Two little CHUK's

[Jasonb]

Graham, would I be right in assuming the reduced flywheel overhang is to reduce load on the bearings? If so have you ever considered a 2 flywheel version with a 2nd flywheel overhanging the back of the engine?

[Alyn Foundry]

Hi Jason.

No, not in this situation. I have deliberately used two bearings side by side to reduce the stress I was more thinking of the overall " footprint " the engine presents.

A twin flywheel, hmmm, probably not.... I absolutely loath making crankshafts!   

Cheers Graham.

[Alyn Foundry]

Well....

September the 19th 2019  ( hmmm, all the 9's ) was the day Jo got her CHUK 2 running. A little behind schedule see's its twin burst into life.

This was the second CHUK 2 for me, the first being the prototype. Having built several versions ( of all 3 ) I always try to be a little different in presentation and innovation, this model was no exception.

After all these years I actually got around to making a pattern for the main bearing housing and added a little " vintage " feel by using a spare oil box cover from my Barker type " B " to hide the mounting screws.

I used a length of 2x15 Gauge plate for the shutter arrangement, Silver soldering a piece at right angles in place of the Stanley knife blade. I opted for a " lift to close " and fitted a small tension return spring from the port face adjustment/preload mounting.

The beauty of the forum is that ideas can be shared, in " real time " so I adopted a couple of Andy's
 ( Chipmaster ) suggestions. The use of a cast Iron disc for the exhaust, much easier to lap and the use of the 4 jaw chuck to machine the cam profile. Thanks again Andy. 

I had fitted a " Shim Steel " exhaust closing spring but this collapsed during a first test run caused by some unburnt mixture ignighting inside the cylinder. After several attempts trying to use this method, without success I decided to drill 3 X 5 mm pockets into the base and put 3, equal length compression springs. This proved to work, flawlessly. Older UK members will surely remember the " Proops packs " of various miscellaneous items? I'm on my last bag of " small compression spring " assortment!!

Three Brass " clock feet " are fitted to allow adequate exhaust function.

Enough said, 9 months after Jo here's my half of " Two little CHUK's "

Cheers Graham.

<a href="https://www.youtube.com/watch?v=A1oYDbV4Ij8" target="_blank">http://www.youtube.com/watch?v=A1oYDbV4Ij8</a>

[Jo]

  That runs nicely

I will have to get my skates on and finish the other one

Jo

[Twizseven]

Looks good Graham. That’s one hell of a flame.

[Alyn Foundry]

Looks good Graham. That’s one hell of a flame.

Hi Colin.

Yes it looks quite dramatic, doesn't it?

I've always found they seem to need much more heat in the  early " bedding in " stage. After a few longish runs you can usually trim them down quite a bit. The video was shot on its second run after building, having  finished the shot I left it to run until the oil started smoking. A glazed cylinder seems to be beneficial to this " breed " of engine.

Cheers Graham.

[Twizseven]

Since modifying the burner with more holes mine has run a lot better.  Still takes a good few spins to get it started.  But last week I ran it for around 15 minutes no problem.  Was able to get it running quite slowly.   Only trouble with a giant flame is everything is completely sooted up.

Out of interest what other casting sets do you have?

Colin

[Dave Otto]

That runs nice Graham, congrats!

Dave

[Zephyrin]

That's a great runner, looks impressive, the flame too !

I had fitted a " Shim Steel " exhaust closing spring but this collapsed during a first test run caused by some unburnt mixture ignighting inside the cylinder.

unburnt gas, probably present in this frightening flame, would require more oxygen and more heat to burn entirely, an opportunity not occuring in the closed cylinder, IMO.
 Cheers

[Alyn Foundry]

Thanks for the comments one and all.   

After a good couple of hours running yesterday I've just " de coked " the engine. Whilst apart took a photo of the " improved " exhaust valve spring arrangement.

With hindsight I wish I'd have thought of this earlier.

Eagle eyes will spot a mistake, 'Twas a good job I wasn't cutting gears.... 

Cheers Graham.

[Twizseven]

Graham,

I like that exhaust valve solution.  Looks a lot more positive than the 4 legged bent version.  Upgraditus???

Colin

[Alyn Foundry]

Hi Colin.

Indeed it is, but you'll have to find some springs of fairly even tension and length.

Luckily I hadn't machined too much off the underside but I still have 3 tiny holes where the drill bit tip just broke through. A slot drill would have been much better but I don't have one at the correct size at the moment.

Cheers Graham.

[Alyn Foundry]

Well....

With each successive run my CHUK 2 just gets better and better. Easier to start and better control. I guess that finally concludes this build thread?

However....

We've seen three contributors with builds and a fourth successfully " scaled " version " Chuky " from Jason B. A simple question, which flywheel is preferred towards the " look " of the engine? My original prototype used an R.L.E. flywheel and now we've all done one with a flywheel that was a half scale replica of the Robinson number 4 hot air engine.

This question is open to all the membership here please feel free to comment. I'm about to commit to a run of castings and I'd like to know which of the pattern plates to strip for use?

Cheers Graham.

[Jasonb]

I think the lighter spokes of the top photo look better plus the fact that you have not had to machine the edge of the web inside the rim. But smaller hub of the lower engihe looks better

[Alyn Foundry]

Thanks Jason....

So to conclude this thread....

CHUK 2 Inverted vertical flame licker, gulper or just plain vacuum engine. Bore 41 mm stroke 26 mm.

The photographs show the cam follower and tensioner arrangement plus a front and rear view of the cleaned but unpainted engine.

Thanks to you all, cheers Graham.