Strange happenings in the heat on a machine.
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  1. #1
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    Default Strange happenings in the heat on a machine.

    I thought this worthy of sharing amongst a knowledgable crowd like you lot:

    Here in Melbourne we are having a bit of a heat wave of 30-35DegC this week. I went to use my Feeler FTL-618-EM last night and found the saddle slide was very sticky when it normally feels like silk.

    Here is a pic of my machine.

    After a little mumble&^$##@$*&!mumble as to what the help was going on I worked out the oil viscosity had changed in the heat and was squeezing out of the turcite ways without maintaining a film thickness like it did in the colder weather.

    This simply means I had the main dovetail gib a little bit tight to start with but never picked up on that when the oil was filming properly in the cooler weather. So I backed it off a tad and we are back to normal silky smooth.

    Anyone else ever noticed strange happenings like this?

  2. #2
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    My stuff gets sticky when it gets below about -12 deg C

    But I just take that as God's hint and go inside where it's warm!

  3. #3
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    Yeah ive had something similar. With lots of roughing on a manual lathe and minimal coolant, the pile of blue swarf on the cross slide heats it up and makes it go tighter.

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    Does Turcite contain Teflon? I'm guessing it is a mixture of teflon and a harder plastic, as are most of the Rulon versions. Teflon has a high coefficient of expansion and in addition it undergoes a change in crystal structure at around 20 degrees C with a dimensional jump of about 1 1/2%. Possibly what you have is just enough expansion of the Turcite, sandwiched between the metal, to squeeze out the oil film.

    - Mike -

  5. #5
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    Knudsen: I suppose you try to turn on the coolant at that temperature too?? "dang its frozen up again... I just don't understand..." Its a wonder the machine doesn't have some sort of "humanity for the operator" cut out switch at about +5Degc, that would work for me.

    HelEx: I never thought of that, the stuff on my slides is a kinda light blue color, almost sky blue. I don't really know what it is but I am assuming turcite. There is only 1mm or so of layer on there, not enough to bother it, or so I would have thought. This is getting technical now but bring it on. Maybe I need a NATA certified climate controlled lab to keep the lathe in now... mmmmm that would be nice.

  6. #6
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    Turcite will have a significantly higher coefficient of thermal expansion due to the organic resin that is part of the composite. When it heats up, it is effectively tightening up the gib. An all-cast iron machine would not suffer that effect. Next winter, you will need to tighten the gib quite a bit.

  7. #7
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    The oil isn't a multi grade automotive oil, 10w-40, is it?

  8. #8
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    Absolutely NOT! No multigrade crap goes near my machine slideways.

    Is slideway oil for me.

    Sometimes for other machine parts I use straight 30W, less of those additives and muck that will gum up the works down the track.

  9. #9
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    Uh...Sorry. 10w-40 is the only thing I could think of the gets thicker when it gets hot.


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