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screw thread size help


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I'm replacing my trunk lock and found two of the four screws missing that hold the assembly to the trunk, the other two screws have striped heads and will need to be drilled out. The Triumph parts catalog shows those screws as part number 518104 but they do not tell me the bolt/thread size. Anyone know what size these bolts are?

 

many thanks,

 

Bob

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I finally finished getting the boot lid lock replacement. I had to drill out two of the screw holding it to the car and then had to drill out the two rivets holding the lock plate to the lock mechanism before I could unscrew the lock from the mounting plate. As my luck would have it the screws on the old lock would not fit the new, I had to use my tap and die set to open the holds to 6/32 before I could reassemble. now everything fits and works perfectly.

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There is no such thread size as 3/16 in UNF. Thats the spanner size. http://www.carbidedepot.com/formulas-tap-standard.htm It was the thread size that was requested and all the ones I have done have had 10/32 screws fitted. (FWIW 2BA will also fit) 6/32 is very small indeed and is a UNC (coarse) thread..

Stuart.

Edited by stuart
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Then the info on a site I checked must be wrong. I ordered a whole bunch of UNF bolts a couple of years ago from them and they have a 3/16 UNF bolt listed, varying in length from 1/2" to 2"....

 

 

But it must be UNC instead of UNF then... learning more everyday, thanks for the lesson Stuart.. ^_^

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Hi Edwin,

the Americans (I think) had/have a fancy way of naming metal screws.

They named them after wood screws ie 6, 8, 10, 12 etc then added the thread TPI.

So a 10/32 has a diameter of a #10 wood screw with 32TPI

Once they got near 1/4" they stopped and followed the English (wise move)

As it happens the #10 screw is apprx 3/16" diameter hence your 3/16 UNF - sadly there is not 3/16 UNF but a 10/32 UNF

 

Roger

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Thread nomenclature.

10 refers to the rod diameter the bolt or screw is made from ie number 10 in the SAE sizing charts.

32 is the thread pitch per inch ie crests per inch.

UNF is the thread form ie 60 degree angle.

This is useful

http://www.leytonfasteners.co.uk/pdfs/UN%20Thread%20Chart.pdf

 

Or

 

http://www.marylandmetrics.com/tech/THREAD%20IDENTIFICATION%20CHART.pdf

 

Cheers

Peter W

Edited by BlueTR3A-5EKT
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