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- since 1996 -

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Technical Discussions
Debdutta Mallik
Consultant,
Malaysia, Joined Jun 2005, 37

Debdutta Mallik

Consultant,
Malaysia,
Joined Jun 2005
37
01:31 May-06-2007
Checking FBH

Please let me know how to check the 1.5MM OR 2.Omm FBH. How to check whether the angle is 90 degree i.e bottom flat.

Regards,

D.Mallik


    
 
 
S.V.Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
787
00:51 May-07-2007
Re: Checking FBH
The best way is to use a tool that is specifically designed to produce the FBH and check that it is doing its job by using depth measuring microscopes for small depths. That way, the procedure can be qualified. And for deeper holes, maximising the reflected signal amplitude (the echo from the FBH) and comparing it with a standard should be acceptable.

I have some more ideas on the subject if you need them.

Swamy

----------- Start Original Message -----------
: Please let me know how to check the 1.5MM OR 2.Omm FBH. How to check whether the angle is 90 degree i.e bottom flat.
: Regards,
: D.Mallik
------------ End Original Message ------------




    
 
 
Charles Truskolasky
Test Examiner Mil-2132, Level III
Lehigh Heavy Forge, USA, Joined Jan 2007, 10

Charles Truskolasky

Test Examiner Mil-2132, Level III
Lehigh Heavy Forge,
USA,
Joined Jan 2007
10
05:56 May-07-2007
Re: Checking FBH
----------- Start Original Message -----------
: Please let me know how to check the 1.5MM OR 2.Omm FBH. How to check whether the angle is 90 degree i.e bottom flat.
: Regards,
: D.Mallik
------------ End Original Message ------------

Mr. Mallik, depending on the depth of the flat bottom hole, you may be able to measure the flatness, diameter and the angle by taking a casting of the hole and examining it on an optical comparator. I've had success using this method with fbh to 2.0mm but I've never tried it on anything smaller. There are several replicating casting materials available; the trick is removing trapped air bubbles from the hole. The casting must be intact otherwise you'll be scrapping trapped cast material from the hole.



    
 
 
Phil Herman
Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards, USA, Joined Oct 1999, 79

Phil Herman

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
09:09 May-07-2007
Re: Checking FBH
Dear Mr. Mallik,
As Mr. Truskolasky noted, a cast silicone replica is the ideal way to determine the flatness of the hole bottom. ASTM E127 and 428 require that the hole bottom be flat with 0.001" per each 0.125" of hole diameter. This means that the 1.5mm FBH must be flat within 0.00047" over its reflective surface. From a cast replica, one can easily verify this on an Optical Comparator, or better yet, a high magnification Video Measurement System (VMS). Try using a syringe to "encourage" the material to get to the bottom of the hole. As you press the plunger, slowly retract the needle from the hole, leaving a knob of material on top to use as leverage when removing the replica. The replica will be of little use to verify the angular error of the hole, however. Here, I suggest inserting a high-precision gage pin of the same diameter as the FBH, allowing 1" to extend out of the block. This will enable you to measure the angular error on a VMS by picking up points on the pin, and block surface. This assumes the block is of manageable size.

Contact me if you need more help, or would like us to handle the certification of the hole.


----------- Start Original Message -----------
: Please let me know how to check the 1.5MM OR 2.Omm FBH. How to check whether the angle is 90 degree i.e bottom flat.
: Regards,
: D.Mallik
------------ End Original Message ------------




    
 
 
keith moxey
keith moxey
09:52 May-08-2007
Re: Checking FBH
Hi
would a casting / optical comparator method only detect protrusions on the 'flat' surface of the casting. What about indentations in the casting eg a central pip in the bottom of the hole (a common problem if holes are drilled rather than EDMed)

Regards
Keith Moxey

----------- Start Original Message -----------
: Dear Mr. Mallik,
: As Mr. Truskolasky noted, a cast silicone replica is the ideal way to determine the flatness of the hole bottom. ASTM E127 and 428 require that the hole bottom be flat with 0.001" per each 0.125" of hole diameter. This means that the 1.5mm FBH must be flat within 0.00047" over its reflective surface. From a cast replica, one can easily verify this on an Optical Comparator, or better yet, a high magnification Video Measurement System (VMS). Try using a syringe to "encourage" the material to get to the bottom of the hole. As you press the plunger, slowly retract the needle from the hole, leaving a knob of material on top to use as leverage when removing the replica. The replica will be of little use to verify the angular error of the hole, however. Here, I suggest inserting a high-precision gage pin of the same diameter as the FBH, allowing 1" to extend out of the block. This will enable you to measure the angular error on a VMS by picking up points on the pin, and block surface. This assumes the block is of manageable size.
: Contact me if you need more help, or would like us to handle the certification of the hole.
:
: : Please let me know how to check the 1.5MM OR 2.Omm FBH. How to check whether the angle is 90 degree i.e bottom flat.
: : Regards,
: : D.Mallik
------------ End Original Message ------------





    
 
 
Charles Truskolasky
Test Examiner Mil-2132, Level III
Lehigh Heavy Forge, USA, Joined Jan 2007, 10

Charles Truskolasky

Test Examiner Mil-2132, Level III
Lehigh Heavy Forge,
USA,
Joined Jan 2007
10
00:51 May-08-2007
Re: Checking FBH
----------- Start Original Message -----------
: Hi
: would a casting / optical comparator method only detect protrusions on the 'flat' surface of the casting. What about indentations in the casting eg a central pip in the bottom of the hole (a common problem if holes are drilled rather than EDMed)
: Regards
: Keith Moxey
: : Dear Mr. Mallik,
: : As Mr. Truskolasky noted, a cast silicone replica is the ideal way to determine the flatness of the hole bottom. ASTM E127 and 428 require that the hole bottom be flat with 0.001" per each 0.125" of hole diameter. This means that the 1.5mm FBH must be flat within 0.00047" over its reflective surface. From a cast replica, one can easily verify this on an Optical Comparator, or better yet, a high magnification Video Measurement System (VMS). Try using a syringe to "encourage" the material to get to the bottom of the hole. As you press the plunger, slowly retract the needle from the hole, leaving a knob of material on top to use as leverage whenremoving the replica. The replica will be of little use to verify the angular error of the hole, however. Here, I suggest inserting a high-precision gage pin of the same diameter as the FBH, allowing 1" to extend out of the block. This will enable you to measure the angular error on a VMS by picking up points on the pin, and block surface. This assumes the block is of manageable size.
: : Contact me if you need more help, or would like us to handle the certification of the hole.
: :
: : : Please let me know how to check the 1.5MM OR 2.Omm FBH. How to check whether the angle is 90 degree i.e bottom flat.
: : : Regards,
: : : D.Mallik
------------ End Original Message ------------

Mr. Moxey, indentations formed on the flat surface of the FBH caused by the center point of the drill will fill with the casting and appear in relief. Flat bottom drills (mills) are used for the final drilling operations, if the cutting edge becomes damaged, concentric grooves appear on the casting face. If it's damaged at the center then a void will form at the center of the casting face. A low power microscope should be used to exam the face. A hand held brinell hardness microscope does the job very nicely.



    
 
 
Mahesh Govani
Mahesh Govani
11:23 Jan-12-2015
Re: Checking FBH
In Reply to Charles Truskolasky at 05:56 May-07-2007 .

hello Mr. Charles, what kind of casting material we can use to take out replica. Please if you can let me know.

    
 
 

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