Peristaltic Fine Spray: no mist: no fog coolant pump

[Vixen]

I guess most of us will have tried one (or more) of the varius pressurised container, fogger, mister or air tool lubricator systems that are offered for sale. Most work on the pressure balanced spray gun principle and are generally difficult to set up and use. It's famine or feast; either no fluid or too much. Some have the unfortunate habit of filling the workshop with a fog of coolant. It always appears difficult to find the "sweet spot" and keep it there.

I decided to try something different; to build a mist lubricator system, where the fluid supply was totally independant of the air supply. In fact, there are two separate pumps; An air compressor and a peristaltic fluid dosing pump. You can operate either or both independantly.

Small Peristaltic pumps are now readily available on the net. They are used to deliver controlled doses of fluid in chemical, pharmacutical and aquatic applications. This is the one I selected.   https://www.ebay.co.uk/itm/403142010424?var=673262876871     you need a pump with the smallest 1 x 3 size tubing but as they seem difficult to find, so use a 2 X 4 pump and buy some 1 x 3 silicon tube elsewhere. This pump, when fitted with the smallest 1 mm bore silicon tubing will deliver 11ml/min. This low dose rate can be reduced further if the 12 volt pump is driven by a suitable PWM motor controller.

This is the PWM motor controller I selected.  https://www.ebay.co.uk/itm/373747433026 Lots of choice for these. I bought one with a reversing switch but that was unnecessary as the rotary knob already has an 'off' switch position. You run the peri pump in the top 2/3 of the knob range.

I also bought a new link-lock delivery hose. https://www.ebay.co.uk/itm/402926661688. I will replace the big brass nozzle with a standard orange plastic one.



So what did I do with all that stuff?        The Peristaltic pump and the PWM motor controller were mounted in a small plastic box, a standard wall wart supplies the 12 volt. I collect these, as you never know when you need a convenient low voltage supply for something or other.







I mounted the link-lock supply pipe to the spindle head, so that it moves up and down with the spindle head and keeps the nozzle directed at the cutting zone.





This shows the installation on the mill. The peristaltic pump is self priming so the fluid supply container can be positioned in any convenient position.








I joined the 1 mm bore silicone pipe from the pump to the 3 mm bore nylon pipe with and adapter made from two diameters of brass tube soldered together





So how well did the pump work?          With the PWM knob set at max, the pump delivers 3 to 4 small drops per second. When the PWM knob is turned back, the pump flow can be reduced to one drop every three seconds and that is independant of any air flow through the delivery pipe. The first two photos show the pump delivering one drop every three seconds with no air supply.  It's actually difficult to catch the drops falling.






This final image shows how the air flow effects the distribution of the coolant/ lubricant. The pump flow rate was turned up for this shot.





For the initial tests I used a water soluble cutting oil, the neat cutting oil is red and the immulsion is that pink colour.      I am still undecided what to use for the coolant/ lubricant. Some people recommend water soluable cutting oil, some say to use neat cutting oil, others say WD40, or neat paraffin for aluminum and there is always KoolMist and the like.    It is so easy to replace the fluid in the bottle, a differnt coolant/ lubricants can be used for different stock materials; iron, steel, brass or aluminium. the choice is yours.

Now I need to do some serious machining to understand just how well this perisataltic pump system works.

Mike

[Jasonb]

It will be interesting to see how it performs Mike. Two thoughts I had since your recent PM were:

Firstly if any of the lubricants may affect the silicon tube as I know some oils and solvents can swell silicon (o rings and fuel tube) and I noticed that other sellers of systems with these pumps (cold end) warn against this happening.

Also as your liquid is not under pressure it will be interesting to see if the flow is reduced as the pressure within the pipe is increased, hopefully not as the end is open to atmosphere and not a lot of pressure is needed.

Look forward to seeing your soggy chips

[Vixen]

Hello Jason,

Silicone tube is so inexpensive, you can quickly replace it, if there are compatability issues. I would expect hydrocarbons (paraffin, WD40) to be more problematic. the only way to know is to try it. Unfortunately the product sold by 'Cold End' is difficult to import these days

The pristaltic pumps are fixed displacement/ fixed delivey pumps and the supply pipe is always open to atmosphere, so there should be no change in flow rate or pressure build up.

