The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Gunsmithing Why are they not square?Go | New | Find | Notify | Tools | Reply | |
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| one of us |
Hmmm...If a Remington tubular action will need a lathe to square the recoil lug bearing surface, then it is not cut with a parting tool bit in a lathe in the first place? Did a rotary saw did it? What about non-tube actions like Winchester 70 classic? Are they cut with some band saw as well? What about other surfaces, like receiver locking lugs, aren't they machined with a lathe too? There might be rough marks but how can they not be square? ![[Confused]](images/icons/confused.gif){kind=icon} | ||
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| one of us |
being square is easy on a lathe for cutting a piece of metal. The problem occurs with rifles because there is a predefined center, the bore. So if the spindles spin even slightly off the centerline of the bore, you end up with an action that is not square. It is much harder to setup a lathe on a predefined center, if you are just cutting a barstock, spinning it inbetween two of center spindles that are off center, there is no problem since the bar will define it's own center as it spins and is shaped. | |||
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| <JBelk> |
Pyrotech--- THat's been a mystery since I saw my first one about 1983. I studied that action for a LONG time trying to figure out *how* a tubular action could be crooked. I *think* they do it by NOT using a lathe. The action *must be* held in a fixture and the tool is rotated. That's totally bass-ackwards but it's the only explaination I have. If the action is spun and the tool is fed into it and the action is NOT centered, the hole/recess/threads cut with the tool will either be oversize, tapered, or offset, but square. The only way I can see it happens is a rigidly held action and a misaligned tool. Barrel threads are much more likely to be out of square than the lug recesses. It's possible the action is cut for the bolt body and the lug recesses cut at the same time but the threads done in a seperate set-up. I've spent the day in the bowels of the Ilion plant but they kept me out of the production facilities. | ||
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| one of us |
Three years ago I bought all of Greg Tannell's tapes and a great deal of his accurizing tools. Good stuff ! Recently, however, I've begun to rethink "squareness" and "blueprinting". Is the bolt raceway really the important reference? With the bolt in battery it seems to me that the important relationship is the face of bolt and bore. Boltface honed or lapped 90 degrees to bore with 100% contact of lugs by lapping. Out of battery the bolt only needs not to bind and provide smooth feeding, extraction, and ejection. Wally | |||
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| one of us |
Jack - I once read an article about Remingtons use of Flexible Machining (back when that was the buzzword of the day) and the machine that was shown was a horizontal machining center. Granted that the receivers that were shown were either 870s or 1100s, but I think mention was made of using the same type of machine for M700s. As for crookedness, here's my theory. The threading is done on a lathe, but as a second operation, after the bolt bore, lug recesses and receiver face are done. The fixturing that holds the workpiece (the receiver) rotates concentric to the tap that does the threading. A better way to say it is that the axis of rotation of the lathe is concentric with the axis of the tap. However, the bolt bore of the receiver is not concentric with the tap, perhaps because there is a chip embedded in the jaws that hold the receiver. So, you don't get oversized or tapered threads because the axis of the lathe is concentric with the tap, but you do end up with threads that are not concentric to the bolt bore, or normal to the lug recesses or receiver face. Substitute a single point cutting tool for the tap and the principle still applies. Regards, Scott | |||
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quote:Is this critical if locked and loaded boltface is square to bore? Wally | |||
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| one of us |
Wally, The bore is used as a reference point only because it is handy and perhaps the esaiest to use. I believe you are correct and, from an accuracy standpoint, everything would be fine as long as the bolt face is square to the axis of the chamber and barrel and the lugs bear evenly. However, if the bolt face becomes misaligned as the bolt is rotated difficulty in lifting the bolt is bound to occur. Carrying things to extremes, you should be able to have a floating bolt head which is aligned with the barrel and perpendicular to the bore while the bolt body is decidedly misaligned. It is quite easy to cut threads, bores, or any surfaces so they are misaligned using a lathe. If this were not so guys would not screw up so often! I can cut threads which are concentric or eccentric, angled or not, square to the bore of the action or the face or whatever depending on how the action is set up. I can cut locking lug seats which are perpendicular to the bore or not. Figure out how to induce an error and you will know how to avoid it or correct it. Regards, Bill. | |||
