# UNC to metric



## Gary (7 Nov 2014)

Can anyone tell me which If amy metric nut will fit a 1/2-13 UNC thread?

Thankd


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## bugbear (8 Nov 2014)

UNC - 1/2-13	

So - 12.7 mm major diameter, 1.9538mm pitch

A metric thread chart shows that the OD jumps from 12mm straight to 14mm, so Im afraid the answer to your question is "no".

http://mdmetric.com/tech/M-thead%20600.htm

BugBear


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## nanscombe (8 Nov 2014)

Currently on eBay.

1/2 UNC (13tpi) Stainless Full Nuts - 1/2-13 UNC Stainless Full Nuts (3/4 AF) x5 @ £2.89 (presumably plus p&p).

There is also contact info in the listing.


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## Gary (8 Nov 2014)

bugbear":23adqdd9 said:


> UNC - 1/2-13
> 
> So - 12.7 mm major diameter, 1.9538mm pitch
> 
> ...




Yeah I wasn't sure that's why I asked

Is it therefore possible to tap a 3/8-16 thread to make it 1/2-13?


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## Gary (8 Nov 2014)

Or would these tap out to 1/2-13?

http://www.ebay.co.uk/itm/like/22148940 ... 0&ff14=108

Can't find any unc ones.


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## Inspector (8 Nov 2014)

Drill out the 3/8" thread with a 27/64 drill and then tap with the 1/2-13 UNC. Metric drill bit would be 10.7mm (a touch tight) or 10.8 (a touch loose) if you can't get you hands on a 27/64" bit. 

If you are going to drill out the thread then why wouldn't you just go to a metric size that you have readily available rather than stick with the UNC?

Pete


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## Gary (8 Nov 2014)

The quick answer is I want to fit some kreg casters and their thread is 1/2-13 UNC.


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## marcros (8 Nov 2014)

try these people- no prices but they are willing to supply small quantities

http://www.anchorinserts.co.uk/?threadfamily=2&thread=7


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## Gary (8 Nov 2014)

Thanks for that. Didn't even know that place as there. I could walk there from work.


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## marcros (8 Nov 2014)

Unc inserts aren't cheap (relatively speaking)- I just bought some 1/4 from eBay but even if they are a pound each they would be cheaper than other solutions, other than possibly epoxy inch in a nut.


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## Gary (8 Nov 2014)

I've ordered a sample. Maybe I can find three other to do the same.


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## Gary (18 Nov 2014)

Sorry to ask another stupid question. 

If the current thread is 3/8-16 can this be drilled and re tapped so I can fit a 10mm bolt?

I'm not sure having looked at some figures.


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