# Spindle Cooler -and just chatting a bit...



## Ray C (May 16, 2014)

So...  Been doing a LOT of CNC work these days with the PM45-CNC.  That machine is getting used far more than I ever imagined.    Anyhow, typical RPMs are 1800 to 2800 for most everything I do which, by high-end standards is fairly slow.   A typical job can easily take from 45 to 90 minutes and during that time, the external spindle collar gets up to 115 degrees.  -Not abnormal at all.  The gearbox gets warm to the touch and registers about 100 F.   Interestingly enough, the motor stays virtually cold the whole time.  It has a forced-air electric fan that blows like a tornado.

Have a look at it...





Anyhow...  I decided to make an aluminum cooler ring for the spindle.  I also have another trick up my sleeve to force air to move past it but, won't implement that until I experiment with just the cooling ring first.

Here's a few pictures of the ring which is a drops piece of 6061.  The holes were drilled in the CNC mill.  The center-drilling and bore-drilling took about 8 minutes -which was a long time because I didn't bother to tweak the CAM tool paths to optimize it.

As you can see, it was a solid cylinder to start-out and instead of making bird-nest swarf on the lathe, I milled-out the center -and that gives me a nice little piece of drops to play with some day.  I did touch-up the inside bore and face the edges on the lathe though... 

I'll let you know how it works.  I'm guessing it will keep the spindle about 8-10F degrees cooler.

And BTW, if you have a normal speed mill of this type, don't bother with this cooler contraption.  I run my old PM45 for hours at a time at high speed and at 1900 RPM, it barely gets warm to the touch...







And as far as chatting goes... 

 I might not be allowed to hang around here anymore...  With any luck, at the end of this summer, I'm moving into a 1200 sqft industrial building, 10 minutes from the house.  I also plan to fill that space with an additional piece of machinery.  I'm looking at another very nice CNC mill to help crank-out parts.  I'm doing low/medium production runs of some specialized parts these days.   I think that might push me out of the ranks of hobby machinist and therefore, we'll have to see if Tony, Bill, George, Marcel, Nelson et.al. will still let me hang-out here...  LOL... 

Ray


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## xalky (May 17, 2014)

Good morning Ray. I'd like to see a picture of the cooling ring installed on the spindle.

I don't think the fact that you've gone "pro" is gonna affect your status here.) I'm right behind you buddy! With any luck, I'll be doing this full time too.:thumbzup:


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## Ray C (May 17, 2014)

xalky said:


> Good morning Ray. I'd like to see a picture of the cooling ring installed on the spindle.
> 
> I don't think the fact that you've gone "pro" is gonna affect your status here.) I'm right behind you buddy! With any luck, I'll be doing this full time too.:thumbzup:



Will do.  This isn't a priority project but I'll get to it soon enough.  BTW, this cooler does not spin; it's located on the external/fixed part of the spindle housing.  It's a very slight friction fit now but, I'll probably split one side in the bandsaw and tack a couple screw tabs on there.


Ray


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## kizmit99 (May 17, 2014)

In the picture where you're milling out the center section.  It appears that you're using a 4 fluted end-mill to create a slot which (eventually) frees the center section.  If that's the case, if you don't mind, I have a few questions...

1) I believe I've read (somewhere) that when milling a slot a 2 or 3 flute end-mill should be used (and 4 flute should be avoided).  I think the reason had to do with the cutting edges on the opposite sides being in contact with edges of the slot at the same time.  So, I'm curious whether there's some reason that doesn't apply in this situation, or maybe I'm just wrong, or maybe it's just not that big of a deal, or what?

2) When milling out that section, I'm curious how deep each pass was?  Also, can I assume that was a center cutting end-mill?  If not, was there some other trick going on here that I'm not seeing?

3) How do you deal with the final pass when the center section breaks free?  It seems to me that once the center piece is free that it would just cock and jam the mill.

These are just questions born out of curiosity, thanks for sharing!
Good luck with the new shop!


