Retrofitting a spindle chiller onto a Fadal VMC15
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    Default Retrofitting a spindle chiller onto a Fadal VMC15

    Hey guys!
    I have a Fadal VMC15 that I am rebuilding, one thing I would like to add is a spindle chiller. My current machine is also a Fadal (with the 7500RPM grease pack spindle, same as the new machine) and it exhibits quite a bit of thermal growth in the spindle throughout the day... enough that I actually can't change tools once it's warm as otherwise my offsets don't work out unless I manually tweak the tool length.

    To avoid the thermal growth I'd like to fit a chiller onto the 'new' machine. It looks like there is an NPT threaded port in the side of the spindle nose that appears to be where the coolant should be plumbed in, and then the coolant goes from there into the inside of the head casting, and then through a return collar at the top of the spindle cartridge... I know I need to take the spindle out and add in the large o-rings that keep the coolant inside the head casting, but is there anything else I need to worry about when retrofitting this?

    Were all Fadal spindles setup internally for chilling? Opening the side NPT port on the spindle I can see a solid polished surface that's either the back of the bearing races or a sub-wall of some kind...

    I've attached some annotated photos that show the various ports with labels matching their intended use as far as I know, please correct me if I'm incorrect on anything. I know the air curtain port is correct as that is currently connected and working on this machine.





    Thanks guys!
    -Aaron

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    It is a Fadal. It will grow in Z not just n the spindle but because of the construction of the Z axis assembly. I would spend that money on a tool setter that can be used during production to offset the thermal growth.

    Andy

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    Quote Originally Posted by 2outof3 View Post
    It is a Fadal. It will grow in Z not just n the spindle but because of the construction of the Z axis assembly. I would spend that money on a tool setter that can be used during production to offset the thermal growth.

    Andy
    I wouldn't mind reducing tool sticking/banging due to taper growth as well

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    Quote Originally Posted by aarongough View Post
    I wouldn't mind reducing tool sticking/banging due to taper growth as well
    Thats generally due to draw bar problems , air pressure problems, and or that pusher block that compresses the drawbar (forgot the name) problems.

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    Quote Originally Posted by Delw View Post
    Thats generally due to draw bar problems , air pressure problems, and or that pusher block that compresses the drawbar (forgot the name) problems.
    In this case I think the issue is that I have long finishing operations at max RPM, followed by a change to a cold toolholder and slower operations... During the finishing op the spindle heats up and the taper expands. Change over to the cold toolholder and an operation that produces less heat in the spindle and the taper tries to close up around the toolholder and makes it stick in place a bit. Changing tools quickly in succession is fine, ditto with a cold spindle, sticking only seems to happen after long finishing operations or sometimes heavy roughing. The tools always come free, it just sounds a bit more violent than I'd like at times.

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    I always thought the tool sticking problems were just because it was a Fadal. My fix was upping the air pressure to 110 psi, the most I could, and lubing the tapers after cleaning them and the spindle taper. I tried a few things but found clean Trim Sol mixed coolant to work as well as anything. Belleville were good, replaced yearly, knockout was set correctly, etc.

    What your trying to do is interesting and I am curious how much it would help.

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    FWIW, I have an old hurco with a 6krpm 40 taper spindle and a chiller.

    I ran it without the chiller for a couple of weeks a while ago when the pump died and it absolutely makes a difference to tool ejection.

    Tool changes are smooth as silk on that old machine, but when the chiller was down, they were coming out with a pop frequently.

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    I haven't run a chiller in quite some time.. They are a pain in the ass...
    I even have at least one extra pump kicking around and 2 jugs of Dow Frost.

    I get some thermal growth on the 4020's, but I haven't yet noticed any at
    all on my VMC15. The 4020's tended to creep on the Z even with the chillers
    running.

    As for tools banging out of the spindle.. Every once in a while, when I get some
    tool banging, usually when running the spindle warm, or taking stupid heavy cuts..

