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  • Newbie Questions

    Hello all!

    Although I have a bit of electrical/mechanical/civil engineering background and am currently a Systems Analyst, but I have absolutely no machining background. I am trying to do some "no cost" research into lathes and mills in order to do some hobby work.

    I am an avid airsoft player (Kinda like paintball except that our guns are replicas of real-steel firearms but shoot 6mm plastic BBs) and I am looking to do some custom airsoft gunsmithing.

    I've already looked into a lathe and am now looking into a mill specifically to make custom pistol slides.

    Will someone tell me if I can cut custom pistol slides from a block of aluminum using a mill only? I believe it can be done except I have no idea how to cut the groove on the inside of the slide (the grooves rides along a rail on the lower portion of the pistol frame).

    I'll try to elaborate with words although I know that pictures would be much better. Pistol slides are basically rectangular in shape. I will refer to the rectangular block as a 2D object only: the front and back surfaces are left out so we are left with the top, left, right, and bottom edges.

    The bottom surface of the slide is almost completely open to allow the pistol internals to function within. There is a groove for the slide rail cut into the inside of both the left and right surfaces.

    If you are using what is essentially a drill bit, how would you make this groove with a milling machine (because the bit would have to be pependicular to the inside surface of the slide which is obstructed by the opposite edge: i.e. - if you are milling a groove on the inside left edge, a "drill bit" would have to go through the entire right edge)?

    Also, if you know of any general machining "how to's" online please suggest away. I could use the help. =)

    Thanks!
    Lance

  • #2
    Hi Lance,
    RE: "can you cut custom pistol slides from a block of aluminum using a mill only?" Ans. yes.

    The slots can be cut using a "T" shaped cutter. The block is first milled out to size inside and then the "T" shaped cutter is used to cut the slots on the insides of the block that the rails fit in from the handle.
    The "T" shaped cutter has a round cutting wheel with teeth on its periphery. The shank that holds the cutter on its end is held in the spindle and rotates. The head of the cutter is naturally bigger in diameter then the shank so it can cut the slot.
    Get Travers Tools catalog or MSC's (both free) and look at the Woodruff keyway cutters. You'll see right away how the cutters work.
    Most any small mill/drill will work on aluminum. The slots will be about 6-8" long maximum? Right now machines are dirt cheap on Ebay. Go there after asking lots of questions here and you'll have it made.
    Now the actuall machining will be harder. I highly recommend that you take an adult education Machine Shop course. Always remember SAFETY FIRST! That cute little machine can cut steel so rest assured it can cut you three ways, frequent, deep and wide!
    Welcome to the happy land of chip making!
    Regards,Ken

    Comment


    • #3
      kgarver,

      Thanks very much for you quick reply! I was also extremely delighted to find that the first response to my question wasn't a flame post.

      I do have more questions, too... (aren't there always?) ... for anyone who cares to answer.

      I was looking into a Sherline mini-mill because I will not be working on anything very large. And because I heard that you can add CNC capability at a later date. Before I buy, though, I probably need to clear up a few things:

      Do the Sherline mill products have enough power to work in both aluminum and steel?

      Are the Sherline products a good way to go or are there better recommendations?

      Do most brands of mills/lathes have both metric and standard markings?

      I am assuming that mills cut in straight along either a x, y, or z axis. How would one go about milling curves (i.e. - circles, hemispheres, or irregular s-curves) without CNC capability?

      Here's a basic lathe question, also. I want to put a 6.03 bore through a steel rod. I am assuming that this is an irregular size for a bit ... how would I go about accomplishing this?

      I told you I was a total newbie!

      Thanks in advance!

      Comment


      • #4
        Sherline is a very light duty, low torque,high speed machine. It can work steel and aluminum. It is capable of high precision, is well made and highly thought of. It is easy to CNC. It is a good start for "small" stuff.


        "Do most brands of mills/lathes have both metric and standard markings?" Most new machines do, older machines don't.

        " How would one go about milling curves (i.e. - circles, hemispheres, or irregular s-curves) without CNC capability? " One of the more popular things people do with their new machines is make tools, holders, adapters and doohickeys for their machines. One such is a spherical section pivoting device that runs the tool through a smooth arc allowing either a concave or convex cut to be made. If the S curve can be made from circular arcs then in theory it could be cut with a pivoting tool holder. Interference
        may be a problem. Few machinists incorporate these into their work and CNC is the best but not only approach. There are lots of articles in HSM, MW and MEW, Lautard's books etc explaining how to make spherical section pivoting cutters.

        "Here's a basic lathe question, also. I want to put a 6.03 bore through a steel rod. I am assuming that this is an irregular size for a bit ... how would I go about accomplishing this? " I assume millimeters (?): drill under size and ream to size. Reamers are not cheap but available in an incredible # of sizes, and also in adjustable sizes that can cover a small range of diameters. Another easy thing to do is make 'one of' boring bits with drill rod: so called D bits
        that can be made to the exact size you want and used to make the final cut. If your 6.03 is cm then an offset boring bar holder head would do for the cm cut. 6.03"
        bore would require heavy iron. Precision of the bore would dictate the method used.

