Author Topic: Spraymist  (Read 25097 times)

bogstandard

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Spraymist
« on: November 23, 2009, 07:24:48 PM »
Still on my tuit list, this project definitely needs to be done sooner than later.

I have been using flood coolant for many years, but since my new machines were installed, I have only ever used it on my mill, never on the lathe. This project, if it works, will get me away from flood coolant altogether, and I will make a spraymist unit for the four machines that require it, lathe, mill, surface grinder and power hacksaw.
Having read both good and bad reports about spraymist, I have decided that good far outweighs the bad, and with a little redesign of a cheapo unit, I should be able to eliminate some of the bad faults.

I think the main complaint is that the mist gets airbourne, and soon fills up the shop. I hope to get my systems using very small quantities of air and only tiny amounts of coolant. To such an extent, it will be a total loss system, just a quick wipe up in the area you are working in after you have finished.

Please remember, this is experimentation on my part, and really the results won't be known for a fair while, as I play about with different size and design of nozzle. But what I will be doing first off, should get me a basic working system.

Over the last few months, I have been gathering together all the bits to make the required number (and some). The main parts are the linkline type type coolant pipes. They can be as cheap or as expensive as you want to make them, but I have found that, the really cheap stuff is just that, and only really suitable for fitting into a fixed position, like on the power hacksaw.




Earlier this year a friend brought me a unit back from the US, a nice cheapo job from LMS.

http://littlemachineshop.com/products/product_view.php?ProductID=2725&category=

Cheap and cheerful, and I suppose it must work, otherwise they wouldn't be selling it.

The main problem that I can recognise instantly is the way the nozzle works, and it is this area that I will concentrate my main effort on.
It works on the venturi principle, where air is speeded up as it goes past the pipe end, and when it hits the larger opening of atmosphere, the pressure drops (lower pressure than surrounding air, it could be described as a partial vacuum, if such a thing existed) and the coolant is sucked up the pipe and mixed with the jet of air. Hence it is spraying a mist of coolant.
I will be attempting to reduce the amount of coolant flowing and trying to get a more efficient venturi effect.
There is no coolant loose in the linkline at all, that is reserved for pressurised air, the small tube you see actually runs all the way back to the coolant tank.




I scribbled up a bit of a design for a more efficient nozzle, and this will evolve as it is made.




This is a rough sketch of the commercial unit air block, with a slight addition of my own of the stuffing gland, to assist in stopping air leakage, and also hold the inner pipe so that it cannot be pulled out easily.




So now to get on my way. I will be using the pipe on the left, and as you can see, the orange nozzle has already been discarded, I will be making my own up to fit.
Because there is actually no loose liquid inside the big tube, I am hoping that friction or Loctited joints will be satisfactory, plus I am expecting to use very low pressure and volumes of air, maybe around 20 to 30 psi, and micro litres in volume.




The piece of brass was mounted up in the lathe and the end shaped up.
I will just explain what the bits are for.
The hole in the end goes all the way thru the nozzle, and is a very tight fit for the small pipe. The pipe will be forced up the end by say 1/2" and loctited in. The middle diameter is a friction fit into the end of the outer plastic tube.
I now need to drill air tranfer ports to get the pressurised air from this side to the other.




This shows how it fits into the end of the locline.




Set in the RT, I carefully drilled down on the land between the medium spigot and the small one. I drilled 6 off by 1mm holes. I am not worried that they stay straight, as long as they reach the other end without breaking into the central hole or the outside of the central spigot.




The six transfer holes drilled, no breakouts but they were a bit higgledy-piggledy on the other side. No concerns over that, the holes are thru and that is all that matters.




The other end of the nozzle was cleaned up ready to accept a fine bore tube.
The ones shown here are actually tungsten tubes off a spark eroding machine, the big one just behind the nozzle is about 2mm diameter with a 1mm hole up the centre. I will be starting off with a fairly small one, and experimenting with larger ones if I can't get the flow I require.
Once things work out just fine, I can turn the whole nozzles up out of brass, and drill the correct hole in the middle.




To be continued.................