    I just take a single tool holder and put a very light smear of the light white anti-seeze
    on the taper, and tool banging issue goes away for a while.. Maybe twice a week at most
    when I'm running long heavy cuts.. Every few months when doing the kind of work where a
    days worth of chips will fit in a lunch bag.


    And since we are talking about chillers. I'll say a few things that most of you
    already know, but might benefit somebody.. The pump is nothing more than a soda
    fountain pump.. What makes it expensive is the low pressure it needs to run with
    the "liquid leaking cooled ball screws".. If you UN-plumb the ballscrews, you can
    run a higher pressure.. And you can also adjust the pumps for pressure. Then
    you can buy dirt cheap pumps on e-bay.

    Where I used to work, the chiller there was running full out all the time, it did
    not regulate the temp, and the pump was a little noisy... In the winter the spindle
    nose would start to freeze.. So I added some switches to the control panel that
    could turn off the pump and the chiller, just saved time from having to go in the
    back and un-plug them.. And it was also in your face so that it was easier to
    remember to turn them on when needed.

    Aaron, Those 2 ports should be in and out.. Also, if you are starting from scratch
    you could use any kind of pump you want and possibly eliminate the complexity of the
    chiller portion of the system by running a radiator or a just a bigger coolant reservoir.

    And don't run it with just water.. Bad things happen.. I don't think you have to ask
    how I know that...

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    The original Fadal design was an drinking fountain cooler, and an Procon pump to circulate the antifreeze and water mix. Simple and effective.

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    Quote Originally Posted by Bobw View Post
    Aaron, Those 2 ports should be in and out.. Also, if you are starting from scratch
    you could use any kind of pump you want and possibly eliminate the complexity of the
    chiller portion of the system by running a radiator or a just a bigger coolant reservoir.
    Hey Bob!
    Yeah running a radiator was exactly what I was thinking... That way I don't have to worry about exact temperature control or accidentally getting the spindle below ambient and growing condensation. I think a decent system with a radiator should keep the temperatures pretty darn close to ambient anyway, the spindles don't create that much heat after all.

    From what you're saying it sounds like you think I've got the connections all labelled correctly?
    -Aaron

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    Quote Originally Posted by aarongough View Post
    In this case I think the issue is that I have long finishing operations at max RPM, followed by a change to a cold toolholder and slower operations... During the finishing op the spindle heats up and the taper expands. Change over to the cold tool holder and an operation that produces less heat in the spindle and the taper tries to close up around the toolholder and makes it stick in place a bit. Changing tools quickly in succession is fine, ditto with a cold spindle, sticking only seems to happen after long finishing operations or sometimes heavy roughing. The tools always come free, it just sounds a bit more violent than I'd like at times.
    I understand what your saying, I went through the same thing off an on. there are main varribles that come into play. the last 4 months I been running one job on our fadal. I have tools that pop and tools that dont tried if I change the holder and pull stud it goes way the spindle on this job doesnt go over 4k rpms no heavy cuts. I rebuilt the things I mentioned above and it pretty much went away. I dont run my cooler. for 16 years I ran 9000rpms all day long on aluminum surfacing all light cuts never had a tool stick or a pop. once I replaced the beville washers and balls I had a problem/ I used the same bar and the same ring at the bottom of spindle. I have a BNIB draw bar assembly in stock waiting to go it.
    I did rebuild the axis and replaced the seals for the holder just never filled it back up and turned it on yet.

    Its an annoyance forsure.been trying to figure it out and started playing with holders and studs. I a running the same holders from 15 years ago and believe it or not same pull studs I see can hear the difference between different holders. funny thing is when I use the those same holders in my vf2ss and change out the pull studs I get the same stickiness as the fadal.

    also noticed today is a really humid day and they started sticking a tad about 4 hours ago. maybe humidity is cause the problems? all except 2 holders. side cut tooling does stick more than drilling and I am only removing .030 per side on stainless

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    Quote Originally Posted by Bobw View Post
    And don't run it with just water.. Bad things happen.. I don't think you have to ask
    how I know that...
    here's the outcome of that, on a lathe but you get the picture

    img_3646.jpgimg_3640.jpgimg_3655.jpg

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    Quote Originally Posted by pcasanova View Post
    here's the outcome of that, on a lathe but you get the picture

    img_3646.jpgimg_3640.jpgimg_3655.jpg
    Ouch! Yeah I'm definitely not planning to run water, either Dowfrost or some equivalent.

