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  • #46
    Ya mine tried to bite but I bit back harder. Getting the bugs worked out of it.

    Bernd
    New York, Vermont & Northern Rwy. - Route of the Black Diamonds

    Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

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    • #47
      Lesson for today is “vibration 101”. I went on a search after I wasn’t satisfied with the cut edges I was getting on brass. I’ll explain at the end what I found and what can be done about it.

      When I first ran the ROBO I noticed the motor had quite a vibration issue. I figured it was just inherent of the machine since it’s not as ridged as a machine weighing several
      thousand pounds and is made of cast iron. I continued with setting it up and figuring out how and where all the parameters are and what their settings are. After accomplishing that
      I was ready to do some cutting/engraving. As I showed in the last picture where I was using a 15° “V” engraving tool. I went around with the cutter set to only cut .005” deep. The motor
      vibrated the machine pretty good. On the second try I set the cutter another .005” deeper to cut out the part but didn’t even make it through the beginning of the part. So I decided to
      move on to using a milling cutter. A section of the wood on the table is being set up to cut multiple pieces in the same position piece after piece. I could have set up a whole sheet of
      .010” brass and cut out multiple parts, but I was confident the machine or cutter would make it through the whole cycle without breaking.

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      Here I’m using a two fluted 1/8” dia. cutter and setting it to “0” using a piece of paper. Once the you can’t more the paper you set the “Z” depth to “0”. Once that’s done you’re ready
      to run your program.

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      The machine is cutting an upside down “L” slot so I can glued in some ¼” wide wood pieces for a fence.

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      This is what the software looks like that controls the machine. It’s called “GRBL” (Candle). The GRBL is pronounce “gerbel”. Like gerbil the animal only with a sound of Grrrrr!. I’ll
      post some pictures later of the whole process it takes to get to this point.

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      The machine did a nice job of mill some Baltic birch plywood.

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      The two pieces of ¼” wood glued in the slots to form a locating fence for individual multiple part cutting.

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      I used the same piece of brass to see how a 2 flute end mill would cut.

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      It didn’t take long to find out. (OUCH)

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      Not to be deterred by the incident I used a slightly larger diameter end mill and ran the program again. This didn’t look good at all. Note the rough edges and the jog in the lower right
      corner. What the hell is that. I discovered what caused the jog after going back through my CAD and CAM program. Seems the CAM program did that. I fixed that and cut another piece.

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      This is not the second piece. I’ll explain later what happened to the second piece.
      As the machine finished this piece I saw that when the motor coasted to a stop that the cutter had quite a bit of “wobble” in it. At first I thought that is was a bad cutter. Anyway here’s
      the part finished.

      Why was that cutter wobbling so badly? Watch the video and you’ll see what I found the problem was. I know what you may be thinking, “If I were him I’d through that machine out the door.”
      No, not me. I didn’t spend 30 years in the machine tool industry and didn’t learn anything. Something is wrong with that spindle assembly to cause that tool to wobble like that.
      There was one other part I cut since I felt the machine would cut the part even though it vibrated the way it did.

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      The part started moving on me while cutting. The reason being I used 3M paper adhesive the same two sided adhesive I used on the upper portion of the rock crusher building. Worked fine on
      the first piece of brass. Not so good on the second. I think I didn’t wipe off the spot good enough to get rid of the wood dust. Going to need to change the process. See that dimple inside the red circle? (of course you do) That's what happens when you push the wrong button. The down button was the wrong one.

      That’ll do it for now. I’ve spent two days solving this problem. Time for a beverage and some quite time.

      Bernd

      Attached Files
      Last edited by Bernd; 02-14-2022, 04:42 PM.
      New York, Vermont & Northern Rwy. - Route of the Black Diamonds

      Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

      Comment


      • #48
        Possibly try an aluminum substrate. Crazy glue the brass to it.. then use solvent once cut

        j

        Comment


        • #49
          Bernd, try using a little soapy water mixed with just a tad bit of Mazola oil as a cutting fluid,. I've always have had a heck of a time with milling brass tool. Higher speed and slower feed. I couldn't view the wobble video.

          Jim
          Take the red pill

          Comment


          • #50
            Originally posted by BurleyJim View Post
            Bernd, try using a little soapy water mixed with just a tad bit of Mazola oil as a cutting fluid,. I've always have had a heck of a time with milling brass tool. Higher speed and slower feed. I couldn't view the wobble video.

