In search of the "perfect" shaper cutting edge

[Dawai]

I saw one.. broke it I did.. yep.. I break plenty of tooling, nobody said I was perfect.

A quarter inch wide tool, with a dip right behind the cutting edge on the top side, as the tool raked the metal it cut curls.

I have not been able to reproduce it.. Been trying to.. Is there any key to this I am missing? Does it need to be polished in the dip? Hand Stoned on the front edge??

I've been cutting keyways on my southbend 7.. they are chattering and leaving a rough finish. I am running as slow as I can and got a good edge, it throws tiny needle swarf thou, not curls.

Tooling holder is a old boring bar to hold the 1/4" tool steel.. about six inches long, clapper box removed and adapter bushing stuck right in the ram swivel and locked down. Boring bar is 5/8"..

Madman suggested I cut the cutter width down to 1/8" wide at tip.. machine is too weak? or?? Perhaps boring bar is too flexible..

This is the fourth or fifth tooling holder I have made for the southbend, this one works best.. so far.. I am on about my tenth keyway with it..

[nheng]

I've only run a shaper once or twice but did lots of planer work some years back. Don't remember anything special about the bits. Seems like the back rake always took the chip off perpendicular to the cutting edge. It sounds like you have the low speed version of chatter perhaps. As you already mentioned, something in the drive or rigidity of the setup.

You may want to try reducing your end relief to reduce any tendency to dig in. Such digging could cause the needles you are collecting. Den

[Spin Doctor]

Used to use one shaper tool that had about a 1/8th tool nose radius with the back side of the tool ground back about 45D. The top rake was say 5D back and a good 10D to the side. This was in a 1/2 x 1 tool bit. Worked great in Ampco, CRS and L-6 tool steel.

[dp]

Here's a tool I ground for my shaper: http://thevirtualbarandgrill.com/mac...p/index-2.html

It's used in the video at http://www.youtube.com/watch?v=oZFFYIvTLiE to do a finish cut.

See also our friend the Artful Bodger's cutters at http://www.artfulbodger.net/docs/shaper/index.html

Just about everything to do with shapers: http://www.neme-s.org/shapers/shaper_columns.html

And if you still don't have enough: http://finance.groups.yahoo.com/group/Metal_Shapers/

[Dawai]

Well.. Still hunting the holy grail..

The cutter I was successful with, it was squared off on the end.. the top edge was dipped right behind the cutting edge like you'd taken a rat tail file and cross cut it behind it..

Kinda like a C-- with the cutting edge down.. I've so far been unable to reproduce it.. Perhaps I have too much rake on it.. I am using the 118Deg?(if I am remembering right) on the tool grinder I use for drill bits and lathe tooling. THE lathe is much more rigid and chatters less thou.

The favorite cutter there on one the pages DP posted was angled across the cutting surface on the front.. making a sideways pressure it appears like..

Ohh when you get it right, it is soooo goood.. but when it is not.. it is sooo aggravating..

[Duffy]

David, all I have been able to find on this seems to indicate that it is a "chip limiting" bit. I read that a narrow groove cut with either the edge of the wheel, or a cutoff blade from an angle grinder works just fine. You grind the groove first, and then grind the end relief until the flat spot between the groove and the end of the bit JUST disappears. This leaves LOTS of meat behind the cutting edge. The downside is that you have to grind everything away and start again when it gets dull. Some people feel that that is wasteful of tool bit. By the way, apparently there is nothing very critical about the size,(width or depth,) of the groove, since its only purpose is to break up the swarf. hope that this helps.

[Bob Ford]

Dave

I think you may have too much relief in the front. This allows the tool to dig in and chatter. Try 3 ° or less just enough to cut, but no extra.

Bob

[dp]

David - is what you have in mind similar to a single tooth profile as used in a broach? http://www.dbcbroach.com/images/illu...s/basics_2.gif

[Forrest Addy]

Not much science to shaper tools. Metal cutting it metal cutting. In high speed steel tooling for general machining, you want about 7 degrees side, top, and end rake and about 4-6 times the feed rate in nose radius. The cutting edge needs to be stoned a bit to remove most of the grind marks. If you grind a chip curler in it (not needed for a shaper because the chip length is lomited but the piece length.)

However the chip curler (when used - it's over rated) needs a good finish in the direction of chip flow. The usual method for free hand grinding the chip curler is to use the corner of a rat wheel on a bench grinder. The finish of the curler is left rough as a file and lays crossways to the chip flow. All that's needed is to tune it up by running the edge of a fine india wedge stone in the curler until the tops are knocked off the rough ground surface. A full bright clean-up is nice and even warrented in some cases, but glossy tops are OK for most applications.

[dp]

Hey Forrest - be careful of shaper/keyway cutter threads!

http://bbs.homeshopmachinist.net/archive/index.php/t-4723.html

[Forrest Addy]

Bad day for computer doofuses back then.

[Dawai]

Hope you're well Forrest...

That kinda reminds me of a young Polish lady we knew growing up..

Older brother gave her a slip of paper.. she read it, flipped it over, read it, flipped it.. over and over and over..

She then handed it to me...
On both sides it said "how to keep a dumb polock busy".. she was so red in the face I don't think he got a kiss that night..

Stuck in a endless program loop and I don't know what to do.. (a bit of gcode error?)