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    all the jap machines that I know of use oil as the medium for the thermal solution, like Velocite. Mori for several generations used velocite in the chillers and DTE light for the air-oil spindle bearing lube.

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    Quote Originally Posted by GENERALDISARRAY View Post
    all the jap machines that I know of use oil as the medium for the thermal solution, like Velocite. Mori for several generations used velocite in the chillers and DTE light for the air-oil spindle bearing lube.
    Fadals ran Dowfrost, but there's no real reason that I can't use oil, might be a good idea actually! Only issue I can see is that I believe the heat capacity of oils is lower than glycol solutions, so might work less well with a radiator solution, but I'm not sure on that to be honest. In every other way it'd be better for sure, no concerns about corrosion!

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    My Kitamura uses Velocite #6 for both the chiller coolant that gets circulated around the spindle and through the spindle motor mounting plate and air/oil spindle lube. I am rebuilding my spindle so it's out of the machine right now. Absolutely no signs of corrosion anywhere. As you said the spindle doesn't generate much heat so oil will absorb more than enough heat.

    I agree with your radiator heat exchanger as a nice simple setup. If you need to supercharge it put the radiator in a tub of water with the fan on the water and a pump to move the water over the radiator. Plenty of cheap transmission coolers available that would work well for this application.

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    I took a small coolant tank and put a 1/8HP ebay coolant pump in it, ran that to the head, then ran the return to a pressure washer screen filter, then to a transmission cooler with a couple 12v muffin fans. I used RV plumbing antifreeze with "Dowfrost" in it, was cheap.

    I have to look, but I think the coolant ports on mine were all in the casting and none in the spindle. Mine is a grease packed 10k spindle of unknown vintage.

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    During the dark, sad days that I had to do field service on Fadals, I saw plenty get corrosion trouble in the water jacket despite using Dowfrost or automotive anti-freeze. Go with oil like Velocite 6.

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    I have a 4020 and when I got it the spindle cooler wasn't working. Long, high rpm operation will make the spindle heat up like your saying. After fixing the cooler it ran much better, Z height is very consistent now, tool changes are better and I feel better with the spindle running nice and cool.

    Running with a radiator will probably work ok but I think the chiller would be better. Doesnt have to be just like factory, you can probably rig up anything. Im not sure exactly how the fadal control handled the chiller but there are two temperature sensors in the system, one for ambient temperature (in casting, close to floor) and another for coolant temperature. My machine is a retrofit and I monitored these sensors and programmed it to turn on chiller when temperature exceeds ambient by 2 degrees. Works really well. You could probably do it with an arduino or something if you wanted get it perfect. If you do try and rig up something yourself, keep in mind these chillers need to be shut down for a period of time (30 seconds maybe?) to allow pressure to equalize before you can restart or the compressor will stall. Good luck with it.

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    Quote Originally Posted by Perry Harrington View Post
    I took a small coolant tank and put a 1/8HP ebay coolant pump in it, ran that to the head, then ran the return to a pressure washer screen filter, then to a transmission cooler with a couple 12v muffin fans. I used RV plumbing antifreeze with "Dowfrost" in it, was cheap.

    I have to look, but I think the coolant ports on mine were all in the casting and none in the spindle. Mine is a grease packed 10k spindle of unknown vintage.
    Just realized I have seen your youtube channel! I recognized the logo

    If you get a chance to take a photo of the spindle nose wit your setup that would be great! I'm curious where the coolant input was on your machine, maybe there's something I'm overlooking on mine!


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