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Instructor approves cutting steel at 2000sfm

plastikdreams

Diamond
Joined
May 31, 2011
Location
upstate nj
Just for a little action, I ran a 5 flute .500 40° helix .030 carbide AlTiN coated, .100 deep full width 1800 rpm 10 ipm (coulda gone faster) on a Bridgeport, air blast in o1 steel. (the carnage) all was good until I took a chip to the corner of my left eye...all is well and was able to finish the task...hurt like a mother fucker for about a half hour lol.

Beat that!
 

barbter

Diamond
Joined
Oct 27, 2007
Location
On Tour...
Just for a little action, I ran a 5 flute .500 40° helix .030 carbide AlTiN coated, .100 deep full width 1800 rpm 10 ipm (coulda gone faster) on a Bridgeport, air blast in o1 steel. (the carnage) all was good until I took a chip to the corner of my left eye...all is well and was able to finish the task...hurt like a mother fucker for about a half hour lol.

Beat that!

That will teach you!
 

G00 Proto

Hot Rolled
Joined
Feb 18, 2013
Location
Dirkdirkistan, ID
Just for a little action, I ran a 5 flute .500 40° helix .030 carbide AlTiN coated, .100 deep full width 1800 rpm 10 ipm (coulda gone faster) on a Bridgeport, air blast in o1 steel. (the carnage) all was good until I took a chip to the corner of my left eye...all is well and was able to finish the task...hurt like a mother fucker for about a half hour lol.

Beat that!

I was doing a similar experiment using 1.5” long 1/8” 3 degree drafted endmill around the outside of a standing mold core. The cut sounded funny so I walked around the back of the open mill table just as the cutter broke. It flew up several feet and buried itself through my lower lip all the way to my incisor. It bled and hurt a lot.


Sent from my iPhone using Tapatalk
 

plastikdreams

Diamond
Joined
May 31, 2011
Location
upstate nj
I was doing a similar experiment using 1.5” long 1/8” 3 degree drafted endmill around the outside of a standing mold core. The cut sounded funny so I walked around the back of the open mill table just as the cutter broke. It flew up several feet and buried itself through my lower lip all the way to my incisor. It bled and hurt a lot.


Sent from my iPhone using Tapatalk

Got me beat!

I had a punch explode trying to get a stuck pin out, took a few days to dig all the shrapnel out of my fingers lol.

I used to wear a face shield, I've been meaning to go back to it.
 

Strostkovy

Stainless
Joined
Oct 29, 2017
Got me beat!

I had a punch explode trying to get a stuck pin out, took a few days to dig all the shrapnel out of my fingers lol.

Long ago my dad was in a shop class and they demonstrated heat treating by tempering punches all differently and showing the failure mode of each, including brittle failure. In that same class my dad tempered a wrench as hard as he could and proceeded to slice his hand when it snapped.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
OT old crash this thread just recalled to mind

Sort of off topic here. This thread reminded my of a crash I saw long ago, like a new Mori sl-2 ago.

Guy from England was visiting the owner's son, who was sort of a dummy. In the shop we were all kids and the visitor was a pretty nerdy english home shop hobbyist sort so we were getting a kick out of watching him. He'd never seen a cnc lathe run so the boss told Brent, the guy setting the thing up, to press the green button and show the little guy what it woud do. Brent said it wasn't set up yet. The son said awww go ahead and show him what it will do. This went back and forth several several times until boss's son finally told Brent to "just push the goddamn button". Brent closed the door and pushed the GD button. The cycle started and the indexable drill came down and crashed right into the chuck. The little british guy musta did a personal best vertical jump. Brent turned to the Brit and in a deapan said "what did you think of that?" Boss's son just stood there like a dummy. We all howled. Like I said we were all kids and we were so proud of Brent.:D

Luckily no blood on the floor but ruined tooling and misaligned machine. And a shamed boss's son.

Now for the on-topic rest of the story. Guy in power was a dummy and put the operator/programmer in a bad spot, just like this idiot instructor. Hopefully nobody will get hurt. Or better yet he will see reason.

It has been my long experience running HSS endmills in mild steel w/o flood coolant just mist or brushed on that much over 100 SFM and tool life goes to hell in a hurry. That has only been on manual stuff. Never have used or very, very sedlom used HSS in the CNC's. Out of curiosity I googled HSS endmill speeds and feeds. For 1/2" 2 flute em slotting 300 BHN alloy steel .25 deep regal cutting tools suggests 360 SFM and 11 IPM. Chip load sound reasonable to low but that SFM is crazy high and 300 BHN is not mild steel territory either. That is carbide speed. Maybe the instructor got his info from some chart like this, or maybe a forum somewhere. Lots of bad info out there! Or maybe he has SFM and RPM mixed up. I don't have a machining center anymore but if I did I'd try the regal recommendation. It's not inherently dangerous and now I'm really curious if it would work for any amount of time at all.:skep:
 

plastikdreams

Diamond
Joined
May 31, 2011
Location
upstate nj
Sort of off topic here. This thread reminded my of a crash I saw long ago, like a new Mori sl-2 ago.

