Peter,

You need to show us a view from the boring tool slide axis (a 90 degree shot to the current one) to allow us to judge how the tool is set with regard to centre line. Normally for boring operations I set the tool slightly 'high' as you would when boring from a lathe toolpost. The other question is what is the tool top rake like, if set slightly high you need a good positive top rake when working with most aluminium otherwise you can get tip welding.

Was the tip brazed on by a passing seagull? Not a good boring tool in my estimation – just a general purpose item. I use either Boremasters, Criterion (solid carbide), or a reputable insert tip boring tool with a decent polished high rake insert for a good quality bore in aluminium. Plus, of course, a little white spirit / WD40 / or Russian Fat.

The final thing is did you have a lose gib or one that was nipped?

Martinl

Hi

It looks to me that you have the tool in the head the wrong way around, the clamping screw usually clamps down on the top of the boring bar and pushes the bar down into its seat, you feed the bar out to the right as we are looking at it, you have the tool upside down and facing the wrong way also the cutting tip needs to be on centre to the feed out axis if that makes any sense, a high speed steel tool will cut well on this material at the speeds stated with cutting fluid as mentioned above.

cheers Colin.

Were you going from 10 to 22 in one go?

I've had that effect with a drill bit in very soft alloy.

Colin I have a similar Japanese boring head and if you use in a tailstock the fixing screws are underneath.

Another thing which caught me out, is that these brazed carbide tools seem to come unsharpened.

I had issues with boring with a similar head until I read this in the forum previously. Sharpening them on a green wheel and then touching up with a diamond hone from time to time has made all the difference.

I also found that if you don't tighten the grub screws up well, the tool tends to rotate, so even if you have it aligned correctly (as described above) after a couple of passes it's twisted out of alignment and rubs rather than cuts.

Iain

Having melted the aluminium on a cutter in the past learning the CNC to the point where it becomes "plastic" I would say that as the cutter looks to have about 45deg of negative rake it has scraped/pushed the metal off the stock rather than cut it and what you see is in effect one big burr that has been pushed out the bottom of the hole

When setting up a boring bar put a 6 inch rule edge on the face of the cutting edge and look at its relationship to the bore and center line, with the face of the boring bar square to the center line. You can see the top rake of the cutting face and adjust to give appropriate angle for material ie very little for brass and much more for aluminium. You can then look at the back clearance of the radius to be cut and grind a bit more if necessary to prevent rubbing. This is how I set up.

David

The first photo views the tool as if looking from the left of the second photo, so the tip is mounted normally, it just has an unusually large lump of braze doing nothing behind it.