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Tacho for mill

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boatmadman:
Being the proud new owner of a seig x2 mill and accessories, courtesy of CC - thanks Dave - I couldnt wait to have a play.

So, plugged it in, clamped it to my workmate and turned it on, without a tool, just to see it work!

All went well, looked around it...mmm nice, played with the variable sppeed.....nice, but hold on a sec, this means that I only know for sure what speed it is doing when it is stopped and at full speed in either ratio....need to improve this.

Idea, optical hand held tacho, £25 and upwards, but means I have to find it and hold it every time I turn on the mill.

0300 hrs wandering around work and  :smart: a bike computer measures rpm of the wheel and displays in kmh - a rev counter!!!!

Got the abacus out, and after much work, realised that there is a constant number that when input as the wheel size, will display a number in kmh that is numerically the same as the wheel revs.

And the magic number is..1667

Went to that well known car and bike parts shop, bought a computer for £9.99, first having checked it has a 4 figure output, 000.0  took it home and entered the magic number, mounted it on the mill using a small neodym magnet (not the supplied one) on the mill spindle, glued the pickup on the body with superglue, turned it on and bingo, it works.

Now, is it accurate? YES!! but you do have to ignore the decimal point in the speed readout to gt the revs.

I borrowed an optical tacho from work to check it and its spot on.

Drawbacks? only one so far, it only goes up to 2000rpm!

Nice touch? It has an auto power up when the mill starts, and auto off 10 mins after stopping. :thumbup:

Ian

andyf:
Hi Ian, I got one last year from Halfords, but it only goes up to 100kph, representing 1000 rpm. No doubt the makers thought that most cyclists wouldn't be doing more than that - it's 60mph, ater all. I might drop in to see if the Altrincham branch has one like yours - what was the name on the packaging, please?

Andy

Darren:
Very nice idea, my only worry would be the magnet taking flying lessons  :zap:

Oh and balance now being off a touch?

boatmadman:
The unit is an 'echowell star'

I have just done a few more trials with it and found that, yes, the magnet flew off at high revs, over 2000. As far as the balance is concerned, the magnet is very light and the shaft radius is small, so out of balance forces will the there, but small. I think I will mark on the dial a range of speeds then remove the magnet to avoid out of balance issues.

Using the borrowed optical tach, I have found that the spindle speed is actually twice that indicated on the machine label. The machine has had a drive belt conversion fitted, so I was wondering if this is the result of the conversion.

More trials needed, but for now, its off to work :scratch:

Ian

bogstandard:
Cut the magnet in half, then your readings should only be half of what it should be. :doh:

Very nice improvisation BTW.


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