Bogs

bogstandard

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Re: Spraymist
« Reply #1 on: November 25, 2009, 06:20:09 PM »
This bit might be a little more interesting, because it shows how to make a most underated tool, the lowly D-bit.

Just to explain a little, a venturi nozzle can be very difficult to design and make, because there are so many variables, and I couldn't even start to be anything but a total novice in the design of one. But there are a couple of basic figures that I know will give me a design that works. These are shown in the C-o-C.
I will be chopping off the front cone part, and it should work well enough to give me a usable spray nozzle.




I want to make the back cone, and at this time I will make it adjustable, so I can find the optimum position for the inner nozzle itself.

But how to cut an internal taper as small as I want it? A boring bar is out of the question as it would have to be so fine, it would be almost guaranteed to break. I could get a reamer made to the angle I want, but it would cost lots of pennies. The answer is a D-bit, and if well made, is just as accurate as a commercially made reamer.
I am going to show you how I make one to continue with this job.

Mounted up a piece of silver steel (drill rod), and faced off the end.




Kicked the topslide (compound) over by half the angle required, in this case 11 degrees.




Then using the topslide, the taper was being cut.




The taper was finished when the small end was at about 2mm. I will be drilling a 3mm hole thru the nozzle material, so this D-bit will not require a cutting edge putting onto the very end.




The machining marks were gently removed with fine emery.




The bar was accurately measured up (this was 3/8" or 0.375"). Then it was divided by 2 and the figure rounded up. It was at this stage I changed my normal making practice. I would harden at this stage and grind the end down on my surface grinder. But because most people don't own such a machine, I am going to do it the normal way.




Mounted up perfectly level in the milling vice, the bar is reduced down by not quite half it's diameter. One or two thou larger is ideal.




Mine measured up when finished at 0.1885", one thou over half size.




This is what it looked like close up. The machining marks are only tenths of a thou deep, so no worries over those. I would forget about deburring, as you can easily take too much off the edges and prevent it being sharpened.




It was now time to get things warmed up and hardened.
Just the part that was machined was heated up to cherry red, and held there for a minute or two, then it was quickly quenched in water.
This should make the tool as hard as glass. I don't bother tempering the tool, and that is just a personal thing.




The machined face is then gently smoothed down on a smooth oiled stone until the machine marks are gone. You should end up with edges as sharp as a razor.




You tend to hoard the good and more useful ones that you make. Just in case.




So that is the D-bit made.

Next time I will be using it to make the adjustable brass nozzle.


Bogs

Offline Andy

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Re: Spraymist
« Reply #2 on: November 25, 2009, 06:42:30 PM »
Much appreciated, as always. I'm following this with great interest, learning all the time. Making D bits is a nice 'bonus feature'.
From probably the smallest, dampest and most untidy workshop in Bradford, West Yorks, England, if not the world..

Offline Darren

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Re: Spraymist
« Reply #3 on: November 25, 2009, 06:48:31 PM »
Nicely shown John,

I've been itching to make a D-bit but for a totally different reason/job.  :thumbup:
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Offline chuck foster

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Re: Spraymist
« Reply #4 on: November 27, 2009, 10:15:53 PM »
i have used d bits for those once in a life time odd ball size holes that just don't warrent buying a reamer for, with a bit of care they work just fine.

thanks john

chuck  :wave:
hitting and missing all the way :)

skype:  aermotor8

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bogstandard

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Re: Spraymist
« Reply #5 on: November 28, 2009, 04:36:58 AM »
You are spot on Chuck, D-bits can get you out of those silly situations you tend to end up in where there is no easy way out of.

If care is taken, they are a fine replacement for a reamer.

The one I have made doesn't have to cut on the nose, so to give you some idea of what it should be like with a cutting nose, say for a blind hole or as a reamer, I have done a C-o-C sketch.

I was hoping to get this nozzle finished very soon, but personal issues have taken it's toll, so it might be a couple of days still.


John

bogstandard

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Re: Spraymist
« Reply #6 on: November 30, 2009, 04:36:09 PM »
Lets get this nozzle finished off.

I have almost done the inside bit, but before going any further the outside nozzle needs to be made.
So a bit of brass bar about 2" long was chucked up. A 3mm hole was drilled to a depth of about 40mm, then it was followed down by a 10.5mm hole to a depth of 12.5mm.




