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  • rrladmin
    replied
    Bernd, always a nice shop project !
    Joe

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  • BurleyJim
    commented on 's reply
    I thought that was a Roman Numeral II.

  • Bernd
    replied
    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

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  • Bernd
    replied
    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

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  • Bernd
    commented on 's reply
    Those are ER11. The smallest they make.

  • Almostretired
    replied
    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.

    Leave a comment:


  • BurleyJim
    commented on 's reply
    Is that an ER-2 collet?

  • Bernd
    replied
    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.

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    Bernd

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  • Bernd
    replied
    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

    Leave a comment:


  • BurleyJim
    replied
    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

    Leave a comment:


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

    j

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  • Bernd
    replied
    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.

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

    Bernd

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  • k9wrangler
    replied
    Interesting and fully immersed way over my head….

    Gotta watch that GRBL deal carefully….my kids had one yrs ago and that little summabeech Bit and wouldn’t let go!

    Have fun, I can see the smiling in your posts.

    Leave a comment:


  • Bernd
    replied
    Originally posted by BurleyJim View Post
    Change your cutting depth to .003 and make 3 passes. No production schedule here. It looked pretty good until you 'pushed it. I knew getting those kitchen cabinet doors on, would get you away from the early frustration with this router.

    Your pal - Jim
    Ah, we won't talk about those doors. That was another frustration but I over came it.

    The problem with that first cut was I tried it with an engraving tool. I really didn't know what I was doing. It was just a total ____ up on my part. It was also a learning experience. This machine reacts a little different than compared to the Sherline. Did a redesign of the window frame. I made it a little wider. It was supposedly .030" (3" scale inches) wide. Using a, I think, 115° engraver tool going down into .010" thick wouldn't work to good. I now made the frame .060" wide. I'm doing a profile cut instead of an engraving cut. Ran a dry cycle last night at a real slow feed. Going to give it another try today. Going to use a .047" diameter cutter with a depth of .010" and 3 passes. It'll probably break the cutter. The motor sets up a lot of vibration in the machine. I'll post the results later.

    Thanks Pal Jim. Always good to have stop by and comment. (thumbs up emoji)

    Bernd

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