Metalworking

[siddharth]

In my college, I have a workshop on metalworking in the first semester which involves obtaining a cube out of a Mild Steel cylindrical rod.
First, I have to file (using a 14 inch steel file) the upper and lower surfaces of the rod to level. Next, I have to mark a square on one face of the cylinder and then using a hacksaw, I have to cut off three sides. The fourth side must be chiselled using a hammer and a chisel.
The major problem I have is in chiselling off the fourth side. To me, this looks like an impossible task. After 3 hours of chiselling ( a mild steel rod), I have progressed very little and even hurt my finger with a misplaced blow.
So, does any College in other countries have tasks which require a lot of physical effort? Or is it mechanised where most of it is performed with the help of automated machines?

[Smurf]

you could always cheat... Hacksaw it off, but leave a extra space, and then chisel it down the few more milimeters. If you do it well it'll be impossible to tell.

[dmail]

ok if you where ever to do this in the real world then you would use machines(normally), but they are showing you things which you need to know how to do, ie
file a block correctly (probably using engineers blue)
saw a straight line (not as easy as it sounds)
how to use a chisel. etc etc

when i started engineering for the first two weeks i cut round bar with a hacksaw, beleive me i have no probs in cutting metal to follow a scribed line and even without one.

and even hurt my finger with a misplaced blow.
lmao and its not going to be the last time you do this. ;) make sure the chisel doesnt have a mushroomed head.

[Astronuc]

I believe some German training programs use this approach.

The objective is to teach the student to appreciate the difficulties associated with machining a material.

What kind of chisel? I hope it is hardened.

[siddharth]

I believe some German training programs use this approach.
The objective is to teach the student to appreciate the difficulties associated with machining a material.
What kind of chisel? I hope it is hardened.
The German Government did offer technical assistance in setting up my college. So I guess that's where this came from. I do "appreciate" the difficulties now!
I'm using a cold chisel.

[Integral]

Wow! And I was thinking of lathes and milling machines!

What are the to lances you need to hold?

You project sounded fine till you said chisel! That is a bit extreme.

I once watched a documentary of an old Native American making arrows by hand. His comment "Precision does not know time"
If you want precision work you have to be patient, filing to a line will teach you this.

Chiseling even mild steel can only teach frustration. I would recommend a good sharp chisel , see if you can get a chip running?

Good Luck

[siddharth]

What are "to lances"?
What do you mean by "get a chip running"?

[Danger]

I believe that the old guy meant 'tolerances'. One must allow for his rheumatism and failing eyesight when reading his posts.:tongue:
If he uses the same terminology that I do, a 'chip' would be a strip of metal that peels off as you chisel under it, sort of like peeling an apple.

[Integral]

opps! sorry about that my vision is not all that sharp right now. That should read ,,,,tolerances.....

I initially misspelled it, then assumed that my spell checker had fixed it... Unfortunately it was still wrong.

When cutting metal with a machine tool (lathe for instance) the thin strip of metal being cut off often forms a long very thin strip which usually curls into a long helix. This is referred to as the "chip" .

A dull chisel will simply deform the steel it will not remove any material. To actually remove material with a chisel you will need to cut into the metal. Try clamping your "cube to be" into your vise (I hope you have a vise!) with say .5mm above the plane of the vise jaws. Now attack that edge with your chisel, if it is sharp enough you may be able to get under a bit of the steel. Hammer away.

I do not envy you your task!

[Integral]

I believe that the old guy meant 'tolerances'. One must allow for his rheumatism and failing eyesight when reading his posts.:tongue:
If he uses the same terminology that I do, a 'chip' would be a strip of metal that peels off as you chisel under it, sort of like peeling an apple.
You are exactly correct... even to the cause!

I guess all it takes is another blind old geezer to understand me!

[Danger]

:rofl:
In my case it's arthritis, not rheumatism. The vision thing is irritating for sure. I have to wear my glasses for the monitor here at work, and have to have them off for the one at home.:grumpy:

[dmail]

don't want to correct you, but why not?

When cutting metal with a machine tool (lathe for instance) the thin strip of metal being cut off often forms a long very thin strip which usually curls into a long helix. This is referred to as the "chip" ...!


this is swarf :)

[Danger]

this is swarf :)
I thought swarf was that little blue dude from B.C.:confused:

[dmail]

lmao do you more morf ;)

[Integral]

don't want to correct you, but why not?



this is swarf :)
Interesting, I have not heard that term. Could it be regional?