Soggy chips  Yuck   

Mike

[Hugh Currin]

Mike:

Very intriguing. Where do you mix the coolant and air? I didn't see that "block" in your descriptions or pictures. It does sound like the passages and build are less critical than for a no fog mister. Nice job.

Please do report back on your results.

Thanks.

[fumopuc]

Hi Mike, that does look very functional.
The main difference in functionality to the Coldend from Sebastian seems to be the manual on and off switch.
I can not recognize any connection to your CNC controller software at the moment.
The Coldend is ready to be used by a controller signal and and simple push button is in his system for any kind of manual needed running of the pump at any time.
I.e. if the pump is dry by any reason.
If needed, you can buy the Jokisch stuff at the Sorotec shop.
I do use it since 3 or more years now for everything.

[Vixen]

Hello Hugh,

Well, thats the beauty of a peristaltic pump arrangement. There is no mixing unit and no needle valves with which to try and contol the air and coolant flows.

The air supply is provided by the compressor and the fluid is directly pumped by the peri-pump down a separate tube to the tip of the link-lock pipe. The two flows are independant of each other and do not interact



Hello Achim,

I took my inspiration from Sabastian's Coldend system. I thought I could make one for a fraction of the price. 

It is easily possible to make LinuxCNC or Mach 3/4 control the operation of an electrical relay to apply power to the peri-pump. But, you know, I am still quite capable of operating a switch manually, the computer does not have to do everything. 

Which Jokisch fluid do you use? I checked their website and thay have hundreds to chose from. I would like to find a UK distributer who can supply the fluid in smaller quantities than 5 litres. Importing stuff from Europeis no longer as easy, since we regained our independance earlier in the year.

Mike

[Jasonb]

The Cold End ones use a stepper motor driven pump so will dose at a very low rate as you have more control over the 6 roller pumps revs and I think the rate can be varied by the computer so if you were say running with a tool changer it could up the flow if drilling or boring and reduce it when you change to an external adaptive. It will also adjust air flow by the use of one of the two solonoid valves. This also means the circuitry inside his black box is a bit more involved.

But for a lot of us a simple on off switch and a twist of the pot to get the flow we want at the start of a run is good enough.

https://www.ebay.co.uk/itm/224415115638?hash=item34402ee976:g:ESgAAOSw0Y9gbWsC

It was not so much the cost of replacing a swollen silicon tube I was thinking of but if it's going to swell overnight then having to pull the pump out of the enclosure, replace the tube and put it all back together again would be a bit of a pain and I would probably move away from my Usual paraffin on aluminium and try something else that was safe with the tube

UK dealer for the Jokisch is given on their site https://www.jokisch-fluids.de/catalog/en/dealer-search/ The S3G seems to be the same one both Seb End and Sorotek sell

[fumopuc]

Which Jokisch fluid do you use? I checked their website and thay have hundreds to chose from. I would like to find a UK distributer who can supply the fluid in smaller quantities than 5 litres. Importing stuff from Europeis no longer as easy, since we regained our independance earlier in the year.

Mike

Hi Mike, it is Monos Miko S3G.
https://www.jokisch-fluids.de/catalog/en/jokisch-monos-miko-s3g-p1055/?search=1
https://www.sorotec.de/shop/Monos-Miko-S3G-Cooling-Lubricant.html


http://www.jokisch.co.uk

[Vixen]

Hello all,

Thanks for the information about the correct Jokisch fluid and the UK agent, I will see what they can do.

Using a stepper motor drive will certainly give more computer control over the pump but at a cost. Integrating an additional (5th) axis to control the pump is possible, but not so easy, with LinuxCNC.  The manual PWM control of a DC pump motor, is both simple and inexpensive

Thats an interesting stepper motor driven peri-pump you found on e-bay. The manufactures name amused me,   SHENZHEN MORNING THUNDERCLAP TECHNOLOGY CO LTD.

