View Full Version : Techschool instruction

09-23-2002, 12:39 AM
I have been hired by a local techschool as an instructor. My question is; What would you like to have learned when you took shop classes? Do you have any suggestion for projects that would be good learning exercizes? I learned OJT and had no formal training when I started many years ago.
Thanks in advance for your suggestions.

09-23-2002, 04:39 PM
Heck, when i was in school, the projects i wanted to make would have got me kicked out or put in jail. Now that I teach the stuff, I know what to look for to keep them from getting kicked out or put in jail...or at least I do a good job holding my own against this type of thing.

Hey ytsudwas, you need some info and such, please feel free to e-mail.

S. Pope - Machine Tool Instructor whom according to the students has been doing this since dirt was machined (or 15 years, whatever came first).

John Foster
09-23-2002, 06:28 PM
Ernie, welcome to the club. I wonder how many retired/active shop teachers we have. This makes 3 and I know that stepside is also for 4. Any of you want to share what and where you taught?
I put in 35 years at Des Moines Technical High school with high school and also day and night adult training in machine shop. The bigggest challange (and rewards) was working with blind students. I usually had one or two full time in the adult day program. We got them trained and usually employed in the trade.
What to teach. Blueprint reading, math, speeds and feeds, how to setup and run all of the machines but most important of all is how to think! I still go back and help some of the new shop teachers and I'm ashamed to say many do not know how to solve a problem. One example; a shop teacher called and asked if I could fix his Variable speed Rockwell lathe. I had never worked on one before but in 15 minutes it was running again. He could have done it but didn't know where to start. Don't just hand them the answers, make the students think and try to solve the problems.
Even if they end up all running CNC equipment it seems to me that they need to be able to plan the job and they learn this from the manual machines.Sorry I do get carried away. Good luck, John

09-23-2002, 07:02 PM
I guess I rank up on the retirement rolls as well. Since 1969, I have been teaching anything that came through a factory door. Casuals that couldn't hold a mic had to learn how to run a turret lathe.I actually kept most of them from wrapping themselves in their work. My first lesson was 'go chase the chuck key'. Some idiot would launch a 3 lb. chuck key about 40 feet. This always resulted in the near-recipient being cured of constipation...aahem. If I was still teaching it would be how to think while doing bench work.We'd go from there.
Regards, and good luck! Toolabard

09-23-2002, 11:35 PM
The first thing we learned was safety! The next thing was probably mic's. and other tools, then speeds and feeds. I don't know if you even need to know these things anymore. Alot of so called machinists comming to the work place can't even use a mic. or know what feed rate even is. When the computer is down so are they. I believe machining basics are still very much in order even today.


09-24-2002, 05:11 AM
Safety first and always. Special handling requirements - many metals are toxic, awareness of safety considerations are a must for every material. Even I have erred in this area and I had considered myself "in the know". Some metals are readily known as toxic such as Cadnium, Berrylium, Mercury - all with extreme health risks. There are fire risks with a number of metals - the Halides, Uranium, Titainium, Zirconium, Tantalum, Magnesium, and a few others unlikely to be encountered.

Filing. File, file, file, file some more. More filing - look teach its perfect. "What about that gouge down the middle" as he picks up a sledge and a chisel and whacks away - "better file that out..." File, file, file. Teacher, - whack! File, file, file. Two months of that, but now I can almost "FILE".

Drill sharpening by hand. If you can't do that, you can't do the rest IMHO.

How to glean useful information from machinery's handbook or other "references".

Basic hand tools and measuring tools - use and care. Lathe bit geometry & grinding. Lathe and mill tooling. Safe fixturing - rotary faceplates and static beds. Machine pre-check, maintenance, and warm-up. Coolants and cutting lubes. Joining metal; spot welding, stick, mig, tig, plasma cutting, gas welding, soldering & cutting; proper use of fasteners; thread fit classes; pop rivets; nutserts; rethreading coils; hardened thread inserts. Thread, shaft, and assembly adhesives - the world of loctite.

