Very true. Hardinge mills were never pitched at the home hobbyist, but the industrial manufacturer of smaller items. Benchmasters were pitched at the vocational trade schools. And these were FAR from the smallest mills out there.
General motors, during the Korean war, made instruments in a huge factory in Livonia, MI. They used large numbers of Atlas 6" lathes and Child's (tiny) horizontal mills to make parts. and some work demanded even smaller machines made by Bulova, Dixi, Levin, and others. These were no bigger than 'Unimat' sized machines, but totally industrial in application (and price).
I have a partly restored (ongoing project) Levin 4" (?) lathe, and a 'bag of bones' Dixi vertical mill (about a foot high). The Levin's getting close to useable again. I hope to put both back in service someday.
If you attempt to climb mill in a decent size horizontal mill with about anything other than a slotting cutter, you better make sure you have a machine with a minimum of my namesake (Backlash), or you are likely to get one nasty surprise. Even with narrower cutters, we have to set the drag on the table fairly stiff to help prevent jolting. Sometimes climb milling is absolutely necessary, such as is often our case, but it's still a little nerve-wracking. That kind of stuff will make pros out of amateurs real quick.
Best way for holding stuff like that is to scotch tape them to a 3x5 card. By the end of the shank, not along the flutes.
I have a boley lathe for stuff like that, I bought it 'one piece at a time' like the Johnny Cash song goes. They wouldn't sell me the bed though!
A nice gent in the model shop made it for me.
Jim
================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================
Nope..not climb milling. It wasnt struggling a bit. and there was no movement of the vise. I was taking about .06 off the top, to get under the mill scale and it came loose.
I keep the table clean, flat etc. I often use clean dry paper between the jaws and the work piece as well. It seems to hold better on some materials. And of course I often have only one side supported, the other has a brass rod between the jaws and the work, particularly when flattening a block. In this case however..the work was moderately square, clean, dry etc. It cut about .25 then pulled the work out of one end of the jaws and pulled it into the cutter.
I use paper in the shaper vise quite often too. Its a recommendation in all the shaper books.
Ah...people pay me to fix their mistakes..ie broken machines. Im pretty knowlegable about how to not bust a machine.
Gunner
"As my father told me long ago, the objective is not to convince someone with your arguments but to provide the arguments with which he later convinces himself." David Friedman
You said: "It broke off a couple flutes from the cutter, started the belts smoking, and moved the vise 2" down the table before I got it shut off." Which is what prompted me to ask about the duration of the cut to permit such vise movement. ?? I guess what you meant was that once it crashed, the vise then moved before you got it shut down. Do I have it clear?
I'm of the opinion that in this case it could easily have been a part of the problem. I'm not sure what the crush strength of paper is, but it's way less than metallic substances. While it's good for filling gaps, it simply does not provide the necessary clamping pressure needed under tough conditions. If you don't mind a tip, when you're holding something in a vise that is quite wide, possibly not perfectly parallel, and the cutting pressure is extreme, you're far better served to grip the item with two equal sized pieces against the moveable jaw, one on each end, which allows the moveable jaw to tip enough to load both ends of your part equally. You were most likely a victim of holding your piece only on one end. With a paper filler, it wouldn't be real obvious, and certainly wouldn't be clamped well.
And of course I often have only one side supported, the other
That's a great trick I use too. More or less guarantees you load the fixed jaw such as to keep parts square. The only difference is I generally use a hardened dowel instead of a brass rod, and I try to have it line up with the center of the jaw vertically, for obvious reasons.
In this case however..the work was moderately
Gotcha. Sort of speaks volumes about the amount of pressure in the cut when running such a large surface with a cutter. I recall guys used to beat on the vise handles to make sure things didn't come out under like circumstances. Always made me shudder to think what they were doing to precision vises. All of that can be avoided by the method I suggested above.
Interesting. By the time I got in the shop, shapers were just about history. I can honestly say I was never trained on them, although I have run one. There was one in the tool & die department that I saw run only one time, when the supervisor tried to convince the mill department that he could rough some 4140 parts faster than the 10 horse K&T vertical mill could running an 8" insert carbide shell mill. The shaper didn't have a chance. They were pulling so much with the K&T that it would occasionally shut down from overheating. Easily did twice the work of the 24" Cincinnati shaper. It's pretty clear why they fell out of favor as mills got better and better.
And you still use paper?
