Author Topic: Two little CHUK's  (Read 16492 times)

Offline Alyn Foundry

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Re: Two little CHUK's
« Reply #90 on: September 09, 2019, 07:19:46 PM »
So the next question is will the shape of the cam need altering?

That cam would have held the shutter down for longer when pushing but will hold it up for longer now it is lifting.

I'm not sure it makes any difference Jason. It's just a reverse action. The " dwell " is determined by the outer diameter of the cam the difference in the top and bottom radii determine the stroke of the shutter.


Offline Jo

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Re: Two little CHUK's
« Reply #91 on: September 11, 2019, 01:44:41 PM »
A little more swarf has been made and the rattle cans have been exercised.

The flywheel casting was very nice and hardly needed any fettling  8) Mounted on the outside surface of the three jaw chucks the outer surface on either side of the flywheel was made to run nearly true before the rim was skimmed and the outer rim. While mounted up the centre was drilled, bored and reamed for the crankshaft.

Now that the paint has gone off on the bearing block the two bearings have been pressed in and it has been mounted on the bearing yoke. Finally I am able to work out if the stroke could be extended and the length of the connecting rod  :thinking:

I have also started machining the piston. The main body of the piston was very tapered so it was necessary to mount it in the three jaw chuck using tailstock support with the casting jammed against the chuck body.

Jo
Enjoyment is more important than achievement.

Offline Alyn Foundry

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Re: Two little CHUK's
« Reply #92 on: September 11, 2019, 02:28:50 PM »
Hi Jo, wonderful progress.

I'm assuming you've guessed the origin of the flywheel you've just machined?   ;)

That's how the other should have been.... Amateurs!!

My engine has an R.L.E. flywheel, I changed over to the Robinson to reduce production costs as we had 2 patterns on a single plate and that considerably reduced the price.

I know you've painted but you might want to consider the overhang and perhaps remove the inner boss completely? That's up to you however.

As you're now onto the piston try to remove as much metal as you can, I'm suggesting down to as little as 1 mm all over. I was most generous with material because it has the effect of reducing " chill " that dogs most thin section Iron castings.

Carry on, I'll meet up with you somewhere down the line.

Cheers Graham.

Offline b.lindsey

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Re: Two little CHUK's
« Reply #93 on: September 11, 2019, 02:46:58 PM »
Having been out of action for a few days what with moving and such, its good to see your additional progress Jo. Finally, now that the shop is just a short walk down the drive, I hope to  find my way there and start contributing again.

Bill

Offline Jo

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Re: Two little CHUK's
« Reply #94 on: September 11, 2019, 04:31:56 PM »
Hi Graham,

I have just looked at the alignment and yes I think there is a bit of balance to be gained by reducing those flywheel bosses.

The crank web is too short to allow for a 28mm throw. Which is the maximum throw if the piston is keep in the cylinder casting rather than using the spare extension of the bearing yoke, which I think might cause some drag  :paranoia: That would need a crank rod with centres at 125mm   :thinking: I've found a bit of scrap-bin-inum complete with look-a-like special coating from which I can make a new crank web. The coating isn't properly aged   :-\

Having been out of action for a few days what with moving and such, its good to see your additional progress Jo. Finally, now that the shop is just a short walk down the drive, I hope to  find my way there and start contributing again.

 8)

Looking forward to it Bill, I am sure you'll find it great to be making swarf again  :cheers:

Jo
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Offline Jo

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Re: Two little CHUK's
« Reply #95 on: September 12, 2019, 04:18:20 PM »
The piston has been turned to have 1.5mm walls for now  ::)

The outside of the piston and the cylinder have been honed until the piston is a firm push fit through the cylinder. To work out just how much polishing is required I need to first properly clean the bore. Brake cleaner is ok for this but the ultrasonic cleaner filled with boiling soapy water is even better  ;)

I might not want that noisy thing running in the kitchen while I eat my dinner  :thinking:

Jo
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Offline Admiral_dk

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Re: Two little CHUK's
« Reply #96 on: September 12, 2019, 09:50:46 PM »
You're really moving quickly with this build Jo and the last picture tells me that it is a lot bigger than I thought. Finished parts are looking good  :ThumbsUp:

Quote
I might not want that noisy thing running in the kitchen while I eat my dinner  :thinking:.

On mine there are big warnings about not running it near any living being (bugs excluded  ;) ) as it can have hazardous consequences ...!  so please do not eat near it when it is running !!!!

Offline Jo

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Re: Two little CHUK's
« Reply #97 on: September 13, 2019, 08:23:29 AM »
Thanks Per  :)

... and the last picture tells me that it is a lot bigger than I thought.

Its not a cute little one like Jason's, this is an Elephant size one  :pinkelephant:  ::)

Jo
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Offline Admiral_dk

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Re: Two little CHUK's
« Reply #98 on: September 13, 2019, 11:19:24 AM »
 :o  Ok, that monster should have a "Quack" loud enough to scare all the cats out of the neiborhood  :Director:

Offline b.lindsey

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Re: Two little CHUK's
« Reply #99 on: September 13, 2019, 01:25:11 PM »
Beginning to look like a proper engine Jo. Were you able to get the entire bore cleaned in the ultrasonic by flipping it over?