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## Ray C (May 17, 2014)

kizmit99 said:


> In the picture where you're milling out the center section.  It appears that you're using a 4 fluted end-mill to create a slot which (eventually) frees the center section.  If that's the case, if you don't mind, I have a few questions...
> 
> 1) I believe I've read (somewhere) that when milling a slot a 2 or 3 flute end-mill should be used (and 4 flute should be avoided).  I think the reason had to do with the cutting edges on the opposite sides being in contact with edges of the slot at the same time.  So, I'm curious whether there's some reason that doesn't apply in this situation, or maybe I'm just wrong, or maybe it's just not that big of a deal, or what?
> 
> ...



Hi...

I should have used a 2 flute but, that's what happened to be in the mill so I just used it. It's also just a plain-Jane endmill.  For full width cuts like that, it's perfectly fine for the cutter to contact at both sides -matter of fact it's preferred.   Each circular cut was 0.25" deep with a 3 ipm straight plunge.  Cutting speed was 20 ipm.   There was 25PSI of compressed air keeping the chips out of the slot.  To prevent the piece from getting wedged on the last pass, I set the program to cut all but the last 5 thou of depth.  Then I put it in the lathe and poked it through at low speed....  FWIW, I had a block of wood supporting it from the bottom.  My vises aren't big enough to hold a piece that size with V-blocks.  I didn't feel like messing around with top clamps.  This is/was a very quick, non-critical part...

BTW:  Sorry, didn't mean to mislead anyone with my occasionally sloppy techniques but, when working with aluminum, you've got a lot of latitude.


As an aside, I sized the ID of the hole to be 15 thou oversize so I could clean it up on the lathe.  Surprisingly enough it was indeed 15 thou pretty much on the money and it was fairly round too.  


Ray


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## Ray C (May 17, 2014)

... And here's the spindle cooler installed on the machine.  -Just cut the ring, welded a couple tabs and used a thru-bolt to pinch it closed.

I'll let you know how it performs once I find-out...




Ray


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## jumps4 (May 17, 2014)

nice job Ray
my spindle got hot at first but calmed down when the machine broke in, Now it's just warm to the touch after long runs.
have you changed the oil yet?
I ran my mill to warm it up and then drained it, The factory oil looked like something I just drained out of a diesel truck. I think China recycles their oil by sending it to the us in machines.
steve


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## Ray C (May 17, 2014)

jumps4 said:


> nice job Ray
> my spindle got hot at first but calmed down when the machine broke in, Now it's just warm to the touch after long runs.
> have you changed the oil yet?
> I ran my mill to warm it up and then drained it, The factory oil looked like something I just drained out of a diesel truck. I think China recycles their oil by sending it to the us in machines.
> steve



Hi Steve...

Yes, I just changed the oil.  It wasn't all that bad but had the usual amount of residue, paint chips and some grit.   I did in-fact run it at high speed for about 5 minutes to get all the grit suspended.  That's a good practice.  And of course, I got a fair amount of oil dripping down my elbow getting the plug in and out.  And of course, during the procedure, I dropped the plug and it somehow rolled half way across the shop from where it fell.  -Sheesh...


Ray


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## Jamespvill (May 17, 2014)

Very cool! and Awesome news about moving up in the world of CNC, I really, really need an excuse to buy a 45 CNC...

Was that what you had to go and tig weld yesterday?

Im sure the good folks will keep you around once your making chips with the big boys...It's more of a matter of whether your even going to have time to even cruise the forum!


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## Ray C (May 17, 2014)

Jamespvill said:


> Very cool! and Awesome news about moving up in the world of CNC, I really, really need an excuse to buy a 45 CNC...
> 
> Was that what you had to go and tig weld yesterday?
> 
> Im sure the good folks will keep you around once your making chips with the big boys...It's more of a matter of whether your even going to have time to even cruise the forum!




Hi James...

I TIGged a couple things yesterday.  A walk-in guy needed a couple inches of weld on a titanium tube.  That was easy.  I also welded the little tabs on the back of that cooler ring.  -Another easy job.  I spent the rest of the day, cleaning the shop and working with customers on the phone.  All fun stuff.

CNC is fun and a lot moreso than what I expected.  I need to work and push myself a little harder in terms of learning more tricks of the trade.  The learning curve was steep but, before I touched a CNC machine, I read and studied as much as I could.  That really helped.