        Steve



        [This message has been edited by sch (edited 12-11-2002).]
        Steve

        Comment


        • #5
          Cliffy15:
          We don't flame here.

          To cut curves with manual equipment requires a fair bit of ingenuity. If you are going to pick up a Sherline lathe get Joe Martin's "Table Top Machining" - it is a pretty good book to get you started on their machine. Tell them it should be included free as a users manual and tell they you seen it here recommended as such. It is worth it if you own the Sherline, but Joe should include it with the machine. Gorgeous colour photography.

          The other way you cut curves is the same way they are cut on CNC machines - geometry calculations and incremental cuts.

          As to smooth boring a barrel for your airgun, sure you can drill it. It will take patience and hard work to make sure you get a straight hole though. With a drill bit in the tailstock and the near end of the workpiece supported by a steady and the far end clamped and turned by the chuck you can bore a clean straight hole. 6.03mm is .2374" the closest standard drill is a "B" (.2380" or 6.0452mm)

          I suspect that is proper measurement were done the barrel is closer to the "B" size. this is good as standard drill can be purchased, you will have to get an "aircraft drill" of 6" or longer length. It might be best to make and use a "D-Bit" from 12" of "B" sized drill rod (trimming it to the proper length to bore the hole, of course).

          good luck.

          Comment


          • #6
            Cliff: first , thrud is right. we don't flame. Seems to me that the few flames I have seen here, is when some one mistakenly jumps on some one. The flamer gets an explaination, most time apoligizes/ I take this time to say that that because this group is best i have ever seen (on the net or in real life) about answering questions, they consider the most basic question worthy of a well considered reply. And to top it off, some of the most basic questions some times lead to lengthy discussions of great depth and much useful insight- and a lot of bs.

            My reply is really to your Metric/ inch markings on same machine. I would advise getting one in inch OR metric. The machines cannot do both very well. One or the other marks will have to be "off" just alittle on the second crank ofthe wheel. Then the book keeping starts. you aim for a mm or .001 and two turns of the crank. you wind up missing .1 in or cm. My solution (and I am not as good as most here- is to us Dail indicators when I am wanting to get it nearly right (which i all I need most times).

            Steve

            Comment


            • #7
              I expect we can all remember how hopelessly ignorant we felt when first starting out, so there's a lot of understanding for new guys who are flailing around trying to get their bearings. Been there, done that...still do that occasionally....

              I think there are expen$ive machines that have both inch and metric dials, but they have gearing to make both of them come out correctly. Steve's right -- the cheap inch/metric machines don't do it very well.
              These days, of course, machines have digital readouts that do either inch or metric at the touch of a button.

              To get your 6.03mm hole, you may want to drill slightly under that and then put a "B" size reamer through it to get a better finish.
              ----------
              Try to make a living, not a killing. -- Utah Phillips
              Don't believe everything you know. -- Bumper sticker
              Everybody is ignorant, only on different subjects. -- Will Rogers
              There are lots of people who mistake their imagination for their memory. - Josh Billings
              Law of Logical Argument - Anything is possible if you don't know what you are talking about.
              Don't own anything you have to feed or paint. - Hood River Blackie

              Comment


              • #8
                Thanks to all for your wonderful answers to my basic questions! I'm wondering if I should create a new thread to post additional questions, but since there aren't a huge avalanche of replies in this thread I'll continue on here, for now.

                Although I believe I will be going with the Sherline product line to begin with, I am still researching basic lathe and mill operations (I don't have the equipment yet, but I'm going to have to know what I need before I order it) and have another question...

                As I understand it, lathes have an adjustable feed setting where the tool can be moved across the turning piece, at a certain rate for a certain distance automatically. Whether this is on the tailstock or the tool holder, itself, I'm not sure.

                Does a mill also have an "adjustable feed"? Since the work is basically moved about a single tool, I'm assuming this feature would be incorporated into the x,y, and z table adjustments.

                I guess what I'm asking is: Can the table be automatically (automagically?) set to move at a certain rate for a certain distance in any axis?

                Thanks much! =)

                Comment


                • #9
                  Sherline will certainly get you started. I assume you've visited their web site and seen some of the incredible things people have built with that equipment. Even if you later get larger machinery, I think you'd still find a use in the shop for the small Sherline machines.

                  If you don't have 'em already, request a catalog from MSC (www.mscdirect.com) and Travers (www.travers.com). They're free. The MSC catalog, especially, is mind-boggling. It's about 4" thick and weighs about 17 pounds. Looking through those, seeing what's available, can teach you a lot. Other people may have their own favorite catalogs they can recommend.