[dmail]

not that i know of. google for metal swarf it seems to be universal
http://www.google.co.uk/search?q=metal+swarf

[Danger]

I didn't pursue that link too deeply, but it appears that 'swarf' is fine-grained particles as opposed to the ribbon-like stuff that we call 'chips'.

[Integral]

Your link seems to be referring to something different from the chip, which is scrap, not the desired product.

In this link swarf (http://woodworking.about.com/od/glossaries/g/swarf.htm) is the term for the results of a grinding process, yet again something different from the chip produced by a lathe. Though this time it is used to refer to the waste product of grinding.

I could see where it could be generalized to any waste product. Is this common terminology where you machine?

[zoobyshoe]

Interesting, I have not heard that term. Could it be regional?
I worked in machine shops here in San Diego for ten years. If you called chips swarf no one would know what the heck you were talking about.

[Smurf]

I thought swarf was that little blue dude from B.C.:confused:
No, that's smurf. Different.

[zoobyshoe]

So, does any College in other countries have tasks which require a lot of physical effort? Or is it mechanised where most of it is performed with the help of automated machines?
I went to shop school here in the states about 20 years ago, and we never had to do any major work by hand like this. You would never encounter a work situation where something like this would have to be done. Squaring up parts, especially a special single part, would be done on the mill. All the dimensions would be rough cut with the cut-off saw. The hack saw is only used for small, quick cuts. You would never be required to take off a large amount of material with a hack saw. As for chisels: I never saw anyone use one for any metal work in ten years; not in school or in real work situations. That's like something from the 1850's. I don't think it's ever done anymore, except by people who are going to machine flats on large cast parts: I believe the hard outer skin is sometimes removed by hand with chisels. That's not precision work, though.

Most machine shop work nowadays is done on CNC machines: Computer Numerical Control, and if you ask me the most important thing for a young person learning shop to shoot for would be learning how to program a print into the CNC. That job makes more money. Set up and operation of the CNC, which involves choosing and installing the end mills or drill bits, or lathe cutters, and running trials, adjusting the settings till the parts are in tolerance, involves knowing how to make changes to the program, but it's alot more "hands on" than the programmer job. Once the set up guy is done, the actual running of the parts might be turned over to a machine operator who is less skilled, and whose main job is to put the parts in and take them out, and to keep an eye on critical tolerances, and watch for tool wear.

A manual machinist sets up and operates only non-CNC machines. This is the kind of work I did. Sometimes we cut and squared parts up for the CNC, and other times we did second operations to them after the CNC was done. Sometimes we did whole runs of parts that were never sent to the CNCs. The boss made the decisions about which operations were better done by which method.

[dmail]

... which is scrap, not the desired product.this is correct

http://woodworking.about.com/od/glossaries/g/swarf.htm
nice link pitty its talking about woodwork lmao.

I could see where it could be generalized to any waste product. Is this common terminology where you machine?

i machined on lathes and mills both cnc and manual for different companies for about 10 years and have never heard it called anything else, infact it was even in my city and guilds exam. i thought it was called the same no matter of the place, but maybe it is a british engineering term.?

[zoobyshoe]

i machined on lathes and mills both cnc and manual for different companies for about 10 years and have never heard it called anything else, infact it was even in my city and guilds exam. i thought it was called the same no matter of the place, but maybe it is a british engineering term.?
It must be British. I haven't ever heard chips called "swarf". Haven't ever seen it in books for that matter.

[Integral]

It must be British. I haven't ever heard chips called "swarf". Haven't ever seen it in books for that matter.

Me neither, like I said WAY up thread... Regional. What region are you from? Guilds imply somewhere Euorpe, I do not know of anywhere in the US that uses that term either.

[siddharth]

A dull chisel will simply deform the steel it will not remove any material. To actually remove material with a chisel you will need to cut into the metal. Try clamping your "cube to be" into your vise (I hope you have a vise!) with say .5mm above the plane of the vise jaws. Now attack that edge with your chisel, if it is sharp enough you may be able to get under a bit of the steel. Hammer away.

That's an excellent suggestion. Till now, I have just been hammering different parts trying to get pieces of metal flying out. I have 12 hours of worktime left to get the cube.
The diameter of the cylinder was 45mm and the hieght was 35.7mm. I filed the cylinder to 32mm (±.01mm). Then, the marking was done with a vernier hieght gauge. The side of the cube must be 30mm, which means I must file once again after chiselling around 6.5mm of the fourth side.

