Taper pin reamers that rub…

[YouraTParticipant @yourat]

Hi all.

Needing a larger (10mm) taper pin reamer, I bought one from a supplier I've previously used, and who have thus far always supplied decent kit.

It rubs, rather than cuts.

Looking at the grind on the flutes, there is a flat that runs the entire length of each (straight) flute which is pretty well parallel to the cutting diameter. Looking at all my other taper pin reamers (all Dormer) this flat is absent.

The new reamer:

an older Dormer reamer:

I also have some spiral flute reamers (not taper), and they all have this 'leading edge flat' geometry, but with the spiral shape, this falls away from the cutting edge and they perform just fine.

I've already sent one back for this problem, and replacement came performing just as badly – I'm taking it up with the supplier again, but what should I expect to see at the leading edge?

Cheers,

Y.

[YouraTParticipant @yourat]

[BazyleParticipant @bazyle]

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.

[YouraTParticipant @yourat]

Posted by Bazyle on 30/03/2022 19:32:13:

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.

Bazyle,

No – other than that feature, it looks as I would expect – the root at the bottom of the flutes tapers along with the flutes, so I think this was meant to be a taper reamer from the start.

I'll try to talk to the supplier tomorrow rather than just do email ping-pong….

[John ReeseParticipant @johnreese12848]

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

[not done it yetParticipant @notdoneityet]

May not be, on this occasion, but the supplier reminds me of bang good (a supplier I have had trouble with previously).

Selling sub-standard (or even rejects?) to unsuspecting purchasers is not good. I would be very careful, if buying anything from ‘cheap’ far-eastern suppliers, if it was a critical item.

[jimmy bParticipant @jimmyb]

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

[not done it yetParticipant @notdoneityet]

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

Because it is still relevant? There are a lot of readers who think that a good review, from a ‘paid’ reviewer, is completely honest, truthful and comprehensively accurate. I don’t believe all they say, any more than I believe what car journalists write about cars that they get ‘jollies’ for reporting on them (favourably). I am a realist, not like a lot of readers.

You may think that the Sun shines from their orifice, but I don’t. They cheated me and thoroughly deserve to get some truthful feedback to potentially protect other potential purchasers. If they receive carp, they only have themselves to chastise. ‘Does a leopard change its spots’ – I doubt it.

[Mark RandParticipant @markrand96270]

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.

[bernard towersParticipant @bernardtowers37738]

Why would you do that, its a new tool it should work!!

[Martin ConnellyParticipant @martinconnelly55370]

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 martParticipant @oldmart]

I would send it back for a replacement, and get a refund if that was also unusable.

[YouraTParticipant @yourat]

Thanks for ask the comments and suggestions.

The supplier has agreed to a refund, including postage, so that's all good. Interestingly they say that they have sold around a dozen of that exact item and in the only one to have complained…

I've now found a NOS Dormer reamer, which I've bought and I'm sure will be just fine.

[old martParticipant @oldmart]

I can think of a reason why that reamer did not cut. The managing director brings visitors to see the production line and cannot resist picking out one of the products to show them. Then he puts it carefully back in the wrong box along with the finished ones, thereby missing the final stage.

[BazParticipant @baz89810]

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.

[jimmy bParticipant @jimmyb]

Posted by old mart on 03/04/2022 14:26:02:

I can think of a reason why that reamer did not cut. The managing director brings visitors to see the production line and cannot resist picking out one of the products to show them. Then he puts it carefully back in the wrong box along with the finished ones, thereby missing the final stage.

Had this happen to me a few times!

Jim

[BazyleParticipant @bazyle]

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.

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