CNC Coolant

[Steve355Participant @steve355]

There seem to be 24l and 8l Hyundai compressors at Screwfix both for around £150…

[DiogenesParticipant @diogenes]

Do the £150 ones deliver enough air – they’re quoted at about 150L/min FAD..?

[Steve355Participant @steve355]

One is 120 and the other is 150 l/m.

The smaller is 8l and the larger 24l. I guess that’s the capacity of the reservoir.

[JasonBModerator @jasonb]

One thing to be aware of is that most hobby compressors state the displacement. due to losses this is a higher figure that what you will get out of the compressor which is known as Free Air Delivery or FAD.

Typicaly the FAD will be 50-70% of the displacement. Hence my post yesterday where I said 8CFM( 225l/m) from mine when they are sold as 11cfm as that is the displacement but just looking it is acually less than 8cfm.

So if the screwfix ones are single motor expect 60-75l/m out of them.

Yes the 8 and  24 are the tank capacities, I have a 50lts

[JasonBModerator @jasonb]

Screwfix are quoting the wrong figure for FAD. On the cheaper 8lts tank model they give FAD as 120l/m but if you look at Hyundai site the 120lts is displacement and the actual FAD is 53l/min.

Also £30 cheaper from Hyundai

 

[Steve355Participant @steve355]

Aha… I thought the Screwfix figures looked fishy. Hyundai website it is then.

[Steve355Participant @steve355]

Well, it takes me an embarrassingly long time to get around to things but I usually do I the end. So I have my blower, and I need to plumb it on to my compressor. I still have the old noisy compressor, but I’ll get the Hyundai compressor if it works well.

Does anybody have any thoughts about the fittings to plumb a compressor fitting onto a 8 mm air pipe? (I think – it says 8 on it)

I’m guessing I’m gonna end up with a block of aluminium screwed to the wall somewhere near my CNC machine, which will have a compressor fitting on one side, and an air hose coming out of the other side?

Furthermore, does anybody have any advice about the best air compressor fittings? There are a myriad of different ones, I’ve always wanted to settle on one system for my workshop, but I always end up messing around with them because different air tools come with different input fittings.

 

 

[JasonBModerator @jasonb]

Simple connection would be  a QR with a 1/4 BSP male screwed into an 8mm pushfit with 1/4 BSP female and that will join the two.

If it is a manifold then tap it 1/4″ BSP and screw in a male QR fitting with 1/4″ bsp male end as the inlet. ( you want female QR connectors as outlers to compressor and compressor hoses as they shut off the air).

Outlets tap the block to what you fancy – 1/4 or 1/8 BSP, M10 or M8.

If you want to regulate separate outlets then the banjo type flow regulators with a thread to suit your chosen tapped hole and 8mm pushfit outlet. Unregulated then just a straight male thread to 8mm pushfit.

 

Lidl QR connectors work for me

[Steve355Participant @steve355]

[JasonBModerator @jasonb]

That’s it, screw a male QR into that which will plug into the hose or compressor. Other options I mentioned also shown below

[Neil LickfoldParticipant @neillickfold44316]

Do a material test with the coolant to see if the brass is going to make the coolant turn green.

From  Memory HysolX is just fine. I mix at 10-12 %, Work is using Blaser fluid.

I do like the look or clarity of the Blaser full synthetic coolant. It is a pro biotic coolant. Very different to that of Hysolx.

I only use the IPA hand gel where for what ever reasons, the surface finish is not as expected. It just gets a very thin brushed on amount.

There are companies that do use IPA as a cutting fluid. They use antistatic hoses, and it has a water mist that is injected into the vac hose. The mister nozzle looks very similar to what Jason posted.

For the cnc router I use a mister and the Blaser CFS35 oil in combination with shopvac system. The shopvac has a cyclon between it and a 20 l catch can. The combination of the blow and vacuum to control chip evacuation works very well.

Neil

[JasonB]

On JasonB Said:

That’s it, screw a male QR into that which will plug into the hose or compressor. Other options I mentioned also shown below

Awesome, when I get around to my pneumatic logic ATC extravaganza, something like that would be just the ticket.