[Mk]

I don't know anything about metalworking, but cutting steel with a chisel sounds REALLY HARD!! :surprised

[Gokul43201]

I don't know anything about metalworking, but cutting steel with a chisel sounds REALLY HARD!! :surprisedI thought I'd cut steel most ways that were possible...and I've never heard of, nor would I care to try to cut steel with a chisel. Honestly, I just can't see it working ! :confused:

[Integral]

I thought I'd cut steel most ways that were possible...and I've never heard of, nor would I care to try to cut steel with a chisel. Honestly, I just can't see it working ! :confused:
I am wondering if this is a lesson to demonstrate the need for machine tools? Seems like an exercise if frustration and a waste of time. I would not spend to much time in the endeavor.

[siddharth]

Gokul, Did you not have do the same thing when you were at IIT-M? In fact, my instructor was telling me that my batch is lucky as we have to chisel only 1 side while the previous batches had to chisel 2 sides.

[zoobyshoe]

I thought I'd cut steel most ways that were possible...and I've never heard of, nor would I care to try to cut steel with a chisel. Honestly, I just can't see it working ! :confused:
This is exactly how they used to work metal in metal shops back before shapers and milling machines: chisels and files, but it became pretty much obsolete with the introduction of the metal lathe. You can square things up on a lathe if that's all you have.

[devil-fire]

i worked with an old polish guy who had to make hammer heads with files. he figgured it was more to get rid of people who had no patience for doing work they felt could be done better other ways. the applicable lesson here is that when you cut corners on an actual job because you dont have enough patience, it can reduce quality. if you start off my learning patience you wount have that problem

[Gokul43201]

This is exactly how they used to work metal in metal shops back before shapers and milling machines: chisels and filesChisels ? Are you sure ? Hacksaws and files, I can understand, but how on earth do you cut metal with a chisel ??? The only reason that you can chisel wood, is that wood has extremely acicular grains; but mild steel doesn't. Have you actually done this, Zoob ? And I'm not talking about cutting shapes out of sheet-metal.

Siddharth : I had to sit with a giant block of steel, and essentially file it all away (under the despotic glare of a duo named Guptan and Goodman...they still around ?). After weeks of filing away at pc steel (a ridiculous waste of time, IMO), we could intimately relate to the name 'bastard file'. And while that was a nightmare in itself...it sure didn't involve any chiseling.

[Moonbear]

I just started reading this thread. Out of curiousity, what do you make a chisel out of to cut steel? I was under the impression that most chisels were steel, which would make that a very futile task. :confused:

[Gokul43201]

Chisels are made out of....chisel steel - a type of hardened steel (typically, much harder than mild steel). It's not the material hardness that concerns me as much as the principle behind the process.

Metal cutting is typically an abrasion based process - that's true whether you use a file or a saw or a diamond tip on a lathe. Granted, cutting on a mill or a lathe is nothing but a microscopic version of chiseling, but with a far sharper cutting edge and much better control than you can dream of achieving with a hand chisel. But mild steel is not brittle like wood; it goes through a good bit of plastic deformation before it will begin to fracture - and fracturing it is what you want if you hope to cut it. That's why it's possible to do this at the very small scales, where the deformation is localized to a small region, but there's no way you can do that with a chisel !!

Also, most wear/abrasion resistant materials (like carbides) are extremely brittle and have terrible impact strengths. And chiseling is just that - an impact process.

I'll accept it's doable if someone tells me they've actually done it.

Siddharth : did the instructor not show you how it's supposed to be done ?

[Moonbear]

Okay, that's what I thought. I was thinking that saws would be carbide tipped, but carbide would just shatter if you tried banging on it like you do a chisel. I would think that even if you could get a strong enough chisel, you'd just dent and ding the steel rather than cut it.

Maybe you can just dent and ding it until you have an overhang onto one of the sides you're supposed to cut or file and then claim it's part of one of those sides and saw off the excess? :tongue2:

At the very least, get a thumb-guard on the top of that chisel so your fingers don't take the direct hit! Even wood can be hard to chisel if you're going against the grain. Trying to get something sharp enough to cut steel sounds like a good way of sending half your students to the emergency room!

[zoobyshoe]

Metal cutting is typically an abrasion based process
No, metal cutting is a shearing process.
I'll accept it's doable if someone tells me they've actually done it.
It's certainly doable, it's just frickin' hard. Back in the day, people were good at it, and had all the tricks down. Certainly you have to hold the piece in a massive, rock solid vise. As you chisel along the chip curls up in front of the chisel. Depending on the depth of the cut, each hammer blow may only advance the chisel 1/8 inch or so. The chisels have to be resharpened constantly, and they wear out fast, but back then, they made all their own right there in the shop. There is, no doubt, a set of specific angles at which to grind the chisels for various kinds of cuts.