Bill

Offline Alyn Foundry

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Re: Two little CHUK's
« Reply #100 on: September 14, 2019, 11:37:16 AM »
 I finally ventured out to the workshop yesterday evening, there's a distinct chill in the air here.

The piston casting was waiting for me in the Le Blonde ready to be reversed with the chucking stub held firmly. It was at this point I noticed that the stub didn't want to centralise, my method is to gently rotate the casting against the lightly tightened jaws. Try as I might I couldn't seem to get things true. I eventually found a position that came near and locked the jaws tightly, knowing that I could get concentricity whatever.

I use a large diameter end mill to " rough out " the inside and then follow up with a boring bar, using a drill bit can sometimes overshoot your depth. Several noisey passes later began to reveal a clue as to why I'd been having trouble earlier.

The swarf kept changing in its characteristics from dust to large curls, I'm a little embarrassed with the photo presented.

Needless to say, patience ruled and I finally found the piston from within the mess. A fit worthy of the time spent. I will, however heat treat it before final fitting. A 4 mm hole was drilled and tapped to 2BA for the small end yoke before gently cutting off the stub with a hacksaw.

My bearing housing will come next.

Cheers Graham.

Offline Jo

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Re: Two little CHUK's
« Reply #101 on: September 14, 2019, 03:46:11 PM »
Thanks Bill,

Were you able to get the entire bore cleaned in the ultrasonic by flipping it over?

Yes, just  :)

I've been looking to get the rod done and be able to attach it to the piston. For both the rod and the attaching fork I have used HE30 aluminium, I can't see this engine putting the sort of stresses through the rod that it needed HE15 to be used.

The rod had its big end bored to fit a bearing I had and the small end was reamed 5mm for a bush, the rest is just milling and filing. The small end bearings are a pair of dinky rollers for a 3mm shaft which have been fitted to the piston adapter thingy  :noidea: . The great thing about doing it this way is that the bearings are a good fit on the 3mm shaft so it holds in place on its own so there is no need for nuts, circlips etc.

The only thing to watch now is not to knock the rod against the side of the cylinder as I do a bit of up and down testing (there is a spring currently helping the piston back up the cylinder in this important testing phase ::) ).

Tomorrow I need to make the crankweb and a crankpin  :wine1:

Jo
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Offline Jo

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Re: Two little CHUK's
« Reply #102 on: September 15, 2019, 04:07:18 PM »
A Crank web was found inside a piece of hard as  :censored: come-in-handie-um. I should have spotted the obvious clue from the amount of rust on the outside of it that it was going to have a high carbon content that enhanced the experience of hacksawing off the two unwanted bits ::)

There is nothing exciting about the crank pin, it is just threaded 2BA to screw into the crank web, which is in turn held onto the crankshaft by a 6B grub screw hiding behind, I might also Loctite it later.

Initial round and round testing is showing up that the piston is still dragging a little so requires more round and round testing, this could be done with an electric drill  :facepalm2: or my preferred manual technique of flicking it over every time I walk by  :) . The piston seems to dangle about 1mm into the port at BDC.

I need to get the cam in place to discourage the crankshaft from sliding in the top bearing when it is flicked over

Jo

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Offline Alyn Foundry

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Re: Two little CHUK's
« Reply #103 on: September 16, 2019, 12:03:11 PM »
The " home straight " is in sight Jo.

The cam and a few " fiddlely bits " to finish. I wouldn't worry too much about the position of the piston at TDC, it'll be fine.

I didn't reply yesterday as we were waiting to hear some news, finally came at 7:32 PM. A granddaughter at a little over 7 Lbs entered the world. Both mum and daughter are doing fine.

I was looking at the gauge plate that I bought the other day for the cam follower, perhaps a prime candidate for the shutter? My use of a " Stanley " knife blade originally was perhaps inspired by the shape and thickness of the one fitted to my Planck engine. This however needed a lot of fine lapping to get it flat after Silver soldering the pivot, the gauge plate shouldn't.

Don't forget to lap the cylinder port Jo, I can see it looks a little rough at the moment from your last photos. ;)

Cheers Graham.

Offline Jo

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Re: Two little CHUK's
« Reply #104 on: September 16, 2019, 04:58:33 PM »
The " home straight " is in sight Jo.

Thanks Graham, congrats on the new member of your family  :cartwheel: You will have to design another engine to celebrate  ;)


I've been making the cam, I worked out that with a 62mm diameter face I needed to set the boring head at 65mm diameter to cut a profile that gave me 8mm of movement. Hopefully this is sufficient to allow for a clean opening and closing of the valve.

To cut this the mill head was run in reverse and I used the vertical power feed (which also had to be reversed due to the spindle motor reversal ::) ). I decided that removing the cam surface would make the crankshaft out of balance so added some lightening holes on the opposite side.

The final stage was to turn a 2mm long 16mm diameter boss on the inside of the cam to fit next to the main bearing and to reduce the boss on the other side down to 4mm long so that I can bring the flywheel in a bit later  :)

Jo
Enjoyment is more important than achievement.

 

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