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| one of us |
Good post Bill. Illustrates the importance of doing as much work as possible from one setup with rigidity and well honed tooling. Wally | |||
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one of us |
Unfortunately, Remington seems to use either machinists who should have remained floor sweepers, or Engineers who should have taken up gardening, possibly a combination of both. In order to properly manufacturer the Remington receiver with a reliable method, that would ensure the utmost in accuracy, it is neccessary that the most critical areas be machined in a single setup. These areas being the bore, receiver face, threads, locking abutments, and cocking cams. All of which should be done on a CNC lathe, without exception. The outside of the receiver is more or less irrelivent except to provide a consistent area to mount your scope mounts to. So, with that in mind, it would be more or less reasonable to begin with ground and polished barstock. Once you've located from the outside of the ground stock, and machined everything within tolearance, your receiver would be as good as it gets prior to heat treat. Why in the world Remington uses any other system than that is beyond me. This is basic machining guidelines that they haven't obviously picked up on, considering their lack of quality that they consisently obtain. Now there are at least one manufacturer of custom actions that mill the threads and receiver face on a round receiver. This is not necessarily bad, but it's just inviting more potential error into the equation when it's not necessary. This system makes perfect sense on a flat-bottom action, but not when you're dealing with a round action, that lends itself perfectly to a lathe. It's also worth noting that this particular manufacturer did not have a lathe at the time, so one must do, with what they have to do it with. They may now be using a lathe, who knows. | |||
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quote:Doesn't even make since on flat bottom receivers. Many of us are chucking, centering and machining Winchesters, mausers etc. Imagine if receiver rings were ground concentric to centerline and you could afford a the expensive chuck to set it up for machining. Wally | |||
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| one of us |
The majority of manufacturers machine to close tolerances. The problem is usually due to the heat treatment of the part after the machining. When the part is machined you are cutting ejection ports, magazine well openings and many other cuts. When heat treated, the part moves because of these openings and cuts creating different stresses and the lack of squareness. What 'blueprinting' does is true up the parts after heat treat. This is much more difficult and costly because of the hardness and is usually left for the custom gunsmiths to do. Headache | |||
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quote:I was told by a friend that use to work for Remington that a lot of their quality problems are the result of union workers not letting Remington update there machinery/techniques, in the Ilion plant, for fear of job lose through automation. This is one of the reasons Remington has built plants in other states. Now I don't know how many of the new 710's and 597 22's you have looked at but I would say the quality of the machining process is ok just bad design in the 710. so in other words if you took the machines that build the 710 and build 700's they would probably be as straight as could be. Oh well just thought I would throw that out there. Shawn | |||
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If there is any truth to the union story that's a shame.....I am pro labor and a working class grunt myself, but when a company has to have quality suffer because of labor issues there is a problem. | |||
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Good point about the heat treating caused warpage, Headache. Maybe one can tell from the machining marks on the factory receiver face to determine how it is cut? | |||
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quote:Believe it. Most unions and their members resist automation and lean manufacturing, which reduce costs and increase quailty through the reduction of non-value adding activity. Union leadership in the plant is all for it when presented with the idea, but when some overpaid union machinist has to get off his ass and run two machines in a properly set up lean cell, all hell breaks lose. Most unions are so stupid that they don't realize they are screwing themselves and their members by resisting the inevitable. The company and its management will survive, even if all it becomes is an assembly house for stuff made elsewhere, or worse yet, and import house that just puts its name on stuff (Browning). | |||