                  On your questions: not all lathes have power feed, but most do. The carriage is driven through the leadscrew, as would occur if you were cutting a thread on a workpiece. Instead of threading though, you're just turning down the work. The feed is generally set much finer than it would be for threading, too. Some (cheaper) lathes use the actual leadscrew thread to move the carriage for power feed, but that tends to wear out the leadscrew. Better lathes use a keyway in the leadscrew (or sometimes a separate shaft) to drive the carriage for power feed, saving the leadscrew thread for doing thread-cutting only. Some lathes also have power crossfeed. The South Bend 9" Model B had carriage feed but no power crossfeed, while the Model A had both, for instance.

                  Power feed can be added to a milling machine. You're right, adjustable-feed motors are added to the X and Y leadscrews. (Look up "Servo" brand in the MSC catalog.) Z can be done either with a motor on the knee leadscrew, assuming it's a knee-type mill, or on the quill. The Bridgeport J head has power feed for the quill built into it.

                  [This message has been edited by SGW (edited 12-14-2002).]
                  ----------
                  Try to make a living, not a killing. -- Utah Phillips
                  Don't believe everything you know. -- Bumper sticker
                  Everybody is ignorant, only on different subjects. -- Will Rogers
                  There are lots of people who mistake their imagination for their memory. - Josh Billings
                  Law of Logical Argument - Anything is possible if you don't know what you are talking about.
                  Don't own anything you have to feed or paint. - Hood River Blackie

                  Comment


                  • #10
                    Lance, it's a pleasure to hear from somebody who knows less about machining than I do! I guarantee that you will find all the answers on this BBS or the directions to find the answers. With your background I think you will find that figuring out how to do the machining is half the fun!
                    My advice is to buy the best machine you can afford once you determine the size you need. I bought cheap and was lucky to find a decent machine, but finding the few parts that I did need was a lengthy and sometimes expensive path. But I found them as a result of this BBS. Have fun!

                    Comment


                    • #11
                      Lance

                      One thing to consider with a smaller machine is that you are limited to smaller projects. The biggest disadvantage with them, IMHO, is the high cost of accessories. A fully outfitted Sherline is far more money than a sturdy old lathe with lots of tooling. But the sherline also takes up less space.

                      I looked for and purchased a EMCO Maximat 7 Toolroom lathe & mini-mill. It has 1-1/2"x8TPI spindle nose and precision grade bearings. Its capacity is 7"x18". A damn nice lathe. I bought it because I was very limited as to space. I want a Dean Smith & Grace 17"x84 Lathe, a Hardinge HLV-DR, and a CNC VMC, and a 50" grinder - but I don't have any space right now.

                      Other machines I would say have a definate look at is the Taig (about the same size as Sherline), Prazi, and Wabeco. The Last two are well known German machines and serious machines that use standard tooling - not cheap.

                      A used full sized machine is the best bargain in the long run if you have room for one.

                      Comment


                      • #12
                        At the risk of sounding redundant, IMHO if you have the space, a full sized machine is the way to go.
                        You will be able to anything a small one can, but usually faster, easier, and with less chatter or vibration. You will also be able to use standard tooling, which many times can be had surplus, at low prices, or on Ebay.
                        I have a Taig lathe for about 17 years, its great for real small stuff, precise too, but when I have anything larger than about 2" to turn it can get frustrating. After I've had it for a few years, I figured all the money I had spent on it and the special accessories, I realized that for a bit more I could have bought a used full size machine with accessories. (BTW I recently bought a LARGE lathe with a bunch of chucks for less than I paid for the Taig with the accessories I originally got, but I'm still stuck without a QC, thats another story)
                        There will always be a project too big for whatever machine you may get, but the mini machines may be outgrown quickly.
                        To get an idea what kind of machine will serve best, it would help if you could actually try out some machines, at a friends shop, or any place you can beg, borrow or buy machine time. Personal experience is worth more than all the machinery advertising in the world. Reading anything related to machine work helps too. Most important is safety, especially in a home shop where there is no one to warn you if you do something unsafe, but plenty to criticize you, if you get hurt. (been there)
                        To be brief I would advise, not being in a rush to buy a new machine, but if a suitable used one shows up, to make a quick decision, because good machines tend to be sold quickly. I'm sure I left out most of the points I wanted to make, but if I remember them I'll reply again.
                        BTW I am notan OF I just sound and act that way.

                        Comment


                        • #13
                          That is good advice. Especially the part about not being in too much of a hurry.
                          Try to get some training, adult ed. or voc. school. This will give you a much better feel of what you will need to accomplish your goals.
                          The smaller machines such as Sherline and Taig are capable of doing most of what you describe, but a larger machine will do it much better, easier, and be more economical in the long run for the reasons yf gives.
                          There is a lot to learn in machining, and a lot of people give up because of the frustrations involved in using equipment that is not suited to the job at hand.
                          Jim H.

                          Comment


                          • #14
                            Yes, well said. A course to get you train in the safe operation of the machine is an excellent idea.

                            Fingers are hard to grow back - Safety first and Always! Then have fun.

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