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[Metrology] Caliper Adjustment

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RV-N8ZG

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#1
I have a MBI Helios 5332-6 dial caliper that reads 0.0425" with the anvils closed.
the dial bezel is fixed, and there are no adjustments that I can find.
So far, Google has not been helpful...
Anybody have any suggestions for correcting the reading?

Neal
 

Bob Korves

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#2
The gearing may have jumped a tooth or two. That is fairly common. Hopefully all the teeth are OK. Helios made some great tools. Dial calipers are delicate compared to vernier or digital versions.
 

Holescreek

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#3
All the dial calipers I've had were adjusted by inserting a straightened paperclip just under the rack gear and pushing the moveable jaw into the end of it to separate the pinion gear from the rack and moving the jaw forward a bit. The pinion gears have always been on a spring arrangement under the dial.
 

EmilioG

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#4
It's common for calipers to jump a geared tooth or two? I've never seen it myself, but it does happen. There may be DIY repair info on the web.

On many dial calipers, there is a tension spring that prevents backlash. I don't know how Helios calipers were made but if they're like Etalon, it would take prying open the case and possibly destroying the holders.

According to LIIS> http://longislandindicator.com/p11.html
Helios dial calipers are a brand made in Germany currently owned by Mahr. Originally, they were copies of the Etalon calipers. Several models are available in the US market from Fred Fowler Company, among others.

  • Sales: Fred Fowler Company for some models
  • Repairs: not possible on old models
  • Parts: not available
  • Information: search the web for Helios using the German language option
 

Holescreek

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#5
Yes it happens quite often especially where fine metal chips get onto the rack. Most of the good makers used to include a tool with a loop on the end similar to the opened paperclip. Ive got some old Helios in the shop, I'll take a look at them.
 

EmilioG

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#6
The Etalon and other Swiss made dial calipers come with a covered rack. Some calipers require that the crystal be removed to take them apart
and I read that the crystal has to be replaced. Parts for old Helios calipers are no longer available, so repair of worn or broken parts will be difficult.
 

RV-N8ZG

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#7
On many dial calipers, there is a tension spring that prevents backlash. I don't know how Helios calipers were made but if they're like Etalon, it would take prying open the case and possibly destroying the holders.
Emilio -
Excellent input, thanks!

A little gingerly probing with a bobbypin has it back to close enough...

caliper.jpg
 
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