Any tips for the new guys?

Hey everybody im new to machining and im currently in trade school and having issues hitting tolerences while manually machining. For our projects at school its + - .001 for tolerences and i for the life of me cant seem to hit them. It's really discouraging, i mean i love machining it seemed to be my calling but after 6 months i still seem to be bad at it.

Any of you veterans out there got any advice on how to stay motivated and not get discouraged on learning how to machine.

Well that depends all on what you are doing and what they are expecting you to do it with. Are you having trouble with milling or turning? Are you trying to turn a part to within .002 on a 1950's Cincinnati that's been crashed with the chuck key at max RPM with the gears half engaged? Or maybe a fleet of Grizzly machines that couldn't cut a strait line if you welded the cross slide in place.

+- .001 on an manual can be tricky I will give some general advice.

Don't take the part out of the vice of chuck until you are done do the the setup/operation.

Clamp the ways that are not moving this applies to mills and larger.

When milling rough to within .020" and take it to final size in a couple cuts measuring after each cut and compensate for any springing. Remember there is backlash no matter how new the machine is.

When turning rough to within .020"-.030" and take a .010" spring pass and measure, measure, measure. If you have a couple thou to go then file and or emery it down.

If the option exist learn how to program.

A few things to remember:

-Everything is subject to flexing and moving. Even carbide.
-Accuracy is relative. There is no perfect part.
-You will never know everything about machining. None of us will, except John Weldon.
-There is such a thing as an impossible part, no matter what the engineer says.

Condition of your machine and your tooling matter a lot when you get to fine tolerances, especially whether your cutters are dull or ground incorrectly.

Describing a specific situation you're having trouble with will help, or posting pictures (detailed closeups) of workpiece surface finish and cutting tool edges for review will help.

Are other people in your class able to get the needed numbers using the same machines and tooling? Ask around, if you're willing (good to tamp down ego early). Have you gotten help from the instructors?

jojo1993 said:

Hey everybody im new to machining and im currently in trade school and having issues hitting tolerences while manually machining. For our projects at school its + - .001 for tolerences and i for the life of me cant seem to hit them. It's really discouraging, i mean i love machining it seemed to be my calling but after 6 months i still seem to be bad at it.

Any of you veterans out there got any advice on how to stay motivated and not get discouraged on learning how to machine.

Click to expand...

"Depends on the situation". Early days, new job, called my foreman over:

"George? Bearings are shot in this old Niles. It is showing me six thou oval on my test cut for that bearing fit."

"That old German taught you how to fix shit like that?'

"Sure did."

"Then what's your question?"

I just went and got out my files and abrasives. George went off to piss on some other minor fire. Fit came out good as it needed to be.

Paid by the HOUR.. and "Union Scale", after all.

There are machine-tools that can just "hand you" the splitting of a thou. Or even a "tenth".

You might live a very long time before ever you meet the first one of those.

Meanwhile?

Learn what it is you've got. RUN what you've got.. with what you have learnt.

Ability to assess, FAST, then "compensate" between his ears for the limitations of whatever is between his hands is what differentiates a "Machinist" from merely a "machine operator".

Primary need for learning that? You have to "want to".

Really strongly "want to". Because there ain't a lot of brilliance nor "magic" to it at first. TEDIUM, and sore wearying, rather!

It only looks "magical" after you have mastered it and "appear" to nail your numbers directly. THEN it has become a "tough act to follow" ...for those who have not.. yet ... even understood what it was you had to DO.

DAMHIKT! Just "work toward it". Diligently, please. Or someone in CHINA will do!

I've had quite enough of that "offshoring" bullshit, thanks. If we wish to do with LESS of it, going forward? We'll have to step-up and prove we can earn it back.

At decent US wages, too, thank you very much, cooperative CONSUMERS as might get YOUR heads out of yer anatomy and BUY American ..so YOUR wage is not so much at risk ALSO!

Very often you think about the accuracy of the machine, runout and variables then shoot for + .005 / .010 or what will leave some finish pass stock and shoot for that number. Then come closer with small take stock amounts.

You might start thinking in tenths if there is no rush on the work and shoot for a half thow on some parts just to get used to smaller numbers.

You might sit down with JoBlocks and practice measuring to know how hitting the mark feels.

Might have a note pad and write you sizes as you get closer to the mark.

Sneak up on the spot a half thousandth at a time.

You might practice/try taking one more thousandth when you are far from finish size just to prove the machine, set-up, job or cutter can do that.

Thank you all for the words of encouragement guys. School's on a weird schedule due to covid and im still new to the forum scene but ll try and give a little bit of details as i go, the machines i normally run are an OLD Victor lathe and a clapped out sharps clone of a bridge port. So i imagine that one of my problems is just worn out machines. Another i guess is just an unchecked ego. My instructor has been doing manual machining for 35ish years and he makes it look so easy.

But any way i just wanted to say i really appreciate the kind words and will definitely use the advice. i will keep at it and try to work on a machine that hasn't been ran into the dirt lol.

thermite said:

"Depends on the situation". Early days, new job, called my foreman over:

"George? Bearings are shot in this old Niles. It is showing me six thou oval on my test cut for that bearing fit."

