End mill question?

My opinion is that as long as your mill is trammed properly (i.e. the spindle axis is perpendicular to the mill table) you would be better off milling this using the end of the end mill. If you did it with the side, the end mill would deflect slightly (although a 3/4" one wouldn't deflect all that much) and you would have to take several passes with no infeed to get all the deflection out. The biggest difference is in the chips. Chips cut by the end of an end mill aren't too bad to deal with, they look like little curls. But chips cut off the side look like tiny needles and oh boy do you get slivers.

If you do opt to mill with the side of an end mill I recommend a 1" roughing end mill. I have one of those and use it a lot on mild steel. I've never sharpened it on the periphery and it is still usable (although not razor sharp) after quite a few sessions. Then you can take your last finishing pass with a regular end mill.

Grant Erw> Here is a question for you more experienced machinists: Does the end of an

In both cases the *side* of the end mill is doing the cutting, not the end. The end only cuts during plunging.

My understanding is that the more cutter one has engaged in the work at a given time, the lower the chip load per unit edge area. I would use the side.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Not that you asked, but I like facemills and flycutters myself. Due to their massive size (especially compared to endmills) they offer significantly increased rigidity and allow greater depth of cut, chipload/tooth and spindle speed (assuming the standard carbide indexable facemill as opposed to the standard HSS endmill). With endmills, the operator must be conscious of breaking the cutter by feeding too fast. With facemills, you'll stall the spindle before you break something.

Your example is an excellent candidate for facemilling.

Mind you, facemills are fairly expensive (roughly $150+ and then inserts, although they can be had inexpensively on the net).

HTH.

Regards,

Robin

My experience is that I get much better surface finish using the side rather than the end of an end mill. With my projects, maximum metal removal rate usually isn't much of an issue, but a good surface finish always helps.

Mike Eberle> Here is a question for you more experienced machinists: Does the end of an

Really, his example cries out for a plain milling cutter in a horizontal.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Thanks Jim but it's not an option. I was just curious about the cutting properties of an endmill.

Thanks for all the replies!

Dave

End mills run fine in a horizontal, I do it all the time! When you are cutting 'on the side' you are basically emulating how a horizontal machine works.

A famous poster (teenut) here once said, that to shift stock you need to 'bury the cutter in the work' which is to say make all the cutting edges take an equal share of the load.

Trying to remove material with the very tip of an endmill means you are forcing the bottom 1/8 inch or so to do all the work. This means that last bit dulls faster. Spreading the work out over the entire cutting edge means you can make the chips fly faster, and keep the edges sharp longer.

This of course is figuring that the machine is rigid enough to engage two inches of endmill edge into the stock. Many bridgeports are not.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Slab mill in a horizontal. One pass, good surface finish, no muss no fuss.

Gunner

"To be civilized is to restrain the ability to commit mayhem. To be incapable of committing mayhem is not the mark of the civilized, merely the domesticated." - Trefor Thomas

As I told Jim Rozen, it's not an option because I don't have a horizontal mill! The best I can do is use the side of the cutter in a vertical mill. I was just curious which was the better way to do it.

Thanks,

Dave

Want one?

The best I can do is use the side of the cutter in a vertical mill.

Gunner

"To be civilized is to restrain the ability to commit mayhem. To be incapable of committing mayhem is not the mark of the civilized, merely the domesticated." - Trefor Thomas

Use the end of the cutter. It might not be the best solution mathematically, but then, you don't have to worry about tool deflection or machine capacity, either. If you want a better surface finish you can remove most of the stock with the end and finish up the last few thou. with the side of the end mill.

If you are going to do much of this, get a horizontal mill.....

It my also be more economical to use the end of the mill in a small shop.

The ends of end-mill cutters are easy to resharpen with minimal tooling (an inexpensive jig) on a surface grinder. These jigs can even be used in the mill itself, with a cup wheel mounted in the spindle (be careful to keep the abrasive swarf out of the mill ways, etc.). This leaves the sides of the cutter unaffected, and to full (diameter) dimension. You can then still use the sides of the cutter if/when that's more appropriate.

The spiral sides of the cutters are FAR harder to resharpen. This takes more sophisticated apparatus, beyond the means of most home shops. You can, of course, send the mills away to a cutter shop for regrinding, but that's expensive too. And, the cutters then come out undersized.

So, by putting most of the wear on the end of the mill you can potentially save money by having your cutters last longer, stay closer to size, and avoid expensive commercial reginding.

Dan Mitchell ==========

Gene Kearns wrote:

First I had to get a horizontal mill, now I've got to get a surface grinder? :-D

Dave

Yep - and it doesn't end there either.