Just goes to show that all of us have the odd mishap, even when we do our best and have a good sense of direction. Did your arbor come out of the crash without being bent?
Correct. I had just walked across the shop after starting the cut.
I cut a lot of aluminum and crs, and often times a hard dowel will sink into finished side, which is not a good thing when squaring a block etc.
Yup. Helical milling cutters really help, but they still but incredible loads on the work piece.
Hard to cut an internal dovetail with a horizontal mill. . For a non production environment, when time is not a great concern, a good shaper is a great versitile machine. Able to use a chunk of tool steel for cutting complex angles and dovetails. A very handy machine.
Yup, in certain applications.
I havent checked yet. Shrug.
Gunner
"As my father told me long ago, the objective is not to convince someone with your arguments but to provide the arguments with which he later convinces himself." David Friedman
I deal with that by selectively choosing which face of the piece gets treated next. Considering I am the only one that touches my machines, I know my equipment and can rely on the fact that my vise is in good condition. Once I have three faces machined, I always abandon the dowel in favor of the parallel face of the moveable jaw. That way any damage done by the dowel is removed in the final cut. I do a tremendous amount of fly cutting for finish, makes no difference what the material is, so my end resutls are usually very acceptable both cosmetically and precision wise. I can pretty much rely on less than a thou parallelism and square.
snip-
Exactly the reason I entertained buying a 12" model a few years ago. The guy had replaced the 3 phase motor with a single phase of smaller HP, and wanted $1,500 for it. I knew that was more than market value, especially to me, and I wasn't thrilled that he no longer had the 3 phase motor. I've always had 3 phase in my shops. I held out, thinking no one would buy it, but a week later he found just the right guy. What's something worth? What ever traffic will bear, apparently.
I ended up buying a shaper head for my Bridgeport at a bargain price. Just restored it last year, and I'm proud to say it looks like new. I've done more than enough stroking by hand and am looking forward to the convenience of the head. I've yet to run it, thanks to the house building project at hand.
Keep a good thought, and a nice arbor press if things don't go as hoped!
In my experience almost square doesn't work well. If the two sides are not parallel when held in my kurt vise it doesn't clamp well because the movable jaw won't tilt. This can lead to the part moving.
I always thought paper was used to protect the surface finish and I only take very light cuts in that mode. My logic is that metal to metal is tighter than metal to paper. I could be wrong, but it just doesn't sound right.
If I really want to hold something solid, I use some thin pieces of soft aluminum(1100) between the vise jaws and the work and really clamp it down. My theory is the aluminum will deform and distribute the pressure. I prefer copper, but its too expensive to use all the time. I do use copper sheet if I want to hold something precious like a partially machined crankshaft.
Your experience is dead on. Almost square is a quick introduction to trouble, especially if you're taking a serious cut. I posted a suggestion for holding such parts, and it's extremelly reliable, even in a Kurt, which I use. The moveable jaw will tilt, but only if there's no contact anywhere near center. By using two relatively narrow equall sized contact pieces, one on each end of the jaws, you get perfect gripping power. I've held parts that way for what seems for ever. That works only if the part is "almost square", however. The jaw isn't willing to tilt a great amount.
I don't give a damn what any book suggests, shaper manuals or others, you're right. Holding with paper is risky business if you need gripping power. Same goes for holding items with wood. Intimate contact with metallic jaws is the preferred, and most reliable, method of holding. Beyond that, it's a PITA. Imagine running a multiple quantity of parts with coolant, which you'd most likely be doing with a horizontal mill. Constantly fighting wet paper? Not for me, thanks.
Because of the possible error introduction by holding with shims, I generally work right off the hardened jaw faces. So long as you keep them in fine fettle, they won't mark your work. It's also a good idea to know when to lean on the hanlde and when not to. I've used something like a 2" parallel clamp as the handle when holding small precision pieces that I didn't want to hurt. Cutting pressures tend to diminish with part size, and you'll find that it takes very little effort to hold them as they get smaller.
If you have a surface grinder at your disposal, it's common practice in commercial shops to occasionally grind mill vise jaws to keep the surfaces in good condition ("fine fettle"). You grind the gripping surface and the tops of the jaws. A thou or two is usually all that is required to restore a perfect surface. If you do that, you'll be amazed how holding parts does them no damage, even won't disturb a surface patina if you don't horse the handle. It's worked for me for years.
Custom vise jaws work well too under certain circumstances.