            Jim
            That sounds yummy. I'll have to give it a try. The Sherline gave good results milling brass. Vibration can do weird things to metal.

            The video is a standard You-Tube video. It shows how much runout there is in the one collet. Anybody else having problems seeing the video?

            https://youtu.be/pHdBFpKdO0U Try watching it on You-Tube.

            Bernd
            New York, Vermont & Northern Rwy. - Route of the Black Diamonds

            Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

            Comment


            • BurleyJim
              BurleyJim commented
              Editing a comment
              Is that an ER-2 collet?

            • Bernd
              Bernd commented
              Editing a comment
              Those are ER11. The smallest they make.

            • BurleyJim
              BurleyJim commented
              Editing a comment
              I thought that was a Roman Numeral II.

          • #51
            A procedural update.


            Here's how I'm going to do those window frames. What I'm going to show is what I did when I was interested in TT scale. I started on a protolance design of a standard gauge caboose using a narrow-gauge Drovers caboose as a template for window and door layout.

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            The Cowichan Valley caboose was an article way back in MRC as a scratch build article. The standard gauge caboose below it was from an old MR article on building cabooses. I believe the name of the builder for the drovers caboose is Doug Leffler. He also did a scratch build article of one of the EBT's narrow gauge cabooses, which I will do in brass once I get more familiar with the router.

            I used my two software programs, DraftSight & CamBam, to get the measurements so I could feed the cutting software with the proper G-codes. It involved scribing .030" thick brass sheet and then changing from a carbide tip engraver to a very small end mill. This was all done on my Sherline CNC mill.

            This is how it was set up in the mill.

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            A closer view of one of the ends shows the tabs, circled in red, that the CAM software allows you to add so when parts are milled out they don't get tangled in the cutter when they are cut loose. This is what I'll do on the router.Click image for larger version

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            Using a vacuum plate will not work with this cut through operation since you would be opening up the part and uncovering the holes that are sucking down the material. A vacuum plate will work great if you are only doing cutting on the surface, not through cutting.

            Here's a link to many You-Tube videos of vacuum clamps.

            LINK: https://www.youtube.com/results?sear...y+vacuum+clamp

            Here are the sides after a little clean up. Note the bridges left to hold the doors?

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            I'm going to make up a little jig to hold pieces of approximately 1.5" X 1.5" of .010" sheet brass to cut out the frame. This will work better than an adhesive. Why not use an adhesive? As the cutter breaks through the brass it picks up the adhesive and it sticks to the bottom of the cutter. Also add to this the microchips the cutter is producing and you'll have a ball of adhesive with chips stuck to the bottom of the cutter as it tries to cut through the material. Somewhere along the line the cutter is going to break because the chips haven't been cleared out.

            Here's a picture of the sides. The caboose was never finished as I threw it out. There was nobody interested in doing scratch build work on the forum. All they wanted to do was buy finished products. They all thought I was going to produce this as a small side business. No way. I get very aggravated with modelers who want to buy from you and then complain about the smallest error. I'd rather show somebody how to do it on their own than sell a finished product and listen to the complaints.

            Click image for larger version

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            Bernd

            New York, Vermont & Northern Rwy. - Route of the Black Diamonds

            Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

            Comment


            • #52
              Looks like you are making headway.

              IMHO, clamping is so much better than tape or glue as glue can and does "creep", and even a minute amount of creep would tend to cause a vibration. Tape is basically glue on a fabric or paper, neither of which is rigid, and might be contributing to movement that is causing vibration.
              Mark from Illinois

              Comment


              • #53
                Originally posted by Almostretired View Post
                Looks like you are making headway.

                IMHO, clamping is so much better than tape or glue as glue can and does "creep", and even a minute amount of creep would tend to cause a vibration. Tape is basically glue on a fabric or paper, neither of which is rigid, and might be contributing to movement that is causing vibration.
                Actually it was the ER11 collet was a bad collet. The video shows the runout. Once I changed the collets it didn't vibrate at all.

