Author Topic: MUNCASTER OSCILLATING ENGINE  (Read 2423 times)

Offline Robert Hornby

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MUNCASTER OSCILLATING ENGINE
« on: March 30, 2020, 05:56:01 AM »
I am well into a build of a double acting Muncaster engine and up to the point of making the crankshaft. I have made the two webs (in stainless steel) and will be using standard SS rod 3/8" dia. I have bored the webs as a pair giving a firm push fit for the rod. I am thinking of locktighting the rods then cross drilling the webs 1/8" and putting in pins also locktighted. So question  -  Is this a good process or should I be doing something else?



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Offline Robert Hornby

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #1 on: March 30, 2020, 07:08:06 AM »
I forgot to add a third photo with the rods in place and I intend to leave the main shaft as one length and cut the centre bit after pinning.
« Last Edit: March 30, 2020, 07:13:38 AM by Robert Hornby »
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Online Jasonb

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #2 on: March 30, 2020, 08:20:24 AM »
A lot will depend on how good a Loctite joint you get and what you intend to do with the engine. At 10mm dia there is enough room to add pins though I would probably go for less than 1/8", they won't do any harm and if you intend to make the engine work then offer piece of mind. I've done about 10 engines of the same 24mm bore now and most of those have just loctited cranks or crank discs and all have held up OK though I only run them for display.

There have been a couple of these engines built on ME Forum recently though they were to the original Muncaster sizes of 5/8" bore.

ChuckKey

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #3 on: March 30, 2020, 08:51:51 AM »
Interestingly, in Muncaster's book he says that cross-drilling for pins is 'perhaps the worst possible way to make a shaft'. He suggests pins axially, half in the shaft and half in the web. He does not give a reason for his opinion, and in any case he did not have the benefit of Loctite but was using press fits. Full size built-up crankshafts never have cross-drilled pins, but are keyed or pinned as he describes.

Personally, I would want some kind of pin as a belt-and-braces measure. It occurs to me that a sensible and easy compromise might be to drill across the webs, but at a position that puts the pin tangential to the joint, like a bicycle crank cotter, instead of across the diameter.


Offline Thor

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #4 on: March 30, 2020, 10:07:01 AM »
Hi Robert,

 Like Jason I have made several crankshafts using an anaerobic glue and pinning to make the crankshaft. I clean the mating surfaces well first and have had no problems even if some of the engines has a 8mm dia. crankshaft.

Thor

Offline Jim Nic

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #5 on: March 30, 2020, 10:23:16 AM »
Here are a couple of photos of my Muncaster Double Oscillator crankshaft showing the pinning arrangement I use.  The pins go right through the 8mm journal and shaft.  After drilling the hole I don't deburr it and there is less evidence of the pins after I clean up the web.  For pins I use 2mm silver steel, mainly for its dimensional consistency.  The whole thing is stuck together with Loctite 603.
Jim
« Last Edit: March 30, 2020, 10:26:50 AM by Jim Nic »
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Offline Robert Hornby

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #6 on: April 11, 2020, 07:59:27 AM »
Thank you very much for the imput on the crankshaft fixing. I went with loctite and 2mm pins and am pleased with the result, after cutting out the centre bit of the main shaft the assembly staid true.
I have attached a few pictures of the progress.
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Offline Robert Hornby

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #7 on: April 14, 2020, 06:03:34 AM »
The finished model. I made a short video but I think I need to size it down somehow, any help here will be welcome.
Age and treachery will always overcome youth and skill

Online Jasonb

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #8 on: April 14, 2020, 07:23:04 AM »
That looks to have turned out very nicely.

Probably have to upload the video to Youtube or similar and then post a link as file size limits are so small here.

Offline Jim Nic

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #9 on: April 14, 2020, 09:04:12 AM »
A very good looking engine Robert. I look forward to the video.
Jim
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Offline Robert Hornby

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #10 on: April 14, 2020, 10:59:27 PM »
A link to the video, except it isn't. You will have to copy and past into Google, sorry about that https://studio.youtube.com/video/_IEyFH7VNHY/edit
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Offline Robert Hornby

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #11 on: April 18, 2020, 12:47:14 AM »
Trying again with the video of the engine.

<a href="https://www.youtube.com/watch?v=_IEyFH7VNHY" target="_blank">http://www.youtube.com/watch?v=_IEyFH7VNHY</a>
Age and treachery will always overcome youth and skill

Offline zeeprogrammer

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #12 on: April 18, 2020, 12:58:28 AM »
Nice! Very smooth and shiny.  :ThumbsUp:
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Offline Jim Nic

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #13 on: April 18, 2020, 11:29:14 AM »
A lovely runner Robert.
I hadn't noticed before your air inlet arrangement up through the base of the manifold; very neat. I wish I'd thought of that.
All in all an excellent model.
Jim
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Offline Admiral_dk

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #14 on: April 18, 2020, 06:41:20 PM »
Fantastic result - looks great and runs smoothly - what's not to like  :praise2:

Offline Robert Hornby

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Re: MUNCASTER OSCILLATING ENGINE
« Reply #15 on: April 20, 2020, 09:25:53 AM »
A lovely runner Robert.
I hadn't noticed before your air inlet arrangement up through the base of the manifold; very neat. I wish I'd thought of that.
All in all an excellent model.
Jim

Thanks Jim, I thought it would look a bit cleaner with the air line away from the engine.
Age and treachery will always overcome youth and skill

 

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