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quote:Wally, Everyone has to do it that way when you start off with a turd from Remington or Wincheseter, but when you are manufacturing a reciever from scratch that must have milled contours, then the only reasonable, expedient, and accurate way to do it would be with a thread milling interpolation. As long as all of the critical parts of the receiver are being machined in a single setup, then your part is qualified. It is when you setup to one operation, then come from those surfaces to setup another, and so on, and so forth, that you invite a stacking of tolerances. As far as labor unions, I've got zero use for them. They're good for encouraging laziness. When I toured the Winchester facility a few weeks ago I got to witness first hand the hardworking union members there.LOL There was more people standing around with there thumb up their ass than you could shake a stick at, but management couldn't say anything for fear of getting in trouble with the union. All the while, you the customer, pays the difference. Unfortunately, our gun companies are being ran by people who do not hunt, shoot, or care whether or not they provide a quality product. If you ever looked at where Winchester was located, you'd see why it's hard to find good help. It looks like the backdrop for a Charles Bronson Death Wish 10 movie. | |||
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Thread milling via interpolation isn't necessarily the final answer. Especially when working with relatively small holes (like a receiver). Tool flex is a problem that frequently rears it's ugly head. I have spent many hours setting up and recutting interpolated threads on hydraulic valve bodies. Wichita cut the threads in their actions with a piloted tap and the threads were generally very good. Shilen used an unpiloted tap and their's were not. Regards, Bill. | |||
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Matt!! So why do we have these labor unions, and why does Winchester have to hire these people? | |||
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One of Us |
Headache, based on your experience I'd encourage everyone on this thread to weigh your words carefully as they're based on real, firsthand knowledge and NOT speculation... | |||
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quote:I might be misunderstanding you, but what I'm referring to as thread interpolation, is using a single point, or form tool to literally generate the threads, not tapping them. This system produces some of the finest threads imaginable, and receiver threads are quite large compared to what you can actually interpolate. We thread mill 1/4-28 holes, if that will tell you how low you can go. I've heard that Shilen tapped their recievers, which blows me away that anyone would even consider that method. Talk about rude and crude. As far as the labor unions, basically they get into a company like Winchester by being voted on by the employees. Once they're there, it's almost impossible to get them out, unless you go bankrupt and shut the doors. That's exactly what happened to several plywood mills here in Oregon. Labor unions began with honorable intentions, and were benficial to not only the employees, but the employers as well. In time, with the corruption of the union leaders and crappy way they began to treat the employers, they managed to produce a lazy american worker, who believes the world owes them a handout, and lacks any drive to work harder or better than their coworkers, or produce a higher quality product. They know that within reason, no matter what they do, they're not gonna get fired or disciplined because their union leader will be all over management. Brad, Headache is correct in that a lot of the problems that these receivers suffer from is within the heat treating process. Remington is a little worse than Winchester due to the fact that the Winchester receiver tends to be a little more stable, not only by it's design, but because it is forged as well. Forging helps eliminate the stresses within the material that cause the part to move once the part begins getting machined. But more important than the heat treat, is the fact that it is machined properly before the heat treat. This will minimize the movement of the part both before and after heat treat. | |||
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| one of us |
I always kept the labor union issues to myself because it would piss my father off when I talked about them in a negative way. Now I see people feel the way I do about them. For over 20 years my brother and I had our own contracting business, an open shop. I paid my help well, and they treated me well. Good work good pay. My brother decided to go work for a major utility company, union shop, benefits, etc., and left the business. I closed it and went into sales. Anyway, when he first started working for the utility he was told to slow down. Basically he was getting too much work done too fast. He had a very hard time relearning how to work, not for efficiency but for killing time. As Matt Williams said when unions were formed they were formed for all the right reasons. Somewhere along the line something messed up. What a shame!!!! Happy 4th | |||
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| one of us |