Ray


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## Marco Bernardini (May 17, 2014)

No fins on your cooler, Ray?
Some CPU coolers now are bigger than the head of a moped… I guess the larger ones can be used as spindle coolers without many modifications:


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## AlanR (May 17, 2014)

Ray C said:


> I'll let you know how it performs once I find-out...
> 
> Ray


Probably be better if you cut slots vertically through the holes. What forces air through them?


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## Ray C (May 17, 2014)

LOL... Yes, some of the CPU cooling products in the retail arena are pretty amusing and I sometimes think are more about aesthetics than thermodynamics.  Of course, they're necessary but on the highest end server boards I've seen, crammed with 4 or 8 quad core CPUs, there was just a basic heatsink with a 50mm mag-lev fan sitting atop each CPU.

I did think about cutting slots/fins in the cooling ring but that's just one more thing for me to crack a knuckle into and draw blood; thus, I left it round with rounded-out edges.  As is, I suspect it will lower the temperature a little bit.  If you've ever welded aluminum, you're aware of it's absolutely amazing ability to suck-up and dissipate heat.  In a way, I'm solving a problem that doesn't exist as the temperature without cooling modifications is nowhere near an abnormal level.  It makes sense though to keep things as cool as possible so, for now, I'm just tinkering and experimenting.   For extra credit and as further tribute to "playing around for the heck of it", if I'm so inclined to force air past the vent holes, I'll get a thin, round disk of plastic or aluminum, mill some sloped areas on one side to serve as crude propeller and mount it to the spinning part of the spindle.  Even a crude design (as long as it's fairly well balanced and doesn't fly apart at 3000 RPM) will generate enough draft to blow air through the vent holes.

LOL... I'm really just killing some time with this endeavor...  ...just satisfying my curiosity about spindle temperature.   The idea of all this was inspired by looking at the specs on several high-end CNC machines and reading the glossy brochures about their techniques for addressing spindle temperature.  At 8, 10, 12 and 20,000 RPM, the issue is non-trivial and the solutions are both diverse and interesting. 


Ray


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## markknx (May 19, 2014)

Ray,I get it.  When we weld SS if it will need multipal passes and is cridical, a 350*f max inter pass temp is required. So a trick used is to clap AL chill bars tothe SS sucks the heat right out of the SS and I'm sure you know how SS likes to hold heat. An example is I just did a Cert. cupon 3/8 x 7 45* v grove in vert. up. Clamped 1 piece of 1/2 x3 AL bar to either side of the weld and it needed 5 min. or less to get back down to around 250*FAs faras the New CNC and shop go congrats, glad to hear it. As far as you getting pushed out, not while I'm around!By the way still love that Dog!Mark


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## Ray C (May 19, 2014)

markknx said:


> Ray,I get it.  When we weld SS if it will need multipal passes and is cridical, a 350*f max inter pass temp is required. So a trick used is to clap AL chill bars tothe SS sucks the heat right out of the SS and I'm sure you know how SS likes to hold heat. An example is I just did a Cert. cupon 3/8 x 7 45* v grove in vert. up. Clamped 1 piece of 1/2 x3 AL bar to either side of the weld and it needed 5 min. or less to get back down to around 250*FAs faras the New CNC and shop go congrats, glad to hear it. As far as you getting pushed out, not while I'm around!By the way still love that Dog!Mark



Oh yeah, I clamp pieces of aluminum to welding project as a matter of due course.  Works like a magical charm.  I've had a slow spell in the machine work and haven't run the CNC for an extended time but when I do, I'll let folks know the outcome.   On one of the last go-arounds, I checked it with an IR temp gun so, I know the "before" condition.

Sash the dog... Yes, I like getting her in the pictures -it's kinda like my version of the ever-popular children's books "Where's Waldo".   Sash is kinda easy to point out in most cases...  .


