Water cooling a spindle

[javeria]

HI Koning - i have a doubt

the pump which I have has a half inch pipe fitting and the spindle has the quarter inch - I have the reducer for them too.

now the question is at what length do I put the reducers.

should I get the half inch pipe all the way near to the spindle and put the reducer just there?

or do I just put the reducers at the start of the pump outlet.

I am a bit confused here

Kindly guide me here.

RGDS
IRfan

[javeria]

bump bump :D

anyone kindly help me decide

[Gerald D]

Come on Irfan, I thought you were a qualified mechanical engineer? ;)

The bigger the pipe, the less the resistance, the more the flow. . . . . position the fittings to give the biggest pipes over the longest distance.

[javeria]

G' it been long - i am now master of microsoft excel and powerpoint -

where as I knew about the resistance being lesser with bigger tubes I was looking if Koning used smaller tubing and it worked. :)

sometimes I myself forget I am a Mech Engineer - :(

[kaartman]

Hi Irfan
Sorry for replying only now,
water pump, the water fountain pump is a low performance centrifugal pump, the impeller design and tollerance inside the pump housing is not of the greatest, i tried a 1/2 inh diameter clear pipe and i found it pinch cose easily and the pump does not deliver the pressure required to keep it open,
so I used a pipe with inner diameter(6mm) and a wall thickness of 3mm, I got some fittings at the hardware shop that screw direct to the spindle and fit to the pipe, at the pump side i had to file the edges of the brass fitting so that it could clear the pump casing, I could not find a all in one reducer at the pump side that would fit the screw thread and pipe so i used a 9mm drill bit and enlarged the inner diameter of the end, you will see the scrape markes on the inside at the brass fiting, this is one of the reasons for the bigger wall thickness. inside the bucket the return pipe is above the water level so that when the pump is switched off the water drain from the pipes - this is my indicator that the pump is working when switched on

[Gerald D]

If the return pipe is above the water level in the tank(bucket), that means you "break the siphon" and this causes the pipes to drain at switch-off, making it harder for the pump to start and get the siphon working again. If you want the pump to start easier, you could either "hold the siphon" permanently (return under the water surface), or raise the bucket off the floor. Nothing wrong with a tank next to the control box . . . . .

[javeria]

ok Koning - I was offered a series of 6 fountain pumps (all submerged type) I took the one which could pump water 4 ft into the air without a pipe attached to it at half inch diameter.

I will try the large tube (pneumatic which will not pinch) till the spindle and reduce it there - should work

will keep all posted on this one.

RGDS
Irfan

the pump is rated at 18 watts @ 220V

[javeria]

Hi Irfan
An ordinary submersable water fountain pump,
Regards

Hi Koning - what is the wattage of your pump - I got a 18watts one and with 12mm dia pneumatic hosing no good results - I have to suck the water out - and then the water starts coming - then if I stop the pump put it on again then there is no-show :(

just wanted to know before I get a new one - or is there something I am overlooking?

RGDS
Irfan

[kaartman]

Hi Irfan
Sorry for replying so late,,, never home,,,,work,work work!
I have a 35 WATT pump, if I used a 12mm hose, I would also had no show off water.
You must keep in mind that these type of pumps do not have the most technologically advanced impellers and guide vanes in the world, The design of impeller produce pressure and volume of water, what helps the impeller to produce pressure at a certain volume of water is the design of the impeller housing http://www.kiwipumps.com/centrifugal-pumps2.html


The type of impeller that is found in a fountain pump and I can assure you that the pump housing tolerances and flow design is 10000 times less efficient than a proper pump,, so what do we need to do to get some pressure and volume out of this low efficient type of pump, my answer is , small inner diameter hose to reduce the demand on the volume that the pump need to fill before the water get to he spindle, small diameter = less volume (less weight of water) = better lift, when using a small diameter hose try to get a hose with thick wall to prevent kinking of the hose, the thicker wall can increase the pressure by reducing stretching when the coolant temperature increases, This is the principals I used and it works for me, I also keep the return hose submersed in the water, this way the tubing does not drain empty when the pump is turned off, so circulation of water is quicker with start-up no air in the tube and our cheap pumps work less on the initial start

[javeria]

Think i will just get a better pump

[Gerald D]

An absolutely key factor with pump systems is HEIGHTS. A fish tank pump does not need to lift water any higher than the reservoir - easy job. A small indoor ornamental fountain pump is probably going to need to lift 0.5 meter max. For a MM, if you have the pump and reservoir at floor level, you need to lift over 1 meter. An outdoor fountain pump should handle that. . . . . . or you need to lift your small pump + reservoir off the floor.

Do not lift just the pump. While they can push water uphill, these cheapies cannot suck it uphill. The pumps must be mounted below the water level in the reservoir.

For a test, run your pump outside like a garden hose, and check how much difference the height of the outlet in your hand causes.

