DTI Repair

[bp]

When I had to work for a living I was able to score a couple of DTIs. They are Mitytoyos, a 0.01mm 513-404, and a 0.001" 513-118.
Neither of them work. The metric one seems "lazy" the needle moves but not smoothly, and the needle seems to lag behind the probe and it doesn't return to zero.  The imperial one is locked up solid.
Does anyone have any advice concerning the repair/refurb of these bits of kit.  I'm mainly concerned with the metric one as that's what I use, but knowing whats wrong with them both would be good.  As I'm not an instrument dude I'm reluctant to hoe into them without knowing what I'm getting into.
cheers
Bill Pudney
Adelaide, Australia

[Bernd]

Bill,

Since they don't work right away, a look inside would help find out what's casuing the problem. Sounds like they may have been dropped or are dirty and need a cleaning and adjustment.

Bernd

[bp]

Yes but I was concerned that if I undid a hypothetical "screw A", then a spring would go "boing" and spread bits all over the workshop, whereas if I undid "screw B" all would be revealed.
The down to earth questions are, I suppose
1/  Which is screw A?
2/  Which is screw B?
cheers
Bill Pudney
Adelaide, Australia

[Bernd]

Bill,

Any chance of taking a picture and posting?

Most indicators have screws on the back cover that hold it on.

Bernd

[bp]

I'll try, might take a while though.
cheers
bp

[jim]

one place i worked would get through 4 or 5 DTI's a week!

i once spent a shift fixing some out the scrap bin.

The only ones that worked ok after were the ones that had chucked out because they'd gone "stiff".

all the ones that had been dropped etc, just wouldn't work ok. the slightest bit of bending don't do them much good!

Thats why they chucked them away, if you are clocking something up to a couple of tenths (0.0002"), you need a clock thats right!!

As for rebuilding them, its not too bad, i'd do it over a white sheet, them little screws bounce and seem to evaporate when they are dropped!
I'd start on the one thats not moving first, less to lose if it goes wrong!

[Stilldrillin]

Our Inspector used to work wonders, with some degreasing spray. 

Anything bent/ dropped was scrapped....... 

David D

[Davo J]

Hi,
I took one apart a few years ago and from memory mine (best test) had a side plate that unscrewed, nothing poped out or anything. Both metric and imperial are OK to use as the DTI are not usually used to measure just compare, because of the mathematics that go with them. Dial indicators are better for measuring distance.
This might help you out
http://longislandindicator.com/p201.html
Dave