Author Topic: Alyn Foundry Nattie  (Read 8680 times)

Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #45 on: November 29, 2022, 11:48:50 AM »
Not at all Ray….

It was my mistake after all.

May I suggest you try your Silver soldering on a piece of scrap first?  Cast Iron can oxidise in a twink, making further progress impossible.

 :cheers:  Graham.

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #46 on: November 29, 2022, 06:45:39 PM »
Just discovered that Graham.  Silver soldered everything (or so I thought), then spent ages cleaning up only to discover that  the crank pin joints had not taken at all, although the main shaft ones seem rock solid. Pulled the crank pin out, cleaned up the holes in the webs and used a new piece of silver steel. Tried to re-solder, but not sure if it has penetrated the joint. Will see when everything is cleaned up.
Crank is running pretty true but not perfect.
Think I will probably end up scrapping it and starting from scratch with all steel silver soldered construction.
Very frustrating after all the hours of heat treating and machining the hard web castings.
Will just have to put it down to experience.
« Last Edit: December 01, 2022, 03:32:08 PM by RayW »
Ray

Offline Jasonb

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Re: Alyn Foundry Nattie
« Reply #47 on: November 29, 2022, 07:31:35 PM »
To solder CI you want to get it upto red hot and then allow to cool, the heating will drive the carbon to the surface which then needs to be cleaned off with a wire brush or similar. You can then flux and assemble your crank and this time apply the solder.

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #48 on: December 01, 2022, 03:25:58 PM »
Thanks Jason. I cleaned up and re-tried after the first failed attempt, but still couldn't get the solder to take so that crankshaft has now been consigned to the scrap bin. I have now made new webs of steel and that should hopefully be more successful. I have opted for a 40mm stroke like you. I plan to put the exhaust port near to the head.
Ray

Offline Jasonb

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Re: Alyn Foundry Nattie
« Reply #49 on: December 01, 2022, 08:01:38 PM »
Ray, I could not put this image in a PM so will post it here

You need to buy TWO of the 0.5MOD 15T gears, tooth counts selected from the drop down

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #50 on: December 01, 2022, 09:25:36 PM »
Thanks Jason. I have now ordered them. As a point of interest, how did you secure the one on the crankshaft?  The hub diameter is shown as 8mm and if the shaft is 6mm that only leaves 1mm wall thickness for a grub screw. Did you drill through the teeth?
Ray

Offline Jasonb

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Re: Alyn Foundry Nattie
« Reply #51 on: December 03, 2022, 07:56:55 PM »
I put a 3mm hole part way into the crankshaft so the grub screw is acting more like a pin and taking the drive on it's side rather than risk stripping the thread if it were purely clamping the gear to the shaft

Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #52 on: December 04, 2022, 12:25:52 PM »
Hi Ray.

Sorry for my delayed reply.

As you know I’ve been more than a tad unwell this week. The sideshaft drives a simple Scotch yoke which presents minimal friction to the gear train. My method is to drill a small, say 2 mm diameter hole into the crankshaft at right angles. Just outside of the main bearing cap. A short peg of Steel is then inserted into it. I then carefully drill a 2 mm hole into the gear, end on. You can either choose a peak or trough to place the hole. Using this method the fixture becomes a “ secret “ when the gear is slid over it. The flywheel boss is then butted up against it to complete the operation.

I do remember Mike inserting the capital letter “ G “ in front of the title nattie due to his immense frustration in one email, however Nattie is definitely Gnat power and the sideshaft gear only needs a dab of Loctite to secure it. In fact I would have simply glued the crankshaft together personally.

On a brighter note “ that very nice man “ has been in touch and I’m hoping to receive a delivery before Christmas, fingers crossed.

 :cheers:  Graham.

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #53 on: December 04, 2022, 02:01:00 PM »
HI Graham,
You've got me a bit confused there, but I think I get the general idea.
I have just e-mailed you with the following link, which shows a rather good view of a National at a museum in Spain. It clearly shows the main bearing oil cups and the mechanical oiler driven fron the sideshaft.
https://museudeltractordepoca.com/en/portfolio_category/national-gas-engine-co_en/
Ray

Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #54 on: December 04, 2022, 02:31:46 PM »
Hi Ray.

Having re-read my post even I’m confused….. :lolb:

Talk about brain fog, more like a Pea souper from back in the day. Regarding the Loctite I was referring to glueing the gear onto the sideshaft only. The valve timing can be set by the adjustable face cam at the front of the engine.

That’s a very fine looking National sporting early HT ignition.

 :cheers:  Graham.

Edit.

My exhaust port had already been decided by some previous, now forgotten modifications….. But it’s roughly a 1/2” in diameter. Please see attached photos.
« Last Edit: December 04, 2022, 02:50:42 PM by Alyn Foundry »

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #55 on: December 04, 2022, 03:21:05 PM »
Thanks Graham. I like the idea of Loctiting the crankshaft, possibly with pins as extra security. Just tried gluing one of the scrap cast webs and a scrap of shaft and they were absolutely solid within a few seconds. It will also save all the cleaning up needed after soldering.

As regards the crankshaft gear, the attached photo shows my Westbury Wyvern gear. A small pin is fitted through the crankshaft and a notch cut in the end of the gear boss to fit it. The gear is then held in position against the pin by the flywheel boss. Is that something like what you were suggesting?
Ray

Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #56 on: December 04, 2022, 04:05:15 PM »
Yes, that’s pretty much what I was trying to describe. I was able to get the notch into one of the gear teeth so the peg becomes hidden from view. The point is there’s so little power required into the gear train even a 1 mm peg would be over engineering!

I have just tried to remove the gear from mine to take a photo but the acid “ episode “ has wreaked havoc and the two are now a permanent feature….

 :cheers:  Graham.
« Last Edit: December 04, 2022, 06:15:04 PM by Alyn Foundry »

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #57 on: December 04, 2022, 05:03:51 PM »
Don't think I've heard the acid story.
Ray

Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #58 on: December 04, 2022, 06:35:41 PM »
Don't think I've heard the acid story.

Well….

This has absolutely nothing to do with what Jo refers to as the Alyn Foundry special coatings department whatsoever.   ;D   

Some years ago I needed to do some Nickel plating and one of the requirements was high strength Hydrochloric acid. I bought a 5 Litre bottle of 30+% from eBay. After doing the job I put the bottle on the shelf alongside little Nattie. Unbeknownst to me I had failed to screw up the cap fully tight and the acid vapour reacted with the humidity to produce a highly corrosive mixture that ate into the engine with a vengeance.

The castings coated up quite well but the Steel components virtually disappeared, needless to say the acid is now stored in a suitable area away from my delicates….  :)

 :cheers:  Graham.


Offline RayW

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Re: Alyn Foundry Nattie
« Reply #59 on: December 04, 2022, 10:28:21 PM »
That sounds nasty. Definitely keep it away from your delicates!!
Ray

 

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