How would you do this

On 3 Jul 2004 18:13:47 -0400, snipped-for-privacy@d-and-d.com (DoN. Nichols) calmly ranted:

Interesting. How does that work? If the mill cutting edge takes away a sliver of steel, the steel would no longer seem to be in its way. How would it work-harden the area?

Would deflection be built (calculated) into the program running a CNC mill? "Toss it a couple thou thataway when moving thisaway at this speed and cutting depth with this particular mill type and size."

"Be the change you want to see in the world." --Mahatma Gandhi - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Below a certain feed rate, you reach a point where the mill deflects instead of cutting under the surface, and rubs on the workpiece. This compresses the workpiece a bit, work hardening it. Some metals are a lot more vulnerable to this than others. Some stainless steels are particularly bad about this. You have to feed fairly aggressively to keep cutting under the surface, or you will reach a point where the end mill is just skating on the surface, and you'll never make progress with that.

Not normally. It would be better to select the proper tool to avoid the problem in the first place (2 or three flute end mill, instead of four flute in this case.) The four-flute (or more) is better when just side cutting, as the more teeth the more feed per revolution you can apply.

I guess for extremely high precision work, it might happen, but since the hardness of the workpiece can be variable, it would be likely that what worked just perfectly for the first workpiece would not work as well for a second -- or perhaps the fifth, or whatever. So I would not want to bet on it. I would rather go for the proper selection of tooling instead.

Enjoy, DoN.

The cutting action is the same in a home shop or a production shop. The main difference is the horsepower (usually) and the machine is likely to be CNC with faster feed rates. If you are simply doing something quick and dirty..and dont care about the slot size or internal slot finish..no..it makes no difference.

Btw..google Endmill manufacture will bring up scads of online info. Same with taps, etc.

Most manufactures have realized that the Net is a great way to not only hype their product, but to explain in great detail why. LOL..so some of the best minds in cutting technology of all types have been paid copious sums to teach you all about the whys and wherefores.

Its a very cheap way to learn the mechanics of the tools you use in the shop.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

On 4 Jul 2004 02:01:34 -0400, snipped-for-privacy@d-and-d.com (DoN. Nichols) calmly ranted:

OK, gotcha: the small bit of rubbing can work-harden some metals.

So would the number of flutes also be a determinant for speed (revs, for chip removal) or are diameter and metal type still the main factors?

Thanks, Don.

"Be the change you want to see in the world." --Mahatma Gandhi - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

No. Speed is determined by surface feet per minute of the cutting edge. Feed is a chipload formula. A quick and dirty way of estimating correct feed is to look at the chips. Blue nines are considered good, most of the time.

Ron Thompson On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

The ultimate result of shielding men from the effects of folly is to fill the world with fools.

--Herbert Spencer, English Philosopher (1820-1903)

The diameter and the metal type (and the tool material) are the main factors in this. It is just that there is a maximum chip load per tooth, and with more teeth, the chip load is divided between them.

The worst case would be either a fly cutter, or a tool with only one remaining flute (for whatever reason). There, the chip load is all handled by the one tooth (or flute), so that is the limit of the feed rate.

Enjoy, DoN.