5" gauge 0-6-0 Sweet Pea

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GTB
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Re: 5" gauge 0-6-0 Sweet Pea

Post by GTB » Tue May 12, 2020 1:24 pm

Neat. You are getting the hang of model engineering.

The valve chest covers on your loco must be high quality castings. Some grey iron castings I've encountered have have a hard skin that can take the edge off a HSS cutter very quickly when taking a light cut.

A couple of things to think about though for the future.......

That probably was a 4BA counterbore. The pilot of a counterbore is designed to fit the clearance hole for a given fastener, not a threaded one. That's why it seemed to be oversize. That's how it works with metric ones, so I assume BA ones were the same.

Dave is right about not using a milling cutter in a bench drill. It usually leads to disaster, as drill chucks can be loosened by the cutter vibration.

How do I know this? There is a chunk out of my milling vice that constantly reminds me that it wasn't a good idea to use the drill chuck to do a quick milling job, instead of taking the time to replace it with the collet chuck.

Also the quill of a bench drill isn't designed for the side loads generated by a milling cutter. That's the reason the cutter wandered around when you practiced on a piece of steel. I think you dodged a bullet by deciding to turn the cutter by hand.

Regards,
Graeme

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Re: 5" gauge 0-6-0 Sweet Pea

Post by tom_tom_go » Tue May 12, 2020 8:13 pm

Thank you guys, it is a slow process but I somehow get there in the end.
GTB wrote:
Tue May 12, 2020 1:24 pm
Neat. You are getting the hang of model engineering.
I am trying, I hope to one day be able to get into it properly using a lathe and mill.
GTB wrote:
Tue May 12, 2020 1:24 pm
The valve chest covers on your loco must be high quality castings. Some grey iron castings I've encountered have have a hard skin that can take the edge off a HSS cutter very quickly when taking a light cut.
I agree. The covers are interchangeable with both cylinders (I know this because each cover + cylinder is stamped with the numbers one and two for identification and when I received the loco the covers were on opposite cylinders and bolted upside down). Either that or the original builder was very diligent (the chassis has been made with care as the loco can run just under 10 PSI on my rolling road).
GTB wrote:
Tue May 12, 2020 1:24 pm
That probably was a 4BA counterbore. The pilot of a counterbore is designed to fit the clearance hole for a given fastener, not a threaded one. That's why it seemed to be oversize. That's how it works with metric ones, so I assume BA ones were the same.
My engineering friend did mention this, however, I assumed as the seller had confirmed the part was sized incorrectly that it was wrong as I did message them explaining what I was trying to achieve.
GTB wrote:
Tue May 12, 2020 1:24 pm
I think you dodged a bullet by deciding to turn the cutter by hand.
I was very concerned about damaging the covers so this is why I turned it by hand. I only thought to do this as previously I had tapped the holes turning the chuck by hand, experience paid off here!

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Re: 5" gauge 0-6-0 Sweet Pea

Post by benchmark » Sat May 16, 2020 11:12 am

What a lovely documentation of the whole process, once u started i had to read the while thing. i could very much relate to the challenges and appreciate your ingenuity and resolution to solve them.

As regards your injector, onle one out of 2 on mine work, i have cleaned , adjusted and everyother thing in between, i will likely order the same one as you have , it looks much like the same size in mine. Can I burden you with to measure the approximate dimensions please?

Your solution to oiling the steam chests is great, however not easily possible on my own model as the steam chest is completely under metal shroud . Maybe u can work something out.

Coincidentally , 3 days ago i also ordered the same rolling Roads as you have, I will be making a running setup with maybe with the possibility of adding resistance to some of the rolling bearing to simulate load, I noticed my loco loves working against an opposing force.

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Re: 5" gauge 0-6-0 Sweet Pea

Post by tom_tom_go » Wed May 20, 2020 5:05 pm

Thank you for the kind comments.

I will contact you via PM as this thread is about my loco.

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Re: 5" gauge 0-6-0 Sweet Pea

Post by tom_tom_go » Wed May 20, 2020 5:11 pm

Air test of the modified steam chest covers, no leaks on air!


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Re: 5" gauge 0-6-0 Sweet Pea

Post by Jimmyb » Wed May 20, 2020 6:00 pm

Tom, good news, one step at a time :)

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Re: 5" gauge 0-6-0 Sweet Pea

Post by SeamusOD » Fri May 22, 2020 9:38 pm

Tom you need to make some dome nuts for the valve covers :D
https://www.youtube.com/watch?v=OdSOd8zcPEM

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Re: 5" gauge 0-6-0 Sweet Pea

Post by tom_tom_go » Mon Jun 29, 2020 10:00 pm

SeamusOD wrote:
Fri May 22, 2020 9:38 pm
Tom you need to make some dome nuts for the valve covers :D
https://www.youtube.com/watch?v=OdSOd8zcPEM
I don't think I have ever seen domed nuts used on valve covers before. I would of thought that using them would limit how much you can tighten down the cover itself?

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