Ray


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## markknx (May 19, 2014)

kizmit99 said:


> In the picture where you're milling out the center section.  It appears that you're using a 4 fluted end-mill to create a slot which (eventually) frees the center section.  If that's the case, if you don't mind, I have a few questions...1) I believe I've read (somewhere) that when milling a slot a 2 or 3 flute end-mill should be used (and 4 flute should be avoided).  I think the reason had to do with the cutting edges on the opposite sides being in contact with edges of the slot at the same time.  So, I'm curious whether there's some reason that doesn't apply in this situation, or maybe I'm just wrong, or maybe it's just not that big of a deal, or what?2) When milling out that section, I'm curious how deep each pass was?  Also, can I assume that was a center cutting end-mill?  If not, was there some other trick going on here that I'm not seeing?3) How do you deal with the final pass when the center section breaks free?  It seems to me that once the center piece is free that it would just cock and jam the mill.These are just questions born out of curiosity, thanks for sharing!Good luck with the new shop!


I believe the two flute is to help with chip removel, it gives more room. But at the speed and cut depth with air blowing the chips out I would not think it that big of an issue. just as I do not calculate spindle speed for every job I just kind of go with the speed I am at and ajust if needed.    Mark


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## mattthemuppet2 (May 20, 2014)

that's a neat little doodad, although with limited surface area I'm not sure how much it will help for extended runs. Then gain, I've no idea how much wattage it needs to dissipate so it may be just fine. The small prop idea is a good one though, efficiency of heat transfer jumps massively even with a tiny bit of airflow.  It would also be worth using some kind of paste/ gel between the heatsink and the housing (even toothpaste would help) to improve thermal transfer.


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## Marco Bernardini (May 20, 2014)

Uhm… if that cooler would be empty and connected to the cooling fluid pipes, with LocLines starting from it… maybe it will become even more effective: air cooled vs. liquid cooled.
The flushing coolant wouldn't become too hot, but it would bring away some extra degrees anyway.


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## Ray C (May 20, 2014)

Hang on there guys... read post #13.  This is more of an experiment and I'm developing a solution to a problem that doesn't exist...

Marco...  -Liquid Nitrogen...  That should do the trick!



Ray


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## Marco Bernardini (May 20, 2014)

Ray C said:


> Marco...  -Liquid Nitrogen...  That should do the trick!
> Ray



I hope Mach3 has a setting for the piece dilatation, or you'll make a lot of over-sized parts using liquid nitrogen as coolant


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## Ray C (May 20, 2014)

Marco Bernardini said:


> I hope Mach3 has a setting for the piece dilatation, or you'll make a lot of over-sized parts using liquid nitrogen as coolant




No doubt, that will be available in Mach 4...


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## mattthemuppet2 (May 21, 2014)

Ray C said:


> Hang on there guys... read post #13.  This is more of an experiment and I'm developing a solution to a problem that doesn't exist...
> 
> Ray



sure, but why wouldn't you want your solution to a non-existent problem to be the best one there is?!


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## Ray C (May 21, 2014)

mattthemuppet said:


> sure, but why wouldn't you want your solution to a non-existent problem to be the best one there is?!



Old saying... If it ain't broke, fix it till it is...


rc


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## mattthemuppet2 (May 22, 2014)

ha! I thought it was "if it ain't broke, hit with a hammer" 

I've spent a lot of time observing how my LED bike lights I built cope with heat and it's amazing the difference a tiny bit of airflow makes. Stationary all of them will trip their temp monitors within a couple of minutes on full power, but moving at 5mph will keep them cool indefinitely, if the ambient is 25C or less.


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## fatphatboy88 (May 22, 2014)

Why would you want to cool your spindle down if its only at 115f? At work I run a 12hp cnc router and I do a warm up every morning to get the spindle temp above 150F. Then run it at 18k rpm all day long. The guys that came to install it said that the spindle is engineered to run optimally with a decent amount of heat in it so all the bearings/races expand to the correct tolerances. 

I understand your spindle isnt your motor itself like mine is, but I would think the same would apply. That as long as its not burning to the touch, that it would be fine and would tighten up tolerances even more.