                Bernd
                New York, Vermont & Northern Rwy. - Route of the Black Diamonds

                Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

                Comment


                • #54
                  Progress in the shop today. Amongst other projects I managed to make a dozen T-nuts with 10-32 threads. They're about an inch long so they spread the force out over the T-slot. Next will be a base plate to mount jigs on to mill, drill and so forth.

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                  Bernd
                  New York, Vermont & Northern Rwy. - Route of the Black Diamonds

                  Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

                  Comment


                  • #55
                    Bernd, always a nice shop project !
                    Joe

                    Comment


                    • #56
                      Originally posted by rrladmin View Post
                      Bernd, always a nice shop project !
                      Joe
                      Yes, it is when you have the tools to do it with too.

                      Today I got the base plate installed and bolted down. It's with in .005" in 11" of travel. I'm happy with that. Next comes the jig that will hold the brass sheet metal.

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                      Also got some tooling today. Finally ordered the right ER collets. The last set I ordered were ER16. A bit big for this machine. I figure I'll get an arbor for them and see if I can mount them on the Sherline. Along with those I got a surfacing bit. That ought to vibrate the router really good.

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                      Until next time.

                      Bernd
                      New York, Vermont & Northern Rwy. - Route of the Black Diamonds

                      Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

                      Comment


                      • rrladmin
                        rrladmin commented
                        Editing a comment
                        Bernd, looks like you are setting up a bridgeport there... LOL

                    • #57
                      I just heard something fly right by, WAY over my head….

                      Glad you’re having fun Bernd terrific patience….
                      Karl Scribner-Curmudgeon

                      Cedar Swamp
                      SW of Manistique, MI

                      Avatar image by Savannah Lyn Burgess 7-15-2022

                      Comment


                      • #58
                        joe Well you got to have the tooling in order to do the job.

                        Bernd
                        New York, Vermont & Northern Rwy. - Route of the Black Diamonds

                        Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

                        Comment


                        • #59
                          Originally posted by k9wrangler View Post
                          I just heard something fly right by, WAY over my head….

                          Glad you’re having fun Bernd terrific patience….
                          Keep following and you'll pick it up. It' my way of having fun modeling.

                          Bernd
                          New York, Vermont & Northern Rwy. - Route of the Black Diamonds

                          Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

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                          • #60
                            I last left off with the addition of a base plate to mount jigs/fixtures on to machine parts. Once that was done I needed a few of these plates for projects. The first being the window frame of the Suydam Two Stall engine house.

                            This is how I mass produced those plates using my 10" table saw and 1/4" thick aluminum plate.

                            I mounted a 38 tooth carbide tipped blade in the machine.

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                            Next I set the height of the blade just so the small portion of the teeth would be above the aluminum plate.

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                            I place a piece of foam, it could be anything that the blade will cut, over the top. This keeps the spray of chips to a minimum on top.

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                            And the first jig plate.

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                            I also cut up a bunch of strips that will be used for tie downs. You'll see in a later picture where they go.

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                            I fly-cut both top and bottom surfaces to make sure the plate is nice and flat.

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                            Here I'm fly-cutting the sides of the hold down strips. That's the fly-cutter mounted in the spindle. It's a single point tool that you take about a .005" deep cut at a slow feed rate to get and nice surface finish like on the plate in the previous picture.

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                            Notice the difference in surface finish from the last picture. The tool is spinning at about 800 to 1000 rpm.

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                            Back to the router. I drilled and reamed a hole in the exact center of the base plate for 1/4 for a 1/4" dowel. The jig plate also has 1/4" reamed hole an it already has some 3M adhesive applied to hold the plate in place.

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                            A close look at the applied adhesive and the dowel installed ready for mounting on the base plate.

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                            Using a square to align the jig plate perpendicular on the base plate.

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                            Here you can see the hold down strips I made that will hold down the brass sheet. I'm using a printed out CAD drawing to line up where the cutter will start. I've installed a 1/16" dia. cutter to mill out a groove in the aluminum so when the tiny 1/32" dia. cutter cuts out the frame it won't have to cut out the aluminum too.

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                            Milling out the aluminum with 1/16" dia. cutter.

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                            A piece of approximately 2" X 1.75" sheet brass clamped down ready for cutting out the frame.

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                            And we're off.

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                            So how did I get to this point? Several software packages and a lot of hair pulling, not only in design work but machine performance. I'll get into the machines performance after showing what it takes to make a part with this method.

