60 degree included angle double angle cutter, such as http://www.use-enco.com/cgi/INSRIT?PMAKA=367-7100&PMPXNO=948041&PARTPG=INLMK32 might work. not too too spendy, and can be ground to get within a full thread of a step. the solid carbide lathe I.D. thread tools work too if you can set them up to turn eccentrically (a boring head performs this function quite nicely.) the carbide single points are nice because they come in smaller effective cutting diameters, so the deviation from thread profile can be minimized to an extent when just using helical interpolation. if you're using a rotary table set at the proper angle, this is not a problem. another approach is to set the rotary table to cut the thread with the spindle at 90 degrees to the thread axis using a 60 degree chamfer tool, like http://www.use-enco.com/cgi/INSRIT?PMAKA=325-2218&PMPXNO=5809091&PARTPG=INLMK3 note: the sharp points on such tools are REALLY fragile, so go super slow feed if you need a sharp vee. it's possible to hand grind a tool like this out of a broken old carbide tool stub, but in my experience, it takes many many tries to get the point on the center of the shaft (+/- a small flat end tolerance) and still have the required back relief all the way around.
--- On Mon, 12/26/11, gene heskett <ghesk...@wdtv.com> wrote: From: gene heskett <ghesk...@wdtv.com> Subject: Re: [Emc-users] Another off the wall thought To: emc-users@lists.sourceforge.net Date: Monday, December 26, 2011, 5:04 AM On Monday, December 26, 2011 07:37:48 AM Dave Caroline did opine: > I have cut threads that way. > the tooling > http://www.collection.archivist.info/archive/DJCPD/PD/2009/2009_08_13_cn > c/P1010245.JPG > > I also tilt the rotary axis so the cut properly follows the helix, > this requires some maths in the gcode to follow the tilted path > > before I made that tool and also before the B axis I made a worm > jacking the rotary to the required angle with some packing > http://www.youtube.com/watch?v=Jbp8SJ9RxqI > > Dave Caroline > That is exactly what I have in mind, Dave. What sort of a tool is that in the movie, and where can it be obtained? Looks like some sort of a multitooth rig to be able to cut full depth in one pass. If that tool can cut steel with a decent life that is, I note you are doing brass in the movie but this will be in a BP rifle, an un-vented 209 primer nipple TBE. I've found a load that does sub 2" groups at 50 yards, but BH209 powder is so hard to light that in a rifle using #11 caps, I have to put a starter charge of 5 gr of RS into the hole first, then follow that with 60-90 gr of BH209. Then the bullet. But if I change the nipple to one that will put the full power of a std 209 primer into it, that should work w/o the duplex loading & that is what I want to do. But the 209 nipples available to fit this one are all side vented to reduce the primers fire because the full jolt is too much for real black powder. BH209 powder is actually a smokeless, and the cleaning required is a byproduct of having to use the duplex loading to get it to ignite. I tried it once with the vented nipple, and had to remove the nipple and add a few kernels of RS into the hole, put the nipple back in. Next trigger pull did fire, but with about a 250 millisecond hangfire. Bullet off the paper... BH209 is so hard to light, I'm told it doesn't need a hazmat warning or fee, but its still $10/oz. What the heck ever happened to BP being cheap to shoot? Thanks. > On Mon, Dec 26, 2011 at 8:00 AM, gene heskett <ghesk...@wdtv.com> wrote: > > Greetings; > > > > I've about worn out that 7x10 I have, and its rubber tool post > > prevents me from doing anything resembling a fine finish regardless > > of the sharpness of the bit. When cutting threads I have to, before > > reversing the spindle to back away & reset to deepen the cut on the > > next pass, back the crossfeed off a full turn to keep the bit from > > dragging on the thread as it supposedly retraces its path backwards. > > I knew it was a toy when I bought it, and I'm considering its > > replacement with something big enough that its worthwhile cnc'ing it. > > > > I have a need for cutting a clean, nearly interference fitted 1/4x28 > > external thread for a distance of about 1/4", immediately adjacent to > > a 1/2" diameter seating plane when this is screwed into its receiver. > > > > I don't have an encoder on either the lathe or the mills spindle, so > > the thought runs toward a flying cutter in the mill spindle whose tip > > profile is that of the 60 degree included angle tooth. > > > > Now, the cutter would be working on the side of the workpiece, mounted > > with the axis vertical in a chuck on a rotary table, turning very > > slowly as the z axis travels in 1/28 step. > > > > Since I can run the z axis and a axis in lock step, what prevents me > > from cutting this thread with the fly cutter other than finding a > > suitable fly cutter? > > > > I thought so, so where in tunket can I find such a fly cutter that is > > actually holding a single point threading insert, perhaps an inch in > > diameter overall. Googling hasn't found such a beast at less than 3" > > in diameter and many BIG bucks cost. Or is this just another tool > > I'll have to make, in which case it will be holding a less easily > > fractured square piece of HSS tool steel, not a carbide chip. > > > > Or is this just another idea I should forget because I'll not be able > > to hold an edge on the HSS tool because of the impact of its striking > > the workpiece and taking off a thou or less per revolution? > > > > Thanks guys. > > > > Cheers, Gene > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > My web page: <http://coyoteden.dyndns-free.com:85/gene> > > Now I lay me down to sleep > > I pray the double lock will keep; > > May no brick through the window break, > > And, no one rob me till I awake. > > > > ---------------------------------------------------------------------- > > -------- Write once. Port to many. > > Get the SDK and tools to simplify cross-platform app development. > > Create new or port existing apps to sell to consumers worldwide. > > Explore the Intel AppUpSM program developer opportunity. > > appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------ > ------ Write once. Port to many. > Get the SDK and tools to simplify cross-platform app development. Create > new or port existing apps to sell to consumers worldwide. Explore the > Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join > http://p.sf.net/sfu/intel-appdev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> No man's ambition has a right to stand in the way of performing a simple act of justice. -- John Altgeld ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