[javeria]

G' I did run the pump with the 20 meters of 12mm dia pneumatic hose - and there was plenty of water coming out (the hose was kept at a much higher level than Mechmate - once I got the spindle connected it just stopped - and it was like water dripping and not flowing -

today I have bought a decent pump - hope that works :)

RGDS
IRfan

[Gerald D]

once I got the spindle connected it just stopped - and it was like water dripping and not flowing

Well, then we all have to understand that the spindle is drilled with small diameter passages inside, or that your fittings at the spindle have too small holes through them, or that your pipe got pinched somewhere. A bigger pump is not the answer if the pipe got pinched or if you have bad fittings. Can you see the diameter of the drilling in the spindle?

It would be interesting to do a flow test on the spindle: A bucket of water 1 meter above the spindle and let water free flow through it . . . . .

[javeria]

The fittings at the spindle are of 1/4th inch - thats why the resistance to flow I think. there are no pinches on the pipe.

previously I had tried supplying water into and out of the spindle using only quarter inch tubing of about 0.5 meter with a fish tank filter pump and it worked really well.

Think its time to post pictures and move this discussion to the trouble shooting thread.

RGDS
IRfan

[Gerald D]

Have marked this discussion for moving elsewhere.....once it dies down.

[javeria]

Ok issue Solved -

used a brushless(contineous duty) - 28Watt - monoblock pump - head 4.5m, @ 700LPH cost me INR1300 - approx USD 26.00

I was still not able to take pictures as I was busy solving some electrical issues in the supply pole.

RGDS
IRfan

[Gerald D]

Are you sure it is only 28 Watt?

[javeria]

i am in office - will let ya know tomorrow. with pics

[javeria]

http://www.youtube.com/watch?v=a04a_FtbR44

finally the cooling part is sorted out and I am pretty happy with the pump I have - the pictures and video show much more

+ the gear box setups have been mounted - I am presently going to setup the proximities and hard stops and then start running the machine - there is still a lot of wiring left to do in the controller

Hope to have a running Mechmate by this week end!

RGDS
IRfan

[dacostad]

Can you tell me what the thread size is of the fittings on the spindle?

Thanks


David

[waynec]

Cool to see others working on spindle cooling. I want to share a bit about my water cooling setup, a sort of update.

If you remember, I mounted a pump, small resevoir and radiator up on the gantry. It rides along with the Y car, so I don't have much distance for the fluid to travel. I found that even a pretty decent fishtank pump wasn't enough push for the resistance of the parts. I ended up using a Grundfos pump with about 8ft of head. It was a 3 speed unit that cost me about $76 (Gulp). It has enough power to pump from the gantry, and probably enough to pump thru larger tubing from the floor.

This system works just fine- the auto transmission radiator works really well. the resevoir is just a sealing plastic container with some bulkhead fittings installed. It has been reliable and effective even under load.

BUT... the mass of all that mess cantilevered behind and above the Y car and Z axis results in lever action movement at the spindle cutter. Imagine a pole, with the spindle at one end, and a bunch of weight at the other- water, filter, pump, etc. When I make sudden direction changes I get noticeable movement in the tool, and poor cut quality.

So, I'm considering moving the mass off the gantry, and trying with the radiator, resevoir and pump down at the control box. I'll have to pump pretty far, but I'll use a reducer at the end so resistance is as low as possible. If this works, I bet I'll get much lower 'bounce' at the end of the pole.

Thanks for the great ideas here.

Wayne from White Salmon

[Gerald D]

Wayne, that "center-of-mass" observation is quite important. Maybe the other readers should be reminded that you are running a ShopBot that has a relatively flimsy y-car compared to the MechMate. However, there will come a point where a MM will not handle an off-center mass too well.

[waynec]

Mine is a very modified shopbot, with the gantry totally replaced. My gantry is now an upside-down 'T' shape and Bishop Wisecarver rails. The gantry crossbar is a pair of oversized alum extrusions. The Y car is also an oversized linear guide with a new larger motor. Quite an improvement, but still susceptible to trasmitting leveraged motion.

I traced the movement weak link to the Y car motor mount. It flexes on direction change, and that flex is amplified by the extra mass hanging off the top of the Y car.

I was thinking of just modifying the existing setup by remounting the setup to the lower end of the Y car. That might work, because effectively I'd be making the 'pole' shorter. But after reading some of the discussion here, I think I'll consider moving the whole mess off the gantry to a small box with the pump, resevoir, and radiator all in one box under the CNC.

Anyway, thanks for the input. Its great what you learn as you go here.

Wayne

[paul60]

I am looking for an indicator to show if the cooling liquid is flowing in the tubes.
i found once the tube are filled you cannot tell if its moving or just sitting there?
thanks paul

[Gerald D]

These (http://skycraftsurplus.com/liquimobilinsanflowindicators.aspx) look nice.

[paul60]

thanks Gerald
pity they are out of stock
paul

[boaterri]

Greetings:

I was browsing another forum and found this thread on building a cooling system using high(er) quality computer components.

http://www.cnczone.com/forums/showthread.php?t=107444

Thought it might give someone an idea or two.

Rick

[KenC]

Computer component are not cut for a real shop environment...

[danilom]

What would be best to use for coolant in spindle?