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Milling spindle preload
- Thread starter Pevehouse
- Start date
Thank you again for sticking with me during this. Your math skills just blow me away. I think we are probably dealing with metric. There are 4 notches as well. So hour math is spot on.If it's a Chinese mill, it's probably metric. If you're gonna bank on this, you probably want to match it up to a thread gauge. A bolt or a screw with a known thread pitch would suffice in this situation, albeit a little awkward. If the nut is deep enough (has enough threads) for a positive ID, that'd be valid too. And on a
First, (going with 18tpi) turn threads per inch into inches per thread, which is 1/18, or 0.05588. Make that into thousandths, it's 55.555 thousandths of an inch per thread.
Use the spanner notches in that nut to divide 4 sections. (I think there's four, right?...) Then each "quarter" would be 13.75 thousandths of an inch advance per quarter turn. That's a bad number, so I'll insert a fudge factor here where it'll divide out to "who cares", and call it 0.056 thousanths per turn (half a thou liberty there), and it's 14 thousandths per quarter. When you're in the range where you're "close", mark a spot (sharpy is fine, no scribes needed), use a ruler or estimation to mark out those 14 divisions on one of the spanner slots. If they "look" equal- They're equal. Each of your marked divisions will represent 0.001 inches (one thousandth of an inch) of travel. That is the resolution you want to make the smallest meaningful adjustment, without going to the point of getting no returns. Two marks is too big to be considered one "step" of adjustment, and half a mark is pushing the resolution of your adjustments finer than you're going to see any results from.
If it turns out to be a metric 1.5mm thread (very close to 18tpi), the math is exactly the same except it's already in "distance per thread", and it works out (again with slight rounding, done early so it divides away nicely), that's 0.060 per turn, or 15 divisions on each quarter of the nut. to get the 0.001 target resolution. Or any other number you "science" if it turns out to not be one of those two.
If you've got it together and it's good- I'm not suggesting that it can't be. But now or in the future, that's a good way to calibrate your "click elbow" for doing them freehand.
Keep in mind the temperature guns are optical, so they display the temperature of what they see, and not necessarily what you are targeting. If your quill is shiny like a mirror, it will give you the temperature of what is reflected in it plus a bit of your target. When measuring bearings on a bearing heater, we needed to put a piece of Scotch tape on it to give the temperature gun something more accurate to read. A contact sensor will give you a more accurate measurement, but using your finger works too. The temp where it gets painful to hold it there is in the 125-130F range, and that is fine for bearings and the grease. I keep mine at max speed a bit lower than that so that if it gets too hot to touch, then I know something is wrong.Yes I understand exactly where your going and I do have a temperature gun on hand to keep and eye on spindle temperatures. I do have a pretty good feel for these things and my plan was to shoot for zero play. It makes me feel better however knowing you’re here and willing to help where you can, if indeed I run into anything. Thank you. The spindle thread appears to be about 18 threads per inch if that helps
That makes sense. I will keep that in mind. I really appreciate all your help. I just got the gearbox and all back together. What a cluster **** that was. Ready to spin her upKeep in mind the temperature guns are optical, so they display the temperature of what they see, and not necessarily what you are targeting. If your quill is shiny like a mirror, it will give you the temperature of what is reflected in it plus a bit of your target. When measuring bearings on a bearing heater, we needed to put a piece of Scotch tape on it to give the temperature gun something more accurate to read. A contact sensor will give you a more accurate measurement, but using your finger works too. The temp where it gets painful to hold it there is in the 125-130F range, and that is fine for bearings and the grease. I keep mine at max speed a bit lower than that so that if it gets too hot to touch, then I know something is wrong.