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Thread: Warning about Routers

  1. #76
    Quote Originally Posted by Pat Barry View Post
    The reason I was asking the questions was to get at the root cause of the problem. Having actually designed and worked with various motor speed controls I thought it would be wise to understand your circumstances better. Not having that, however, I will say that the type of speed control on a router like the one you used is an open loop design. It simply reduces the input voltage supplied to the motor by limiting the peak voltage and / or duration of each of tje 60 Hz voltage cycles. It has no way to monitor the actual speed or do anything to 'control' it. I suspect, in your situation, the rotational speed of the lathe, coupled with the speed of the router itself caused the router to be overcome by the lathe rotational speed. There is no way the router could do anything but "go along for the ride". Effectively the router couldn't keep up and because of the grinding frictional load on the grinding wheel, the wheel ultimately broke. The noise you heard was the wheel fracturing and disintegrating. Again, this wasn't a failure of the router speed control but simply overload due to the conditions that were set up. Maybe this worked for you previously and you were lucky, maybe this time the wheel was degraded enough from previous uses to fail, maybe the load was greater this time, maybe there wad a metal fragment that got into the motor speed adjuster, etc. Who knows.

    Sorry for your injury. Thanks for your initial posting. We can all learn the need for more personal protection when using machines.
    Hi Pat, I understood from his description that he was not grinding with it when it happened so the wheel wasn't in contact with the piece in the lathe. Also, even if the lathe and router were rotating in complimentary directions , the lathe was probably much slower.
    https://www.youtube.com/c/DovetailTimberworks

  2. #77
    Join Date
    Jul 2007
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    Inkerman, Ontario, Canada
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    Pat.

    The grinding wheel was NOT in contact with the part in the lathe or anything else.
    I turned the lathe on at 65 rpm
    I turned the router on at 8000 rpm
    I left them run for a few minutes to warm up, prior to startling.
    The router ran fine at 8000 for a while, then shot up to 24,000 rpm.
    The grinding wheel exploded from the force produced by 24,000 rpm.
    The noise that i heard was the router increase speed.
    The grinding wheel exploded in an instant, i didn't see it, i didn't hear it, i just felt it.
    Last edited by Mark Hennebury; 06-14-2019 at 1:11 PM.

  3. #78
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    Inkerman, Ontario, Canada
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    Pat.

    From the manufacture;

    The RF1101 has a powerful 11 AMP motor with soft start for smoother start-ups, and electronic speed control that maintains constant speed under load. The variable speed control dial allows the user to match the speed to the application, with 8,000 - 24,000 RPM.
    Last edited by Jim Becker; 06-14-2019 at 9:48 PM. Reason: Defaulted formatting so it is now readable.

  4. #79
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    Aug 2015
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    N. Texas
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    Quote Originally Posted by Mel Fulks View Post
    Mark, just read the whole post. I guess I guessed it was the end of a finger. Some of us will now be using full face shields.
    Thanks for reinforcing safety by relating what must be a most painful and complex injury. "Rule number 1....Obey all rules!" And that applies to Doctor's instructions. But I believe
    in demanding good pain killers ! Wishing you a full and speedy return to full health and confidence in the future.
    Quote Originally Posted by Dave Zellers View Post
    Mine just arrived. Appreciate the heads up from the OP. I own 2 PC 7518 VS routers. Plus a shop full of dangerous tools. No point in pressing my luck any farther.
    Personal Protective Equipment (PPE) is actually the least effective....
    2019-06-14_hoc[2626].jpg
    It is much better to take the human element as far out of the equation as possible, but of course ultimately depends on the willingness of the human.
    Attached Files Attached Files
    Molann an obair an saor.

  5. #80
    Yeah, not doing the job would be pretty safe.

  6. #81
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    Quote Originally Posted by Mel Fulks View Post
    Yeah, not doing the job would be pretty safe.
    Not implying we separate the human from the job; only the human from the hazard. But they gotta be willing.
    Molann an obair an saor.