Time to break out the D-bit I made the other day, in the hope that it works (not really, if you make them to the basic dimensions I showed, they are almost guaranteed to get the job done)
I had marked it up so that it would penetrate to about 35mm. The lathe was set to it's slowest speed of 65 RPM.




It is then a matter of pecking into the hole and clearing very often. As you can see, it is doing a lovely job of scraping the shape out of the inside. As I have said before, if you can make a good one, they can be used instead of a reamer. But that 1 or 2 thou thicker than centre and razor sharp edges are critical.




To allow me to get super fine adjustment for the nozzle, I threaded the inside bit with 7/16ths by 40 TPI. This is the same pitch as an imperial micrometer uses, so one full turn of the nozzle will move it backwards or forwards by 0.025" (0.62mm).




The nozzle was turned around in the chuck, and the end faced away until there was 3mm straight portion left of the previously drilled 3mm hole. After that it started to open out into the taper I had cut with the D-bit.
The topslide was then set over by 11 degrees, the same as the internal taper.




This shot from the top is when I was cutting the outside taper using the topslide.




This is what it ended up like, a 3mm straight bit at the nose and then the taper. This should be the same as the profile on the inside.
I did a little more work on the outside, but nothing that really deserves a mention.




So now onto the other bit of the nozzle. The end was faced up and an external thread the same as the other was cut onto it.




The two mating parts. Now I just need to get the tube into the inside bit.




The inside part was tapped out, and to cut a long story short, the bit of brass was drilled thru with the same diameter as the tube and a thread cut to match the small thread just cut was put onto it.




After Loctiting the tube into the holder, the assembly was screwed into the inside part. If necessary, different sizes of tube with their holder can be made up and screwed into position.




The business end of the nozzle.

Do ya feel lucky, punk!!




This is how it will fit onto the locline.
By doing it this way, I have about 10mm adjustment of the outer nozzle in relation to the inner one.




You might think I am going to a lot of trouble making this nozzle.

By doing it this way, with adjustments to the critical positions and sizes, I should be able to find the ideal settings that I want, and be able to replicate an easier made nozzle for the four units I require. Plus I should also be able to do a sketch so that people can make their own if they want. So all this work will not be wasted, it is called R&D.


The control block will follow soon.

Bogs


Russel

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Re: Spraymist
« Reply #7 on: December 01, 2009, 01:50:14 AM »
Wow, that nozzle looks great! Thank you for posting this...I wouldn't even know where to start. Now I have more great info to file away between the ears, until I need it.

Thanks again,

Russ

Offline kvom

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Re: Spraymist
« Reply #8 on: December 01, 2009, 07:55:50 AM »
If I understand it correctly, then the tapered D-bit is cutting only on the left edge, so you needed to offset it a bit on that the right side wouldn't rub.

Offline NickG

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Re: Spraymist
« Reply #9 on: December 01, 2009, 08:00:47 AM »
Thanks John,

I've seen people making d bits before but never tried it. Will definitely give it a go now. I don't have a set of reamers, all mine are ancient and large and just chucked in a box which as you said once means they are probably all damaged.

Nick
Location: County Durham (North East England)

Offline Darren

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Re: Spraymist
« Reply #10 on: December 01, 2009, 08:03:42 AM »
If I understand it correctly, then the tapered D-bit is cutting only on the left edge, so you needed to offset it a bit on that the right side wouldn't rub.

I think both sides are in contact with the work and that is how D-Bits maintain their accuracy.

Normally D-Bits are used for drilling true/straight holes at specific dia where drill bits have little chance of either.
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)

bogstandard

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Re: Spraymist
« Reply #11 on: December 01, 2009, 09:57:48 AM »
Kvom,

Darren is correct in that both sides remain in contact, and that one or two thou above centre helps to keep it locked down onto the bore. Only when you have a front cutting face do you relieve the right hand side on that front cutting face.