Matt, I am well aware of what is meant by interpolation and how threads are generated on a cnc mill. I am also aware of the difficulties which can arise. Many are the same problems which show up on a manual machine or on a lathe. This includes but is not limited to, tool wear, deflection, chip clearance and machine accuracy. Perhaps the biggest challenge is the making of fixtures and establishment of methods which allow repeatable set up and positive alignment. The threads in some of the Kimbers appear to have been cut in this manner and they were frequently nothing to write home about. Interpolation is certainly a viable method of producing a thread but it is not necessarily the best one in many applications. The tapping of receiver threads has been common and still is in some instances. As I said, the Wichita actions were an example of very good tapped threads while the DGAs were variable. There are still some highly regarded actions which use taps as a means of producing the receiver threads. Remember, a tapped thread which is straight and concentric is just as good as any other. So ultimately the quality of the final product comes down to quality control as much as to methodology. Regards, Bill. | |||
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I don't see any magic in single pointing threads as opposed to tapping. If, as Bill points out" the tap is run on a well fitted mandrel. Isn't this what Manson does with his "accurizing" setup? Wally | |||
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The problem of tool deflection and poor finishes is much more prominent in tapping than in helical interpolation. For shear accuracy and repeatability, as well as control of final dimensions, interpolation of threads is far more accurate, and can produce many times, better finishes than conventional single point threading by way of a lathe on internal threads. The accuracy of 99% of CNC equipment far exceeds what the gun industry even comes close to utilizing. We manufacture our parts on Haas CNC vertical machining centers, and while they are not considered the top of the line machine, they regulary hold tolerances of .0002 all day. This has to do with not only our fixturing methods, but also the fact that we try to machine all critical features of our parts in a single setup. By doing this we eliminate problems of tolerance stackup. In the aerospace industry, when it is necessary to produce a threaded hole that must be extremely accurate, tapping goes out the window. It is then that the part is either threaded on a lathe, or interpolated on a mill, depending on it's geometry. Thread milling also gives you much more control over speeds and feeds, ensuring that a quality surface finish is obtained on the threads, reducing the amount of torque necessary to attach it's male counterpart, namely a barrel in this case. | |||
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Triggerguard1, I think we may have to agree to disagree on this one. I have spent too much time correcting threads cut on vertical CNC mills to be convinced they are the superior method. When it came right down to it the internal threads produced on the CNC lathes using single point tools were invariably better than those produced on the mills. Now maybe our operators were simply inept but I don't think so! I agree there are many cases where the production of an internal thread by interpolation may be preferred from a production standpoint. I also believe that the reason is often one of expedience rather than to obtain a superior product. I'm not saying any of this to denigrate your methods. Just stating my opinion FWIW. Regards, Bill. | |||
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| one of us |
When you're dealing with a round object, like the Remington receiver, it only makes sense to utilize a lathe for the cutting the threads. Anything else would probably be a waste of time as well as accuracy, but this is not always the case. With an object that's outside contour is not round and concentric with the inside, like a Winchester receiver, you cannot qualify both outside and inside surfaces in a single setup on a lathe. It's a physical impossibility. This operation can however be accomplished on a mill utilizing 4 axis. If you had as much problems as you say with milled threads, the only explanation is simply your operators were inept. Unfortunately, CNC machinery can only do what it's told to do by it's operator, and or programmer. I've been making the same parts on CNC mills for over 11 years. I've used probably 50 different operators at one time or another, and I can assure you, there is a difference in quality depending on who was running the machine. Some of the parts we had to scrap because of the poor machining that was taking place. This was due mostly to operators who weren't checking the parts coming off of the machine, and making the appropriate offsets to allow for tool wear and deflection. We would end up catching the problem in the second or third operation before they got pulled. Other operators made almost zero mistakes, and produced quality parts consistently with the same tools and equipment. Just because a person has a CNC sure doesn't mean that they know how to run one properly. There was a joke my buddy used to tell me years ago that said, "Yesterday I couldn't spell machinist, now I is one". There really is a big misconception about what it takes to make quality parts on a CNC. It's not as easy as it may appear. The skill level is just as much or more than making the same part on a manual machine. All the formulas and cutting parameters that you must master as a manual machinist, coupled with all of the programming code and quirks associated with the CNC. I see parts made everyday, claiming to be made on CNC. If this is the case, I think the operator, and or machinist, should have been hung from a tree judging from the obvious lack of quality. | |||
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