They were, for the most part, probably not working steel, but soft iron, probably softer than today's hot rolled steel, which is the softest common steel. In all cases, chiseling produced the rough cut. Finishing had to be done with scrapers and files.

I may hunt up a link if I get amitious. I researched all this machine shop history back when I was in school because it occured to me that you're always copying the straight lines and flat planes built in to the machine tool to the part you're making. That made me wonder how they arrived at the first straight line, or the first flat surface. It took me about three months to find out how it was done. (The web didn't exist back then.) (Edit: I mean back then when I was doing this research.)

[Gokul43201]

No, metal cutting is a shearing process. Sheet-metal cutting is a shearing process, and so are milling, turning, facing, etc. But certainly not filing or sawing. I guess I just find it hard to imagine that shearing of this kind can be achieved with a hand tool.

I'd like to see what a metal-cutting chisel looks like.

[zoobyshoe]

Here's a few pictures of cold chisels:

http://images.google.com/images?hl=en&ie=ISO-8859-1&q=cold+chisel&btnG=Google+Search&sa=N&tab=wi

[Gokul43201]

I've used cold chisels on concrete. Are they what you'd use on metal too ?

Next time I'm in the machine shop I'm going have a go at a hunk of aluminum maybe.

[Moonbear]

I've used cold chisels on concrete. Are they what you'd use on metal too ?

Next time I'm in the machine shop I'm going have a go at a hunk of aluminum maybe.
Hmm...I've used cold chisels on concrete too, but they dulled awfully quickly, which fortunately didn't matter much for what I was doing since I didn't have any means of sharpening the chisel. I'm not so sure about how that would work on steel!

[FredGarvin]

Next time I'm in the machine shop I'm going have a go at a hunk of aluminum maybe.Come on. At least get something to make it a bit sporting. Make you work a bit.

I worked with a machinist who came up through the ranks as a mold maker. He told me that as an apprentice (almost 40 years ago) he had an ongoing project which was to get a block as close to perfectly flat as he possibly could using nothing but files. He said it took him over a year to get it to the acceptable level that his boss would accept.

I have never heard of anyone using chisels, but really, what is the difference between an end mill and a chisel other than whose driving it.

[Gokul43201]

Come on. At least get something to make it a bit sporting. Make you work a bit. Yeah, thanks for the encouragement ! :grumpy:
I worked with a machinist who came up through the ranks as a mold maker. He told me that as an apprentice (almost 40 years ago) he had an ongoing project which was to get a block as close to perfectly flat as he possibly could using nothing but files. He said it took him over a year to get it to the acceptable level that his boss would accept.
I have never heard of anyone using chisels, but really, what is the difference between an end mill and a chisel other than whose driving it.What's the difference between a Rembrandt and my doodling, other than whose drawing it ?

I know a machinist whose self-test was to turn down (in a lathe, not using an auto feed) a 6" long brass rod to the smallest possible diameter without breaking it. He'd start with a 0.25" dia rod and take it down to under 0.100" in a single cut ! I'd have never thought that possible.

[FredGarvin]

I meant in terms of the cutting action. Not tolerances, quality of cut, etc...it's at its most very basic level the same.

[Gokul43201]

And there's this welder who tests his control by grabbing a 3' long metal rod in one hand (actually, not with his bare hands :eek:), a torch in the other and making a near-perfect circle out of the rod without letting go, switching hands, setting anything on any surface, using any other tools, etc.

[Gokul43201]

I meant in terms of the cutting action. Not tolerances, quality of cut, etc...it's at its most very basic level the same.I don't disagree. In fact, I said much the same thing earlier :
Granted, cutting on a mill or a lathe is nothing but a microscopic version of chiseling, but with a far sharper cutting edge and much better control than you can dream of achieving with a hand chisel.

[Integral]

I bet that if you could learn to sharpen a chisel to cut steel when it came time to grind a lathe tool you would have a pretty good feel for it.

Grinding a good lathe tool is an art, now a-days it is to easy to just chuck up a carbide tip, does anyone still grind their own?

I think this chisel assignment is a bit over the edge, but if he can make it work, he will have a good feel for just how much work it takes to cut metal and how to make a tool that will do the job. There is some value it both of those lessons.

[Gokul43201]

I bet that if you could learn to sharpen a chisel to cut steel when it came time to grind a lathe tool you would have a pretty good feel for it.
Grinding a good lathe tool is an art, now a-days it is to easy to just chuck up a carbide tip, does anyone still grind their own?I grind steel cutters now and then, but I wouldn't say I'm great at it. Mostly I don't have the need or patience to get a beautiful cutting edge.

