Milling a small slot, how??

Butch, I'm not about that. I tried to avoid this. I am perfectly comfortable with nobody knowing who I am. I first wrote on this thread to help educate people since there was much misleading being done. I was personally called out as not being credible. In a defensive posture, I've explained a bit of who I am now. I have no motivation to shortchange Mr. Sharrett.
 
Joe Woosman said:
No, speeds and feeds are not technical stuff. Neither is knowing what an M-code coolant command is. The proper application of such things IS technical stuff. This is the difference between the "machine operator" machinists and the guys that actually engineer machining operations.




. Your turn Jerry.
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No, the "proper application of such things" as you put it, is not technical stuff. That field of Manyfacturing Engineering is a specialty titled Process Engineering, a process development sector. The "speeds and feeds" stuff does not come along till the Application Engineering sector of Manufacturing Engineering.

NC, Numerical control, CNC Computer Numerical Control?? Hmm, where have I heard of that term?

For starters, the Numerical Control Society, created in 1965, I was a founding member. The NC Society chapter of Rochester New York, I was a charter member of that group being part of the Eastman Kodak family of companies. (Some of the members of the NCS of Rochester included Kodak, Xerox, Baush & Lomb, Gleason Gear, and a few others I can't readily remember)

IITRI, the Institute Institure of Research Technology, developer of the APT programming language that preceeded CNC? I was at IITRI with Bob Olker who expanded the APT language for NASA and IBM in the late 1960's for a time.

I have been in the HOMES of the CEO's of some of the major machine tool builders such as Giddings & Lewis, Kearney & Trecker, Cincinnatti-Milacron, and American Lathe. Oh, we mentioned MAZAK, I have been in the home of Terry Yamazaki, owner of Mazak, in Osaka, Japan. (Terry has a Ming Dynasty tea pot in his foryer worth some $5 million dollars, but he is a bit of a show-off!)

I have held a Senior Manufacturing Engineers certification in the Society of Manufacturing Engineers since about 1975...but I digress.

Now does that qualify me as having some knowledge about CNC and its applications?

Enough pi$$ing for a while...time for dinner.
 
Speaking of climb milling :)

There's a hand tool out called the RotoZip. we use it in construction, kicker is that they use reverse-twist bits that cut downward, like an upside-down drill bit. For light plywood and sheetrock they're astounding. I did not try one on the trigger guard but now I'm going to. It seems that the cutting pressure acting downward could be helpful.....

Anyone try one of these bits in a mill yet?

I will soon.

al
 
Al,
I have some reverse flutes endmills, is that the same?
I will have to say that I have not read the whole thread. I have seen enough of your post Joe to understand that you know how to turn on a machine. My only point though was Jerry knows how to turn on a machine also. Joe, I understand where you're coming from as it is easy sometimes to get my hackles up.
 
Butch Lambert said:
Al,
I have some reverse flutes endmills, is that the same?
.
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Butch, what you are talking about is probably a left-hand helix endmill. Those are designed to mill thin workpieces that would tend to be pulled away from their fixturing by a right-hand helix.

Shallow helix angle left-hand helix endmills are also used for tough to machine alloys since these endmills 1) tend to not pull out of their holder in heavy cuts and 2) tend to absorb the shock load of heavy cutting better.

Guys, I'm outta here We've hijacked Al's thread enough on side trips.
 
Respectfully to all:

Believe me, Joe is the real deal. And then some.

Good shootin' and don't forget to have fun. :) -Al
 
JerrySharrett said:
I see you have never done any high speed profile milling, like wing spars and such.

With what you just wrote I kind-of wonder if you have done much real machining at all.
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agreed all the theory goes out the window real fast in the real world. come on the 3 times rule what about a mold cavity 6 inches deep with 1/2 rad. corners I guess we'll tell them nobody can make it. george
 
geo.ulrich said:
agreed all the theory goes out the window real fast in the real world. come on the 3 times rule what about a mold cavity 6 inches deep with 1/2 rad. corners I guess we'll tell them nobody can make it. george
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You old toolmaker types are unbelievable. Practically unteachable cuz you already know it all.

Attached are two pics. First one a highlighted line from the Machinist Handbook on the introductory page of "speeds and feeds" citing the correlation of cutting speed to heat and tool failure. What I have stated previously is just a matter of technical fact.

The second pic is of three tools I have mounted in a machine right now. The lowest tool has about a 12:1 length to diameter ratio. The cutters have some very special geometry to make something like this work without the cut looking like a beaver whittled it out. You will also notice some pretty special tool holders. The 3X diameter rule is as I stated, a rule of thumb. Anything less than that and usually no special attention is required. Start getting longer and the game changes.

JerrySharrett said:
Now does that qualify me as having some knowledge about CNC and its applications?
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I suppose so. But it has nothing to do with the technical aspects of machining. My machine tool salesman rubs elbows with the CEOs too but he doesn't know jack about machining. Not saying whether you do or you don't. Just saying discrediting me by arguing with fundamental machining principles isn't building a strong case.
 

