10-15-2014, 01:29 PM
(10-15-2014, 08:13 AM)Sunset Machine Wrote: Wrong side of the arbor,
Walter, what difference does it make which side of the arbor he is on?
Willie
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And he should no better lol
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Walter, what difference does it make which side of the arbor he is on?
10-15-2014, 10:30 PM
Think about the direction of rotation in relationship with the threads. I did something similar when cutting a hex while holding the part with its internal threads on a stud in an index head.
I'd forgotten an incident while I was working in a tool & die shop and the foreman was cutting the OD of a ring using a 18" RT. He was climb milling to make it easier to turn the RT the EM grabbed and wiped out the worm and worm wheel. 
10-15-2014, 11:51 PM
(10-15-2014, 10:30 PM)Dr Stan Wrote: Think about the direction of rotation in relationship with the threads. I am. Facing the part from the front of the mill and cutting the ring on the right hand side, forward spindle rotation (clockwise), the left side of the cutter contacting the part pushes the ring rearward, (counterclockwise) unscrewing the right hand threads. Facing the part from the front of the mill and cutting the ring on the left hand side, forward spindle rotation (clockwise), the right side of the cutter contacting the part pushes the ring forward, (counterclockwise) also unscrewing the right hand threads. ![[Image: mechanics_gearsdirection.gif]](http://www.societyofrobots.com/images/mechanics_gearsdirection.gif) Switch the green gear to the left side and get the same result, no? 
Willie
10-16-2014, 12:28 AM
It doesn't matter which side of the arbor the end mill is on, it's still gonna unscrew the part. What he needed was a left hand end mill, or he could have conventional milled from the center of the part. That would have tightened the part on the threads.
Tom ![[Image: TomsTechLogo-Profile.png]](http://tomstechniques.com/wp-content/uploads/2013/11/TomsTechLogo-Profile.png) 
10-16-2014, 07:39 AM
(10-16-2014, 12:28 AM)TomG Wrote: ...or he could have conventional milled from the center of the part. That would have tightened the part on the threads. I'm not sure I get this part...
Hunting American dentists since 2015.
10-16-2014, 07:44 AM
(This post was last modified: 10-16-2014, 07:54 AM by Sunset Machine.)
(10-15-2014, 01:29 PM)Highpower Wrote:(10-15-2014, 08:13 AM)Sunset Machine Wrote: Wrong side of the arbor, I thought he was cutting a path/ledge/step (rotating the work) and going the wrong way. From the other side he could have continued (reversing rotation), but that wasn't what he was doing - he's cutting notches on the periphery, plunging down. Yes, I finally got the video watched and while I like his pipe-wrench solution, a better idea might have been two or three tapped holes for bolts & washers on top. He could also use a bit of cutting oil - driving a 3/4" side mill dry like that in his test cut. Shame on him twice! 
10-16-2014, 08:37 AM
(10-16-2014, 07:39 AM)Mayhem Wrote:(10-16-2014, 12:28 AM)TomG Wrote: ...or he could have conventional milled from the center of the part. That would have tightened the part on the threads. It looks like there is a rim around the edge of the part. If you start inside the rim and move the cutter out, the rotation of the cutter will tend to rotate the part clockwise, tightening it on the arbor. Tom Thanks given by: Mayhem
10-16-2014, 09:58 AM
(10-16-2014, 12:28 AM)TomG Wrote: It doesn't matter which side of the arbor the end mill is on, it's still gonna unscrew the part. What he needed was a left hand end mill, That is what I was thinking as well. Even if he was cutting a step/ledge around the outer portion of the top of the ring by driving the rotary table, it's still going to want to unscrew the thread using a RH end mill no matter which side of the arbor he is on. Good point about cutting the top of the ring from the inside out with a RH mill Tom. Now I'll just have to try and remember that if the situation comes up on me in the future. 
Willie
10-16-2014, 08:30 PM
(This post was last modified: 10-16-2014, 08:32 PM by Sunset Machine.)
(10-16-2014, 09:58 AM)Highpower Wrote: That is what I was thinking as well. Even if he was cutting a step/ledge around the outer portion of the top of the ring by driving the rotary table, it's still going to want to unscrew the thread using a RH end mill no matter which side of the arbor he is on. Maybe I should change my handle to the Demented Machinist. Specifics- conventional milling a ledge/flange/lip, a light DOC and a 1/2 cutter diameter step over. One side will tighten, and the other will loosen a setup like his as the rotation of the work changes direction in order to maintain conventional cutting. It only becomes a "gear" when the cutter climbs on top of the work, which is prevented by the proper direction of work rotation. Or does it? The heck with it, that was one lousy setup. The threaded arbor was his downfall. Clamps, man, clamps.
10-18-2014, 07:41 AM
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