Equipment: Leica Microsystems - RM2255
thick and thin
RE: Microtome Report Post
I would certainly make SURE it is not the blade holder or the chuck. They can appear nice and tight but still move enough to give you thick/thin. Also make sure the blade is well held. If the leaf springs are getting mushy that will do it also.
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If you are certain the bladeholder, cassette clamp, and orientation head are all correct and without defect or loose, then remove the orientation head from the mirrometer, and use a torque wrench w/ a 3mm bit and drive the micrometer from home to stop. During that ride, the torque should not exceed 24Ncm of force and at the stop position, the torque should not be less than 27, or greater than 35Ncm for the micrometer to break away and free spin.
My bet is, provided you are right, is that the spindle assembly will need to be rebuilt. This is supposed to be done every other year anyway. When it’s ignored too long the soiling on the spindle gets to be too great and the advancement breaks away intermittently vice driving forward. This is set to protect the mechanics from people who don’t know what they’re doing.
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Oh wait, this is an RM2255. I am sorry, I thought I read RM2235. This micrometer should be, ideally, under 8Ncm from home to stop. I have seen where the locking set screws on either side of the coupler that connects the spindle assy to the motor might be loose too. These should be locked to 90Ncm.
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