Im thinking of buying a small benchtop mill to help train my employees on. Thinking it might be easier and cheaper if they crash a benchtop instead of a larger cnc. Are these little machines sturdy enough to withstand a crash without breaking anything? And is the programming similar to Fanuc, Yasnac, Okuma etc. etc.? In other words do they use the standard cnc control G-Code programming codes?

Speaking as someone who's crashed several kinds of desktop machines more than once or twice. : ) It depends on the machine, but generally I you'd most likely bust the tool, screw up the stock or (heaven forbid) the table. I busted a preloaded nut on a MacNC one time, but they're plastic and they go pretty easy.

Having had numerous employees and knowing how creative they can be when destroying something, a desktop mill is certainly cheaper to fix and won't affect your production if it's down, unlike your money making machinery.

I would agree that the smaller machines are pretty fault tolerant, and good training aids. It is pretty hard to crash something in a way that is expensive or dangerous. They just don't have the power to easily break themselves and they remove material slowly enough that you can't do much more than mar the finish before the students realize something is wrong.
I would look for someone more experienced with the big machines to answer the g-code question, though.
The little machines are all pretty interoperable, and eat generic g-code fine, and I think that they are compatible with the bigger units, at least with the basic command set normally used as they don't have as many complex features to address. If I remember correctly some big machines like Fanuc can have some pretty unique extensions and odd function quirks in thier code that may or may not play well with smaller machines. This may not be an issue. I don't know enough to advise.

Are you teaching them hand coding at the control? Very dangerous. I do it sometimes, and still get myself in trouble.

Reason I ask, is that software simulation should be utilized and learned as the first step in crash prevention. New employees might as well be introduced properly to the modern world, and simulation is key.

The next step is of course, prove-out on the machine. Again, tried and true methods of prove-out should be learned. Caution should be taught around new program execution at every tool change: single step mode when the tool change is made, and single step with reduced rapids until the tool is at the first position after the tool change. This will verify that the machinist has not made the usual typos and blunders in setup procedures, and the posted (pre-simulated) code should be safe henceforth, until the next tool change.

Trainees cannot ever be allowed to think that "Oh, this is the expendable trainer mill, it doesn't matter if I Fubar the setup or the part". Its always got to matter.

If anything, a small mill without protective operator screens could be more dangerous with flying bits uncontained.

I want to get them familiar enough with G codeing to be able to write a simple program or make minor adjustments to a program. I personally think its easier to learn hands on rather than a simulator.
i just was wondering if the programming code for these little machines was similar enough to a full size cnc control. If its a whole different ball of wax, then it wouldnt do me much good.

Don't waste your time with a smaller mill, or a simulator.

Train them on the machine that they will be running all the time.

Your just adding an extra step to the situation

It's not the machine that needs help, it's the person your training.


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To answer that question then, yes, the g-code is exactly the same as far as basic functions go. Remember though that unless you add options like toolchangers, etc - which normally don't come included on small mills - you won't be able to teach some advanced functions. Most small mills come stock with manual spindle controls, no coolant pumps, etc. so no M codes either. These things can be added pretty readily but it is something to think about. Just playing with the basic movements and editing they would work fine.

Hu has a great point about the value of simulators, as although I learned right on a machine and started cutting parts like Switcher suggests (and boy do you have a motivation to learn FAST that way), until I got a simulator much later on I wasn't able to play with different WAYS to best cut. My cut strategies got a lot better immediately and cut times got shorter, as I was able to immediately compare dozens of different strategies and bit selections to see what best worked and what didn't and at what stage. You might think about using both simulators and small machines depending on how complex the work and much the cutting strategies need to be refined.

To answer that question then, yes, the g-code is exactly the same as far as basic functions go. Remember though that unless you add options like toolchangers, etc - which normally don't come included on small mills - you won't be able to teach some advanced functions. Most small mills come stock with manual spindle controls, no coolant pumps, etc. so no M codes either. These things can be added pretty readily but it is something to think about. Just playing with the basic movements and editing they would work fine.

Hu has a great point about the value of simulators, as although I learned right on a machine and started cutting parts like Switcher suggests (and boy do you have a motivation to learn FAST that way), until I got a simulator much later on I wasn't able to play with different WAYS to best cut. My cut strategies got a lot better immediately and cut times got shorter, as I was able to immediately compare dozens of different strategies and bit selections to see what best worked and what didn't and at what stage. You might think about using both simulators and small machines depending on how complex the work and much the cutting strategies need to be refined.

I had 2 employees to train a while back (both never touched cnc before), the first guy took forever to get up to speed, the second guy is kickin butt!

