Vertical mill as lathe?


What has been your experience in creating a 'lathe'
part on a CNC vertical mill?
I need two small idler rollers.
I want to put say 6-1/2" of 1-1/4" dia. CRS round
bar in an R8 end mill holder and turn 2" (total)
of the length down to 1" OD to press into needle
bearings.
Between these axles, I want to turn a .3125" radius
semicircle feature and a couple lands.
Other operations will include some polishing and
parting off.
There will be no drilling.
Your thoughts please?
* Don't do it. It'll be Chatter City?
*
Do it but here are a couple gotchas?
* Buy a rotary table and use a ball end mill?
*
Send me your sketch and I will bang out a couple
on my real CNC lathe?
* Make a form tool and make these parts on my
Sherline lathe?
*
Send a sketch out to a machinist?
Thanks!
--Winston
Reply to
Winston
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Works well. You need a way to hold the work in the mill spindle. I had a part that was threaded 1"-20, so i made a 1.25" OD sleeve with matching internal thread, and slit it. When held in a collet, it clamped the work securely. I then put a lathe tool in an Aloris-style dovetail toolholder and put that in the mill vise. I then wrote a program that would look identical to a lathe program, X and Z moves only, having left the Y axis such that the tool was equivalent to what would be "center height" on a lathe.
I needed to cut ball ends on these adjusting rods and don't have a radius attachment for the lathe.
Jon
Reply to
Jon Elson
My 1-1/4" end mill holder wouldn't work then?
I do understand that I would have to take 'centering cuts' to clean up the OD before starting.
Very cool. Thanks, Jon!
--Winston
Reply to
Winston
Well you are already 5:1 on L/D so that stinks. I assume you want to machine the end not near the spindle. Issue #1.
I'm going to say it is do-able. I wish you lived nearby because I'd run you over a chunk of 12L14 from my stash in a heart beat. It would beat doing it with 1018 which is what I assume you mean by CRS.
HSS tool, sharp, positive rake, you know the typical recomendation for shakey lathes.
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
Perhaps not so smelly. :)
The end mill holder swallows 2.75" of the workpiece leaving 3.75" exposed, so 3:1 L/D. Far from perfect but perhaps not so bad for light cuts?
Correct. Say a 1" long axle from the 'wild end' to a 0.05" flange. A 0.375" wide semicircle centered, (with a 0.3125" radius), another 0.05" flange, another 1" axle and then say 1/8" to part off. This'll give me about 1.15" between the end of the end mill holder and the parting line.
over a chunk
Correct. Thanks for the tip!
Hokay. Sounds reasonable. Thanks, Wes.
--Winston
Reply to
Winston
3:1 is good. 4:1 seems to be the limit for work piece not supported or boring bars made out of steel.
over a chunk
We *used* to run a lot of 12L14 7/8 to 1-1/4" diameter bar stock on an Index G200. That came to an end when Korea could supply the part for our cost of material. Quality no better than what we were doing and often worse. I'm thinking our enviromental regs and other things might be a factor in how Korea can sell the fairly tight tolerenced item for less than we could produce it. That is a subject for another time.
I started getting interested in having my own shop back when I could still get a chit to bring home drops. I wish I had got interested a bit earlier in retrospect. The scrap price of metal went up and that job bennie went out the window. :(
Pictures when done.
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
On 8/5/2010 4:43 PM, Wes wrote:(...)
Good! 3:1 did seem reasonable.
(...)
At one outfit I worked at, our Korean OEM would toss just any junk into the mixer when making elastomer feet. Got lots of complaints from customers about furniture marred by the stinky, oozing stuff. Yuk!
Joni was right. >
formatting link
(...)
It'll be a while!
Thanks again.
--Winston
Reply to
Winston

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