"That old German taught you how to fix shit like that?'

"Sure did."

"Then what's your question?"

I just went and got out my files and abrasives. George went off to piss on some other minor fire. Fit came out good as it needed to be.

Paid by the HOUR.. and "Union Scale", after all.

There are machine-tools that can just "hand you" the splitting of a thou. Or even a "tenth".

You might live a very long time before ever you meet the first one of those.

Meanwhile?

Learn what it is you've got. RUN what you've got.. with what you have learnt.

Ability to assess, FAST, then "compensate" between his ears for the limitations of whatever is between his hands is what differentiates a "Machinist" from merely a "machine operator".

Primary need for learning that? You have to "want to".

Really strongly "want to". Because there ain't a lot of brilliance nor "magic" to it at first. TEDIUM, and sore wearying, rather!

It only looks "magical" after you have mastered it and "appear" to nail your numbers directly. THEN it has become a "tough act to follow" ...for those who have not.. yet ... even understood what it was you had to DO.

DAMHIKT! Just "work toward it". Diligently, please. Or someone in CHINA will do!

I've had quite enough of that "offshoring" bullshit, thanks. If we wish to do with LESS of it, going forward? We'll have to step-up and prove we can earn it back.

At decent US wages, too, thank you very much, cooperative CONSUMERS as might get YOUR heads out of yer anatomy and BUY American ..so YOUR wage is not so much at risk ALSO!

Click to expand...

To the OP: Don't worry if this post doesn't make sense. I can't understand it either. Must be thermite got too close to a keyboard again.........

Oh and i forgot i guess the old saying is right " mesure twice and cut once and your still wrong!" Lol.

One thing that will help you understand what some others have said about everything flexing, take a light cut (.005"-.010"), then without moving anything else, run the tool back the other way and see how many more chips you get. Sometimes you can do this 3 or 4 times and still get some feathery chips on the last pass, depending on quality of cutting tools/vise/machine etc.

ChipSplitter said:

To the OP: Don't worry if this post doesn't make sense. I can't understand it either. Must be thermite got too close to a keyboard again.........

Click to expand...

No foul. we are equally "good with that."

I do not even make the ATTEMPT to reach the lower HALF of the human intelligence distribution Bell Curve. Too much like work.

Let alone the least quartile! Too much like insanity.

Fortunately, PM has a LOT of upper-quartile. And well above.

Very much so!

Craft folk are not REQUIRED to be "dummies", after all.

Sometimes they just prefer it that way out of nought but sheer perversity!

For milling or turning to +/-0.001 you should be using a micrometer NOT a digital or dial caliper. Your micrometer should give the exact same dimensions as whoever is grading your work micrometer does.
A micrometer that reads to +/- 0.001 should be good enough but since you are new and perhaps not used to interpreting the readings you may want to use one that can do +/- 0.0001.
I prefer a well made micrometer from Starrett, Brown & Sharpe, or Mitutoyo. I have also had good luck with Scherr-Tumico, Mahr, and Lufkin. Unlike some people I also prefer a good consistent ratchet or friction thimble.
Make sure your measuring faces (anvil and spindle) are clean. Takes a few seconds to snug it down on a clean piece of paper so it can just be drawn out. Then check the zero at three clicks of the ratchet or a half turn of the friction thimble.
Practice taking readings on known standards. Gage blocks and gage pins are good. Drill bit shanks and ground stock are not so good. Keep a few standards in your tool box wrapped in a bit of paper towel or grease paper so you can check your micrometers at the beginning of each session.

On the lathe if the part is so hot you can't keep your hand on it then it is too hot to measure. Let it cool down first before final measurement.
Be sure your part is clean and clear of chips, grit, oil, coolant or grease before taking a measurement. I always knock the fuzz off with a bit of scotchbrite or emery then a wipe with a clean rag or paper towel before taking a measurement. Be careful a few threads from a ragor bit of fiber from a pape towel can cause your measurement to be a couple of thousandths off.
Take measurements at several places along the length of the part and at a couple of places around the circumference. If the measurements differ by more than your tolerance then you have to determine why and correct for the difference.
The causes of differences in diameter are so many that it will require several threads to cover them all. Most can be avoided by chucking the work as close to the headstock as is safe and using *sharp* properly ground tools that are rigidly mounted. The rest is speeds and feeds which can be determined using charts or simple calculations depending on the cutting tool and material.
You should take note of how your tools and machine behave. If you measure the diameter after your first pass over the materail and move the tool in, say, 0.010 inches take a cut and measure again... has the diameter changed by 0.020 or 0.021 or 0.019. Same thing if you take a shallow cut of, say, 0.002 inches... how much has the diameter changed? Some tools (especially carbide) on a thin piece of work don't seem to cut at all when dialed in a few thousandths it just seems to rub... yet add one more thousandth and all of a sudden it cuts several. That is why it is important to have sharp tools and as rigid a setup that is possible.

