[Thorpydo]

Hey,

I'm about to start a project and would like some input before I put things in motion.

The belt driven spindle bypasses the gearbox and has top speeds of 2800 or 5900. Obviously only one belt is used at a time. The thickness is quite a bit less then that of the stock belt which is a bit discerning but I figure if something is going to fail, the belt should be the first thing to go. This belt is .354" and the stock is .545". I couldn't fit two bigger belts stacked like in this design and I couldn't get the speed range I wanted without changing the motor gear.

Coolant flows into the bottom left of the heatsink and two hoses will come off the bottom right side. The hope is to prevent the spindle from overheating.

The cad model is still a work in progress. Using solidworks 08.



Thanks for the peak

[cadmonkey]

Looks like a sound idea - will you share the plans once you complete them?

[Thorpydo]

I just bought a new camera and I can see that the camera and I are not mixing well. I wonder what the problem is.

The model is finalized.I went ahead and bought a heatsink extrusion to cut down on machine time. The gasket was stenciled in with a laser engraver and then I used an exacto knife to cut it out. I might try again with the laser engraver to see if I can get all the way through the rubber.

Whats wrong with the picture with the saw in it?

[Thorpydo]

Cheers.

[JpBinc]

Looks good to me!

[MRM RCModels]

I like the idea. Just signing up.

[CROSSHATCH]

Very nice pieces you got there.


-Jason

[Teyber12]

What about galvanic corrosion?

the drawings and idea look very nice

[Thorpydo]

Got the heatsink pretty much setup today.

I need to order a couple hoses to mount and make a brace on the top and bottom to hold the acrylic to the gasket better.

Bonus picture of a touch probe I'm in the process of setting up.

Edit: Teyber, can you elaborate on galvanic corrosion? I'm unfamiliar with what that is?

Thanks guys!

[Teyber12]

http://en.wikipedia.org/wiki/Galvanic_corrosion

I am just realizing how your system works though- its also the flood coolant! genious! i thought you had a closed cooling system for the head and if you have dis-similar metals in a closed loop(with a conducter between) the metal starts deteriorating.

[pete from TN]

So basiclly this unit is strictly to keep the casting cool so the bearings stay cooler is that right? I know that the plexiglass looks cool but you could just make the cover out of aluminum and machine some more cooling fins into it and be even better off. Do you have any way of checking to see how much cooling you are actually getting. I suppose that you are doing a belt drive conversion on this to do all this modification no? Nice work and good idea...peace

[SScnc]

Thorpydo,

Where's the outlet ?

I thought the idea was to have coolant flow though your heat sink and out through the coolant nozzle onto the cutter and stock.

Maybe I'm misunderstanding.

[cjdavis618]

Looks good.

How thick is your acrylic?

[Thorpydo]

You guys are both on track.

I'm going to be doing a belt conversion and will be running the spindle at a higher RPM. The heatsink's purpose is to keep the spindle cool.

I have no way to gauge the effectiveness. I suppose down the road I could run a job with and without the heatsink and compare temperatures but without any real recourse to increase the effectiveness there isn't too much of a point.

There are two outlets at the bottom left of the heatsink. The hoses aren't installed; I need to order two hoses with 1/8 NPT fittings. In the last picture I am plugging the two holes to see if the gasket will hold with any sort of pressure. The gasket fails at the top and bottom because the acrylic is flexing towards the middle, where there are no screws. I plan to make a brace to fit across the top and bottom to fix the problem.

I considered making the cover our of aluminum instead of acrylic but decided not to for a couple reasons. First, I want to be able to see inside, and make sure the heatsink is full of coolant and there are no chips or anything clogging the system (There shouldn't be as it is upstream of the cutter but you never know. I don't think my filtration system is 100%) And secondly, an aluminum cover will have a minimal effect anyway. It would draw a bit of heat from the fluid to the outside air but that isn't that important. It is far more important to get heat transfer from the casting to the fluid. It's the same reason that a fin is only effective up to a certain height; because the heat at the tip of the fin has to travel all the way through the fin to the base.

