Machining has been my hobby for quite a few years, but I still have beginner questions 
so here goes.
I have two milling machines a big knee type horizontal mill that weights 3k lbs(a German heckert fw250) and a bench top mill. This question is regarding the big mill. So far I've been primary using it like the bench top. Taking many small passes, but I became interested in pushing it further in its material removal rate.
I have various arbors and horizontal milling cutters. My goal is to get fairly fast material removal with a large (4in long, 2.5in diameter) helical cutter without chatter. My machine is a bit worn. All way clearances added together amount to 2~4 thou in the worst possible spot.
So the only way to get a good cut with the above cutter is to lock the knee and the Y axes while the table (X) runs under power.(This is with conventional milling) I tend to run that 2.5in, 10 tooth cutter at 100rpm, with 128mm/min (5ipm) feed. Width of cut is up to 2in and the depth is usually 1mm (40 thou). The machine could do a much bigger cut, but I don't trust the vice enough.
So my question is, is everyone locking all other axes when doing cuts like this? I watched many horizontal milling videos from Keith Rucker and others and I don't remember them locking ways on their quite old machines. I do always lock unused axes on the bench top mill, but that is very quick and easy. With a big machine having to walk around constantly loosening and snugging up bolts (to move Z for example) seems unusual based on all the videos I saw.
Just to clarify. I don't think the wear on my mill is excessive. Each axis ways on its own is only up to slightly over a thou of play in the middle while the ends are snug. The table leadscrew has about 5 thou of backlash when ends are set tight. It seems it has plenty of life left in it. I could do most of my milling near the extremes of travel on X and Y while Z could be snug more, but that would require remembering not to go to far up or down.
What do you do with your similarly worn machines?
so here goes.I have two milling machines a big knee type horizontal mill that weights 3k lbs(a German heckert fw250) and a bench top mill. This question is regarding the big mill. So far I've been primary using it like the bench top. Taking many small passes, but I became interested in pushing it further in its material removal rate.
I have various arbors and horizontal milling cutters. My goal is to get fairly fast material removal with a large (4in long, 2.5in diameter) helical cutter without chatter. My machine is a bit worn. All way clearances added together amount to 2~4 thou in the worst possible spot.
So the only way to get a good cut with the above cutter is to lock the knee and the Y axes while the table (X) runs under power.(This is with conventional milling) I tend to run that 2.5in, 10 tooth cutter at 100rpm, with 128mm/min (5ipm) feed. Width of cut is up to 2in and the depth is usually 1mm (40 thou). The machine could do a much bigger cut, but I don't trust the vice enough.
So my question is, is everyone locking all other axes when doing cuts like this? I watched many horizontal milling videos from Keith Rucker and others and I don't remember them locking ways on their quite old machines. I do always lock unused axes on the bench top mill, but that is very quick and easy. With a big machine having to walk around constantly loosening and snugging up bolts (to move Z for example) seems unusual based on all the videos I saw.
Just to clarify. I don't think the wear on my mill is excessive. Each axis ways on its own is only up to slightly over a thou of play in the middle while the ends are snug. The table leadscrew has about 5 thou of backlash when ends are set tight. It seems it has plenty of life left in it. I could do most of my milling near the extremes of travel on X and Y while Z could be snug more, but that would require remembering not to go to far up or down.
What do you do with your similarly worn machines?
