Milling arbour / chuck purpose?

[Bsmith]

Got this chuck MT3 arbour among some other milling cutters. I can't work out what it is for. The 2 grub screws hold 19mm dia milling cutters but what is the rest of it for?
Spring slides up inside the hollow MT3, then little plunger goes in, then nut holds them in. Brass collar goes round outside and can revolve freely, held in place with 2 spring clips.
2nd pic is the complete item
.

 

[Guzrik]

Internally cooled mill?

 

[Bsmith]

Internally cooled mill?

Thanks, yes I do think it is for some sort of cooling as some of the cutters for this chuck are hollow.

 

[dan.taylor.1]

It's for an Annular cutter from a mag drill, the have a pilot pin that's sprung loaded in the Arbor to eject the slug once it's cut through, and usually have centre feed coolant.

The 3/4" shank with 2 grub screws at 90° to each other is a weldon shank.

 

[Agroshield]

It's for an Annular cutter from a mag drill, the have a pilot pin that's sprung loaded in the Arbor to eject the slug once it's cut through, and usually have centre feed coolant.

I think the pin on the coolant ones also acts as a valve: when the pin is not touching the material (spring uncompressed), the liquid flow is cut off.

 

[dan.taylor.1]

I think the pin on the coolant ones also acts as a valve: when the pin is not touching the material (spring uncompressed), the liquid flow is cut off.

Yeah, I've not seen one with an o ring on so just relies on the spring pressure to seal, but most mag drills are gravity fed coolant anyway.

 

[Bsmith]

It's for an Annular cutter from a mag drill, the have a pilot pin that's sprung loaded in the Arbor to eject the slug once it's cut through, and usually have centre feed coolant.

The 3/4" shank with 2 grub screws at 90° to each other is a weldon shank.

Thanks Dan, so some annular cutters and a weldon shank musta gone astray from a mag drill and ended up in the box amongst the milling end cutters that I bought.
I can't see annular cutters being of much use on a mill, or are they?

 

[Bsmith]

This looks like it

AB3MT Slugger Annular Cutter Arbor Assembly

This Slugger arbor easily adapts Slugger annular cutters to machines that use a 3 Morse taper featuring a spring loaded slug ejection system.

www.trick-tools.com

 

[Kram]

I can't see annular cutters being of much use on a mill, or are they?

Drilling is the most efficient process for making a hole and an annular even more so, as theres less material to cut, plus you get the centre puck instead of a bucket of swarf.

I made up a weldon holder for the lathe tailstock and use it often. The only problem is the cost of the cutters and they need a huge amount of rigidity and torque for the bigger sizes.

 

[dan.taylor.1]

Thanks Dan, so some annular cutters and a weldon shank musta gone astray from a mag drill and ended up in the box amongst the milling end cutters that I bought.
I can't see annular cutters being of much use on a mill, or are they?

Quite the contrary, they're by far the most accurate efficient way to make a hole, and the rigidity of a mill just makes them even more so.

I've an adapter for my pillar drill for them, the mag drill obviously and they go in the collet on the mill with an adapter for the pilot.

 

[Agroshield]

Quite the contrary, they're by far the most accurate efficient way to make a hole...

...and they are also roughly the same length as standard end mills. A standard, say, 25mm twist drill is very long in comparison to a 25mm rotabroach meaning on some machines it won't fit at all and on others much cranking of the knee is needed. Also, price up a 30mm Morse taper shank twist dril against a 30mm rotabroach cutter:

30mm x 296mm HSS Ground Morse Taper 3 Drill Bit, DIN 345

www.orbitalfasteners.co.uk

30mm Rotabroach Mag Drill Cutter Short Series | Mag Drill Cutters Short Series | Tools

www.orbitalfasteners.co.uk

 

[dan.taylor.1]

...and they are also roughly the same length as standard end mills. A standard, say, 25mm twist drill is very long in comparison to a 25mm rotabroach meaning on some machines it won't fit at all and on others much cranking of the knee is needed. Also, price up a 30mm Morse taper shank twist dril against a 30mm rotabroach cutter:

30mm x 296mm HSS Ground Morse Taper 3 Drill Bit, DIN 345

www.orbitalfasteners.co.uk

30mm Rotabroach Mag Drill Cutter Short Series | Mag Drill Cutters Short Series | Tools

www.orbitalfasteners.co.uk

I do wonder how I managed without them tbh!