feed rate long length drills

had a job yesterday and it brings out a
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.266" dia twist drill
20.5 GL
about 15" of flute sticking out of holder (56 to 1 ratio)
75 sfpm
at F3.0
tool life set at 300 minutes and drilling mostly cast iron
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drill start bending 3/4" and i run to control and feed hold. drill slightly dull but not too bad.
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so i change drill, reset time for 100 minutes and change feed to F1.5 and finish drilling holes with no problems
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now i understand short drill can take F3.0 to F6.0 feed
medium length drills (jobber) can take F3.0 often more
but how can a programmer use such a extra long skinny drill at roughly 56 to 1 length to dia ratio and not put a practical feed in program.
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part cost over $5000 and machining time already is already over 20 hours into it so risky programming is definitely not encouraged. our scrap and rework rate for the year is lower than last year i believe mostly because i use
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1) excel checklist to check, measure stuff and never forget things that can cause part to come back for rework. basically i add items to checklist that i have either forgotten once and caused a part to be scrap or need rework.
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2) i have been recording feeds and speeds of all standard tools and recording any problems using tools at certain feeds and speeds and more importantly have been editing programs so tools stop breaking. always the argument slowing tool down takes too long versus not breaking the tool and faster in the long run.
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amazing a programmer does not decide a feed rate taking into account length of drill to dia ratio. then who says it worked once before, but obviously if tool slightly dull it can push it over the edge, drill can bend and break in less than 5 seconds. for myself drilling 4 holes taking 1 minute longer versus breaking drill, possibly scrap part the extra minute drilling slower is far cheaper and faster in the long run

What's the question?

rlockwood said:

What's the question?

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no question other than how can a programmer decide a drill feed rate and not take into account length of drill to diameter ratio ??
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common sense to me says you have to drill slower feed with extra long length drills

As a programmer, F3.0 seems appropriate. You have the documentation to prove otherwise, so you are correct.

Hey GUYS!! He keeps an excel file with all speeds and feeds for jobs!!

deputydawg said:

As a programmer, F3.0 seems appropriate. You have the documentation to prove otherwise, so you are correct.

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F3.0 is fine with jobber length drill not a 15" long flute .266 dia drill. point is feed can be higher with shorter drill and should be less with longer drill.
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it is no different than end milling with a extra long end mill compared to a short length end mill. not the same feeds are used normally
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sure i can use math formulas to precisely calculate feed reduction to compensate for longer length but it does not take a rocket scientist to figure feed needs to be less. i changed to F1.5 immediately after seeing it bending 3/4" as i have no interest maybe saving 10 seconds drilling time compared changing drill and digging out drill pieces and risking part damage

Mike1974 said:

Hey GUYS!! He keeps an excel file with all speeds and feeds for jobs!!

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thats correct i added another programmer basic apprentice mistake and badly chosen feed and speed to excel list i keep on standard tools.
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bad enough to make a mistake once but to keep repeating same mistake is not too smart. when drill bit is bending like a banana 3/4" out of straightness and flopping different directions 3 times a second it gets added to excel list. excel files lists facts and not opinions. hard to argue with the facts

An experienced programmer/layout fella would not start the hole with that long'a tool.
Maybe start with a Taper Length and then move up the ladder. Using even 3 drills total to get to depth is NOT a bad plan.


In this case - of low volume or one-off's. a 1/4" drill would have been fine to start the hole. Then core drill to depth and then .....




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Think Snow Eh!
Ox

DMF_TomB said:

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thats correct i added another programmer basic apprentice mistake and badly chosen feed and speed to excel list i keep on standard tools.
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bad enough to make a mistake once but to keep repeating same mistake is not too smart. when drill bit is bending like a banana 3/4" out of straightness and flopping different directions 3 times a second it gets added to excel list. excel files lists facts and not opinions. hard to argue with the facts

Click to expand...

You didn't happen to look at the program and think, "hey this shits to fast"? Do you just blindly hit start and then when something goes wrong, yell that its all the programmer's fault? I agree that is wrong, but you should be looking at what each tool does before going on. That is YOUR fault. Everyone makes mistakes, especially if you're programming all day.

Do you put how big your dump is along with what you ate on the excel list too?

Ox said:

An experienced programmer/layout fella would not start the hole with that long'a tool.
Maybe start with a Taper Length and then move up the ladder. Using even 3 drills total to get to depth is NOT a bad plan.


In this case - of low volume or one-off's. a 1/4" drill would have been fine to start the hole. Then core drill to depth and then .....




---------------------

Think Snow Eh!
Ox

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.266 dia hole only about 3/4" depth, drill bit with 15" flute is to reach section of part and not crash. picture shows the part thats about 36" wide
...... we machine from all 5 sides as we have a vertical and a rotating horizontal head

AARONT said:

You didn't happen to look at the program and think, "hey this shits to fast"? Do you just blindly hit start and then when something goes wrong, yell that its all the programmer's fault? I agree that is wrong, but you should be looking at what each tool does before going on. That is YOUR fault. Everyone makes mistakes, especially if you're programming all day.

Do you put how big your dump is along with what you ate on the excel list too?

