https://shorturl.at/mRTU3
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.
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.
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.
Yeah, not doing the job would be pretty safe.
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.
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.
Wow....thanks Mark for sharing.
Bob C
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.
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
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?
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.
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.