Flood coolant revisited
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    Default Flood coolant revisited

    I'm revisiting a topic that has come up here many times: flood coolant on an FP2. I was using water soluble cutting oil a few weeks ago for a slitting saw on steel, and again last week as I was working on some mild steel parts that will be welded up to make a bracket for an inside grinding attachment.



    At some point I felt coolant dripping where it is not supposed to go: it was leaking in between the vertical table and the horizontal table and dripping on my hand when I reached for the Z-axis handwheel. So after I was done I decided to pull off the vertical table to have a look. I was worried about trapped coolant between the tables, because my experience with this coolant is that if it is on surfaces exposed to air, then all is well. The water evaporates, leaves a thin oil film behind, and no damage (corrosion) ensures. But I feared trapped coolant, which I thought would lead to rust.

    It turns out that my concerns were unfounded. Here is the vertical table. You can see the path that the coolant was following down:


    Here is the same table after five minutes scrubbing with WD40:


    Here is the horizontal table before:


    and after scrubbing:


    So the bottom line is that the coolant didn't do any damage here: my fears were unfounded.

    During reassembly, I put a thick stripe of grease at the top of the interface where the horizontal and vertical tables meet. This should seal it well enough to prevent coolant ingress in the future.

    PS: an interesting find was this:


    It's a broken M12 T-bolt, one of the 8 that was holding the horizontal table onto the vertical table -- you can see it in the second photo above. I must have overtorqued it. Fortunately it did not damage the vertical table. Curiously the bolt is sheared on the threads, and also broken on the head. I suspect that it first sheared at the threads, then the tension rocketed the remaining part of the bolt into the T-slot with enough force to crack the head against the inside of the T slot.

    I am using coolant more frequently these days when working on steel, because I have a lot of HSS tooling and it works better with coolant. A steady stream doesn't make a mess, because the HSS speeds are slow enough that it doesn't fling coolant everywhere. At the end of the day I do have to spend 15 minutes taking the vise apart and cleaning the table off, but it's worth it IMO. I've got Z-bellows in place, one of those protective hanging skirts to keep coolant out of the Y-axis ram, and the Z wipers are in good shape, so I don't think coolant is getting anywhere else that it's not supposed to be.
    Last edited by ballen; 01-06-2020 at 03:05 PM.

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    I'm guessing that you took the table off not long after you had finished machining with flood coolant. It can take a while for water based coolant to do its worst when trapped in areas like that. Perhaps it is better with some formulations than others - I have never been in a position to compare properly. I do know that my mill (like an FP2) is not really very well sealed against water based coolant ingress to areas like gearboxes, and for that reason I use it only very sparingly. I do use oil based coolant because I have the belief that it will do less damage when it gets into areas where it shouldn't, but again that is not backed up with much in the way of evidence.

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    Quote Originally Posted by billmac View Post
    I'm guessing that you took the table off not long after you had finished machining with flood coolant.
    Nope, I've used flood coolant a handful of times over the past several years. This is the first time I have taken off the horizontal table in that period.

    It can take a while for water based coolant to do its worst when trapped in areas like that.
    Yes. Perhaps the point is that in my case it was not trapped: gravity made most of it run down and drip out, and what was left was too minimal to do real damage.

    I do know that my mill (like an FP2) is not really very well sealed against water based coolant ingress to areas like gearboxes, and for that reason I use it only very sparingly.
    On my machine, the way I use coolant, I think it can not get into either the spindle gearbox or the feed gearbox. The places it might enter are (a) under the Y-axis ram (b) into the vertical spindle or (c) into the horizontal spindle. I'm keeping a close eye on (a) and think nothing is getting through there. Gravity helps with (b) so as long as there is no spray directed at it, I think that's OK. With (c) I am more concerned, because gravity tends to carry stuff inside. So on the work I was doing the past few days I had a shell mill on a long arbor and it kept the coolant well away from the horizontal spindle.

    I do use oil based coolant because I have the belief that it will do less damage when it gets into areas where it shouldn't, but again that is not backed up with much in the way of evidence.
    I always use coolant with my surface grinder and cylindrical grinder. It's the pure synthetic stuff that dries to a rock-hard transparent glue film which locks moving parts together. But on the Deckel FP2 I am using a more traditional soluble oil, the kinds that mixes with wather to form to a thin milky-white liquid.

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    I agree entirely with using coolant on grinders. I don't think you can acheive consistent tight tolerances without it, but they are generally better designed to resist coolant ingress than the mills. That is apart from the surface between magnetic vices and tables.

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    Quote Originally Posted by billmac View Post
    That is apart from the surface between magnetic vices and tables.
    Yes, that's right. Here is what it looked like on my surface grinder when I got it.