Guy from England was visiting the owner's son, who was sort of a dummy. In the shop we were all kids and the visitor was a pretty nerdy english home shop hobbyist sort so we were getting a kick out of watching him. He'd never seen a cnc lathe run so the boss told Brent, the guy setting the thing up, to press the green button and show the little guy what it woud do. Brent said it wasn't set up yet. The son said awww go ahead and show him what it will do. This went back and forth several several times until boss's son finally told Brent to "just push the goddamn button". Brent closed the door and pushed the GD button. The cycle started and the indexable drill came down and crashed right into the chuck. The little british guy musta did a personal best vertical jump. Brent turned to the Brit and in a deapan said "what did you think of that?" Boss's son just stood there like a dummy. We all howled. Like I said we were all kids and we were so proud of Brent.:D

Luckily no blood on the floor but ruined tooling and misaligned machine. And a shamed boss's son.

Now for the on-topic rest of the story. Guy in power was a dummy and put the operator/programmer in a bad spot, just like this idiot instructor. Hopefully nobody will get hurt. Or better yet he will see reason.

It has been my long experience running HSS endmills in mild steel w/o flood coolant just mist or brushed on that much over 100 SFM and tool life goes to hell in a hurry. That has only been on manual stuff. Never have used or very, very sedlom used HSS in the CNC's. Out of curiosity I googled HSS endmill speeds and feeds. For 1/2" 2 flute em slotting 300 BHN alloy steel .25 deep regal cutting tools suggests 360 SFM and 11 IPM. Chip load sound reasonable to low but that SFM is crazy high and 300 BHN is not mild steel territory either. That is carbide speed. Maybe the instructor got his info from some chart like this, or maybe a forum somewhere. Lots of bad info out there! Or maybe he has SFM and RPM mixed up. I don't have a machining center anymore but if I did I'd try the regal recommendation. It's not inherently dangerous and now I'm really curious if it would work for any amount of time at all.:skep:

Personally I don't run hss ever anymore unless I absolutely have to, eg using a .4375 hss endmill for a counterbore in 954 bronze. I've gone so far as to buy my own tooling just to make sure I have what I want. The Kennedy has a drawer full of endmills from .375 - 1.000 endmills :D
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
Personally I don't run hss ever anymore unless I absolutely have to, eg using a .4375 hss endmill for a counterbore in 954 bronze. I've gone so far as to buy my own tooling just to make sure I have what I want. The Kennedy has a drawer full of endmills from .375 - 1.000 endmills <img src="/vb/images/smilies/biggrin.gif" border="0" alt="" title="Big Grin" smilieid="66" class="inlineimg">

A shame you have to do that. And expensive for 1"! Sucks not to have good tooling provided. I've had my own shop for years and good, appropriate tooling always provided. I hope at least, no complaints. Hate to struggle by when proper tooling makes job a breeze. Pay know or pay later you know.

I'm still thinking about some of the comments that hundreds of surface feet per minute in mild steel is ok for HSS. I guess it is ok if you want to ruin stuff.

Here is a couple of charts that reflect what my experience and common wisdom support. The black and white is for HSS.
 

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sendithard

Plastic
Joined
May 18, 2021
Welp....today was the day. I considered recording it, but I took cover after what I witnessed when the program was loaded this am.

I took a picture that isn't great after they tried to AGAIN run a face mill at 10k rpm but with .003 vs .005 chip,load....ill post later. It ain't mind,blowing just smoke pillowing around the mill.

To recap, I was quite geniuinly concerned when I heard the instructor not only approve a student running a 3/4 in end mill at 2000SFM in steel, but then double downed when I raised a firm warning. I'm an idiot, chip load is the only thing that matters. The pressure is the same. Don't run a corvette with only 4 cylinders. Why do they make 10k spindles. The machinist handbook is good if you don't wanna make money. Manufacturers speeds are BS, I could go on. I honestly like the instructor and have learned much, but he just doesn't get it here for some reason.

So I witness the below gcode today. I told the student if he realizes this is 8k sfm. He thinks I'm dumb too. I also found out he is adaptive clearing/opti roughing with the entire part with same speeds.

(Face Milling at Z0, .03-.04 doc, .005 chip load)
(3in Face Mill 7Fl)
T14 M06
S10000 M03
G43 H14 Z1.0 M8
G00 X4.0 Y-1.25
Z0.0
G01 X-7.0 F350.0

The sparks that shot out of the face mill were fkin epic. The vegatable oil roasted the room in a full blanket of smoke and someone from the school must have seen the camera video bc we got a visit.

Face Mill inserts are toast, but honestly the machine looks okay and the holder looks fine.

The instructor thought taking the chipload down from .005 to .003 was 'the ticket'....we got another glorious fireworks show with more smoke, so that is when I left for the day.

We are off next week for break. I do honestly deep down like the instructor but what happened today, while not the carnage that you all would love is imho reckless and needs to be rectified.