BTW which style of air hose connector is the “best”? I think I have at least 3 different types. Every air tool I buy seems to have a different connector. I have an air nailgun, an air paint sprayer, an air dremel thing, and the atomiser for my forge all have different connectors. And I am about to have another with my CNC blower. I’d like to buy a job lot of male and female of one particular type, and ditch the rest.

 

 

 

 

[Clive FosterParticipant @clivefoster55965]

Concerning connectors this picture shows the two common general purpose quick release airline connectors. I had both types floating around and made adapters as a temporary measure pending exploiting very attractive LiDL prices for Euro connectors to convert everything to Euro. As ever temporary became permanent and mumble-mumble years on I still have a mix.

Bottom is a Euro female to PCL male adapter. Note the bulge in the main stem characteristic of the standard PCL

Middle is a modern style PCL female to Euro male adapter. Note the parallel stem characteristic of the Euro.

Top is an old style PCL female.

Pull back on the sleeve to release the female coupling on both types.

Generally standard PCL females have knurled rings to assist grip whilst Euro have plain rings but you can’t assume this is true for everything.

Many PCL females are positive latching requiring the sleeve to be pushed forward to unlatch before pulling back to release the coupling. Generally if there is a gap between the sleeve and the connector entry, as per the middle one in the picture, it will be positive latching. Unless the system is completely de-pressurised it’s usually necessary to push the male connector towards the female one to get the positive lock latch to release. The whole point being that you need two hands to undo the connection which is obviously safer. Ageing positive latch PCL females can be a right pain to undo.

Euro connector has a slightly larger bore and tends to be bit easier to release. It is said they are less durable than PCL but how much of that is due to the proliferation of inexpensive import ones made to slack tolerances I know not. I seriously doubt that any member of our fraternity will use one enough to wear it out.

A major trap for the unwary is that PCL branded PCL-XL range connectors are Euro type not proper, standard PCL.

The female end is self sealing and should be fitted on the pressure side. The male goes on the tool or whatever. Should be obvious but I have encountered a hose connected the wrong way. Fortunately I had a good grip, even with only about 50 psi in it the hoes was, ahem, energetic in attempting to escape.

The simple nylon tube push fit types make effective quick release connections if you don’t mind de-pressuring things before you attempt to disconnect. Alternatively (better) put a tap in the line to cut off pressure.

I would consider a tap on the entry side of the very neat Euro inlet to multiple push fit outlet manifold pictured in previous posts essential.

Theoretically the push fit pipe end should be cut off and re-chamfered before re-connecting but in practice you can disconnect and re-connect several times before the nylon hose deforms where the O-ring seal(s) run leading to leaks. Industrial rated (aka expensive) ones have two O rings and are more reliable at high pressures. Watch the temperature ratings. The cheap and cheerful plastic breed don’t like getting hot. Typically maximum of 60°C. Metal bodied versions rated up to around 150°C can be found, at a price.

Nylon air pipe is generally stiffer, stronger and has higher temperature range than the (cheaper) polyurethane type.

Clive

 

[JasonBModerator @jasonb]

As I said teh Lidl ones work OK for me which are the Euro type. I don’t use a lot of air tools so am not swapping them many times a day.

[noel shelleyParticipant @noelshelley55608]

I’ve used PCL type for 50 years and they work well, more to the point they are available easily, well made and are reasonably priced. Whilst 1/4″ BSP is the standard thread, for larger flow there are 3/8″ and 1/2″ types, the 1/2″ are 100 series. The modern (ish ) female type have the sleeve set back so as to avoid accidental release, and ALWAYS hold the male end tight when releasing – being hit by a flailing end fitting can hurt ! As has been mentioned the PCL- XF type are euro style and will not fit standard PCL. Both male and female fittings are available in male, female and hosetail style to suit the application.

