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Spindle problem with cincinnati tool and cutter grinder 2 spindle
PekkaNF:
I have tried to figure out how to measure bearings and proove shimmed bearings. I have odd ends of 25 mm linear rail rods. They are hardened 3 mm deep and pretty well ground. Shortest piece is as close as I measure same diameter than the grinding head spindle shaft.
Cleaned the ends, cooled down the shaft keeping it hour outside +10C and used hot air blower to heat up the bearing IR to about +50C, then parts fitted with finger pressure.
Tried to measure them on granite surface plate, but I don't have heavy enough prisms to make system rigid enough...I was measuring the flex of the system...
Then I got the idea of nipping the bearings together on press using bushings over the shaft. Worked well.
Now I only have to find out a way to lapp the shaft slightly down.
Pekka
PekkaNF:
The bearings and belt did not arrive for this weekend, leaving me time to make some gauging and fitting utsensils.
1: made small about 25 mm long hole axially at the tight end of the arbor to ease extraction of the bearings - allows cold spray spout where needed.
2: Made M6 internal thread at the other end to lock bearing axially during the measurement.
3: Lapped the other end about 0,002 mm smaller, achieving easy sliding fit, when all parts are at same temperature. This was fun part. Could not really gauge it on cool garage, beacause part was warm.
Lap was not best possible, rather hard structural steel, but cast iron would have been much more work.
Checked the ends this morning against gauge blocks and readings are:
Gauge blocks 25,001 mm
Tight end: 24,990 mm
Sliding fit end: 24,988 mm
Finish loks awfull on the picture, it is rather difficult to see on normal light. I was affraid it would not show.
PekkaNF:
I got bearings Yesterday, rushed to test them.
2305 is "tight" must wash it and fill partially with other grease.
6205 were SKF Explorer" series and seem to rotate very true, hard to measure radial excentricity. Better than speck. Axial play is hard to measure without good rig, it wobbles 0,15 mm axially, pretty close the same than original ones.
Stack them on very close fitting shaft with a 0,2 mm ground washer DIN 988 between outer rings. Almost all axial and radial play disappears, radial exxcentricity statys very close to zero, but there is some axial excentricity (maybe 0,002 mm) and some "mushiness" of 0,005 m with manual force.
I think that anomality I noticed is largely due to ring sides not ground to straightness for pairing these bearings.
I'm going to play a little bit more to see if mutual placement of the rings will mach these bearings better, but it looks nearly good enough.
I have only one try when these bearings are pressed on spindle. They have no provision on exterting the pulling force to inner ring.
Pekka
PekkaNF:
Unbelievable week at the work.
Tried shims:
0,1 mm axial wobble 0,16 mm
0,2 mm hardly any detectable axial clearance, no detectable preload either
0,3 mm, clearly preload
Looks like 0,2 mm shim is a charm.
Pekka
gerritv:
Wow, just wow.
A very educational thread. I don't have tools that measure to that level so not sure what will happen when it is my turn to do this.
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