[siddharth]

Siddharth : I had to sit with a giant block of steel, and essentially file it all away (under the despotic glare of a duo named Guptan and Goodman...they still around ?).

Goodman is still here. There is another person instead of Guptan.
When the instructor showed how it was done, he kept the rod in the vise, the chisel at an angle and hit really hard.
After two good hits, a layer of the metal came out. Of course, when I tried it, all that happened was that the surface just got dented. And a disadvantage of hitting it that hard is that when the chisel slips from the surface, my hand holding the chisel goes along and scratches the surface (Never happened to the instructor when he was demonstrating).

[FredGarvin]

Grinding a good lathe tool is an art, now a-days it is to easy to just chuck up a carbide tip, does anyone still grind their own?
We routinely make our own lathe cutters. There are too many wierd and tough shapes to cut that a standard cutter just won't do. Admittedly, sometimes they look like they could have been dug up on an archeological dig, but they work.

[Moonbear]

And a disadvantage of hitting it that hard is that when the chisel slips from the surface, my hand holding the chisel goes along and scratches the surface (Never happened to the instructor when he was demonstrating).
I can't help you with the whole metal bit, but having used chisels for other applications, I can recommend some tips to not hurt yourself, at least not as badly :uhh:. First, when you hold the chisel, if you're attempting downward cuts, keep your thumb tucked in front of your fingers, not up at the top (make a fist and put your thumb over the top of your fingers so the tip is trying to touch your little finger...hold the chisel the same way). Generally, this gets you a good grip on the chisel, and if you miss it with the hammer, you'll still have bruised fingers, but won't get the very sensitive tip of your thumb that would make it hard to do fine work later. Use your non-dominant hand to hold the chisel (if you are right-handed, hold it with your left hand)...you want to have the best control of your hammer. Position your chisel where you wish to make the cut, and then brace your forearm (from just ahead of your elbow, to about 1/3 to halfway up your forearm...basically the muscular part, not your wrist) against a stable surface...the work table, or your vice grip would be the best. You want to have a firm grip on the chisel, but you don't need to have a death grip on it...that will just tire out your hand needlessly. When you strike the chisel with the hammer, use short strokes...this isn't tennis, you don't need to "follow through." If you try to hammer "through" the chisel, you're more likely to just glance off the side of the chisel and either deflect the chisel in the wrong direction or whack your knuckles. Instead, sort of end the stroke as you hit the head of the chisel and let the hammer rebound back up. You can still do this with considerable force, and as you get the knack for it, you'll have a better idea of just how hard to strike and you'll have more control of your hammer. Some of the control really just relies on forearm muscles though. Focus on keeping the hand holding the chisel as steady as possible when striking it; resist the temptation to try to push it through the material to "help" it.

Intuition tells me you should try starting your cut from a corner (keep a flat surface facing up, hold the chisel at a slight angle at the corner, though not straight into the corner (i.e., not at a 45 degree angle to the flat surface, more like a 25 or 30 degree angle) and strike the chisel off-center (maybe 10 degrees to the surface). This might help give the chisel more of a slicing action than a blunt force action to get that first cut started instead of just denting the metal. But, I've never attempted using a chisel on any sort of metal, so my intuition may not be right, it's just a thought you might want to try if you haven't already and nothing else has worked yet.

Oh, keep the rest of your body away from the front of your work piece! Stand behind it (both of your arms should be somewhat in front of your body), and be absolutely certain if you are sitting that your legs are not under the work piece. You don't want to slip and sent that chisel through your thigh! :eek:

[Averagesupernova]

Some of you act as if using a chisel on steel is like using fire to fight fire. A good chisel will easily cut mild steel. Also, there are plenty of uses for a chisel in this century. Usually it involves disassembly or something. There are just some places you cannot get a grinder or saw into in order to remove metal. One thing I cannot stress enough is to have an anvil or something backing your work that is heavy enough to prevent ANY movement on the workpiece. A bench vise sometimes just won't cut it. A note on sharpening chisels though, don't let the chisel get too hot. Keep a container of water nearby to dip the tool in every few seconds to prevent overheating. Overheating will soften the chisel. Oh yeah, one last thing. If you're really worried about hitting your fingers hold the chisel with a pair of pliers or vise-grips locking pliers. At least until you become accurate with the hammer. Hmmm. I keep coming up with more suggestions. While on the subject of hammers, make sure it is sized for the type of work you are doing.

[siddharth]

I finished the exercise yesterday. The cube came out pretty well though my dimensions were off by 1 mm. I got 30 out of 40 marks for my work which is decent. I chiselled till it was somewhat flat and filed the rest of the uneven part.
Thanks for your suggestions and advice.