How to thin out oil?

[andrew_mx83]

Its not Automotive tech but probably tech nonetheless. someone feel free to move it if there is a better section.


I need to thin out the cutting oil im using on my CNC mill so as it can be pumped upto pressure by a fuel pump and misted out a fuel injector. ive got this working well at the moment with approx 1 part cutting oil to 5 parts kerosene, but the kero stinks and makes the mixture somewhat flammable. is there something else that works well? i dont want to use any water based cutting lubes for obvious reasons (although it is more common)
basically i just kept adding kero til the pump stopped struggling then adjusted the return line pressure and injector duty cycle to suit.


ive already got the thinnest cutting oil i can, the viscosity is around 12 apparently.

[oldcorollas]

thin it out either with solvents (probably flammable/volatile.. low odour turps?) or thinner oil (but you have thinnest)
what type of fuel pump are you using? different mechanisms will react to higher viscosity differently.

what pumps are used for diff/gearbox oil cooling?

[big_zop]

Andrew,

When you say 12, is that in centistokes (cSt)? As 12 is pretty thin, water is about 1 @ 20degC and kerosene is 2.4. Most base oils used to make up cutting fluids are higher than this to begin with so it wont make it any thinner as they make up 80-90% of the mixture. If you are diluting it down with kero (or anything else for that matter), is there any concern that you are reducing the performance of the finished oil?

Is the need to avoid water based fluids to help the fuel pump and injector to survive?


The lab supervisor at work suggested Parrafin oil. It has about the same viscosity of kerosene and since its meant to burn as a fuel, it shouldnt have a nasty smell that you typically get from the solvents in kerosene. And with a 210degC flash point means it should be a little more resistant to making a fireball.

[andrew_mx83]

centistokes sounds about right. they have to mix up the cutting oil for me so i grabbed a small bottle of base oil @ 11 cst to do the initial testing. hopefully the good stuff is ready this afternoon.

the fuel pump is an intake EFI jobbie out of an mx83 and of course the injector is a 7m-ge unit. these are fairly expendable for me, steering away from water is more about looking after the machine. its pretty late when i pack up most nights and the neighbors wont appreciate the compressor running for 30mins to dry the machine off at 1 or 2am. something oil based i can just brush the chips off and the cutting oil can actually protect the table/bedways/leadscrews/etc from rust.

i am concerned about diluting the oil too much and losing its lubrication properties and would love to dilute it with something slippery.
-i thought about diesel but then there is the smell again.
-what about engine oil flush? one tiny bottle of that shit turns a whole sump of oil runny as water... i think i looked at the bottle once and its just hydrocarbon (prepsol)?
-i thought about CRC but this is just oil + kero anyway i think.

ill have a look into parrafin, where would you buy such a thing in say 20lt drums? also will that evaporate in the open air?

kero is uber convenient as my local servo sells it out the bowser. i cant light the kero/oil mix with lighter flint or open flame but it will accelerate open flame on a burning piece of wood, obviously i need to keep this in mind with whatever i use and the less flammable the better.



im open to a different pump but needs to be in the 50-100psi range, preferably higher so i can get the oil to mist -currently im only getting 2 very fine jets. i thought it would be the injector that struggled with the thicker fluid, but its actually the pump.... i feel it has a short lifespan as it sounds like its working pretty hard. injectors seemed fine in testing but got bloody hot when i had the duty cycle cranked right up.
suggestions for another pump of similar pressure would be great, i think this is actually my last spare fuel pump.

[oldcorollas]

thinkin outside the square, what pressure do power steering units produce (probably way too high, but could regulate down since volume not high)? they are designed for thicker oil based fluids, and could easily be driven by a leccy motor and belt as they already come with a pulley.

some info here (numbers, volumes etc)
http://bbs.homeshopmachinist.net/thr...draulics/page2

or just get small hydraulic pump in stead of the fuel pump?

[allencr]

There may be a diesel pump that's not mechanically driven but I doubt it, plenty of pressure though.
Home heating furnaces or boilers that use fuel oil have small electric pumps & injectors.

[George]

diesel fuel as solvent? Not flammable in normal conditions

[lexsmaz]

Why cant you use a cutting oil lubricating system similar to what is on some lathes or drop saws etc, in that it just pours out of a nozzle onto the work piece, after it is pumped up by a mechanical or electrical low volume pump, misting oils especially with Kero in it is not all the best for ones health ..

As i understand it its all about taking the heat away from the subject & cutting tools & also lubricating the area being cut & if you are only misting cutting fluid onto the part i cant see it really doing anything as far as i can see in taking any heat away & the lubricating would be pretty sparce too ?? ..

We used to use a Kero gun many years ago at a workshop to clean down engines etc which i have now heard is banned from being done, due to the atomisation of the Kero ..

