[anglin]

Mine pressed fairly easily, used a 25 ton HF press.

Out of curiousity, how did you ensure you were pressing only on the outer ring of the bearing and not on the inner ring?

[cncoperator]

I was using a caliper and not a micrometer, so they might actually be .0030" tight each, but I'm confident the fits are within the range listed.

The accuracy of my 0-6" Mitituyo is stated as +/.001 and I expect most other calipers have similar accuracy specs. So if the bearing bore and housing seats were both measured the numbers given, .0035 and .0025 tight should include an uncertainty spread of +/- .002. If just the housing was measured and the bearing bore tolerance were looked up then it's +/- .001 plus the bore tolerance which for this size bearing in a high accuracy class is to the order of +/-.00015. In fact I find it hard to use a caliper for measurements that need .001 accuracy let alone a bearing seat that needs tenths measurements since just changing how hard I squeeze the caliper causes the measurement to change a couple .001. Use a micrometer.

Acceptable interferences is not an absolute number but dependent on the size of the bearing and it's application, but invariable a larger bearing will have more interference than a smaller one in the same type of application.

[nitewatchman]

Out of curiousity, how did you ensure you were pressing only on the outer ring of the bearing and not on the inner ring?

Depending on what was being pressed a short tube to contact the surface being pushed. The press fits were really light, like pulling the short jack handle with one finger type light. If you don't have a press, I think it would be easy to lightly tap the bearing into place.

As a matter of a fact, the old bearings fell apart when pressing the spindle out of the housing and the outer races were tapped out with a piece of 1/2" key steel and a copper hammer. Same with reassembly, the lower bearing and spindle could be pressed home but the upper could only be pressed to within 1/8" or so without having a longer tube than I had. The final 1/8" was lightly tapped into place until seated.

Spindle seems to be doing okay. After taking up the last preload adjustment, surface finished improved and the spindle seems to run very well and quiet. This weekend the spindle ran esentially continous for about 30 hours at 5140 rpms (yeah I know I need a High Speed Spindle, looking at the 2.2KW water cooled 24,000rpm units). Spindle temperature rose to 90F to 95F and stayed there.


nitewatchman

[anglin]

After running continously on the castings for 8 hours including a 5/8" End Mill Plunging two holes at 100% of the green on the meter and an engraving cutter at 5100 RPM the spindle temperature was about 95F.

Where did you measure the temperature and how? I recognize that somebody will criticize your method if you publish it, but I'm looking for something to use as a comparison when I test my spindle temperature, since we can't measure the temperature of the bearing outer ring directly.

Thanks.

[nitewatchman]

I used a Fluke Infared Thermometer and scanned to outside of the nose and the face of the spindle and the area under the top spindle pulley. The thermometer will record the highest temperature seen.

If the spindle has only run for a short period the temperature may be much higher inside but after a long period the assembly will be soaked and the temperature of the bearing won't be much higher.

nitewatchman

[anglin]

I finished compiling the video of the spindle rebuild the other day. Here's the link:

Tormach PCNC 1100 - Maintenance: Spindle Cartridge Rebuilt Process - YouTube

[tbaker2500]

Nice vid, thanks for the post.