I ran a Hurco VMC for a couple of years - but after a few months of running it, I realized that the aluminum jaws the shop had on it were way, way too tall. The jaws were flexing so much under the clamp forces that the holes being drilled in the nylon pads were highly non-repeatable.
Worse, they were gripping the parts by only a tiny amount, the jaws had a lip machined in to allow depth location. Because of the nature of the material (moly disulfide loaded nylon) the parts would tend to extract out of the jaws under the drilling operation.
After somebody finally dinged the machine good this way they took the suggestion, and shortened the jaws from four inches tall to only on inch tall, and made the grip area much larger. Further they machined a recess on the horizontal surface, to allow the occasional chip to drop out of the way. This machine was shovelled out with a snow shovel at the end of the night, typically - filling about three 30 gallon trash cans with curly nylon noodles.
After the changes, there were no more part rip-outs. Vises should not have to be tightened down with impact wrenches!
Jim
================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================
I couldn't agree more, especially the use of custom jaws. I've run some jobs that I would not otherwise have been able to hold.
The tall jaws you described sound to me like an invitation to trouble. Loading them that far from the pressure point of the vise most certainly must have been tilting the jaw, encouraging the parts to slip out the top.
Not all my shop experience came in the missile industry. I had a short stint in two shops, ten months between the two. I recall a vise handle in one shop that had been beat on with steel hammers to the point where the handle end itself was gone, and the stub was beaten flat from repeated hammer blows. I get the impression that not all guys on machines are what could be called machinists, regardless of their title. No wonder I sound like I'm talking down to some folks.
I just heard from a trusted and worthy peer, who read my comments. He claims he has used paper between parts and suggests he has had outstanding results with it. Suggests parts that would otherwise move when being held do not. Certainly could be, but it's not something I've witnessed anywhere I've worked. I know and trust this guy well enough to give his comments the benefit of the doubt, however, so my statements above might be taken with a grain of salt. I'm of the opinion most of us come up with ways to get around problems and we might not all achieve the end result the same way. Looks like we're never too old to learn.
Paper intended to be written upon has a high clay content, and won't be very "grabby". Try kraft paper, ie what paper bags are made of. To prove this to yourself, just run your finger over a sample of bond paper and a sample of kraft paper. The latter has a noticably higher friction coefficient.
I always use the yellow legal pad paper. Ive also used file folder cardboard sucessfully.
A practical example of such..is if you put a bit of cardboard on the forks of a forklift before lifting a machine..its far less likely to slide on the forks.
Gunner
"As physicists now know, there is some nonzero probability that any object will, through quantum effects, tunnel from the workbench in your shop to Floyds Knobs, Indiana (unless your shop is already in Indiana, in which case the object will tunnel to Trotters, North Dakota). The smaller mass of the object, the higher the probability. Therefore, disassembled parts, particularly small ones, of machines disappear much faster than assembled machines." Greg Dermer: rec.crafts.metalworking
Considering using paper has never been a part of my machining experience, I posed the question to my trusted colleague. His response was::
H,
I use cereal boxes between the moving jaw and the work. On stock I am squaring up that is very uneven, I will use it on both jaws. I have used notebook paper in the mill on occasion, but if I don't need the cereal boxes, I usually don't need anything. When I used to run a shaper, I normally used cereal boxes. I have had neither shear fibers and allow the work to move, even with heavy cuts, the exception being with stock that is way out of square. If I am working with a flat piece clamped on an angle plate, I always put a piece of notebook paper between the work and the plate. Makes a tremendous difference in the work not moving. I do this even with both surfaces being ground, and it makes a noticeable difference.
You can post this if you like, I can't post to RCM.
Gunner, who maybe does know something after all :)
"As my father told me long ago, the objective is not to convince someone with your arguments but to provide the arguments with which he later convinces himself." David Friedman
Got to start recycling my cereal boxes in a new way!
Its not possbile to know everything. Look at Al Gore, he thought he invented the internet.Shows what he knows. And my favorite is the VP (Dan the Man) that couldn't spell potato.
I see it another way, Gunner. I've been in the shop for over 40 years and have never needed to use cardboard or paper for anything except for writing, or picking up a surface with a cutter. There are ways to get around it with equal or superior results. Adding paper to a machining operation isn't likely to do much for quality. All one has to do is change how holding parts is perceived and it's dead easy to avoid using paper. I still don't endorse the idea, and see no good reason to try using it, at least in my case. Can't speak for others.
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