It's all about motivation, the only thing the first guy had going, was he showed up for work everyday (that's about it). The second guy couldn't learn enough :) . The thing that seperated the 2, was the second guy was computer literate, he loves computers which motivated him, that was enough to let him Kick butt (Siemens 840D/5-axis grinder).


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Part of that motivation from a trial by fire only comes because the student is scared as hell to mess up a machine that costs more than his annual salary and put the company out of production for a week fixing it. They do learn to pay attention fast that way, but not to take chances, because that same fear keeps them from pushing the envelope and figuring out best coding practices, not just the minimal that safely works. Guess it depends on how complex or changing the working variables are at the shop in question. Straightforward repetitive kind of jobs its probably the best solution to put them right on a machine.

For complex stuff I think it is a bit different. I can remember programming six hour runs before the simulator that turned out much less clean work than what is a forty-minute run now, simply because I was unable to try to experiment with new techniques and milling strategies to make the run faster, as experimenting meant breaking expensive things so you just stuck to what was safe. Simulators still do have a point for breaking people out of that.

the safest thing to train your employees to do is raise the tools 1-2" above the part and watch what the tool will be doing , ive caught many programming ,fixturing , and tooling issues this way , it's the number one thing i suggest to the guys when they start a new setup where we can t afford to lose tools or parts

the safest thing to train your employees to do is raise the tools 1-2" above the part and watch what the tool will be doing , ive caught many programming ,fixturing , and tooling issues this way , it's the number one thing i suggest to the guys when they start a new setup where we can t afford to lose tools or parts

Another final step you can add to this when teaching g-code to get a good visual reference is to chuck a Sharpie into the spindle and have them draw out the shapes onto a blank workpiece to check correctness of radii, stepover, tool offsets and radius comp, etc. - the stuff that people learning get confused on and screw up the first few times out that doesn't readily show up on the air cuts.
The pocket Sharpies are about 20 thou shy of a half inch if I remember correctly.

whats a sharpie?
small mills for training are a good idea .....but of more use for complete virgins.
on the job training is probably the most effective as its the machine/software
they are gonna use ,however there is more to cnc'ing than just g-code and
what button to press, (unless your just training loader/operators)
some one with some m/c shop savvy is a better prospect they should know
the basics behind cutting metal etc
mike

i have to agree
the best thing is to explain to the operators why and how the process works,
if they ve been button pushing then i am sure they have been watching the godes , explain to them how the codes work on the jobs they ve been running , lil lights will pop up over their heads when they get it , walk them thru the setups for a while till they are comfortable and you are comfortable to leave them be ,
i have a guy i'm currently training , he's been running one machine with numerous parts that are quite similar , i taught him what to measure , how to make the necessary adjustments , and left him to get comfortable , a couple of weeks ago i spent some time with him explained the workshifts h and d values and touched on basic gcodes ,then it hit him , he said that "now i see why it does that " , i forget what it was but it came together for him anyhow.he is tightly monitored but is doing simple setups
the guy is bright and i need him to shape up fast because i need the help but too much knowledge at one time will overwelm him as well
he come from the deburring corner and he got a good break , most of our work is tough ,and if he keeps going as he is ,he will be an impressive machinist

the machines are expensive and intimidating to anyone new to this stuff ,but with some hand holding and patience the guys who will get it will get the basics quickly, as for the rest of the knowledge it takes a good few years before anyones up to snuff

Feed override, is your best friend! :)

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My approach is similar to dertsap's; put them loading and have them watch what the machine does, then start introducing more responsibility. I also have a Haas simulator, they cost less than $2000 and are excellent for learning the fundamentals on the control without tieing up a machine.

Feed override, is your best friend! :)

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I agree with that. Ive caught tons of would be crashes over the years from single blocking with feed override during a mid program restart. Or just proofing your work.
All the guys ive trained were green as can be. The hardest part and most time consuming was just getting them to understand the coding and how it all worked. Once they grasp the understanding of the codeing they usually pick up pretty fast if they want to learn.

I started out working on my own and learning from scratch....The idea of approaching a full blown unit would wreck my nerves.....I began simple with what I could get my hands on....I would say that it depends on the situation your in....I would have preferred having a live reference to mentor me along....Aswell I utilized machine wax alot until I could find a feel for the unit and programming.. A slammed chunk of it cost way less than what you'll slam in a hard setup.....Anway hope it helps. I wish that trade schools were as popular around here as law schools/med.

Hunters teach kids to hunt........Get your kids greasy and teach'em to machine for pete sakes guys.....lol