    More details are here: The horror under the chuck I think no one had cleaned under there for more than 30 years.

    This is what it looked like when I had finished:




    Cheers,
    Bruce

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    I hate to use coolant on a milling machine and almost never do
    It makes a real mess
    Speed a bit lower Feed on the high end
    All in all makes it faster if you account for the mess with coolant
    Oke my tooling gets dull sooner perhaps But I have plenty of it
    If I must use coolant I use a bottle and apply just a little
    The same on a lathe
    No production here


    Peter

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    Quote Originally Posted by billmac View Post
    I agree entirely with using coolant on grinders. I don't think you can acheive consistent tight tolerances without it, but they are generally better designed to resist coolant ingress than the mills. That is apart from the surface between magnetic vices and tables.
    More than size control, there is the real problem of local surface cracking when grinding without coolant....In particular cylindrical grinding....the small contact foot print can generate very high
    local temps that can easily surface crack heat treated parts....So local that you often can't tell that there is high spot heating...but its there...gotta have coolant there and plenty of it!
    Cheers Ross

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    I think that a lot of people get way too concerned about a little bit of rust on machine tools. It's just part of what happens in a machine shop. Back when I worked for the man I ran surface grinders that probably hadn't had the mag chucks off in 25 years and they all ran fine and held tolerances that we needed. It's just a part of the game of machining on older manual machines.

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    Problem with rust under the magnet on a surface grinder is that it can bend the table

    Peter

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    Quote Originally Posted by Peter from Holland View Post
    Problem with rust under the magnet on a surface grinder is that it can bend the table
    You are right.

    On my machine the chuck was displaced a good fraction of a mm from the pressure of the rust. I was worried that this pressure had permanently deformed the table and messed up the machine geometry. So I checked it by putting a small surface plate good side up on the table with a 3 point support. I then measured a grid on the surface plate and fitted it to a plane. The final fit can be seen in the thread above (details at the end of this post The horror under the chuck). The motion in the two axis was planar to within +-3 microns over a 120 x 450mm area. So even though the rust had deformed the table somewhat, it sprang back to shape ok when the pressure was removed.

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    I have found most greases will wash out so use a silicone grease, O-ring grease for pool filters in my case, when trying to keep the coolant out.

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    Quote Originally Posted by DavidScott View Post
    I have found most greases will wash out so use a silicone grease, O-ring grease for pool filters in my case, when trying to keep the coolant out.
    I used the German equivalent of LP-3. Sometime later this year I'll pull it apart and see how well it worked.

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    Quote Originally Posted by Peter from Holland View Post
    Problem with rust under the magnet on a surface grinder is that it can bend the table

    Peter
    It can and will bend the table. Fortunately it is mounted to a machine that can true it up nicely. Then after 25 years of that you pull the chuck for some reason and clean it all up and true it all up and grind it all in again. Probably in 75 or 100 years you need to buy a new chuck.

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    Quote Originally Posted by ballen View Post
    I used the German equivalent of LP-3. Sometime later this year I'll pull it apart and see how well it worked.
    You may need a sledge hammer to get it loose from what I've seen of dried lps-3. I hope I'm wrong though.

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    Based on your pictures you are not using the sump to store your coolant.

    What kind of setup do you have? Do you use the built in pump to pump the coolant from an external tank? That is an idea I have been considering for myself. I have a coolant tank with pump for my lathe, I have been thinking of using it to serve both the lathe and mill, though I want to keep using the existing pump on the mill so I can use the switch already in place.

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    For lots of machines that can't tolerate water-based coolant (gear machines, screw machines) a light, thin oil works very well. They even make several different varieties for just that purpose.

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    Quote Originally Posted by EmanuelGoldstein View Post
    For lots of machines that can't tolerate water-based coolant (gear machines, screw machines) a light, thin oil works very well. They even make several different varieties for just that purpose.

    I know
    Even a bigger mess on a Deckel if flooded

    Peter

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    Quote Originally Posted by DennisCA View Post
    Based on your pictures you are not using the sump to store your coolant.
    I am using the FP2 sump and FP2 pump. Is there something in the photos that suggests otherwise?

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    Quote Originally Posted by EmanuelGoldstein View Post
    For lots of machines that can't tolerate water-based coolant (gear machines, screw machines) a light, thin oil works very well. They even make several different varieties for just that purpose.
    I originally tried running cutting oil instead of water based coolant. It made a horrible mess. After two sessions I pumped it all out and sold it.

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    Quote Originally Posted by ballen View Post
    I am using the FP2 sump and FP2 pump. Is there something in the photos that suggests otherwise?
    I guess I misinterpreted this photo, looked to me like the hoses went into the white box, but nothing to the sump, so I assumed it was some kind of 2:1 manifold.



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