Nick,

With a little care, you can easily make yourself a set of D-bits until you can afford reamers. Where they really score is what I have used one for this time, cutting tapered holes, but also they are very good for flat bottomed holes or curved bottom holes, usually difficult to do with a normal reamer.
If you have a toolpost grinder, you can always resize them as well if needed, as the centre height isn't altered if you grind the cutting area.

For short holes, you can easily make four or five D-bits from one cheap piece of silver steel.

If you want I can take a piccy of some of the shapes that I have made over the years, just to show how versatile they really are.


John

Offline spuddevans

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Re: Spraymist
« Reply #12 on: December 01, 2009, 11:39:33 AM »
If you want I can take a piccy of some of the shapes that I have made over the years, just to show how versatile they really are.

I think I'm safe in saying that I would absolutely want to see more pictures  :thumbup: :thumbup:


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline ozzie46

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Re: Spraymist
« Reply #13 on: December 01, 2009, 12:37:55 PM »


  Uhh Me to!  :thumbup: :thumbup: :thumbup:

  Ron

Offline NickG

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Re: Spraymist
« Reply #14 on: December 01, 2009, 01:33:45 PM »
That is the main thing I had seen them for John, flat bottomed holes. but also the instructions for sweet pea call for one as a sort of form tool to give the axle boxes a radius.

Thanks,

Nick
Location: County Durham (North East England)

bogstandard

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Re: Spraymist
« Reply #15 on: December 01, 2009, 02:32:14 PM »
For any further discussion about D-bits, could you please do it here. It will save clogging up this post with off topic stuff.

http://madmodder.net/index.php?topic=2312.0

Thanks

Bogs

bogstandard

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Re: Spraymist
« Reply #16 on: December 14, 2009, 01:51:47 PM »
Now I have got the swing tool out of my system, I suppose I had better get this job finished off.

Last time, I had finished the nozzle, so the block comes next.

As usual I did a quickie sketch to remind me what I want to end up with and also a few dimensions if I need it. I had already prepared a little block of ali.




The holes that were required were drilled and if needed tapped.
This pic shows what the assembled unit will look like. I have still to make the stuffing gland to seal where the little pipe comes out of the back, and the metering needle to control the air flow.



My round tuit list is fast disappearing, thank goodness. I should be able to get back to making little engines soon.

I just can't wait.


Bogs

Offline NickG

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Re: Spraymist
« Reply #17 on: December 14, 2009, 02:37:39 PM »
We can't wait either Bogs but your projects in the mean time have been interesting and as always, educational to most of us.  :thumbup:

Nick
Location: County Durham (North East England)

Offline Divided he ad

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Re: Spraymist
« Reply #18 on: December 14, 2009, 02:49:12 PM »
Very interested in the results from this John.

My set up will not really allow flood coolant so this would be the perfect system..... I'll wait to see your results, might get to see this lot first hand some time soon?



Ralph.
I know what I know and need to know more!!!

bogstandard

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Re: Spraymist
« Reply #19 on: December 14, 2009, 02:57:06 PM »
It will have to be after New Year now Ralph, everything starts to happen this Thursday, and I might not even get this bit finished before then.


John

Rob.Wilson

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Re: Spraymist
« Reply #20 on: December 14, 2009, 04:49:33 PM »
Very interesting Bog's

i could do with one on my surface grinder ,,it may help keep the dust down to

Regards Rob

bogstandard

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Re: Spraymist
« Reply #21 on: December 14, 2009, 05:03:23 PM »
Rob,

When it is fully developed, I will be making four of them, one for each of my main power machines. I will still leave the flood on the mill as well as one of these, because at times, it really is needed, but lathe, surface grinder and power hacksaw, will only have one of these.

That will be in the future though, when I have found the best settings by using this one on the lathe for a while.


John

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Re: Spraymist
« Reply #22 on: December 15, 2009, 04:10:35 AM »
No worries john, Holiday season and all.....   :beer:

I forget how it's creeping up on us, I'm just plodding along with work barely noticing the days going by!!!  ::)



Take it easy,  :med:



Ralph.
I know what I know and need to know more!!!

Offline Gadget

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Re: Spraymist
« Reply #23 on: December 15, 2009, 03:14:08 PM »
I wonder if you could modify an airbrush to do this easier.