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21
Chatterbox / Re: Engine video
« Last post by Pete49 on Today at 04:27:36 AM »
very talented people showing great engines.
22
From Plans / Re: Ridder's Stirling Bobber
« Last post by Ian S C on Today at 02:52:38 AM »
In NZ we have what are known here as Demo yards where demolition firms sell the remains of demolished buildings, and thats the place to look.  My last lot had been used as counter weights on sliding doors in my brother in laws' piggery.  The trouble with cast iron is that it is cast to shape using the minimum amount of metal and its some times hard to hang on to to cut a bit out the right shape and size.
Ian S C
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Your Own Design / Re: Double acting Double cylinder Oscillator
« Last post by 10KPete on Today at 02:50:56 AM »
Locomotives don't gallop...

Pete
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Your Own Design / Re: Double acting Double cylinder Oscillator
« Last post by Gas_mantle on Today at 12:20:21 AM »
I'll follow along with interest, your threads always generate good talking points and give people chance to exchange ideas  :)

Looking back at the photos Jason posted, the green engine appears to have a 90o offset - admittedly the air pumps appear to be 180o but they are being driven from the crank so a balanced oscillation seems to make more sense in that case.
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The end result looks good .if you checked the hole was central at top and bottom you can't do any better.
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Your Own Design / Re: Double acting Double cylinder Oscillator
« Last post by john mills on Today at 12:11:46 AM »
i like your engine but 180 degree or 90 degree is up to you 180 degree will be better balanced at high speed not self starting 90 degree will be self starting and run slower so thats for you to decide.
In full size engines there are both.you decide .its what you like.
27
Thanks John, I did wonder about the accuracy of taking a reading from the rough cored hole but it did look like the original bore ran true.

Obviously I couldn't get a non fluctuating reading on the coax indicator in a cast bore but with care I could get to what I thought was the centre enough to try a very fine first cut  :)

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Your Own Design / Re: Double acting Double cylinder Oscillator
« Last post by Brian Rupnow on Today at 12:07:02 AM »
When I suggested a 90o offset I reasoned it would run smoother but I kinda thought a relatively heavy base would be needed to dampen the uneven cylinder movement.

I can appreciate you are building a twin engine as a fun exercise and to look attractive but personally I'd want a twin to have an advantage over a single (whether that be self starting or smoother running) and to me a 180o twin is really little more than a single  :headscratch:

We live---we learn. My first thought was that with a 90 degree crankshaft the engine would tend to "gallop" at low speed. I had that wrong. It might "gallop" if the cylinders were single acting, but with them being double acting, it should run smoother with a 90 degree crank.
29
Your Own Design / Re: Double acting Double cylinder Oscillator
« Last post by Gas_mantle on May 24, 2018, 11:55:06 PM »
When I suggested a 90o offset I reasoned it would run smoother but I kinda thought a relatively heavy base would be needed to dampen the uneven cylinder movement.

I can appreciate you are building a twin engine as a fun exercise and to look attractive but personally I'd want a twin to have an advantage over a single (whether that be self starting or smoother running) and to me a 180o twin is really little more than a single  :headscratch:
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looks like success with that part looks good.
I have not had a milling machine to do them like that  I and set them in the four jaw chuck and face plate to do the top face and bore .I can see were the out side of the casting round the trunk is .i want the bore to be in centre of the casting not in the cored hole if it is not in the centre.
The grub screws are probably metric ,the key needs to be in good condition and right size  see the key fits the socket  then don't over tighten .
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