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## Ray C (May 22, 2014)

fatphatboy88 said:


> Why would you want to cool your spindle down if its only at 115f? At work I run a 12hp cnc router and I do a warm up every morning to get the spindle temp above 150F. Then run it at 18k rpm all day long. The guys that came to install it said that the spindle is engineered to run optimally with a decent amount of heat in it so all the bearings/races expand to the correct tolerances.
> 
> I understand your spindle isnt your motor itself like mine is, but I would think the same would apply. That as long as its not burning to the touch, that it would be fine and would tighten up tolerances even more.



Yep, I'm with you here...  At 2800 to 3000 RPMs the bearing housing gets up to 115.  I have the same machine in a manual (non-CNC) configuration that only goes up to 1970 RPM and you can't really feel any heat at all.  Anyhow, as mentioned in earlier posts, I was just curious if the cooling ring would make a difference.  Time will tell if I leave it on or not.  ---Definitely fixing a problem that doesn't exist.  -Just messing around.


Ray


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## Marco Bernardini (May 22, 2014)

Ray C said:


> Time will tell if I leave it on or not.  ---Definitely fixing a problem that doesn't exist.  -Just messing around.



It can become a good support for some LEDs, too, to have a "quill light"…


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## Ray C (May 22, 2014)

Marco Bernardini said:


> It can become a good support for some LEDs, too, to have a "quill light"…



No, no, no... Disco lights with a mirror ball on the spindle...


Ray


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## markknx (May 23, 2014)

Hey how about strobing laser lights. This is great ray you started a running thread for fixing what ain't broke. You should apply fora government grant to fund your research. Good chance you could get it. HaHa Ha!!! Hopefully some body is taking away the idea of the cooling effects of AL. Or should I sat heat transfer. Gotta go time to see my cardiologist, then if he don't admit me it is off to see if Purdue can/will help me identify some unknown scrap yard steel. Mark


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## John Hasler (May 23, 2014)

markknx said:


> Hey how about strobing laser lights.  Mark



A strobe synchronized to the spindle could be useful.  That way you could see what's really going on in there.


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## AlanR (May 23, 2014)

John Hasler said:


> A strobe synchronized to the spindle could be useful.  That way you could see what's really going on in there.


A strobe wouldn't need to be synchronized to the spindle. Years and years ago we used a strobe tachometer to measure motor speeds in tape recorders and suchlike. You'd vary the strobe rate till the part appeared to stand still and then read off the RPM. The part would appear motionless at any exact multiple of the RPM so you needed to find the lowest or highest rate to get the RPM, it was easy since you knew the approximate rate before you started. If the rate was a little off the part would appear to revolve slowly.

These things can probably still be found - cheap.

Edit: I guess not so cheap: http://www.ebay.com/itm/110986536613


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## John Hasler (May 23, 2014)

AlanR said:


> A strobe wouldn't need to be synchronized to the spindle. Years and years ago we used a strobe tachometer to measure motor speeds in tape recorders and suchlike. You'd vary the strobe rate till the part appeared to stand still and then read off the rate. The part would appear motionless...



...because the strobe was synchronized to it.


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## AlanR (May 23, 2014)

John Hasler said:


> ...because the strobe was synchronized to it.



Manually


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## markknx (May 23, 2014)

Hey that slightly off might be a good way to see chip formation. wonder if any of my halloween strobes might be fash enough. could make a cool video!   Mark


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## Rapscallion (May 23, 2014)

A strobe light can make a revolving cutter look stationary. Safety ishoes here.:nono:


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## Marco Bernardini (May 23, 2014)

markknx said:


> Hey that slightly off might be a good way to see chip formation. wonder if any of my halloween strobes might be fash enough. could make a cool video!   Mark



I don't know the strobe timing, but a flash usually is fast enough (1/10,000 of second or less) to "freeze" an exploding bulb. 
I made this experiment some lives ago, still on Ilford HP4 film. No need of a sound trigger: a couple of bare copper wires behind a bulb, connected with the flash jack, were enough to fire it when the bulb was hit by an U-nail thrown with a rubber band.
Alas, recharging time for flashes is pretty long, even with fresh batteries, and even the time required to store a digital photo is long, if compared with the speed needed for high-speed still frames.
If you have a bit turning at low speed you can be sure a flash will freeze the formation of chips: for the strobes you have to try… But it could be an interesting experiment anyway!


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