Basic Lathe safety. Lathe operations. Faceplate setups & safety, turning between centers, facing, turning with 3 jaw and 4 jaw chucks and when to use them, threading theory, external RH, internal RH, external LH, internal LH, threading to a shoulder or blind hole, cut off operations, use of form tools. Appropriate uses of carbide tooling (when or where it is feasable). Knurling theory & application (bump vs. cutting).

Mill theory. Conventional Milling & Climb milling - pros & cons; proper DOC, feed, and sfpm as well as load per tooth of cutters; types and use of slitting saws; milling accurate width groves (with side cutting slitting saw or mill); T-slots; Dove tails; use of the rotary table or dividing head; gear cutting theory, making involute cutters for specific gear #'s; worms, helical gears, hypoid gears, compounding rotary tables &/or dividing head for complex curves.

Programming CNC - coding and optimization.

Newer technologies - laser machining, AFM, Plunge & wire EDM, Water jet cutting, Plasma/Water jet cutting, Ultrasonic machining.

Metal casting: safety, methods & procedures.

Finishes: Grinding. Polishing, electroplating, beadblasting, tumblers, powder coatings vs solvent based coatings, CVD, PVD.

Some suggestions, if nothing else.

09-24-2002, 09:30 AM
OK, here it is from the active teacher, just a few starting thoughts. Safety is assumed by all to be #1, so I will skip that sermon as understood by all as "JOB 1". I know I am leaving much out here - trying to compress, but here goes.

I am starting off a little different than many of you, and this is based on some amazing success if I don't mind saying. These all work together, and are NOT set specifically different, but build on each other "intertwined".

#1 - what are the tools!!!!! How and why do they work, and when and when not to use them. Simple things such as hand tools to files (see filing above...) to properly identifying and using the tools.

#2 What are the processes. I can talk all day about threading, tapping, face milling, slot milling, turning. I can talk all dy about what a good chip looks like and sounds like, but until this is done, this is like talking about guided missle gyroscope systems to a 10 year old. My processes lessons are very guided and structured, and involve the basic machine math components, but at this point do not necessarily hit on speeds and feeds more on this later. I set these up for success first. Process organization and planning taught here. They make simple parts and a simple project, made to show success first.

#3 How do you measure - mics, scales, all the tools, and processes in measuring. This leads into blueprints easily with tolerances, views, and interpretation.

#4 Blueprints - right on down the line. You can't read the print, you can't make the part

#5 Speeds and feeds - They have seen the good cuts, can recognize them. Now, why is that surface finish biting the big one and looking like beavers attacked the metal, and why is this chip looking bad, and what is that horrible sound? I teach success first because you can recognize crap better. materials work in here, and I love materials and speeds and feeds.

#5 Math - although this is taught inheriently in the lessons before, I get into this now, and the concepts to this point taught in the class make it very applicable - how it applies to the processes learned, and advancing skills. The fer is gone when you have worked already and know when it applies.

#6 Tool grinding. I use carbides heavily in my shop, and grind the drills to start. Now they grind tools, have a better understanding of the angles and why they work from past experience. They ask "why does this drill now cut oversize and egg shaped - they recognize the problem from a good previous experience now gone to hell. The lathe tool now cuts scratchy or rubs, they know this is not right. How do we fix this? How do we make this look like you know what is right. How do speeds and feeds affect this.

5. High end accuracy - setting up wih indicators and inspecting work high end. Craftsmanship on lathes and mills. Advanced processes and set-up. Our parts are checked by poutside shops.

6. CNC - Programming, set-up, operation. How does all of this you learned apply - chip flow, speeds and feeds, processes, math, nmeasuring, craftsmanship, safety, apply. Pre written program set-up, followed by edit problems, followed by programming the jobs whole.

I have my first year basics in a word "Doc" format, can have if you choose.

Within all of this, theory and all of the omponet\nts are worked in. but the idea here, and what killed me in my apprenticeship for the first year. I teach what a good thing looks like FIRST so quality is recognized. My apprenticeship taught what **** looked like first, then moved to quality. OK, worked, but it took me longer to appreciate what I was doing wrong, and identify what was right. This was common with all the people in my group. My theory comes from the second teacher I had, and how the four of us who had him are still working while the other four who kept the first teacher got fired.