The acrylic is a quarter inch thick. It's the scrap left over from building my enclosure.

[HawkJET]

I know that the plexiglass looks cool but you could just make the cover out of aluminum and machine some more cooling fins into it and be even better off.

The system shown has the ability to dissipate far more heat energy than the 3/4 HP the motor consumes. This design is terminal overkill so there is no need for additional fins.

I have no way to gauge the effectiveness.

I bet money that the effectiveness will be almost zero. Yes the heat exchanger you have shown is overkill, but you will not get much heat to it in the first place. The heat is generated at the bearings and to get that heat to the heat exchanger, it has to go through the spindle and quill, The interface between the quill and head casting (small air gap), the cast iron casting, an inch or more to the front of the casting, up the face, through the paint, another small air gap and THEN into the heat exchanger. It won't get there. You'll probably only get about 2% of the cooling you want.

You don't need anything close to the amount of surface area in contact with the coolant. You would be better off with some kind of collar around the spindle itself and located over the bearings. A simple hole (3/16" or 1/4" with no fins or other features) through the periphery of the collar is all that is needed.

I am an engineer and a mold maker. Molds need to be cooled. The amount of energy a mold has to dissipate is orders of magnitude more than what you are doing here. The water passages in a mold are no more that what I described.

I am not trying to rain on your parade here, but I honestly don't know what advice to give you that will make your system very effective.

Something like this:

http://imageevent.com/tppjr/rf45dove...bearingcooling

will be far more effective. It is a coolant manifold that attaches to the spindle and not intended as a bearing cooler but it will probably do that pretty well because it puts the coolant much closer to the heat source.

[philbur]

In a high-speed spindle the heat is generated in the spindle bearings. So to get rid of that heat efficiently you need to circulate coolant as close to the bearings as possible. I think your heat exchanger is to far from the source. Most commercial designs I have seen circulate the coolant through the spindle cartridge.

Just a thought
Phil

Hey,

I'm about to start a project and would like some input before I put things in motion.

The belt driven spindle bypasses the gearbox and has top speeds of 2800 or 5900. Obviously only one belt is used at a time. The thickness is quite a bit less then that of the stock belt which is a bit discerning but I figure if something is going to fail, the belt should be the first thing to go. This belt is .354" and the stock is .545". I couldn't fit two bigger belts stacked like in this design and I couldn't get the speed range I wanted without changing the motor gear.

Coolant flows into the bottom left of the heatsink and two hoses will come off the bottom right side. The hope is to prevent the spindle from overheating.

The cad model is still a work in progress. Using solidworks 08.



Thanks for the peak

[SScnc]

There are two outlets at the bottom left of the heatsink. The hoses aren't installed; I need to order two hoses with 1/8 NPT fittings. In the last picture I am plugging the two holes to see if the gasket will hold with any sort of pressure.

Oh okay, that makes sense now. I thought in the second picture over those were leaks.

Nice job so far. are you going to do temperature checks with and without the coolant flowing ? It'll be interesting to see how much heat it actually "pulls" out.

Steve

[SCzEngrgGroup]

Something like this:

http://imageevent.com/tppjr/rf45dove...bearingcooling

will be far more effective. It is a coolant manifold that attaches to the spindle and not intended as a bearing cooler but it will probably do that pretty well because it puts the coolant much closer to the heat source.

But that's cooling only the lower spindle bearing. What about the upper?

Regards,
Ray L.

[Thorpydo]

I'm so glad you tell me this after the project is completed.

Maybe I'll make a collar in addition.

[HawkJET]

But that's cooling only the lower spindle bearing. What about the upper?

Very good point Ray. I was only using it as an example and to show that all that heat sinking is not necessary. I wasn't thinking beyond that.