some use. The coolant resivoir is at the rear of the machine, just a big square recess in the back of the chip pan, near the floor. ANY liquids used on the lathe would eventually run down and end up in there. The chips fall down through the ways and into the rear, often ontop of the cover to the coolant tank. I can maybe see a problem with this, like the coolant getting contaminated or something. I do have access to chlorine because I have a jacuzzi and it should come in handy.

One thing that has come to my attention, some people have trouble every few months with water soluble coolant and others will let it sit inside their machine for years and it won't go off. Whats the deal? is one getting more contaminated than the other? Is it the climate?

Thanks again

Dave

 

[ksouers]

Dave,
I used oil based coolant years ago and it never when rancid, I suspect because it was used every day and constantly being stirred up. Purhaps a small aquarium air pump and bubbler will keep it from going off when not in use.

You could try a piece of scotch brite to help screen chips out of the return coolant.

 

[shred]

I use an aquarium bubbler on my CNC mill and it does ok. Everything else I machine dry or with a splash of cutting oil from a brush or bottle. Unless absolutely necessary on a manual machine my opinion is coolant is usually more of a nuisance than it's worth.