beatsal

In Toronto, Canada

beatsal

There was a suggestion here to make the backplate with 3D printing so not sure why a lathe needed. After all, it is just a plate.

qazimoto

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No it's not a simple plate. It has to reduce the internal volume of the engine to a minimum to maximize crankcase compression.

I don't have a Merlin myself, but I do have a Spitfire and a ME 1cc, which are similar. I'll try and arrange a photo.

qazimoto

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Here is a picture of a disassembled DC Spitfire (1.0cc c/w .75cc), next size up to the Merlin. It could even share the same crankcase as the Merlin. Note the complexity of the backplate.

beatsal

Never imagined - My best bet (as you stated earlier) is to buy a used one if I can get it!

qazimoto

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Online model diesel forums. This is a good one. You might try explaining what you need within a post there: There's also a good one on Facebook.

https://www.rcgroups.com/forums/show...gines/page1353

qazimoto

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This forum on Facebook is a friendly one full of helpful people.

https://www.facebook.com/groups/753859931325401

beatsal

Thanks. Nice link, posted about my crankcase - no reply yet

qazimoto

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Lets be clear, you want a backplate not a crankcase. How about the screws to hold it on? Do you have them?

beatsal

Yes. At present my crankcase is open i.e. can see the conrod.

beatsal

Yes I need the screws too.

beatsal

No reply yet to my post asking for a crankcase cover.

beatsal

After all the effort and some promising replies, no useful outcome. Wonder if at the very least someone could share the drawing of the backplate for the DC Merlin - thanks.

atesus

My Feedback: (1)

I saw that Peter Valicek offered you help on FB. He's a great guy and a master machinist. Maybe you haven't seen it?

beatsal

I saw it and replied soon after - silence!

qazimoto

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From what I saw you asked for a "crankcase cover" and a "crankcase". What you need is called a backplate. You need to be specific. I for one don't have a DC Merlin engine to measure and sketch.

Why don't you post again?

1QwkSport2.5r

And so the pattern continues.... interesting, and frustrating at the same time.

qazimoto

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It's as if it's some sort of a Psychology Student's semester experiment :-)

Dieseltinus

Let me jump ahead and ask what the size of the screws is, you know... before it becomes an issue.

qazimoto

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I'd guess that they'd be 8 BA. About an inch long. They would also need nuts. I'll check availability after breakfast.

beatsal

Thanks. Good you brtought it up as it would pose a problem later.
Not to overburden you but what model airplane kit would suit this engine

qazimoto

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E J Winters, Model Engineering suppliers have 8 BA x 1" Screws and suitable Nuts in stock. Trouble is that you have to buy a life time supply. Au$16, and Au$10 for a minimum of 50 each.

I can't remember how close the 2:56 US equivalent is. Maybe 2mm metric? I'll have to find my little book of thread specs.

The crankcase could be drilled out if necessary.

Ployd

Beatsal, the answer is below in the photo.
Ployd in OZ



APS Tomboy powered by a DC Merlin.

beatsal

Thanks, now I will try to find where I can get an APS Tomboy kit.

qazimoto

My Feedback: (1)

There are lots of sources for an APS Tomboy lazer cut "kit" in Australia. However, postage may be prohibitive. It's easy to just get the plan and cut your own parts with a balsa knife.
The Tomboy plan is available free on all the online repositories.