Probably an undercut to remove any radius corner made by the cutter and to allow the lathe tool to seat against the bottom and side faces.

Paul.

It is simply bad engineering practice that creates a classic "notch" that will certainly induce a fracture sooner or later.

Avoid tool holders with this feature.

It's to make sure any sharp edge on the tool shank or swarf build up doesn't push it out of square with the holder. (otherwise why wouldn't it be on the adjacent inside corner too, clearly indicative of only applying the undercut on the tool seat?)You can see a similar feature on the seats for decent carbide tip holders. I doubt it would break it's quite thick steel. You couldn't apply enough pressure with your hand.

Michael W

Edited By Michael Walters on 18/11/2016 10:59:22

Probably just a result of the production process and not actually put there for a reason.

Take a look at the machining marks on the lower surface of the tool slot. Can't see it in the pics, but it looks as if the square groove has been rough machined by an end mill or perhaps a side and face mill cutter in a horizontal mill. Both these will leave a bit of an uneven surface for the toolbit to sit on. So it appears they have taken a finishing cut over the bottom face with something like a cheap and readily available dovetail cutter, using the face of the cutter to make a nice flat surface. The nick in the corner is simply the result of running that cutter a tad deep in order to make sure the corner has no step left in it that would foul the tool bit when placed in situ. Remember these are churned out by the hundreds and thousands so each one is not set up individually for milling as we would do at home. Having that nick there ensures none has a ridge in the corner without each one being set up individually to the exact correct position to make a perfectly square corner.

Production engineering, it's how things get made by the thousands. Stress point? Yah probably. But they are so cheap to produce they just give you a new one if it lets go in the warranty period.

Why have i got one dixon holder with a morse 1 socket?

Edited By Hacksaw on 18/11/2016 15:39:35

Exactly what i thought , I've got it because no one else wants it

.

I have watched this thread with interest; albeit with no experience of the item in question.

Three possibilities spring to mind:

1. It is a "Product Improvement" … In which case, Bison might be happy to give an explanation.
2. It is a Manufacturing Error … In which case, Bison should replace the item[s], and look to their Quality Control Procedures.
3. It is a Counterfeit … In which case, Bison would presumably be very grateful for the evidence.

I would send photographs of the item, the receipt, and the box, to Bison **LINK**

http://www.bison-bial.co.uk/contact

MichaelG.

My tool holders are genuine Bison, the slot is radiused on all of them :

They don't have the cut marks on the side face shown in the original post. Regards, Michael.

Edited By Michael Briggs on 19/11/2016 11:39:32