Hi Doc,
I got the spindle bearings from MSC today, they're SKF "Explorer". I received three 6007 2RS JEM for the spindle nose, and one 6006 2RS JEM to replace the top bearing.
When I took these new bearings from the box and removed the cellophane envelope, I immediately noticed a BIG difference from the old bearings. The old bearings would spin freely. In fact, I probably could have spun the inner race on the old bearings just by hitting them with the air hose!
The brand new bearings, on the other hand, did NOT spin freely like that. Their inner races moved smoothly but, compared to the old bearings, there was definite resistance. To give you some idea, they were like filling the old bearings with 40W oil and leaving them out in the cold for a few hours.
I remembered how you said that when I mounted the new bearings on the spindle, the spindle should
"spin with little or no drag". I said to myself "With the resistance I'm feeling on each of these individual bearings, there's NO WAY that I won't feel drag on that spindle when it has these four new bearings mounted on it!"
So I pressed the three 6007 bearings onto the spindle nose, one at a time of course. They went on nice and smooth. Then I ran the retention nut up by hand, until I just felt it touch the bearing stack. I took a height measurement, and the bearing stack with the nut was tall by .010 inch. I adjusted the nut slightly downward until the height was the same as the original bearing stack. That hardly took any effort, I probably could've torqued that nut by hand. Then I tightened the set screw in the nut, and checked the height measurement again. It was perfect. I spun the bearings by hand, and felt the same amount of resistance that I felt when I unwrapped them.
Next, I gently pressed the spindle with its mounted stack of bearings into the quill. They went in smooth, and I could feel when the bearing stack stopped on the shoulder of the bore. I spun the nose cap onto the quill, and it would've needed to go about another 3/8-inch on its threaded circumference for its locking set screw to line up with the original mark left on the threads. If the cap had indexed PAST that mark, I would've known that my bearing stack was pressed together tighter than it was originally. But since it was slightly above that witness, I was sure that the bearings had adequate clearance.
Finally I installed the new top bearing. This one presses onto the spindle and into its quill bore simultaneously. It also went in smooth, and I stopped when I felt it touch the shoulder of its bore in the quill. I then installed the threaded cap over the top bearing, which holds that bearing captive in the quill. It only took a bit of light torque on the spanner to set the depth of that cap to the original measurement.
There is absolutely NO slop in that spindle now, Doc. However, its motion is like I figured it would be. When you grab the drawbar end of the spindle and turn it, there's resistance. It doesn't feel like there's anything wrong, and there certainly isn't any noise like crunching or grinding. The spindle turns smoothly, but it feels a lot stiffer than it did with the old bearings. For example, it's not like my bench grinder where I can give the wheel a push with my finger, and it'll spin several revolutions before it glides to a stop. This one only turns when you turn it, it doesn't free-spin.
Anyway, I mounted the quill horizontally in my bench vise, installed the drawbar, and mounted a 3/8" dowel pin in a collet. I then chucked my drill motor on the dowel, and spun the spindle using the drill motor's highest speed. I did this for five minutes by my wristwatch. When I stopped, the spindle nose was slightly warm to the touch, right up near the end bearing. I couldn't feel any heat through the quill at either end, just a little warmth at that end bearing.
I still need to get that new quill return spring before I can reassemble the head. The guy who is winding it went in for a COVID "vaccine" right after I brought him the broken spring and a sketch, so hopefully he didn't drop dead on me
. But I'm also hoping that I've adequately described my observations on this spindle, and that it's functioning like it's supposed to. It's difficult to describe how a spindle "feels". This one now feels really good as far as any slop or play is concerned, because there is NONE. But on the other hand, it doesn't free-spin like it did when the old bearings were on it, or like the spindle in my bench grinder. But because I really took my time and did everything properly, I can't see where I might have made a mistake.
I'm anxious to hear what you think!
Thanks,
Richie
) places- lotsa things get done for having both types of friends
