Is this tool suitable for upside down internal threading?

[ericc]

https://littlemachineshop.com/products/product_view.php?ProductID=1895

This bit seems to be fatter on the bottom than the top from the picture. Would this be used for threading upside down in reverse?

 

[francist]

I suspect the grind is correct for normal inside work, it's just the clearance below the cutting edge that makes the edge appear to be thicker towards the bottom. In order to cut fairly small inside diameters the clearance needs to be quite aggressive otherwise it will drag the inside of the bore.

-frank

 

[ericc]

I got it, thanks. Mine looks kind of strange too, especially if you just take a photo at one angle.

 

[P. Waller]

The largest problem that you may run into when threading small holes with a large helix angle is tool clearance angle, if this becomes a problem simply grind more clearance on the tool.

I recently had to grind the clearance angles on acme internal thread inserts to clear the thread flanks (1 1/4"-4 TPI), we could have bought the correct inserts for this particular thread but they were 3 weeks out so hand grinding it was.

This tool. This is the gauge, the finished parts were 303 SS


I had no problems with external tool.
24 parts but this was easy because they were 360 FM brass