Author Topic: Two little CHUK's  (Read 4011 times)

Offline Johnmcc69

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Re: Two little CHUK's
« Reply #45 on: September 04, 2019, 02:20:04 AM »
 :ThumbsUp:
Nice work!

 John

Offline Jo

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Re: Two little CHUK's
« Reply #46 on: September 04, 2019, 07:52:31 AM »
I've been thinking about the fit of the bearing yoke support. The base of the casting might clean up to 8mm deep which is the depth that the ring on the top has been machined to, So there will be an odd sized gap above the top fin  - I think I should have left that ring at 14mm tall :wallbang:

The cylinder fins have about 7mm between them so a 1mm deep counter bore could be done to allow the bearing yoke support to fit on the top then be bolted into place with plenty of metal to secure it and it would look like there is an extra fin on this engine  :thinking:

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Two little CHUK's
« Reply #47 on: September 04, 2019, 12:42:31 PM »
Any chance you could post a photo of the two bit sitting one on top of the other to make it a bit clearer to see what you are saying.

Provided the groove does not go too deep and meet the fixing PCD I can't see why it could not be done and will help loose a bit of heat even if at the cooler end

Offline Jo

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Re: Two little CHUK's
« Reply #48 on: September 04, 2019, 01:07:23 PM »
A pic of the two together.

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Two little CHUK's
« Reply #49 on: September 04, 2019, 01:13:19 PM »
So you would cut the top spigot of the cylinder a little smaller dia leaving a fillet and then machine away the bottom of the bracket ring in a similar way so that when they go together it looks like an extra groove. Can't see why not unless Graham knows something we don't.

Poor green lines :-[

Offline Jo

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Re: Two little CHUK's
« Reply #50 on: September 04, 2019, 04:45:15 PM »
Holding the bearing Yoke is a bit of a challenge  :thinking: as the foot is too long big to be able to hold it in a three jaw chuck.

You can hold it with the foot out but even then there is not a lot of space and there is no way it could be bored out to 40mm safely  :-\ It is possible to get 20mm in there to use to secure it on a mandrel.

Once on a suitable mandrel it is possible to turn the outside and to face the bottom, but while it is secure it can be turned round and the top of the bearing mount machined  :)

Which means I still need to do the boring bit  :Doh: But I can still change my decision on the depth for the counter bore if I want to.

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Two little CHUK's
« Reply #51 on: September 04, 2019, 06:35:28 PM »
Could always be bored etc on the mill or try your new welder out with greedy jaws like Graham.

Another option is to drill amd tap the fixing holes and then you just need a plate and a few standoffs

Offline Jo

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Re: Two little CHUK's
« Reply #52 on: September 04, 2019, 06:58:29 PM »
I am not saying I expect there to be any problems boring it  :hellno:

I am saying there are lots of other things to get on and do before I get round to doing the boring as once I have done that it is not as easy to hold it for those other jobs. And I was hoping that Graham might have confirmed before I do it that there is no reason not to leave it with a shallow location bore  ::)

Jo
Enjoyment is more important than achievement.

Offline b.lindsey

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Re: Two little CHUK's
« Reply #53 on: September 04, 2019, 07:19:46 PM »
This one is moving right along Jo even with the few challenges so far.

Bill

Offline Alyn Foundry

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Re: Two little CHUK's
« Reply #54 on: September 04, 2019, 07:49:49 PM »
A pic of the two together.

Jo

Like this per chance?

 :)

Offline Chipmaster

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Re: Two little CHUK's
« Reply #55 on: September 04, 2019, 08:49:15 PM »
Hi Jo,

I think you're keen on the Chuk sound. When yours is running lift the base slightly to get the reverberating quack type sound. For this video I've undone the holding down bolts and used a small screwdriver as a wedge.


My engine would benefit from a de-coke. When its clean I get a better tone right through the rev range.

Andy

Offline Jo

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Re: Two little CHUK's
« Reply #56 on: September 05, 2019, 06:28:35 AM »
Thanks Andy. So it looks like the trick to getting these little CHUKs quacking is all to do with amplifying the exhaust valve. Something to try later. :thinking:

Like this per chance?

Yes. It would be nice to be able to see in the picture how you did that. Your earlier pics seemed to show a slight gap above the 7th fin  :noidea:

And Graham you did not respond to the question about does it need to slide onto the top of the cylinder for a secure fit or would just the screws be sufficient. In which case I can machine a slight register in the bottom of the bearing yoke and do that with mine. My preference if I was to do it again would have been to modify how I machined the top spigot.

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Two little CHUK's
« Reply #57 on: September 05, 2019, 07:26:21 AM »
It's a noise you get from most atmospheric valves to some extent as they open, some quack some are more flatulent like the Robinson


Offline Alyn Foundry

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Re: Two little CHUK's
« Reply #58 on: September 05, 2019, 11:02:00 AM »
Dear Jo.

I'm awfully sorry, I completely misunderstood your question from yesterday; rather preoccupied.   ;)

The spigot at what is the top of the cylinder on CHUK 2 is machined to a clean diameter. This diameter is made as large as is possible from the " cleaning " cuts. The bearing yoke is then counterbored to this diameter to almost the full depth that the casting will allow.

For myself, I like to make this an interference fit. Once the two parts are pressed together no fixings are required and it looks, to all intents and purposes, like a single casting.

Regarding fixings.

There's no need to go overboard on either size or number. We are talking " fractional "  power here. The maximum size I used was 2 BA for securing the bearing carrier to the yoke, all others were 4 BA studs and nuts.

Oh, and a division of 3 was used throughout.

Cheers Graham.

Offline Jasonb

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Re: Two little CHUK's
« Reply #59 on: September 05, 2019, 11:22:59 AM »
This photo of Graham's may help Jo