                            First you will need a CAD program that puts out a DXF file for the next program. I use DraftSight Standard. No it's not free. I pay an annual fee to use. I didn't find it very difficult to use. No really steep learning curve on this software.

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                            Once the DXF file is exported the next program I use is BamCam. This is a CAM program that takes your DXF file and after telling it what you want to do it'll produce the G-code file the machine needs to cut out he part. This is what it looks like when you first import a DXF file. Back in the CAD program you need to tell the CAD program to start or place a corner of you project on the "origin point". That's where the bottom left hand corner of the frame is located. This will be where you G-code program will start from.

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                            This is what the finished CAM file looks like. It has been told what tool to use, where to cut, how deep, what feed, what spindle speed and so forth. Those green blocks are what is known as "tabs". They will hold the frame in place as it gets cut out. The tabs keep the part in place so it doesn't get wrapped up in the cutter or thrown off the machine. Hard to fathom, but I’ve seen both things happen.

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                            Now that it's all finished and the software has done it's calculations to produce a G-code list that will then be loaded into the machine software. This is what a G-code file looks like for a simple project such as this. Note it runs off the bottom of the page.

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                            You can physically go into the G-code and change parameters. It's nothing more than a text file. You could also write your own G-code by typing it into a text file format and load that in the machine.

                            So here's what I start with. A 2" square piece of sheet brass. Yes I changed the size to better fit in the jig.

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                            And here are some of the disasters. Five broken cutters, some unfinished cut's due to machine failure. This is what makes you a machinist. Just don't break the machine. That makes you a failed machinist.

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                            But you feel like a real machinist when the part comes out good, except for one part that wanted to get into this picture instead of the last one. The machine almost finished when it lost the USB connection. I'll get into the all that a bit later. Note the tiny tabs left to hold the frame. These can be cut with a sharp box cutter or spur nippers.

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                            Here's the frame has been separated from the rest of the brass sheet. A little bit of filing and it'll be ready for use.

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                            And I quickly applied it to one of the windows to see what it would look like and for the purpose of this write up.

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                            I need to cut out nine more for the engine house.

                            Now the gory details of learning this machines idiosyncrasies. As I was working on getting the base and jig/fixtures designed and made I was having trouble with the machine. It kept giving errors will in a cycle. One problem was me. If the E-stop button is pushed in it actually start a cycle and run for a bit and then stop due to an error. I always kept getting he same error code as to why it stopped. I finally found out what it was from a guy on the Comgrow Face Book group. Make sure your E-stop button isn't on. Yup, that was the first problem solved. The next occurred while actually trying to cut parts. The machine kept stopping randomly anywhere along the cut path when it lost the USB connection. Having previously purchased a newer computer with more horsepower to learn Fusion 360 on, I hooked the machine to it and have not had a problem with it since. One other issue is that the machine has a lot of vibration whether it is cutting or just running through a dry cycle (not cutting anything). I've traced it down to the motor. This motor runs at 10,000rpm. It can be slowed down through programming, but when you're using a 1/32" dia. cutter you want to run at a high RPM. These types of motors are small and built to run fast but lack the balancing of the rotor to alleviate vibration. I'm looking into seeing if I can find a more suitable motor. Another short coming of a small machine as this is rigidity. Only weighing in a around 17 pounds you can't expect it to perform like a 2000lb Bridgeport. It will do for what I want to do with it. My next test subject for this machine will be the milling out of brass sides for a East Broad Top RR caboose. But this will be a while before that happens.

                            My next adventure is to design a holder for the Cricut deep cut housing and deep cut blade. But first I need to finish the engine house before the April 15 finish date of a build challenge on another forum.

                            Questions and comments welcomed.

                            Until next time.

                            Bernd
                            Last edited by Bernd; 02-25-2022, 02:12 PM.
                            New York, Vermont & Northern Rwy. - Route of the Black Diamonds

                            Main thread to all that's happening on the NY,V & N Rwy. The New York, Vermont -and- Northern Rwy. - Railroad Line Forums (railroad-line.com)

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                            • rrladmin
                              rrladmin commented
                              Editing a comment
                              Bernd, looks like you are making good progress... and you are learning the idiosyncrasies of the machine... next part will be easier, you can only build on it from here, looks like fun !

                              Joe
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