Does the geometry make it look like they took a parallel reamer and tried to regrind it to have a taper? Or just someone who had no idea how to set up the grinder for tapers. Probably who batch will be wrong, and now spread over 1000 vendors in 3 continents.

It is possible that the grind was to provide both primary and secondary relief angles. On your reamer the primary relief was ground wrong.

If its no good just return it. All the sellers stock could be the same, so probably a good idea to go elsewhere on this occasion.

The reamer in question does look wrong to me.

Not sure why NDIY is still Banging the Nanggood drum…..

Jim

Given that it's a taper pin reamer and its exact diameter is not as ctitical as a parallel reamer and given that it's a reasonably large one, I'd 'blue' the edge up with a mrker pen and then stone the flutes until the 'blue' almost disappears.

Job done.

The flat you are looking at is called a margin and it should be 0.2mm to 0.4mm. Larger than this is probably too much and will increase the force needed to make it cut easily.

Martin C

Old mart that exact thing used to happen where I worked, we tried politely to explain to management that if someone wanted to handle a component they should ask the operator, the reply was basically, management don’t ask mere operators for anything, didn’t really matter though, we weren’t making anything important, only parts for aircraft engines.

If the manufacturer had an inspection department how would this be measured? Perhaps as in the old days though as there is probably a million pound digital machine that does it automatically in a German factory nowadays.