  7. #82
    Join Date
    Dec 2008
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    Northern Michigan
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    Mark, I saw a VFD somewhere that was designed for 110 1ph, maybe the Factorymation catalog. May offer a better way to go, something I should look into as well. Saw it but did not relate it to my router speed comtrol. https://www.wolfautomation.com/blog/...-phase-motors/

    Another option if you could find one would be a 3 ph router. I think Stanley made one that looked like an old Speedmatic 3 hp. I remember looking at one that was for sale but its a bit foggy.

  8. #83
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    Apr 2013
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    Okotoks AB
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    Quote Originally Posted by Larry Edgerton View Post
    Mark, I saw a VFD somewhere that was designed for 110 1ph, maybe the Factorymation catalog. May offer a better way to go, something I should look into as well. Saw it but did not relate it to my router speed comtrol. https://www.wolfautomation.com/blog/...-phase-motors/

    Another option if you could find one would be a 3 ph router. I think Stanley made one that looked like an old Speedmatic 3 hp. I remember looking at one that was for sale but its a bit foggy.
    A universal motor speed is independent of line frequency, so that wouldn't work for this. I am almost certain that there is no such thing as a 3 phase line voltage hand held router.

    The closest thing I've seen to a 3 phase router was a big machine (I think called an inline contour shaper) that had a huge 3 phase 'router' that was 3 phase, but used a motor/generator set to feed it with a much higher frequency in order to run at the needed rpm. It ran along the 10' length of the machine & followed a pattern that was copied onto the board.

  9. #84
    Join Date
    Jul 2007
    Location
    Inkerman, Ontario, Canada
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    Video of the speed control failure.

    I have tried the router probable 100 times since the accident on June 4th; On the day after the accident it went crazy again when i tried it, so i set camera up to catch it,the following week it worked fine with the exception of two little twitches. The last time i tried it today it went wild a few times while i had the camera rolling.

    Please forgive my speech I have a hard time speaking at the moment, and as you can see i am more than a little nervous when it ramps up, i am actually quite nervous around the blender right now.

    So the issues of course are that there is no warning of when it will fail, no apparent reason for it to fail, there is the problem of it going from 8000 rpm to 24,000 rpm plus the torque caused be the acceleration. Either way this is a dangerous situation that can happen in an instant.


  10. #85
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    May 2004
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    columbia, sc
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    Wow....thanks Mark for sharing.
    Bob C

  11. #86
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    Quote Originally Posted by Mark Hennebury View Post

    That thing is possessed. Fortunately, "the exorcist" is right there in the frame (at the bottom right-hand corner).

    If it were me, I think I might tame it down some for 15 or 20 minutes – until I was winded or until the sledgehammer broke, whichever came first – then pour it into a box back to Makita, along with a copy of the video and your doctors' bills.
    Last edited by Jacob Reverb; 06-16-2019 at 6:35 AM.

  12. #87
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    Ottawa, ON Canada
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    I hope you that you recover well, Mark?

    I may have missed this in the thread, but have you contacted Makita, especially with a copy of your video. If so, what was their reply?
    Grant
    Ottawa ON

  13. #88
    Join Date
    Feb 2005
    Location
    Canton, MI
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    I don't own any Makita routers, but that doesn't sound normal even before the speed jump. Is that the way they all sound?

  14. #89
    Join Date
    Mar 2019
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    Greeley, CO
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    That Makita router isn't designed for fault tolerance, it's call FMEA or failure mode effects analysis. We can be grateful those Makita engineers don't work in the appliance or automotive industries. The just of Design FMEA is to assure a single point failure can't allow the device to fall in a dangerous mode. In the OP's example something has failed intermittently and the result is the router runs full speed without any input from the user. A recent example of a bad design relying on a single sensor for critical data with no backup mode is the 737MAX.

    I'm sure Makita has seen this failure already, I'd give them a call a listen to their reaction. I might contact the CPSC and see if they want to investigate. If there's a UL listing I'd contact them too.

  15. #90
    Join Date
    Aug 2010
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    USA
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    Thanks Mark. Very convincing that there is something very wrong with that machine. Engineer in me would take it apart so the speed control could be inspected closely, probably cleaned up, reassembled and retested. Otherwise, scrap it out.

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