Not sure how to approach starightening out this instructors hard headed brain from thinking the only thing that matters is chip load. I'm questioning sending and email, but no clue who or how. They recipient would have to understand what 8000sfm really means let alone his program at 2000sfm.


On,a side note, I actually looked up the kennemental calculator and it is strange that higher sfm but same chip load reports similar forces. I told him over and over that you are doing work faster which regardless of tooth force doesn't mean overall pressure force.

Im tired of typing, thanks for,listening and any suggestions are appreciated. I thought running a 3in face mill today at 10k was beyond reckless.
 

mhajicek

Titanium
Joined
May 11, 2017
Location
Minneapolis, MN, USA
Welp....today was the day.

Thanks for the update!

I don't like to rag on people, but... That instructor needs to be fired. He doesn't know machining 101 day 1 basics. He should never be allowed to instruct anyone about machining until he at least gets speeds and feeds down. I would never allow him to touch one of my machines. Please direct his employer to this thread. I was all for the smoke show when we were talking about a 3/4" endmill, but a 3" facemill is dangerous. He well could have trashed the machine, and maybe even hurt someone. Overspeeding a facemill can cause the inserts to shoot off through the guarding like bullets. For kicks, calculate the centrifugal load on the insert screws at 10K RPM. That's over double what this one is rated for:

HSHF, 3" Diameter Shell Mill, 1" Pilot Bore x 15deg Lead Angle, 6 Inserts (Square), TSC
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
Yes. Thanks for the update. I wondered if the cut was ever made.

Truly a case of those that can't do, teach. The crazy part is speeds and feeds are well understood and documented. Maybe this poor soul is illiterate. He is dangerous for sure.

It is a shame students are "learning" from an idjut. Waste of tuition. Get a large group of students together to complain about the guy. Maybe someone will listen. Mention liability. That gets people's attention when nothing else will.
 

sendithard

Plastic
Joined
May 18, 2021
Thanks for the update!

That's over double what this one is rated for:

HSHF, 3" Diameter Shell Mill, 1" Pilot Bore x 15deg Lead Angle, 6 Inserts (Square), TSC

I appreciate that quick pull from the tool library...I tried in the past to warn him in down right arguments he was messed up and maybe a printout will do him some justice. We also have an ST-10 lathe so he is friendly with the Haas website. I'm also most likely going to reach out to someone up higher in the food chain. It is hard to explain the fireworks in the machine. The problem is the machine looks fine tho. Kudos to the dumb 24 yr old on the trigger hitting the reset button quickly. I did also give the kid a piece of my mind, as he is partly to blame, he fought me tooth and nail before this happened. I'm just the idiot older guy taking a cnc class what do I know.
 

sendithard

Plastic
Joined
May 18, 2021
cnc_smoke1.jpgcnc_smoke2.jpg

I'm not really sure if this attach pic deal is working, but if the pics are inserted it just show pillowing smoke coming from the mill, nothing special. It was actually worse than you see on the pics. The smell wasn't bad, but after the second attempt at the 10K rpm run I got pissed, enough was enough. What was awesome, was the sparks that flew. The student kudos to him hit the button fast as fk.
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
It is a shame students are "learning" from an idjut. Waste of tuition. Get a large group of students together to complain about the guy. Maybe someone will listen. Mention liability. That gets people's attention when nothing else will.

The sad thing is this may get the program shut down, rather than the instructor "instructed".

It does seem really odd to me that there's so much hardheadedness going on with stuff that's easily confirmed with a tiny bit of web searching.
 

sendithard

Plastic
Joined
May 18, 2021
Some advice. Don't call people names, makes you come across as an asshole. Do NOT assume the brain cell count of anybody you have never met in person. I doubt you are qualified to hand me a caliper by what you post, but you may be a fookin brain surgeon (well junior brain surgeon). And I like fundamentals, and for damn sure like to push them in most aspects of my life. Comfort zones need to be tested and expanded. Run the program, push till something breaks. Back off just enough to git er done.

Just logged back in today to update. I called you a goofball, b/c you are a goofball. I am not clickbait as you so eloquently called my post. I'm a real life person believe it or not. And my friend...I am a die hard UFC fan so anyone here can understand when I call you a goofball.
 

sendithard

Plastic
Joined
May 18, 2021
The sad thing is this may get the program shut down, rather than the instructor "instructed".

It does seem really odd to me that there's so much hardheadedness going on with stuff that's easily confirmed with a tiny bit of web searching.

I'm not gonna let that happen. I'll see what I can do to get these, what I call dumb and dumber, idiots thinking in terms of sfm vs chipload. I am considering an email to the admin as well.
 
Joined
Apr 14, 2018
Location
Airstrip One, Oceania
I'll see what I can do to get these, what I call dumb and dumber, idiots thinking in terms of sfm vs chipload. I am considering an email to the admin as well.
I have no idea why he's even babbling about "chipload" but ... might work better than Just Another Student telling him he's full of crap - have you got any tool suppliers around there, like Coast Tool ? Ask an outside salesman to drop by and explain the basics of metalcutting ?
 








 
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