Wednesday, February 8, 2012

Ball Bearing Thrust Collar - Completed but...

In less than an hour's time (at the time of writing this), I'll be going for stage 2 of my dental implant.  I've been fasting since 6.30am and are feeling very hungry and thirsty.  I was told to fast 6 hours before the surgery as, this round, I opted to be sedated during the process.  This is my third time going through this - hope this is the last.  I have to remind myself not to bite on sweets that, I was told, causing tooth fracture.  Kind of hard to rid of this bad habit...

To distract myself (excuses excuses excuses), I went to my shop after having my mandatory 2 cups of coffee just before 6.30am, to complete the thrust bearing mod on the Y axis leadscrew.  It was a good session as I made no mistake and was rather proud of myself to be able to find the centre of the bore with the DTI using the method Mike taught me.  Though completed successfully based on the drawings I did (with slight modifications due to the size of the stock I started with), I'm not able to mount the bearing holder with the leadscrew adaptor inserted.  My measurements and calculations of the distance between the leadscrew and the stepper motor mount's screw holes was off by quite a fair bit.  I thought I was getting smarter when I did the measurements and project the numbers using the stock thrust collar - I am obviously not.  But I'm still happy as I managed to fabricate the parts with quite a good level of accuracy from the plans I drawn.

Trimming the face with bearing mounted so as to make the bearing sit flushed in the recess. This was done on both sides in the same manner.
Done! Nice...
Marking out the amount to cut off for the witness mark using the stock thrust collar as a gauge of how much I need to cut.
Flycutter was used to flatten the top for the witness mark.
Nicely done. About 6.8mm was taken off from the top.
I was looking around for the 1mm endmill but saw this in the box.  Been there for maybe a year, sealed in its plastic wrapper.
The witness mark engraved.
This was how the part look before the mounting holes were drilled.
First hole done, shown with a cap screw inserted.
The completed part.
Time to test if this works.
The new bearing thrust collar mounted using 2 x 8-32 3/4" capscrews borrowed from the lathe. They're a little longer than needed.
From the back you can see that the distance between the leadscrew and the 2 x 8-32 mounting holes are quite off.  My measurements were off.

Like I mentioned at the beginning, I'm quite pleased with the adaptor and the bearing thrust collar that I made.  They're both accurate to the dimensions I layed out on the plan.  The error in the thrust collar is in my measuring of the distance between the leadscrew and the mounting holes.  This is something I've yet to learn - accurate measuring from existing parts.

More to learn.

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