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1) i of course calculated feed and speeds and had that program section with posted note on hardcopy listing potential problem as well as a M0. this is why i was at the cnc control and was able to feed hold in time when i saw drill bit bending 3/4"
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2) i am specifically ordered as a CNC operator to NOT adjust feeds and speeds until there is a problem. Facts and not opinions is what they want
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3) it is extremely common for me to find 10 "potential problem" areas in a 10 hour run program run and to add M0 or M1 and warnings to let me be at the cnc control and not 100 feet away on the other side of the cnc changing tools.
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even when programmer makes basic apprentice machinist errors i have to give him the benefit of a doubt and try what he wants to try. 10% of the time he is correct

I don't know what they are called but I have good luck with drills like these. They are a little more stiff don't have a tendency to want to bend and walk around on ya also allows you push harder. I made these but pretty sure you can buy them. That is if im understanding what's going here?

Brent

DMF_TomB said:

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1) i of course calculated feed and speeds and had that program section with posted note on hardcopy listing potential problem as well as a M0. this is why i was at the cnc control and was able to feed hold in time when i saw drill bit bending 3/4"
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2) i am specifically ordered as a CNC operator to NOT adjust feeds and speeds until there is a problem. Facts and not opinions is what they want
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3) it is extremely common for me to find 10 "potential problem" areas in a 10 hour run program run and to add M0 or M1 and warnings to let me be at the cnc control and not 100 feet away on the other side of the cnc changing tools.
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even when programmer makes basic apprentice machinist errors i have to give him the benefit of a doubt and try what he wants to try. 10% of the time he is correct

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If they won't let you modify programs when you see an issue. Then quit. Plan and simple. You are nothing but a button pusher to them. Frankly, I would make the changes anyways. If they like scrap, they can fire me for making good parts.

yardbird said:

I don't know what they are called but I have good luck with drills like these. They are a little more stiff don't have a tendency to want to bend and walk around on ya also allows you push harder. I made these but pretty sure you can buy them. That is if im understanding what's going here?

Brent


View attachment 150649

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yes those drills with the length but not all flutes are stiffer.
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we sometimes use turbo or parabolic flute drills and they are the opposite with extra wide flutes to allow higher feed rates but they tend to break much easier.
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drill i almost broke with it bending 3/4" was a regular flute twist drill.
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we have standard tools setup to specific specifications to prevent crashes, i can change drill bit type for one job and manually load tool but i cannot leave tool in machine like that as on a different part the 15" of flutes can be needed.
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normally i do not change programmed tool types unless there is a reason. for this job it was easier to reduce feed from F3. to F1.5

DMF_TomB said:

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1) i of course calculated feed and speeds and had that program section with posted note on hardcopy listing potential problem as well as a M0. this is why i was at the cnc control and was able to feed hold in time when i saw drill bit bending 3/4"
.
2) i am specifically ordered as a CNC operator to NOT adjust feeds and speeds until there is a problem. Facts and not opinions is what they want
.
3) it is extremely common for me to find 10 "potential problem" areas in a 10 hour run program run and to add M0 or M1 and warnings to let me be at the cnc control and not 100 feet away on the other side of the cnc changing tools.
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even when programmer makes basic apprentice machinist errors i have to give him the benefit of a doubt and try what he wants to try. 10% of the time he is correct

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What a statement! Good luck with that... Why aren't you the programmer Tom???

You obviously are smarter than the rest of us here.

AARONT said:

If they won't let you modify programs when you see an issue. Then quit. Plan and simple. You are nothing but a button pusher to them. Frankly, I would make the changes anyways. If they like scrap, they can fire me for making good parts.

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as a cnc operator i can change program AFTER there is a problem even if feed and speed problem occurred 6 months before with another part. thats why i record standard tool parameter data and problems in a excel list
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as a cnc operator i will easily make over $60,000 this year. they pay me enough that i would never just quit over minor programming mistakes which are often in the gray area of different opinions on programming.

For as long as I have been a part of this forum, I have seen you contribute exactly two things -

1) You keep an excel file with speeds and feeds and tool life.
Good for you, I gave you 'props' for that once, you did some work. Now, get over it. We all know this now, you tell us EVERY TIME YOU POST SOMETHING!

2) As an older machinist it is hard to get a job. Your company went out of business a long time ago and you made $27/hr, now you are lucky you got $20/hr. We know, you tell us every time someone asks about a job, or wages, or if it rained yesterday.

Again, I am going to ask why aren't you the programmer? It seems you work at a place full of idiots, how do they even make money?!?

Mike1974 said:

What a statement! Good luck with that... Why aren't you the programmer Tom???

You obviously are smarter than the rest of us here.

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they do not hire the lowest paid machinist to run big CNC gantry mills machining parts usually over a ton.
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they hire people who can follow a procedures, setup and inspection check lists and keep a eye on potential problems before they happen. but programmers can often have different opinions on the best way to program something. a cnc operator is suppose to try program as written at least once until problem does happen.
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i would only change a bad mistake like tapping with over 5% incorrect feed rate that will break a tap

DMF_TomB said:

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as a cnc operator i can change program AFTER there is a problem even if feed and speed problem occurred 6 months before with another part. thats why i record standard tool parameter data and problems in a excel list
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as a cnc operator i will easily make over $60,000 this year. they pay me enough that i would never just quit over minor programming mistakes which are often in the gray area of different opinions on programming.

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Then quit complaining about it if you're not going to do anything about it.

AARONT said:

Then quit complaining about it if you're not going to do anything about it.

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yes i was basically complaining about a basic apprentice machinist programming mistake about long length drills not using lower feed rates.
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apparently i dont get much sympathy here, only quit complaining about it. i am doing something about programming mistakes given the rules i have to follow