On the point of compressors check out the duty cycle and cooling. One of the common brands we have will cut out on hot days if asked to run at high delivery – at least the thermal cutout works. At 3Hp and twin cylinder with a 150L tank it is NOT fit for industrial use ! If being used unattended on CNC a low pressure alarm may be a good plan. Even if fitted with a 13A plug it should be wired through a proper motor starter/overload device NOT a fuse or MCB, which will only save the wiring.  Good Luck. Noel

[Steve355Participant @steve355]

Well, I went to Lidl today in search and found there none.

Looking at what I have lying around, and I have at least 4 types. As far as I can tell, they are all called PCL. One way or another tomorrow I’m going to choose one type and chuck the rest out.
I suppose I should  check all my air driven tools to see what’s on them too. Might be more variations on the PCL theme.

[HOWARDTParticipant @howardt]

Any type of air mist system ideally requires a totally enclosed machine and an extraction filter system to prevent high levels of noxious mist.  While a flood coolant is easiest a higher pressure system will clear chips from the cutting edge better, but ideally an extraction system would be best.  As a hobbyist you may be better to just use a hand spray bottle filled with a water based coolant to just spray as needed.  One objective of full coolant systems is get a long tool edge life to give a high part count per tool.  Cutting oils will differ according to the metals being cut, a general oil when used on varying metals will obviously be a compromise.

[Clive FosterParticipant @clivefoster55965]

Eek!

PCL is a brand.

They make a wide range of connectors but, like Hoover and vacuum cleaners, the brand name became synonymous with one particular style of connector. PCL Standard.

Looking at the male connectors.

Bottom one is PCL standard.

The three brass ones look to be Euro style. Google is less than helpful at finding any official specification with dimensions but I think :-

overall length forward of the nut 21 mm

diameter of front parallel nose 10 mm

diameter of rear parallel part 11.8 mm

is correct. Too late to go out and measure one.

Not sure about the other two, to my knowledge there are at least 6 connectors sufficiently similar to Euro to be confused at a casual glance.

Verify your females by checking against a known male.

Either type will do just fine so make your choice and stick to it.

Euro has the advantage of being more likely to come as standard on an affordable air tool.

Hose barb fittings in various sizes tend to be easier to find in PCL.

Threaded fittings on both types are almost universally BSP but one trap is whether the thread is taper (BSPT) or parallel (BSPP). If it’s not specified it will almost certainly be taper (BSPT). Air tool bodies et al tend to be taper but if rolling your own fittings parallel (BSPT) is far more convenient. But you will need PTFE tape on a parallel thread.

It’s unwise to assume that the threads on bottom of the range air tools are BSP. I’ve had some right weirdos through my hands, usually just enough smaller than BSP in a minimum metal body to make re-tapping hinkey.

Clive

 

[Clive FosterParticipant @clivefoster55965]

Howardt

If you are getting noxious fumes from a mist systems you have way, way too much oil in the airstream.

Correctly set up its a right pain to see if there is any oil entrained in the air at all. Unlike conventional suds the oil is just for chip extraction and tool tip lubrication. The air blast does the cooling. Correctly set up the mist should only cover the immediate area of the cut.

Hafta say I found my Bjur Spraymist systems way too pernickety to set-up for my tastes. Probably well past their sell by date by the time I got them. So I drilled out the nozzle a bit to produce a narrow droplet spray. Coverage area is probably about the same but having more coolant gong through makes it far easier too see whats going on. Still way less niffy than suds.

If starting over I’d buy the import heads as used by Jason. But such weren’t around 15 or 20 years back. The Bjur cast alloy case containing reservoir, regulator, pressure gauge and on-off solenoid is kinda coll tho’.

Clive

[Neil LickfoldParticipant @neillickfold44316]

When the mister is correctly set, it should take at least 20 seconds to see oil on a piece of printer paper.  if you see oil before then, it is far too high of oil flow rate. Used to say that if the oil was dripping on a plate placed infront of the mister in less than 30 seconds, also too much oil.

The air blast removes the chips and gives a far greater cutter life. Any vacuum system will help too.

If the shop is cold, then heating the oil with a baby bottle heater to 30c or so what ever temp they heat baby drink to, does have a real effect on controlling the oil flow amount.

