Author Topic: Alyn Foundry Nattie  (Read 2706 times)

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #15 on: November 18, 2022, 08:24:42 PM »
As Jason says Jo, the controller is a generic e-bay one. When I converted the mill, a Clarke CMD10, from gear drive to belt drive, I had to fit new electronics as the old ones were integral with the gearbox and had become unreliable anyway. I converted to belt drive because the flimsy plastic gears were constantly breaking.

Jason, the piston ended up as 1.508". I have drilled and tapped the end 2BA for the internal gudgeon pin fork as on CHUK 2.
Ray

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #16 on: November 22, 2022, 03:26:22 PM »
The mill is back up and running with its new controller which means that I have been able to get on with milling the main casting.
The front face of the bed casting has now been bored out to accept the cylinder, which is secured in place with two 2BA grub screws. As this is quite a short casting, I was able to hold it vertically in my little mill and use the boring head.
The main bearing faces have also been milled at a 30 degree angle to mimic the angled main bearings on National engines. Next job will be to make two main bearing caps, possibly from brass. These will house two 0.375" outside diameter ball races each side.
Ray

Offline Admiral_dk

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Re: Alyn Foundry Nattie
« Reply #17 on: November 23, 2022, 10:58:55 AM »
Nice work  :ThumbsUp:

I sit wondering how to hold / clamp the castings in order to ensure that the Crank will run a perfect 90 degrees to the cylinder and the rest  :thinking:

Per             :popcorn:       :cheers:

Offline Jasonb

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Re: Alyn Foundry Nattie
« Reply #18 on: November 23, 2022, 12:23:20 PM »
I tend to bolt the frame down to a steel plate that has been squared up. You can then easily clock an edge of the plate with a DTI to get it true and also the plate can be clamped to an angle plate if needed so you have 3 planes that are easily set rather than trying to clock the ast surfaces.








Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #19 on: November 23, 2022, 12:48:04 PM »
 Hi Per.

I see Jason beat me to it whilst I was having lunch….  :)

At the Alyn workshop which has tooling available for the “ larger “ toys that I play with I use the Denbigh Universal milling machine for line boring etc.  The 150 mm capacity deep jawed machine vice will hold almost anything I need to machine. Like Jason I use a DTI to clock the front face and then adjust the swivel base to suit. Using a series of drills, starting with a centre drill the mains are quickly brought to size and finished with a reamer. All the reamers I use have “ known “ accuracy and the robust nature of the machine ensures a perfect result.

 :cheers:  Graham.

Offline Admiral_dk

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Re: Alyn Foundry Nattie
« Reply #20 on: November 23, 2022, 09:31:05 PM »
If I got this right - you place it on another flat and square (jig-) plate and use that to keep all the rest in the right angles to the previous opperation .... Well that makes much more sense than trying to do that with the casting itself.

Off course it could be easily done if we all have big five axis (quality) CNC's  ;D

I will follow with interest   :popcorn:   :cheers:

Per

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #21 on: November 24, 2022, 05:30:39 PM »
I have been tackling exactly this problem today. After fitting my nice new brass bearing caps, I set everything up to bore them vertically on my little mill. Unfortunately I have no horizontal boring facility.
As Jason and Graham have said, it is a case of ensuring that everything is set up square in all 3 axes when boring. One cap has bored slightly off centre, but I think this is probably because I didn't fit the caps exactly in line with each other. It is not an issue and won't show anyway when the crankshaft and flywheels are fitted.
Fortunately, my reamer cut an exact size and the bearings are a perfect slide fit. It just needs the underside of the caps being given a light rub on some emery paper so that they nip the bearings tight. 

There are two bearings per side as shown in the attached photos. The bearing caps were made in two parts, then silver soldered together.
Ray

Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #22 on: November 24, 2022, 07:19:06 PM »
Nattie is coming along nicely Ray.  :ThumbsUp:

I guess you’re going to soft solder the little square oil boxes separately?

 :cheers:  Graham.

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #23 on: November 24, 2022, 09:19:00 PM »
Drat, I never thought about oil boxes as we are not using oil lubrication for the bearings. As we are not building a scale model of a National N, I may leave them off.
Ray

Offline Jasonb

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Re: Alyn Foundry Nattie
« Reply #24 on: November 25, 2022, 07:15:19 AM »
As Graham had gone to the trouble to cast the oil boxes I thought I should at least add them back after cutting off his caps. JBWeld did it for me as I'd made the new caps from iron.


Offline RayW

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Re: Alyn Foundry Nattie
« Reply #25 on: November 25, 2022, 09:48:15 AM »
As a matter of interest, did the oil boxes have lids? I have scoured the internet for pictures of National N type engines, but can't find any pictures showing clear details of the bearing caps.
Ray

Offline Alyn Foundry

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Re: Alyn Foundry Nattie
« Reply #26 on: November 25, 2022, 12:12:15 PM »
Drat, I never thought about oil boxes as we are not using oil lubrication for the bearings. As we are not building a scale model of a National N, I may leave them off.

Hi Ray.

I agree, whilst not being a scale model the oil boxes are quite prominent features on National gas engines. This is the reason Why I put them on the bed pattern. I didn’t however go to the trouble of making them removable just simply line bored the casting.

As the crankshaft was going to be made as a composite the polished shafts were pushed through each set of races and the webs secured with 6 BA grub screws. The crankpin then tied up the two sides together.

I think it’s highly unlikely that the oil boxes would be left uncovered as they would, quite easily, get contaminated with the debris from their working environment. But, like you I have been unable to find any detailed pictures available on the internet.

I will ask Geoff at the Anson engine museum for some photos. It would be nice to see a mechanical cylinder lubricator in action too.

 :cheers:  Graham.

Offline Jasonb

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Re: Alyn Foundry Nattie
« Reply #27 on: November 25, 2022, 12:21:39 PM »
I think there is a lid on the one the flywheel pattern was based on, arrowed red

Offline RayW

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Re: Alyn Foundry Nattie
« Reply #28 on: November 25, 2022, 02:36:07 PM »
Thanks both of you.OK, you have convinced me. There will be oil boxes on mine!

Thought I would tackle a fairly easy job today and machine the crank webs. At least, I thought it would be easy, but the castings are some of the hardest I have ever tackled. I purchased a set of solid carbide end mills for building Nattie, but I have totally destroyed two of them just trying to mill the edges of the webs. Even turning them in the lathe with carbide inserts, some areas cut OK and others just polished.I will persist to see if I can get a decent finish, otherwise I will make new ones from steel.
Ray

Offline Jasonb

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Re: Alyn Foundry Nattie
« Reply #29 on: November 25, 2022, 02:53:47 PM »
I used steel