Identifying HSS

[atomant48]

A couple of taps (of the thread cutting variety) i ordered arrived yesterday. Even though i only plan to use them for cleaning existing threads (im not having the best success with a thread restorer tap) I had spent a bit more and ordered HSS instead of carbon as the part im cleaning up is irreplaceable and i wanted to reduce the risk of snapping something off in the hole.

Question is, there is nothing at all on the taps except the size etched, so how do i know i havent been "seen coming"?

 

[dan.taylor.1]

Is the square at the end black or the same shiny finish as the rest of he tap? Most I have that are carbon have a black square.

Dan

 

[optima21]

also with hss taps the flues are normally a ground finish, and carbon steel taps are normally a machined finish

 

[atomant48]

Cool thanks. I will put up a photo when i get home.

 

[Buzza]

Touch it on a grinder and do a spark test, this might help : http://www.scrapmetaljunkie.com/241/the-spark-test-and-spark-testing-metals-2

 

[atomant48]

Well thanks for the help. They are black on the shank but the grinder test produced lots of orange sparks which suggests HSS according to that link.

I've emailed the supplier and tried to ask diplomatically. In any case they have achieved what I needed but I'd still like to know for if I ever need to order other sizes.

 

[brightspark]

hss or carbon steel are ok depending on the make .theres difrent qualitys of hss the same as there is carbon i stick to branded names . dormer goliath presto ect ect. after tapping a lot of holes and using taps u get the feel of when there going to snap