BTW the reason the working head of the peri-pump is outside the box enclosure, is to make access to the silicone pipe straitforward. If there are compatability issues, a change of fluid as well as a new silcone pipe is advisable. I am going to suspend samples of my silicon pipe in various candidate fluids and see what happens.

Mike

[Dave Otto]

Hi Mike

Your new system works very much the same way as the Microdrop system I use on my mill, that is as far as how the lubricant is delivered to the tip. The Microdrop does use a pressurized container which forces the lube through the line and does use needle valves for air and fluid control. I have never had an issue setting these.

I took a few minutes to sketch up the Microdrop nozzle, I thought you might find it interesting. They are easy to make and would improve the performance of your system.
Attached are a few screen shots of the assembly. The brass hex has had the points turned down and the Loc-Line nozzle has been reamed so the brass tip is nice push fit into the Loc-Line tip. The lube flows up the center and the air comes down the flats. You can see as the air flows down the tip it collects the droplets of fluid and carries them on to your part. 

Dave

[Mcgyver]

Good stuff!

I also built a mist coolant system mostly for use on benchtop tool and cutter grinder.  I've larger T&CG that has flood but the little guy wasn't set up for it.  After a lot of research on what others had built and what worked and didn't, I concluded you need separately pressurized coolant and air and a way to control the pressure of each.  I built a sort of double regulator and supply it with shop air and control the air coolant and pressure independently.

The ideal scenario for grinding is stream of droplets at a tangent to the grinding wheel at about the speed of the grinding wheel so they more less land on it and stay there.  It worked really well, I can plunge to the motors power capacity into a HSS bit with out overheating things and get no fogging in the shop.  It makes it quick to grind tools.  You usually get a stalactite of damp, ground HSS particles hanging form the bottom of the tool!

[Jasonb]

I am going to suspend samples of my silicon pipe in various candidate fluids and see what happens.

That has saved me chopping off a bit of fuel line to put in paraffin tomorrow, but let me know if you don't have any of that to test and I'll see what happens.

I've just been out playing with my air and can now get good regulation of the air flow while still having a high volume coming through to the blow down gun so looks like I may now be buying a few components.

The Cold End one actually uses the pump to regulate how much of the pressurised liquid is released into the air stream rather than pumping the liquid in. I'll try an unpressurised container first and see what happens though I think the 1 drop every few seconds may still be a bit high for me basing it on what I dab on with the brush.

[Dave Otto]

Good stuff!

I also built a mist coolant system mostly for use on benchtop tool and cutter grinder.  I've larger T&CG that has flood but the little guy wasn't set up for it.  After a lot of research on what others had built and what worked and didn't, I concluded you need separately pressurized coolant and air and a way to control the pressure of each.  I built a sort of double regulator and supply it with shop air and control the air coolant and pressure independently.

This is exactly how the Microdrop system works, they are not cheap but work quite well, I also use their synthetic lube with mine. I have one with two lines and have it controlled by the CNC.

Dave

[Dave Otto]

All the peristaltic pumps that I have been around over the years have used Tygon tubing designed for the pump. It doesn't seen that you would be limited to silicone tubing?

Dave

[Vixen]

Thanks for all the feedback guys.

'There are more than one ways to skin a cat'.  My experiments with the peri-pump are just another approach to the problem. Use what you have and are happy with.

That has saved me chopping off a bit of fuel line to put in paraffin tomorrow, but let me know if you don't have any of that to test and I'll see what happens.

Best for you to put a sample of fuel line in some paraffin, as I am not about to invest in a 5 litre can, just for a compatability test.

I just found this on a RC flying site. "Tygon is a little stiffer to work with and tends to very slowly harden a bit with use and age while
silicon tends to be a little nicer to work with but tends to slowly soften and swell with use and age. As noted above if silicon is used with gasoline, pump diesel, kerosene or Jet A it will rapidly swell and soften becoming unusable in a very sort time."

So maybe it's time to start looking for Tygon tube as an alternative. Either way, it looks like regular pump tube changes will be required.

This all points to the need to use non mineral fluids, such as Jokish fluids, or others still to be identified.


Mike