heavy cut on lathe

[nickleinonen]

i am working in a rail wheel shop now, doing the usual rebuild stuff there [bearings off, inspect axles, cut the wheels, ultrasound the wheels, mag particle the axle defects, bearings on]



when i first started there i was surprised by how deep they can run the lathe on a single pass. . i thought 0. 250" is a heavy cut, but that is a light cut by the simmons lathe. today while training, i did the deepest cut i have ever done. the lathe was programed for 3/4" but at the point on the wheel where my insert broke, i was right at 1". . man that machine makes some noise cutting that deep



inserts cost $29 a piece. good for 4 cuts [4 corners on insert] if you can get them to last that long



[hey, i just noticed the tdr forum software now self resizes pictures. very nice ]

 

[PToombs]

Holy cow, Nick! I never realized they cut the wheels down that much. I figured they cut them some to true them up, but wow!

 

[DJW]

Nick is that the Tire you machine? One railroad shop I worked at they used to re-tire the loco drive wheels. That's where I learned why the tires are beveled. That was in the UK

 

[rbattelle]

Holy cow, 1"!? The lathe and tool must weigh an incredible amount to be rigid enough to take that much off steel.

I also had no idea you shave that much off the wheels. Why not just shave a tenth or so to true them up?

Ryan

 

[John - K5AWO]

A 1 inch cut? That exceeds what I would call sanity. That is way too much metal to be taking off at one time. Far better to take smaller cuts, and not be breaking the cutting tools.

the fact that the tools are breaking is a warning sign, their limits are being exceeded.

 

[nickleinonen]

we started by with this wheel by programing in 2x 3/8" cuts as it had a heavy flat spot on it [just under 3/4"]. . with out regular inserts, as soon as we hit the flat spot, it started to chew up the insert and then one went bang. . so we went to a different style if insert designed for a very heavy cut [the carbide and chip breaker design is different] and slow speed [10rpm] so then we went for a 3/4" cut. .



now that 3/4" is based on what the wheel finger gauge measures. this wheel with the flat spot was also hollow so down the center of the wheel where it runs on the rail, so it was not a 1:20 taper on the wheel, but worn in the middle. if the flats would not have been there, it would have been a 3/8" cut the clean it up. the flats were 11/16" deep, so 3/4" would clean the flat up, but coming in towards the flange, it was at 1" due to the wheel wear



smallest cut i have taken off yet on a wheel that hasn't been trued in the lathe was 1/8". i have taken off skimmed off 0. 012" before, but that was to get back to where i was cutting after breaking an insert. normal cuts are anywhere between 5/16" to 1/2"



these wheels we are getting to rebuild are abused bad. some have shells in the wheels that are over 1/2" deep. a shell is a defect that has broken out of the wheel tread. i'll need to get a picture of one to really to explain it



those wheels really get abused. . as do the tool bits. . if you can't get under the defect in the wheel [shell, skid, flat spot... ] in one pass, you will break the tool inserts. cut deep enough to get under the defect and your tool will survive the cut. now 1" is not a normal cut, but it was needed to get under the defect. lathe was at 8rpm and 1mm feed when the deep cut insert broke. i did pretty good, i only broke 3 inserts that day.



that lathe is also designed to handle cutting 40 wheel sets in 7. 5 hours. that is 20 inserts consumed in one shift assuming you don't break any and don't have to 2-cut any wheels