Gotcha! And I do that when necessary, too, but it sort of supports those that create the argument that you risk making scrap because you don't rely on the tool to make the cut to size. It goes without saying that those of us that work in the trade don't recognize the risk. :-)
Harold
Most folks understand that end mills flex. When they do, the surfaces they cut are no longer where you think they should be, based on a simple 'edge finder, and measure the (still) cutter' calculation.
Those who don't understand this either don't care because they're working to 0.010 tolerance - and there are *plenty* of jobs out there that are done to +/- 1/64 inch in industry - or they're making a lot of scrap.
Woodruff key cutters might cut a thou oversized or so, depending on condition or size. A 1/8 inch end mill could cut oversize, or offside, by ten thou or so. Also small end mills will take a while to do a keyway because they can't do it all in one bite. Chip clearance becomes a big deal.
This is why I like keyseat cutters.
Jim
Agreed. Though the "slot drill" mentioned near the start of this thread is not just *any* endmill -- it is a two-flute center-cutting one, which does the best at cutting to width and with minimal wander, because the sides of the slot are being cut only when there is absolute minimum side force on the end mill.
The "slot drill" term is apparently more common in the UK than in the USA -- but the function remains constant.
[ ... ]
With all the mention of keyseat cutters in horizontal mills, I don't see (yet) any mention of plain milling cutters for keyseats. They work very nicely for the task, if you can accept the longer radius at the end of the cut.
Enjoy, DoN.
Absolutely! I was thinking more on the order of ¼" and above. I've used my share of small end mills, right down to 1/32". Talk about a piece of glass! Yep, for those small keyways, there's nothing that competes with a Woodruff cutter. Interestingly, I have never had a problem with them cutting oversized, either. In fact, they generally cut snug to the cutter. Could be the spindle assembly is quite true. Do keep in mind I've run only my own machines for well over 30 years now.
Like you, I've used Woodruff cutters for many things, not just keyways.
Harold
Not only nicely, but fast. Ever run something like a #3 K&T mill running a side cutter in steel? Almost a frightening experience.
Harold
Yep, much the same as a Woodruff, but not always possible to use due to circumstances at hand. Some times you just have to use an end mill!
Harold
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My experience has been limited to my Nichols horizontal mill, a #40 NMTB taper in the spindle, and a choice of lever feed (rack and pinion) or leadscrew feed. For a lot of things on that machine, including cutting keyways, I prefer the lever feed option. It lets me apply feed until the machine sounds unhappy, and then back off -- except that so far, I have not had the nerve to push it hard enough for it to sound unhappy. It just keeps cutting. :-)
Enjoy, DoN.
Dammit Don, the way this thread was going, I was betting that it'd be a week before someone mentioned plain milling cutters in a horizontal mill. You forgot to mention the added value of such a keyseat: that of a minmised stress riser at the termination.
Tom
That's sort of what you do with a K&T, only it's by increasing the power feed. You simply turn a handle while it's cutting, and it increases with each half revolution. I've taken cuts in chrome moly with large side cutters advancing at 10"/min. It's nothing short of amazing to watch the chips accumulate, all the while the machine isn't even grunting. I'm sure you can imagine the difference when a K&T may weigh three tons as opposed to your hand mill, which sounds like it's doing one hell of a bang up job!
Harold
That's what robert bastow used to say about horizontal mills. His instructions on setting one up involved getting the setup straight, turning on the spindle, and coolant, and then cranking the feed by hand until the machine sounded like it was bogging down.
Then back off a bit, and set the automatic feed to keep up with the hand feed. Then sit back and watch it just shit out chips.
Jim
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