Much of the same applies to milling operations. Make sure you are using sharp tools. That the head is trammed to table and the vise is aligned and the vise jaws are aligned the parallel to the table. Make sure your vise is clean, your parallels are clean and your work piece is clean and deburred. Then tap it in carefully on to the parallels. Get the workpiece all squared up before you start making cuts to dimension. You may have to deburr many times so have a good file handy.

Get a copy of Machine Shop Trade Secrets by James Harvey. He covers a lot of the details very well.

Keep trying. Take your time. Work for accuracy... speed comes later.

-DU-

ChipSplitter said:

To the OP: Don't worry if this post doesn't make sense. I can't understand it either. Must be thermite got too close to a keyboard again.........

Click to expand...

I don't see the problem. Read it in a conversational tone, of spinning yarns and etc of folklore, it makes sense to me! And there is a bit of work wisdom in there, not just shop wisdom but work in general.

jojo1993 said:

Hey everybody im new to machining and im currently in trade school and having issues hitting tolerences while manually machining. For our projects at school its + - .001 for tolerences and i for the life of me cant seem to hit them. It's really discouraging, i mean i love machining it seemed to be my calling but after 6 months i still seem to be bad at it.

Any of you veterans out there got any advice on how to stay motivated and not get discouraged on learning how to machine.

Click to expand...

Grow a thick skin, you will need it if you hang around here for any length of time!

Mike

thermite said:

No foul. we are equally "good with that."

I do not even make the ATTEMPT to reach the lower HALF of the human intelligence distribution Bell Curve. Too much like work.

Let alone the least quartile! Too much like insanity.

Fortunately, PM has a LOT of upper-quartile. And well above.

Very much so!

Craft folk are not REQUIRED to be "dummies", after all.

Sometimes they just prefer it that way out of nought but sheer perversity!

Click to expand...

You keep deepening your hole...............still doesn't make sense.

jojo1993 said:

Thank you all for the words of encouragement guys. School's on a weird schedule due to covid and im still new to the forum scene but ll try and give a little bit of details as i go, the machines i normally run are an OLD Victor lathe and a clapped out sharps clone of a bridge port. So i imagine that one of my problems is just worn out machines. Another i guess is just an unchecked ego. My instructor has been doing manual machining for 35ish years and he makes it look so easy.

But any way i just wanted to say i really appreciate the kind words and will definitely use the advice. i will keep at it and try to work on a machine that hasn't been ran into the dirt lol.

Click to expand...

In a weird way they are giving you valuable experience. On the job you are most likely to encounter machines that are clapped out even worse. Companies hate spending money, even when they *should*.

My last employer had a South Bend 16 with more than an -inch- (4 or 5 full turns) on the cross-slide before the tool even started moving. And yet if you didn't hit your numbers, well... you would be picked on endlessly for the next 6 months.

pavt said:

In a weird way they are giving you valuable experience. On the job you are most likely to encounter machines that are clapped out even worse. Companies hate spending money, even when they *should*.

My last employer had a South Bend 16 with more than an -inch- (4 or 5 full turns) on the cross-slide before the tool even started moving. And yet if you didn't hit your numbers, well... you would be picked on endlessly for the next 6 months.

Click to expand...

Seconded. The very situation I came to the attention of the SECOND one of the two BEST EVER mentors a young craftsman could ever ASK for.

Long story short, the FIRST one had taught me well enough I had beat spec on the first six parts in 8 hours of second-shift, at a nasty Nickel Aluminium Bronze part.

The "only guy in the company who can do those at all", or so it HAD been, finished the other 20 next day, day shift. Then stayed-over after clocking-out to watch me work and twig to how I'd run slower. but cut his deviation to half the range allowed. Watched me dialing-in 4-J with a mirror and a sharpened darning needle. Went over to HIS box, came back and gifted me a teeny-tiny pre-War Starrett "Last Word" DI. Practically teared-up. I'd never had nuthin' so nice in my young life.

REVERENTLY put it into my Kennedy. Still there today.

Went back to the needle and mirror. And then George Mortimer, 81 years young, summer of 1963 - himself trained up before World War one even started - got a huge shit eatin' grin and said:

"Bill, if you can do work that good on the old junk we run here, there isn't a machine shop anywhere in the world you can't do good work!"


Damned right learning to get 'er done on "poor-man's food" will make you better equipped to survive!

Applies to machine tools as well as vittles, too!

From David Utidjian :[For milling or turning to +/-0.001 you should be using a micrometer NOT a digital or dial caliper. Your micrometer should give the exact same dimensions as whoever is grading your work micrometer does.]That is worh saying again and practice with a jo block with your eyes close, and behind your back and left handed..till you are spot on even standing on your head..

Take .001 then another .001 then another .001 when you are .100 away from you target number..then at +.003 from finish size you know you have mastered that part.

Don’t worry about manual machining it’s just there to teach you which way to turn the bits
Learn solid works and mastercam until you can do it with your eyes closed you will be fine
Don


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