# Calibration Procedures for Parallels and V Blocks

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#### dsciara

Hello,

I am new to this forum. I found this site through a quick search and found a thread about this subject posted in 2001. I could not find the information on my own so I am seeking help. We have a CMM machine. Should I use a height gage with surface plate? Please any answers can be very useful. Thank you. By the way I am very new to this department and I am trying to get used to the terminology that you all use on here.

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#### brahmaiah

Re: In need of calibration procedures for parallels and v blocks.

Hello,

I am new to this forum. I found this site through a quick search and found a thread about this subject posted in 2001. I could not find the information on my own so I am seeking help. We have a CMM machine. Should I use a height gage with surface plate? Please any answers can be very useful. Thank you. By the way I am very new to this department and I am trying to get used to the terminology that you all use on here.
Height gauge and surface plate with a dial indicator of 0.001mm least count is required.For v-blocks additionally a sine bar is required..V-blocks are always inspected in pair.both the v-blocks in a pair should be identical in all dimensions.Again 0.001mm is the least count for this measurement.
V.J.Brahmaiah

#### Stijloor

Super Moderator
Re: In need of calibration procedures for parallels and v blocks.

Height gauge and surface plate with a dial indicator of 0.001mm least count is required.For v-blocks additionally a sine bar is required..V-blocks are always inspected in pair.both the v-blocks in a pair should be identical in all dimensions.Again 0.001mm is the least count for this measurement.
V.J.Brahmaiah

Can you cite the specification that requires the 0,001 mm tolerance?

Stijloor.

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#### brahmaiah

Re: In need of calibration procedures for parallels and v blocks.

Can you cite the specification that requires the 0,001 mm tolerance?

Stijloor.
0.001mm I have mentioned is the requirement of the Least count of the dial indicator(Plunger type) that should be used to inspect a pair of V-blocks. The tolerance of precision ground V-BLOCKS is less than 0.005mm.You can refer CORRESSPONDING ISO or BS OR DIN standards for precision V-blocks.I am a trained tool maker started my carreer in the Tool Room of an aero engine factory way back in 1960s.
.V.J.Brahmaiah

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#### dsciara

Re: In need of calibration procedures for parallels and v blocks.

Thank you so much.

#### Stijloor

Super Moderator
Re: In need of calibration procedures for parallels and v blocks.

0.001mm I have mentioned is the requirement of the Least count of the dial indicator(Plunger type) that should be used to inspect a pair of V-blocks. The tolerance of precision ground V-BLOCKS is less than 0.005mm.You can refer CORRESSPONDING ISO or BS OR DIN standards for precision V-blocks.I am a trained tool maker started my carreer in the Tool Room of an aero engine factory way back in 1960s.
.V.J.Brahmaiah

Just to make sure, I checked, but could not find the standards you've mentioned. Often, V-Blocks are produced and finish-ground as a pair. So it does not matter what "precision" as long as they are used as a pair. In addition, V-Blocks are more a work-holding device and any datums and measurements will be made from the part itself, not the V-block.

Stijloor.

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#### brahmaiah

Re: In need of calibration procedures for parallels and v blocks.

Just to make sure, I checked, but could not find the standards you've mentioned. Often, V-Blocks are produced and finish-ground as a pair. So it does not matter what "precision" as long as they are used as a pair. In addition, V-Blocks are more a work-holding device and any datums and measurements will be made from the part itself, not the V-block.

Stijloor.
NO. I donot agree with your statement that V-blocks are only work holding devices.Here I am talking about precision tool makers V-blocks.There are standards for tolerances of precision V-blocks in BS,DIN standards.They come in pairs of Grades 0f 0,1,2 OR grade A.B.C.If you refer to a standards library you will get the corressponding standards.I will myself try get you the standard nos.If you refer to the catalogues of MAHR.STARRET or some similer companies you will get the grade details.
I once again state here that toolmakers V-blocks fall under precision inspection equipment and not just holding devices.It is true they are used for work holding also in production.Those v-blocks donot fall under precision V-block category.Perhaps if you consult an expert on Metrology Lab, he will be able to tell.
V.J.Brahmaiah

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#### merrick65

Re: In need of calibration procedures for parallels and v blocks.

FEDERAL SPEC GGG-V-191D: TECHNICAL MANUAL CALIBRATION PROCEDURE
FOR V BLOCKS. I know you can get a free copy of the specification by joining GIDEP https://www.gidep.org/

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#### brahmaiah

Re: In need of calibration procedures for parallels and v blocks.

FEDERAL SPEC GGG-V-191D: TECHNICAL MANUAL CALIBRATION PROCEDURE
FOR V BLOCKS. I know you can get a free copy of the specification by joining GIDEP https://www.gidep.org/
Thanks for information
v.j.brahmaiah