Announcement

Collapse
No announcement yet.

Dealing with Mistakes

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Dealing with Mistakes

    The metal machining club I belong to is taking up the subject "Dealing With Mistakes". We hope to discuss practices that will help us avoid common mistakes. This is not a Safety in the Shop exchange, even thought performing an unsafe operation in the shop is a big mistake.

    We will share some examples of salvaging parts that are out of print but my question to the group is, "Is there a technique you use to avoid a common blunder". For me , a dykim layout directly on the part has been time well spent. One fellow I worked along side of used masking tape adjacent to his dials to indicate, in plane view, the direction of table travel.

    Shouldn't there be a list of common shop mistakes and how to avoid them, or would that list be too long to garner attention?

  • #2
    My most common and hated mistake is to forget which way to turn the dial on a Bridgeport when making long slots or milling around something that turns thru 90 degrees at the end.

    DRO would eliminate this ...as you get instant indication of direction change.

    all the best.mark

    Comment


    • #3
      I'll play along. Most of these were learned the hard way.

      -I always try to move the workpiece on a mag chuck before starting to grind.
      I flung a workpiece and blew up a wheel in my face when I tried to grind a piece of mystery steel that happened to be non-magnetic stainless.

      -Always check to make sure the vise is tight and parallels won't move before starting to mill.

      -Mark the zero or reference corner with a centerpunch or red marker. Especially on multiple pieces with similar widths vs. lengths.

      -Turn the rapids down and creep up to the workpiece in single-block when proving out a new program. Machinist's typos don't go away with whiteout. A quick lay-out helps here also.

      -Make a few practice pases away from the workpiece when threading to get the rhythm back on when to pull out.

      _Make a scratch cut on the first threading pass to make sure you are cutting the right pitch.

      -Run your hand over the bottom of the workpice before setting it in the vise/chuck to check for burrs or dirt.

      -Never trust the second shift guy when he tells you the program and set-up are all ready, all you have to do is hit Cycle Start.
      Jon Bohlander
      My PM Blog

      Comment


      • #4
        Always make sure your end mills are center cutting before plunging.

        Comment


        • #5
          All my mistakes have turned into opportunities to make smaller parts.

          Comment


          • #6
            After dialing in a vice and finding the edge set the mills cross feed dial to 0.

            That way you can zero a dro as many times as you want and still find the 0 again.(too many times people dont do that and have to put an edgefinder back in to find zero again and again)

            Again time your tools on a lathe, set the dial on zero, loosen the set screw on the tool holder and slide the tool up and tighten them down on a known diameter. do this with all your tools and you can have a gang of tools all set to +/- . 005 or less.

            With all the tools timed you can put a black marker mark on the cross slide and a black marker mark on the carrage and that works like an "idiots guide" so you know you are getting close.

            Comment


            • #7
              Originally posted by aboard_epsilon
              My most common and hated mistake is to forget which way to turn the dial on a Bridgeport when making long slots or milling around something that turns thru 90 degrees at the end.

              DRO would eliminate this ...as you get instant indication of direction change.

              all the best.mark
              No it won't. Don't ask how I know.

              Well, at least I'm not the only one. I think I'll go with the masking tape idea, or draw on the mill with a Sharpie. As for CNC-related mistakes, my shop is so far too poor to worry about that stuff.

              -Mark
              The curse of having precise measuring tools is being able to actually see how imperfect everything is.

              Comment


              • #8
                Originally posted by dp
                All my mistakes have turned into opportunities to make smaller parts.
                Soooo true! But you must be a pro.... my parts just end up in the trash. Seems I have to make three of everything.

                ...okay on the serious side.

                It seems most mistakes come from machining order which may be as simple as how to hold a part for a simple c-clip...but if the part can't be held for that last operation, it's trash. Most of the things I make I add to the plans a list stating the machining order for each part. I'm a big believer of good plans and careful thought. Fixing a mistake with an eraser is pretty inexpensive.
                Last edited by Mike Burdick; 06-28-2007, 11:26 PM.

                Comment


                • #9
                  Think!!

                  I find that I can avoid many mistakes if one sits and think about what is are going to be done. Which cut do I make first? If I make this cut, how will I hold the piece to make the angle cut?

                  If you can't get a mental picture of what is to be done, sketch out the part and look at it from all angles. Just yesterday, I was looking at how to make the curved portion flow evenly into the straight part. I sketched it out and by adding 1/4" to the one side of the part, there was no need to make a special cut to flow the two parts together. The additional material made the joint flow together.

                  Bill
                  Bill

                  Being ROAD KILL on the Information Super Highway and Electronically Challenged really SUCKS!!

                  Every problem can be solved through the proper application of explosives, duct tape, teflon, WD-40, or any combo of the aforementioned items.

                  Comment


                  • #10
                    Just learn from it. Make a rule to Never make that mistake again. and think about why you made it.
                    Every Mans Work Is A Portrait of Him Self
                    http://sites.google.com/site/machinistsite/TWO-BUDDIES
                    http://s178.photobucket.com/user/lan...?sort=3&page=1

                    Comment


                    • #11
                      If it weren't for mistakes machine parts would have never been damaged in
                      the first place, and I'd be out of a job....
                      As for mistakes in the machining of parts, we can stick to the tried and
                      proofed ways. A part that took 6 hours to make in 1962 will take 6 hours to
                      make today. Now if we try using a wiper carbide insert that allows us to take
                      a .100 depth finish cut, or a 3/8-16 spiral tap that we can spin straight in at
                      450RPM that part will only take 2 hours. Will we f......, make mistakes?
                      Sure we will. Will we cut the times and become more productive. No Doubt!
                      I bring those learned lessons home to my basement shop and it makes my
                      hobby easier and more enjoyable.

                      If it doesn't involve blood it's not a mistake. It's a learning process.
                      Last edited by rake60; 06-28-2007, 10:30 PM.
                      Home Model Engine Machinist

                      Comment


                      • #12
                        Here is one that starts pretty much out of our control but can have serious consequences.

                        Interruptions, by phone, friend, co-worker, boss, even the shop pet wanting out, makes no difference, getting back to exactly where you stopped takes a deliberate and concentrated "Where was I" and not just some casual lets get back to it.

                        Comment


                        • #13
                          This may sound stupid ,and Common Knowledge,But...
                          Stay alert, the more tired you get the more mistakes you do.

                          If you get too tired walk away, get some sleep,or coffee, It will pay off believe me.

                          Comment


                          • #14
                            Don't get in a hurry . More mistakes happen because we get in a rush. Do things slow and deliberate.
                            Every Mans Work Is A Portrait of Him Self
                            http://sites.google.com/site/machinistsite/TWO-BUDDIES
                            http://s178.photobucket.com/user/lan...?sort=3&page=1

                            Comment


                            • #15
                              Free software for calculating bolt circles and similar: Click Here

                              Comment

                              Working...
                              X