View Full Version : How do I get the shaft out of a depth mic?
06-19-2009, 10:10 PM
Older Starrett. I unscrewed the end cap, even the little end on the rod. Not coming out at all.
Doesn't seem anything more to remove.
06-19-2009, 11:14 PM
Screw the spindle back on the depth mic. The rod is just stuck in place. Try to get a little WD40 or kerosene down the rod to get it loose. Then grip the rod in a vise and tap the back of the mic spindle using something soft like a piece of wood to get tap the mic to slip down down the rod. The nut you took off the rod is used to adjust the depth. I'm sure it was kind of hard to remove.
If you have to soak it overnight in kerosene.
06-20-2009, 02:01 AM
I agree with Jim Sehr.
Irrespective of brand or country of origin, the basic principles and construction are the same.
Here are a couple of pics on my (metric) 0 - 4":
The spindle/rod partially withdrawn:
The whole she-bang with all spindles/rods removed - also shows the tools for adjustment.
I take the spindles/rods out as soon as I've finished with them. I only put them in when I need them - to avoid the OP's problem.
I make very sure that the rods are clean before they are put into the depth mic. The back of my main spindle has two slots to rotate the rod nuts against to remove any dirt etc. that might be there.
I check the setting of my depth micrometer every time I put a rod/spindle in.
I find that my mic which has a "rounded-end" on the rod where it is used foe measuring has an entirely different "feel" than a "flat/square-ended" rod - So I need to be careful. Once I got used to it I preferred it to the square-ended rod/s.
Do be very careful when re-assembling the main spindle back into its thread/"nut" in the main body of the micrometer.
06-20-2009, 08:04 AM
If you got the adjusting nut off the end, the rod must be stuck very tight.
The adjuster nut is usually a split nut that is made to hold tight, and should be difficult to remove. At least it is on my Lufkins, I do have a Starrett somewhere, and IIRC it is similar.
The rods in the Lufkin slide out without trouble.
Jimsehr's plan sounds good.
You may want to put the adjuster nut back on before you take the rod out. It won't interfere with removing the rod, and it will be closer to correct calibration when you get done loosening the rod up.
Since you removed the nut, the mic will need calibrated again.
06-20-2009, 08:57 PM
It's probably stuck with gummed up oil. Try soaking it in acetone or something similar for a while.
On second thought:
On my Scherr-Tumico depth mics, the pin is screwed in (the adjusting nut has an outside thread). You take off the cap, then unscrew the rod. I can take a pic tomorrow if it'll help...
06-21-2009, 12:19 PM
The black knurled ring near the base of your depth mic is likely a lock. First things first, makes sure it's unlocked by rotating it counter clockwise. Your mic looks fairly clean -- it may not be corrosion or gummed oil that's keeping the rod in place.
Failing that, the lock area and barrel need to be doused in something like Kroil and worked free.
06-21-2009, 12:45 PM
Thank you for posting this question. I've been wanting to know *how* to replace the current rod with various longer rods but frankly, I was afraid to ask. :o Now I know.;)
06-21-2009, 01:03 PM
Angle Grinder? :D
..I'll get me coat...
06-21-2009, 03:03 PM
06-21-2009, 09:04 PM
Thanks all. It's quietly soaking.
I'll pretend to not be paying attention to it as well, which usually helps.