internal threading tool bar

3

3strucking

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I was looking at purchasing a Carmex #: SIR 0500 M16 holder and inserts for internal threading. The minimum bore is .640. Is there a mini tool bar for internal threading .500" and smaller? I have a small diameter holder for HSS but I would like to use inserts.
 
I use Carmex SIR 0375 M11 for internal threading. It uses a 11IR size (1/4" inscribed circle) insert & the smallest internal thread I cut with it is 1/2". Anything smaller I prefer to use a tap anyway. The bar you listed uses a 16 size (3/8" IC) insert, I use the 16 size insert for external threading.

But Carmex does make smaller internal bars that use 06IR (5/32" IC) & 08IR (3/16" IC) inserts. Enco used to sell these mini threading bars individually & as kits, don't know who sells them for good prices now. They come in various shank sizes. See Carmex's website for the P/Ns.

06IR Internal Threading
08IR Internal Threading


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Does it have to be inserted carbide? Micro 100 sells solid carbide internal threading tools that are very stiff for their size and they allow you to thread really small holes. I much prefer these bars in tiny holes.

Circle Machine sells solid carbide bars with inserts. Their CCMI bars come in 3/16" and 1/4"; I own the 3/16" one and it has a minimum bore diameter of 0.272". I also have QCMI bars in 3/8" and 1/2"; both will bore, groove and thread. All these bars produce really accurate threads in a deep hole, primarily because the carbide shanks are stiff for the bar diameter.
 
Shars sells a small internal threading kit that uses 06IR inserts. It comes with 10 inserts, wrench and boring bar for $129 + $6.50 shipping off eBay. Item# is 300915888114. eBay add says a minimum bore size of 0.240", neck length 0.5".

Bruce

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