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Thread: What did you learn today?
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13th May 2019, 11:14 AM #751Most Valued Member
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Friends with a scrappie
Still got a substantial pile of lead bricks of 6kg each left over from ballasting the boat. Better to have too much than too little. I'm not selling them though, one day I might want to build another boat.
Well actually I'd love to build another boat (or 3) but I can't buy another 10 years of life and I'm quite happy with the one I've got. Just - you always know you could do it faster & better the second time round......
PDW
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13th May 2019, 08:09 PM #752Diamond Member
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14th May 2019, 09:17 AM #753Most Valued Member
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23rd May 2019, 02:34 PM #754Golden Member
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I was cutting this 190mm round stock yesterday and thought it will take awhile so I went inside for a drink for a few minutes. Then I heard the noise as if the machine is jumping between the gears. I quickly ran out and saw the stock is too far forward at the moving jaw and the mounting end of the pull stroke was hitting on the stock, the big gear is lifting up! I think I have broke it, I will have a good look tonight when I get home.
I remember someone was asking how to stop the machine from rocking back/forth with the wheels on. I am using the timber frame underneath for mine.
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23rd May 2019, 05:38 PM #755Most Valued Member
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23rd May 2019, 06:51 PM #756Golden Member
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23rd May 2019, 07:58 PM #757Member: Blue and white apron brigade
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Whenever I'm going to cut something that may have clearance issues before I start the cut I butt the end of the stock up against the blade/band and allow the arm to move through the full movement its gonna make in the cut..
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23rd May 2019, 10:57 PM #758Golden Member
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I thought that is a crack but I was lucky, one of the dowels has sheared off and the thread on the main bolt is stripped. I tapped it to 3/4" 10 tpi and put a stud in replacement of the 5/8" bolt. I also replaced 2 dowels by 8mm. There is one problem, the mating gears appear to be "grinding", I think I need a gasket to give them a bit of clearance?
Regards,
Trong
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24th Jun 2019, 06:59 PM #759Most Valued Member
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I had a scary one today. Misread the powtran manual for a p1500 inverter and set the frequency control element from 0.01hz to 0.1hz, thinking this would change the size of the steps when incrementing speeds. But it just changes the frequency multiplier so displaying 50hz it really meant 500hz. Which means my spindle and motor attempted to do 20000rpm very very briefly
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24th Jun 2019, 07:22 PM #760Member: Blue and white apron brigade
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Did the VFD shut itself down? this is what usually happens when the motor can't cope.
A similar thing happened to me when one of the band new HYs tried to crank up the 4 pole motor up to 400 Hz.
Fortunately the VFD looked after everything and it never went past~ 200 Hz before shutting itself down.
Now I always perform a factory reset on all new VFDs
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24th Jun 2019, 07:25 PM #761Most Valued Member
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I shut it down when I heard it making what I call 'the scary bad whistle' and because I had have the breaking resistor set up it stopped almost instantly.
Your point brings up something interesting, why does the VFD care about pole count? Just curious what it would change in supply characteristics?
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24th Jun 2019, 10:08 PM #762
Hi Ralph,
The motor speed is frequency dependant. If you feed a two pole motor with 50 Hz it will run at 3000 rpm. Do the same with a four pole motor and it will run at 1500 rpm, and so on 8 poles 750 rpm.
The VFD wants to know then it can use the correct frequency to provide the speed you asked for.Best Regards:
Baron J.
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24th Jun 2019, 11:25 PM #763Most Valued Member
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Ahhh I guess I just don't ever use motor rpm as my control element.
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25th Jun 2019, 12:22 AM #764Most Valued Member
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25th Jun 2019, 12:33 AM #765Most Valued Member
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Yeah I sure did it's driving me nuts. If I find out I'll let you know straight away!
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