09-24-2002, 10:57 AM
Started teaching in 1965. Stopped learning--not yet. Infuse your students with the idea that everyday you should learn something new.
I agree with the safety issues, the tool knowledge and the bench work. But work at it so they aren't bored. Give them a taste of what is ahead so they want to get there. I always have (at least most of the time) a project going that challenges me, that I share with the students as it progresses. I do not tie up school equipment with this project, but rather bring it from home or do the work after school hours. In other words demonstrate your abilities to validate what you are having them do. I will not tolerate poor working manners and spent quite a bit of effort on how to work with others and related information.


09-24-2002, 12:56 PM
Blueprint reading what an anachronism, sort of like dialing a touch tone phone. None the less it is the key to being a good machinist or an engineer for that matter. Spope14 has a good scheme building on success.

Break edge and chamfered threaded holes etc are good design practice. The machinist should be aware of these things but it is a failure of the designer in not capturng this on the drawings.

Neil Peters

[This message has been edited by NAMPeters (edited 09-24-2002).]

09-24-2002, 04:01 PM
yes, ah Blueprint reading. The new term is "Technical Drawing", but it will always be "Blueprint". Kind of like Xerox for any copier, or IBM for any PC type computer.

I tried the old method of information until you are full then get on the machine for many years. It worked with the small majority of students. Tried "grind the tool first" before you turn like I was taught, and had the same problem with the kids I had - I had the darnmedest time knowing what a good chip looked like until I was told it was a good chip. Now they see it first, they know it, then they can identify the bad chip, poor finish and such much better.

I must have drilled about 100 egg shaped holes and triangle holes until I got one right - though this was the nature of the drill - Realize in both cases I was 13 years old when i started, the kids I teach are 15 and 16 when they start. heck, they know no different.

My best experience was working in the "Deburring" department during my second six weeks of my apprenticeship. Prior to that, I worked in the Lubrication department, which was also the best thing I could have done. The classes wanted me to know all of this stuff I had never seen before like tapping, good thread form, good sounding cuts, "boring?", so I was lost for about 18 weeks until I got a guy who showed me what good looks like first, then what no good looks like second - thus giving me the idea of how to troubleshoot and identify quality.

Deburring gave me craftsmanship, lubrication gave me the appreciation of what a well lubed and properly maintained machine should run like and sound like. I still do lube the first week with the kids, and they just really get into it.

Know quality first. Like driving a good car can tell you what a bad car has wrong by experience.

Works for me anyway.

John Foster
09-24-2002, 06:13 PM
You might save yourself some time, at the start, by finding out if they can read a ruler. Don't just ask if they can, hand them a rule and outside caliper and have them set it for 15/16, then 27/32 and finally 33/64 or some such numbers. Most peoople will not admit they don't know but this way you find out and know where to start. I found that fully 25% of 10th grade boys could not read a ruler, as above. Adults were not too far behind.
I would get my students on a lathe just as soon as possible. We went over the parts and safety first. Then how to turn it on, set speeds, using different chucks, how to set a tool and everybody , in turn, doing all of the operations. You always have one or two that catch on and are eager to show what they know. Use them and let them show the slow/bashful ones how to do it. They will make mistakes, but this just lets you reinforce the correct way. By the time you get to the slow ones they will be able to do it too, which builds their confidence. I haven't even mentioned speed but as soon as they chuck a piece and get their tool set (one I have ground so it will cut right, they grind theirs later) soneone will ask, "How fast are we supposed to run these things?" Now you can explain speed selection and they listen because they see a need for it. I usually had students in the shop, making chips, within the first 3 to 6 hours. That may not work for you but I did for me as I had their interest and attention.

09-25-2002, 03:54 AM
WOW! Thanks again everyone this is all great advice. Spope14---I would love to have a copy of your first year. Email anytime. After I begin the classes I'll be sure to update everyone.
Thanks Ernie

09-25-2002, 04:42 AM
I'm an amateur and have had the opportunity to study at two different community colleges...one focused on machining, the other really a CNC curriculum that happened to have two semesters of basic HNC (Human Neuronal Control) machining. I'm assuming you'll be teaching beginners.

