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Repairing Mitutoyo Height Gage

MDM3D

Plastic
Joined
Jun 18, 2018
Hello Practical Machinist,

I have been a lurker here for a while and have finally run into a problem that I would like your advice on.

I have acquired an older Mitutoyo 12 inch Height Gage at a local auction in unknown condition. I repaired the battery cover and put a new battery in and the display came to life. However when I was checking using some gage/joe blocks I discovered that the height gage was off linearly by roughly .0005 in/in so at the bottom it would have an error of zero and at the top(12 inches) it was off .006 inches and in the middle it was off .003 inches.

The thing I don't know is what direction the top is leaning. The base feels solid and doesn't rock and I can't get a feeler gage in anywhere to find a high spot.

My next idea is to blue the bottom of the gage and run it over the surface plate a bit and see if I can get the high spot to show up. Let me know if this a a wise idea.

Basically what do you think would be the best way to bring this height gage back into spec (+- .001)?

Thank you for your time.

MDM3D
 
do a search, as this has been discussed before.

The height gage simply needs to be calibrated. There are set screws at the top which secure the beams to the upper mount. By adjusting the "Tweak" on these screws, the error you see can be reduced to zero.

DO NOT attempt to think this through. It will make no sense. It also has NOTHINNG whatsoever to do with sine error, so save your breath.

If you don't believe me, then just send it to Mits, and for $550 they'll adjust it for you.
 
Another check (on a surface plate) is the measuring jaw. Get a .0001 indicator and run it along the measuring surface; this will tell you if your beam is square to the table and, therefore, the condition of your base. At increasing heights it should read zero to a couple of tenths, back to front.
 
Larry I almost didn't believe you until it saw the 4 screws myself hiding in plain sight on the back. I haven't had a chance to do the actual tweaking yet but I know I would never had guessed that those screws actually controlled the alignment of the beams. I merely assumed that they were there to hold the cap in place. I will report back with my results. Thank you for your help.
 
The adjustment is made on the rear beam screws only. The front beam is glued in place. Just tightening/loosening the screws won't change a thing usually, they just retain the position when clamped against the beam.

If you're numbers are too high at the top (zero at the bottom) the beams are leaning backward.
 
do a search, as this has been discussed before.

The height gage simply needs to be calibrated. There are set screws at the top which secure the beams to the upper mount. By adjusting the "Tweak" on these screws, the error you see can be reduced to zero.

DO NOT attempt to think this through. It will make no sense. It also has NOTHINNG whatsoever to do with sine error, so save your breath.

If you don't believe me, then just send it to Mits, and for $550 they'll adjust it for you.

Larry you are spot and and now my height gage is as well. Thank you again for your time and your advice. I undid the set screws and tapped the top block with my palm and checked using a set of gage blocks and they matched perfectly followed by snugging up the set screws and checking again.
 
Larry you are spot and and now my height gage is as well. Thank you again for your time and your advice. I undid the set screws and tapped the top block with my palm and checked using a set of gage blocks and they matched perfectly followed by snugging up the set screws and checking again.

Glad I could help :)
 
do a search, as this has been discussed before.

The height gage simply needs to be calibrated. There are set screws at the top which secure the beams to the upper mount. By adjusting the "Tweak" on these screws, the error you see can be reduced to zero.

DO NOT attempt to think this through. It will make no sense. It also has NOTHINNG whatsoever to do with sine error, so save your breath.

If you don't believe me, then just send it to Mits, and for $550 they'll adjust it for you.

I am only commenting because I noticed this thread in passing, and want others who possibly google for it to find this thread easier.

I had posted a nearly identical question about them before, and Larry told me to do this before.

I highlighted the most important part of his comment, DO NOT TRY TO UNDERSTAND IT. But it does work. It works very well. I don't understand why. I swear that it bends space and time when you put tap it a little, putting it into calibration.
 








 
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