1 drop of oil every 30 seconds or so is about right, even 1 drop in a minute is still ok.

Neil

[JasonBModerator @jasonb]

I thought we were talking MQL or “Fogbuster” type systems where it is not a mist but coarser though still small droplets carried by the air not atomised in with it. These do not form a fog and you are only looking at maybe 10mls per hour of liquid being used at the most.

Just looked back at an old post and for 6hrs of machining I used 40mls of fluid. No Fog, No dripping wet pile of swarf.

I built my head, rare thing for me to make tooling. The liquid is pumped VERY SLOWLY into the airflow so does not atomise, mist systems are more like a spray diffuser and suck up the liquid which vaporises it into timy drops which cause the fog.

I useit on aluminium to stop tip build up, air clears the chips from the immediate area around the tool, I doubt there is much in the way of cooling.

[Clive FosterParticipant @clivefoster55965]

Mist is something of a misnomer. Albeit somewhat true when applied to the badly set-up systems used by folk wanting to see plenty of oil on the job. Wound up to the n’th degree by the terminally incompetent, I don’t need to read no instructions types, a Bjur or similar pro system can produce an atmosphere that puts an old fashioned London pea-souper fog to shame. Especially if fed with the wrong oil.

Like a standard suds mix!

Mist, microdrop, fog buster or my modded Bjurs all produce droplets when properly set up. Mist probably being the smallest closely followed by micro drop. The point of a mist system is that careful manipulation of lubrication flow and air pressure allows considerable control over the area covered. Which can be useful. In a practical world mist systems are quite sensitive to oil viscosity variations and wear in the needle valve that controls the oil. My needle valves are almost certainly well worn are worn and don’t have good enough control to operate at the very low flows implied by the vastly inadequate manual. I imagine a new, factory fresh Bjur set up pretty much “just works” tho’. Of necessity the very small, near atomised, droplets produced by a mist system have very little momentum and, if all isn’t working well, they don’t carry properly into the bottom of a deep cut. Easy fix being to wind up the oil so at least some gets through. Which most likely also creates paper atomisation. Hence mist issues.

Micro-drops are effectively pumped individually into the air stream so they are (possibly) a little larger and better defined so they have more momentum to carry into deep cuts. Generally provided with independent control of air and oil which really helps.

Fogbuster types (and my modified Bjurs) produce defined drops with decent momentum to get into the cut. But, unlike a sophisticated micro drop, air and oil delivery aren’t really independent so you pretty much get the drop size and coverage defined by the system design. With limited adjustment. Which generally is plenty good enough for the likes of us. As Neil says sensitivity to viscosity and temperature is inevitable.

Whatever you do just don’t turn the oil feed up too far!

I will say that the modified Bjur on my S&B 1024 lathe is arranged to produce slightly larger drops than the one my Bridgeport. Bigger drops consume more oil but are much more reliable at getting into deep parting cuts. I really should make proper fog buster nozzles but running drill through the standard was a lot easier. Something small out of the number drill box.

Clive

[Clive FosterParticipant @clivefoster55965]

Gah spell check

For “paper atomisation” in above post read “proper atomisation”.

Clive

[JasonBModerator @jasonb]

The system I use does not need a needle valve and the amount of liquid is totally independant of the air flow.

Liquid is metered by a peristaltic pump driven by a geared motor on a variable speed power supply. Some link that to their CNC control, I’m happy to just twiddle a knob. So I can up the airflow if boring down a deep hole with a 3-flute to get the chips out or up the the liquid if I feel a ball nosed cutter may be more likely to get edge build up.

This is the pump at full speed, I can run at about 1/10th of that so a couple of small drops per min is all that is used.

[Clive FosterParticipant @clivefoster55965]

Jason

Given the independence of oil delivery and air flow I reckon that technically speaking yours is more properly considered a micro drop system.  Looking around the internet the term “fog buster” seems to be applied quite loosely to a variety of devices.

Objectively yours is by far the best way of going about things. Wish I’d thought of it.

Clive

 

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