Just a couple peeves and things I liked

...in the first class I took we made a tap wrench, in the second we just made some precision scrap...I really prefer that projects assigned be actually useful...like a tool or guage.

...go into generalities, in the second class I took, the instructor presented precision screws as the basis of Micrometer function...Seemed to me that the "screw" should have been presented as a fundamental part of precision movement throughout machining and manufacture.

...the instructor I had for my second class read directly from the textbook as his lecture...I really cant stand that, especially when the reading has already been assigned.

...Last but not least, though beginner's courses are "breadth" courses, go into "depth" in at least one subject. The first class I had, the teacher went into deep detail on threaded fasteners from metallurgy and grain structure to geometry and it's relation on stress/strain. Anyway, it's nice to see the engineering and years of technical evolution that have gone into something as "trivial" (to the non machinist/pilot/racer/mechanical type) as a bolt. It doesn't have to be bolts...just something you like enough to teach about in detail that can show the evolution and thought "beneath the surface" of a part.

09-25-2002, 03:25 PM
Surface finish! It is nice to know what crap looks like but one also needs to know how to aquire a given finish as to roughness and lay. A good designer will take this very seriously as it affects the function of the part and the assembly that it is a part of. One of my favorit design tools were those neat looking surface finish sample plates. A lot of folks have no clue what the lay control symbol part of the surface finish callout means. That is were the sample plate came into the picture, just pointed to what was needed.

Neil Peters

09-25-2002, 10:06 PM
I agree with Thrud. I had forgotten, we had to be graded on sharpening a 5 gallon bucket of drill bits all sizes. One poor fellow was so bad the second week of the course, the instructor told him in a nice way he was welcome to stay but he didn't believe it would help him much.


George Hodge
09-25-2002, 10:39 PM
What impressed me in shop was when the instructor scheduled a trip to a machine shop and a welding shop and then a tire manufacturing plant. Gee,I'm glad I never built tires!

09-25-2002, 10:53 PM
Geeze, you guys are bringing back memories - I wonder what happen to my slide rule?? Oh yeah, I forgot - RPN!

Any of you teachers ever get asked "What's a log table"

I always tell them it is what Fred Flintstone sits in front of to eat his dinner with Wilma. Betty was the hotty - IMHO. Redheads are "badluck".

09-28-2002, 11:35 PM
OK, Thursday night I had to explain "Interpolation". As in an example like when a CNC machine sends the signals to the servos to make an arc, how the machine makes the moves for us and such. I tried this example, from a way back in my earlier education.

I pulled out a trig chart in an old (1995) textbook. Showed it off and asked if anyone had ever interpolated from a trig chart. There the class of 13 people sat, not a SINGLE ONE OF THEM HAD EVER SEEN A TRIG CHART. Hell, I am 42 years old, still think of myself as reasonably young, but in front of this class, two others from industry helping me teach, and someone who is my supposed boss (more on this sometime when I quit melting down over that situation), NOT A FREAKING PERSON HAD EVER SEEN A TRIG CHART - 16 PEOPLE!!!!!!! And they probably thought I was about 100 years old.

09-29-2002, 10:08 PM
If you want to have some fun with your students-- Have them build a random length "sine bar" and then work backwards to determine its roll centers. In the middle of the fun and figuring take away their calculators and show them the trig table in machinerys' handbook. The eager ones enjoy it and the rest bitch a bunch.

10-01-2002, 12:39 AM
That reminds me of my first honours physics class with a professor emeritus of theoretical physics. One assignment we were told to linearise a complex formula - I was lost as how to do this. I went to my professor and explained the problem, wrote the equations on his blackboard, spent two hours while he checked my math and proudly proclaimed in broken English "I don't know - go ask your TA". Off to my TA I trot. Same poo different pile "I don't know, go ask the proffessor!". Fat lot of help those two were. Ended up talking to my Calculus Professor who was able to explain the error of my ways in moments, yet horrified to learn the Physics professor was clueless - special moments like these really bond students and their profs. Or, it might have been the GM in the tea... http://bbs.homeshopmachinist.net//smile.gif