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alinwa said:
I recently milled a short slot through a cast trigger guard for the Jewell trigger to clear. The action is FAT, the trigger is on a hanger and the stock is too shallow.....and I didn't want to shorten the trigger.


Anyway, The slot is about 3/16 wide, I milled it using an endmill slotting progressively deeper and it came out looking like dung. I filed it to clean it up.

My question is, what would be the appropriate cutter to just plunge thru and then walk sideways?

Will a rougher work? Do they come that small? Is there a "sheet cutter?"

I'm a rank newbie on the Bridgeport :)

Thanks
al
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Al, Isolate your vibrations and your troubles will likely be gone. You will always need to make minimal cleanup cuts if you want the finishes purdy. Another rule of thumb to follow is a typical endmill can usually take about 50% its diameter in depth of cut. Less than that is safer with less tool/part deflection forces. Your vibrations and dung finish are likely caused by the weakness of the trigger guard itself. If you could somehow clamp the trigger guard near the cut you should see a big improvement. Your cutter design is probably secondary to your presumed rigidity problem.

If I am not of help to you, there is no sense in my sticking around. I sure got better things to do so just let me know.
 
Joe Woosman said:
You old toolmaker types are unbelievable. Practically unteachable cuz you already know it all.
Sounds kinda like mfg. engineers have all the theories and can find it in a book, but the actual doing they are totally lost.sorry if your feelings are hurt us old GAGEMAKERS have seen and made more than you can even dream of just about any 1 yr. apprentice can write a program and hit cycle start and spit a part out,lets move into working in the .00002 area then come and talk.also the reference of s.f,m. should be know by anyone running machinery, unless they have an unlimited tooling budget. george
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Joe Woosman said:
Al, Isolate your vibrations and your troubles will likely be gone. You will always need to make minimal cleanup cuts if you want the finishes purdy. Another rule of thumb to follow is a typical endmill can usually take about 50% its diameter in depth of cut. Less than that is safer with less tool/part deflection forces. Your vibrations and dung finish are likely caused by the weakness of the trigger guard itself. If you could somehow clamp the trigger guard near the cut you should see a big improvement. Your cutter design is probably secondary to your presumed rigidity problem.

If I am not of help to you, there is no sense in my sticking around. I sure got better things to do so just let me know.
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Isolate your vibrations and your troubles will likely be gone.
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"Catch 'em on the bounce" eh??? It's funny you should bring this up :) I went and played with a similar hunk of metal hung flat and hung at at an angle (The slot runs down over the end) and rolled the VFD around and found that in my case the vibration thing is huge. Of course as the slot lengthens and widens the harmonics change so at times I felt that having a twist throttle woulda' been hoovis LOL! (In fact I did play with this idea.... VFD's is awesome!)

Anyways, it's making sense now. Your description of vibration control resonates with my psyche....

Thanks to you all for the help. The next one will be better (altho I'll probably never slot another cast iron triggerguard)

al
 
Time Marches on:

In one of the Shakespeare plays is the Quote, "The Old Order Changeth, yielding place to the new." It may be FOR the new; it's been a long time since High School English but I think it is a good quote to be mindful of. A lot of times what we have known to be true in the past is no longer, in spite of having seen whatever it was work. No disrespect meant with this but sometimes one should just consider that time marches on.
 
Shucks-I hate to see these arguments-Joe, Jerry, George -I know all three of you and have the utmost respect for each of you and your abilities. I am sure that if all three of you were in the same room-the conversation would go differently! :) I can vouch for the skills and knowledge of each you. Each of you just have different ideas and approaches.

So-Al--the suggestions you got from each have loads of value

Jim
 
Al

climb milling is definitely way to go-but make sure you tighten up your gibbs and put tension on the table travel with the lock screw to prevent the "jumping" that can occur when climb milling on a normal lead screw. I have seen kits available to change standard lead screws to ball screws so that you do not have to worry about that.

Climb milling will provide a much smoother cut.....................
 
Thanks Jim, I'll try it.

To all of you, thank you for the level of expertise you'all brought to bear. I got more hunnerd years of experience than I expected that's for sure.

al
 
Just a couple of points Al

Your Roto-Zip runs at between 18,000 and 25,000 rpm. And if you could mount it rigidly enough would probably do light milling great. Building the mount would be prohibitive though.

But in the same vein as attacking it from a different direction.

I make no claims to being an accomplished machinist or tool maker, but....

Have you thought about using a slot cutter? Like cutting a Woodruff Key. And mounting the trigger guard 90° from the spindle? If you are relieving for trigger travel on the inside of the guard, the cutter radius might actually be beneficial. Not to mention it being possible to be closer to the spindle and stiffer.
 
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