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Davek0974
05-07-2009, 02:11 AM
Hi all,

can someone verify a machine setup for me. I'm cutting cast iron on a bridgeport with BR2J head. Its an interrupted cut, probably 45 degrees of a circle 13" diameter. I'm using a 3" boring head with 3/4" brazed carbide tooling.

I have set these figures:-
depth of cut=0.25mm
feed rate=0.15mm/rev (.006")
speed=90rpm (300fpm)

does that sound ok or too heavy in one way or another?

i'm only asking as its a long job and i have two to do.

results so far seem ok but i dont want to kill the tool or machine.

thanks in advance

dave

Carld
05-07-2009, 09:43 AM
Dave, it sounds ok to me and if it is working do it that way. The only thing you could do is to increase the DOC or spindle speed to go faster. You will have to experiment but try to avoid any hammering because the tool and work surface will suffer.

rkepler
05-07-2009, 10:27 AM
Hi all,

can someone verify a machine setup for me. I'm cutting cast iron on a bridgeport with BR2J head. Its an interrupted cut, probably 45 degrees of a circle 13" diameter. I'm using a 3" boring head with 3/4" brazed carbide tooling.

I have set these figures:-
depth of cut=0.25mm
feed rate=0.15mm/rev (.006")
speed=90rpm (300fpm)


Depth of cut seems low, .25mm - .010", but you must have the tool really stuck out there with a 3" diameter tool and a 13" diameter cut. Speed could be increased a bit if the CI is fairly soft, I doa lot of CI work with carbide running 450 sfm (TiN coated inserts, though). How's the tool mounted? For something like this I might use something that holds a LH lathe tool in the right position, no boring bar is going to be setup for this sort of work.

Davek0974
05-07-2009, 10:52 AM
Its the standard round base tool with tapered shank and brazed carbide tip.

The tip is about 5" from the body of the boring head.

Its mounted in the side like this...
http://d.yimg.com/kq/groups/17605961/sn/2087686386/name/DSCN0958.jpg

Dave

rkepler
05-07-2009, 11:08 AM
That looks like a standard RH boring bar. Even cutting with the feed "up" you're using the 'wrong' edge for cutting as it's designed to cut lengthwise into the material, but with a little regrinding you can use it for a normal facing cut or, perhaps, for an up cut on this work. But if I had this in my shop (and I have, if that's a base for a loco steam or sand dome) I'd make a holder for a lathe tool for the beefiest boring head or bypass the boring head and make one heck of a flycutter. A LH lathe tool is ideal for this, just a 12" piece of square stock, run in a 3/4 pin for a chucking point and a slot for the lathe tool with a couple of setscrews to retain it.

(BTW: you don't need the micrometer adjust on the boring head for this work, just indicate a good edge (vise jaw, etc.), back off the sindle the radius and then adjust the tool to just touch the edge you indicated on. The tool can be tapped into place or moved with a micrometer adjust, makes no difference. I'm sure that you know this but others may not, and it's an easy way to get a radius cut using a rough tool or in places where it's not easy to measure things).

Davek0974
05-07-2009, 11:19 AM
Yep, its a chimney base for a traction engine.

Feed-up is right. The tool geometry looked the same on both edges of the tip, its not rubbing anywhere so i figured its good to go, plus its cast iron not titanium so i guess thats helping.

The head was recently bought as i figured it will be far more useful than a lump of steel for other jobs. The micro adjust is very handy too.

The tips not looking too bothered so i guess i'm in the right area as far as settings go. I know its not good for the mill but what can you do, when you need to get the job done.

Dave