Bangin yer vmc for maximum bux....

PV:

Here are the essentials of a post I made in March of '99.

============================================================= The reminds me of a boo boo I made back in the 80's on a Bridgeport Boss I. I was grinding (with a surface grinding wheel in a special holder I made to fit the CNC) some mold ejector pins at an angle to the axis of the pin. The grinding wheel would come and contact the pin and circle around the pin until the pin was to size and go home. Well something happened one time (I don't remember now just what) and the grinding wheel tried to go sideways right through the pin and cracked the grinding wheel which then broke and tried to throw a chunk of grinding wheel, the size of about 1/3 of the grinding wheel, right through my chest at 3600 rpm! I stood there just stunned holding may hand to my chest on top of the chunk of grinding wheel. Man, my chest was black and blue for weeks. :) ==============================================================

Boss 1? Stepper machine if I recall correctly. It probably missed a whole load of steps.

Wayne.....

Grinding drills? You need to set some, like, loftier goals for yourself, man!

Like for example, I grind the threads on unscrewing cores for dies like the one in the following video on a VMC, specifically a Fadal 4020 w/Fanuc 18i control.

(13.3MB)

I took a standard surface grinder wheel hub, turned an arbor (left hand thread and taper) to hold the hub and wheels with in a CAT 40 tool holder, mount precision radius chisel point diamonds in vee blocks bolted to the table to form dress the thread profiles on the wheels (at first it's kinda' weird wrapping your head around the programming for the form dressing since the programming is a mirror image of the final shape on the wheel) and grind the the threads, which are tapered .001" per revolution for molding purposes BTW, from solid on the cores.

It's impossible to generate a perfect thread form this way, ideally the wheel should be tilted the lead angle of the thread, but we're making cores for molded magnesium nuts here, not lead screws for Swiss jig boring machines.

You forgot beer can smasher...

I gather Boss 1's were not enclosed??

Well, the wheels I was thinking of were more along the lines of mounted points, mebbe 1 to 1.5" dia for larger drills, on the order of 1/4" dia for smaller drills.

And, for drills of a similar angle, and setting a common z0, a variety of diameters could be done in one setting. I think I've seen drill chucks with thru holes, that would make very convenient drill holders for this process.

Offhand it would seem that two 180 deg simple-ish helix's would do the job, one CW, the other ccw.

From a $$ pov, with enough drills in the right fixture, it would seem that this could more than machine time, esp. with specialty drills, large drills, better alloys/carbide, etc.

It also pains me to have to buy stub drills -- I spose I could get a drill doctor. But if the right wheels/fixture were readily available, this would actually be pretty convenient -- all's you would have to do is mount it in a vise, indicate center, and get z0.

A pain perhaps for just 1 drill, but not for a bunch, or a special grind.

Wayne:

Steppers sounds right, it was a long time ago. IIRC, the table had a built in pin in the lower left quadrant that you had to indicate on startup for set machine zero.

PV:

Correct, no enclosure. This was pretty much antique technology compared to today. The days of machines run from programs saved to paper tape punched by Flexiwriters.

Well, for any drills smaller than about 1/4", it's probably more cost effective to just throw them away when they get dull.

There are companies that specialize in drill sharpening for the larger drills. Using your CNC mill for that purpose seems more along the lines of a hobby exercise to me. You could always hand sharpen them. People have been doing that for

100 years.

Don't miss this one, with an appropriate bit of home made tooling, you could have the coolest, fastest, and most expensive beer can crusher in the neighborhood!

When I worked at Ames Research Center, they had what I thought at the time was a pretty drop hammer press. Well not sure of the exact term for it, but massive air cylinder up top and about a 4' square platen. Once in a while this one guy would bring in a couple trash bags full of aluminum cans and spend his lunch carefully filling the whole platen. He'd gently bring the ram down to a few inches over the cans, then whomp the crap out of them. In an eye blink, 12 cases worth of cans squashed to about 1/8" thick!

Jon

He could start by learning to tell the truth instead of lying his ass off:

"Kristofer Hogg... has an extensive background in machining and manufacturing processes."

He could attend adult education for machining.

He could move out of manufacturing wasteland like Yonkers, NY and get a job as a machine operator in a job shop and start learning the trade cause he isn=92t gonna get rich selling his bogus door jamb mounted exercise equipment.

Jon Banquer San Diego, CA

He could start by learning to tell the truth instead of lying his ass off:

"Kristofer Hogg... has an extensive background in machining and manufacturing processes."

He could attend adult education for machining.

He could move out of manufacturing wasteland like Yonkers, NY and get a job as a machine operator in a job shop and start learning the trade cause he isn?t gonna get rich selling his bogus door jamb mounted exercise equipment. ==========================

Oh, I see, in addition to being a cadcam 'spert, yer also an exercise physiologist...

Have you talked to anyone who has a HoloBarre? Two people on this group have one. I indeed may not get rich off it, but the one thing for sure it's not is bogus. If you think it is, support your assertion.

Try not to support this assertion the same way you supported your assertion that one could not manually program g-code/contour from a spreadsheet.

Oh, that's right, you don't know how to use a spreadsheet or manually contour -- too many of those darn sines and cosines, eh??

Other opinions on jb:

"Have you ever wished you could get all of Jon Banquer?s brilliance in one place? . . . . . . ."

"Jon, I agree with you. For the situations that you bring up: interroperability, teamwork, and many others like concept design, rapid design cycles, unexpected change - history is a disaster. Strangely enough though, many companies still cast their vote of approval for the stuff with every dollar they spend on it."

Jon Banquer San Diego, CA

It's just a matter of tweaking the dressing profile, should the need for= a more precise thread arise. Studer, and probably many others, does this on their cylindrical grinders. If we're *really* nitpicking, the profile = must be corrected slightly even with a tilted wheel.

Was it you who mentioned using old razor blades for checking the = profile? I thought it a good idea, but everybody around here either use a = disposable razor or one of them buzzing thingies... so we use gauge strip instead.

Pretty sure I mentioned that at one time in the past, likely was upon some discussion of J threads.

Shhhh!

Don't tell my employer that, damnit.

They'll go out and get even more work we're barely properly equipped to do.

Short of having thread profiles inspected / traced on a CMM, I have no idea what the best methods are to check them. In the case of the threaded cores an optical comparator was suffice.