[sc400]

a gear pump of some description will work with straight cutting oil you can still use the injector if you want as for the pump i would find a old junk clothes dryer and get the motor and make a adapter for a pushrod v8 oil pump to run a pulley on it and use that

[thechuckster]

what he ^^ said, gear pump from a old wrecker 6 or 8 cyl motor, attach suitable motor to drive. Most will have relief valve built into body - modify spring to adjust pressure.

Also run at a lot lower pressure and use larger nozzles (e.g. gas fittings).

Personally, I think atomised/ high pressure oil spraying onto a lathe or metal work piece is a disaster waiting to happen - if you are intending to go down this route, at least have a very reliable way of shutting down the pump, have the pump reservoir well away from the work area and have fire fighting gear nearby.

Personally, I'd suggest you go down the water-based cutting fluids route, or at least consider mixing an emulsifier into a batch of water+kero/diesel - then you can use the higher flow and lower pressure spray or drip nozzles.

[andrew_mx83]

while im all about thinking outside the box and overkill, i think another mechanical drive setup is probably too much overkill at this point. at the moment the whole system is contained inside a 20lt oil drum, with a hose coming out for the injector and a couple of wires, its very neat and id like to keep it that way. another submersible electric pump would be great, ill hunt around for what i can find.
it goes without saying that if i went for a mechanical drive it would be with a 7m oil pump anyway....

i got the drum of oil on friday, its BLOODY thin, almost like water.

im familiar with the ole' low pressure pump and nozzle setups for lathes etc, in fact i built and used one on my lathe for ages before i discovered cutting tools that dont need coolant and never looked back. for any other jobs where i cant use the ceramic cutters i have been brushing this thick cutting oil on (neat) and in my opinion this is far superior to the old water based oil flood type systems. taking heat away seems to become less of an issue with the right lubricant as you are cutting better with less friction therefore less heat being generated. i also do the same with my tungsten bladed drop saw and band saw, just brush a line on where you are going to cut and brush some on the blade occasionally for good measure. i can cut through 80mm aluminium on either saw and pick up the cut end straight away, barely warm.

flood coolant also has the mess, need for catchment/recycling and rust issues all of which i want to move away from.

i guess i dont really need to mist it, but i was thinking i could then pulse the injector every couple of seconds rather than full time. all i really want to do is dribble some oil on or around the cutter.

didnt know about atomising kero being no good the shit absolutely stinks anyway i and really dont wanna use it.



chuckster its not coming out the injector at crazy pressure at the moment, also its not hot at all so i dont see so much of the danger in it? the injector shuts off with any of the e-stop buttons but the pump is currently setup to run continuous so i dont have to worry about waiting for the line to pressurise.

[andrew_mx83]

[andrew_mx83]

/end rant

i might experiment with a couple of options, will try some engine oil flush and some diesel -does anyone know if the low sulphur or bio diesels smell any less than the normal stuff?

[andrew_mx83]

Update

I now have the lube system running well using straight cutting oil. I am running the fuel pump off a 12v 20a power supply and have replaced the tap i was using in the drum for adjustable pressure with a spring type pressure relief valve. The fuel pump adds a lot of heat to the oil which means the viscosity drops over time, i had to keep bumping up the pressure at the tap however now it remains much more constant, although it does drop off a bit after a while, at which point i just increase the injector duty cycle.
I can get enough pressure to turn the oil into a mist but it seems to work better as a thin jet of liquid aimed directly at the tool which can be seen here:
https://www.youtube.com/watch?v=Nxco...e_gdata_player

The injector on/off time is controlled in mach3, and i can turn the coolant on/off in my code. Mach3 has commands for flood coolant and mist coolant which you can call separately that i am using as high/low coolant flow based on how hard the machine is working. Flood gives a 0.02s pulse every 5 seconds and mist gives 0.02s every 10 seconds.
This is plenty enough oil to cut with, i can run the tools way deeper and way faster than i ever thought possible and still have great tool life and clean cuts without too much heat in the material. If i turn the lube off for more than about 60 seconds when its working hard all hell breaks loose, the cutter gets so hot that it melts through the alloy and the tool itself is permanently discolored... add lube at this point and it instantly turns into a cloud of smoke. So the system is definitely effective.
I havent measured oil consumption accurately but i would guess its in the league of 1lt/5hrs of constant cutting with flood coolant on. Last week i was cutting through 5mm plate in a single pass with a 6mm cutter for 12 hours a day, flood coolant the whole time so the machine was certainly working hard.

[schnitzel]

/end rant

i might experiment with a couple of options, will try some engine oil flush and some diesel -does anyone know if the low sulphur or bio diesels smell any less than the normal stuff?

have you tried using deodorised kerosene, used to sell it a lot to people using kero fired kilns in pottery etc as it didn't have the smell. Look up oilchem as they make it.