Recent Posts

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Electronics & IC Programing / Re: capacitive fuel gauge for petrol
« Last post by awemawson on January 22, 2018, 04:23:18 PM »
To improve the stability to eliminate the sloshing effect it's only necessary to average the last N readings, adjusting N to meet the practical circumstances.
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How to's / Re: Grinding the jaws on my three jaw chuck
« Last post by philf on January 22, 2018, 04:11:35 PM »
Just out of interest, how are the scrolls in a 3-jaw (or any self-centring chuck) made? Rough cast then machined on a mill? Milled from billet? Forged?

I'm wondering.... how hard can it be  :lol: to just make a new scroll? :scratch: This is not a serious project BTW, I'm just curious.

Ade,

I would have thought a "useable" scroll could easily be made on a cnc mill.

Make out of heat treatable steel. Rough it out, harden and temper and then finish with a decent carbide end mill.

Phil.

(Do you still want the vice?)

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Project Logs / Re: Little Blazer X4
« Last post by kayzed1 on January 22, 2018, 03:16:11 PM »
I'm watching also Doc...keep up the good work.
Lyn.
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How to's / Re: Grinding the jaws on my three jaw chuck
« Last post by timby on January 22, 2018, 03:12:54 PM »
We had a scroll made for a special application a few years ago,  it was turned on  a lathe.
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How to's / Re: Grinding the jaws on my three jaw chuck
« Last post by AdeV on January 22, 2018, 01:44:53 PM »
Just out of interest, how are the scrolls in a 3-jaw (or any self-centring chuck) made? Rough cast then machined on a mill? Milled from billet? Forged?

I'm wondering.... how hard can it be  :lol: to just make a new scroll? :scratch: This is not a serious project BTW, I'm just curious.
16
Electronics & IC Programing / Re: capacitive fuel gauge for petrol
« Last post by AdeV on January 22, 2018, 01:38:56 PM »
I'm not 100% sure with the library he's using, but it will probably work like this:

The fuel sensor pin D5 is driven high. This starts to charge the capacitor (actually the sensor) through the 1MOhm resistor (i.e. slowly). After a certain period of time, it's full, and current starts to flow to the other pin it's connected to, D6. The Arduino counts the number of times it goes around in a tight loop before D6 goes high. The count is effectively a period of time. This time is then divided/multipled/whatever to produce a range 1-10 which the Arduino then displays on the LEDs. After each "read", the pin goes low, and the charge in the capacitor is dumped to earth.  All of this happens so quickly, he's actually taking 200 readings & averaging them, for both sensor & compensator, this in theory gives a more stable reading (in practice, I've found the readings don't jump about too badly; but that's on a deskbound setup, not in a moving vehicle).

The temperature compensation works the same way. In theory, the capacitor in free air should always charge in the same number of cycles. If the temperature drops & therefore the charge takes longer (assuming it's that way around), then the % difference can be applied to the fuel sensor, thus removing any temperature change error from the sensor reading.

I've done something similar for a touch-sensitive doorbell; that uses the fact that the human body is effectively a big capacitor, and when you touch the panel, its natural capacitance jumps up. This is a much easier application (since I'm only looking to detect the presence or absence of a human-sized capacitance), rather than trying to accurately read tiny differences...
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Electronics & IC Programing / Re: capacitive fuel gauge for petrol
« Last post by angus on January 22, 2018, 11:36:06 AM »
to be honest, am not entirely sure how the arduino is doing its black magic!!
about to start soldering now!
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Scraping / Re: DIY Electric scraper
« Last post by Joules on January 22, 2018, 07:21:26 AM »


Neat solution, just needs better bearing surfaces, change angle sleeves for different travel.



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Project Logs / Re: Little Blazer X4
« Last post by philf on January 22, 2018, 06:25:10 AM »
Hi Doc,

I'm watching!

Phil.
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How to's / Re: Grinding the jaws on my three jaw chuck
« Last post by mattinker on January 22, 2018, 05:24:30 AM »
Exactly!!
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