Author Topic: A Robinson from rejects.  (Read 42686 times)

Offline Zephyrin

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Re: A Robinson from rejects.
« Reply #45 on: October 03, 2017, 10:39:10 AM »
Thanks for documenting the die and the moulding process, lot to learn.
A nice and interesting engine, even if the gears are not visible while running !

Offline Alyn Foundry

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Re: A Robinson from rejects.
« Reply #46 on: October 03, 2017, 11:37:26 AM »
Hi Graham, I've been redrawing up the X Type drawings in Alibre..... There are a few what we term "features" in the drawings  ::)

Just finished drawing up the Ignition tube and Chimney but still not sure how it works  :headscratch:

Jo

Hi Jo.

Hmmm... Alibra.... Nothing to do with Tee and Set squares then?   :) How easy it is these days!

" Features " ? Could you elaborate please?

Hot tube ignition was considered to be the most reliable form during the early years of engine manufacture, particularly with engines that used a gaseous fuel.

Jason has pretty much summed up the MO.

As time progressed and manufacturers began increasing compression pressures to increase power output it soon became apparent that " preignition " was a real issue. Some makers employed mechanically actuated valves to open the ignition tube at the right time. By this time " electric " ignition had become far more reliable and began to replace the heated tube method.

Thought of the day....

" Chauffeur " ?? Goes right back to the early IC engine era.

Cheers Graham.

Offline Alyn Foundry

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Re: A Robinson from rejects.
« Reply #47 on: October 03, 2017, 11:55:52 AM »
Hi Zephyrin.

You're welcome.

After the success of the cast gear for the Robinson engine I started to look at other " gravity cast " items.

I made many Steel moulds for both the big end and main bearings for my Gardner model, the original, later engines used " Babbit " metal, the Zinc looking very authentic indeed! The real beauty is that by factoring the shrinkage the outside of your part will fit without any further machining.

Being such a low melting point metal it's easy to create intricate castings with fantastic detail.

Cheers Graham.

Offline Jo

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Re: A Robinson from rejects.
« Reply #48 on: October 03, 2017, 01:10:15 PM »
" Features " ? Could you elaborate please?

A couple of measurements that when drawn to dimension don't look like your original drawing  ::).... Measurements crossed out and not replaced and the use of 1/6th as an imperial measurement fraction :Lol:

When I have finished putting the bits together I will lay them out in 2D and attach them to the thread, in nice modern measurements  ;D. Yes I know I have invented unique measurements for all those "as cast" dimensions which may be wrong  ;)

Jo
Usus est optimum magister

Offline Jasonb

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Re: A Robinson from rejects.
« Reply #49 on: October 03, 2017, 01:19:42 PM »
Why not wait until you have the castings in your hand then you can take sizes off of the actual part rather than make things up?

Offline Jo

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Re: A Robinson from rejects.
« Reply #50 on: October 03, 2017, 01:24:25 PM »
Why not wait until you have the castings in your hand then you can take sizes off of the actual part rather than make things up?

That would mean waiting until a week before I may have to return to work  :facepalm: :hellno:

Jo
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Offline Jasonb

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Re: A Robinson from rejects.
« Reply #51 on: October 03, 2017, 01:27:03 PM »
You could fill in the time completing the Otto drawings that you were going to do while off sick :LittleDevil:

Offline Jo

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Re: A Robinson from rejects.
« Reply #52 on: October 03, 2017, 01:29:04 PM »
You could fill in the time completing the Otto drawings that you were going to do while off sick :LittleDevil:

There are four more items left to finish those and there is also the Scorpion drawings underway.

Jo
Usus est optimum magister

Offline Alyn Foundry

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Re: A Robinson from rejects.
« Reply #53 on: October 03, 2017, 02:23:58 PM »
Hi Jo.

I'm looking forward to seeing the fruit of your labours.

I'll be going back to the workshop in a few days to continue my build but I'm beginning to think I should have used a couple of plurals in the title of this thread!   ;) I have a feeling that there will be a few more contributors joining us come November.

The Robinson is really quite a simple engine to build, in fact one of my former customers built his with just a Drummond roundbed lathe and a pillar drill!

Cheers Graham.

Offline Jo

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Re: A Robinson from rejects.
« Reply #54 on: October 05, 2017, 05:04:30 PM »
Look what I just found  :naughty:

Now this Sphinx seems to have my name on it  :mischief:

Jo
Usus est optimum magister

Offline Alyn Foundry

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Re: A Robinson from rejects.
« Reply #55 on: October 05, 2017, 05:47:01 PM »
 :lolb:

Look at the highly professional date change and price increase !

My goodness, the year our youngest was born.

I hope you're joking Jo? But I might just have the last laugh.... >:D

Need any help in the garden?? Perhaps a Gardner....  :naughty:

Cheers Graham.

Offline Jo

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Re: A Robinson from rejects.
« Reply #56 on: October 05, 2017, 06:32:17 PM »
I am looking to employ a gardener due to :old:

But I still think there are not enough Sphinx's in the world  ;)

Jo
Usus est optimum magister

Offline Alyn Foundry

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Re: A Robinson from rejects.
« Reply #57 on: October 05, 2017, 08:11:28 PM »
Well....

Here's the very first one, slightly modded over time.


Cheers Graham.


Offline Jasonb

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Re: A Robinson from rejects.
« Reply #58 on: October 05, 2017, 08:31:34 PM »
Graham, is that a burner "ring" at the bottom of the hot tube?

On the valve I assume the exhaust seat is machined into the right hand end and the inlet valve seats on the end of the screw in brass part to the left.

Offline Alyn Foundry

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Re: A Robinson from rejects.
« Reply #59 on: October 05, 2017, 09:13:47 PM »
Hi Jason.

Right on the nose !!   :)

Over the years I learned a few tricks.... The gas ring is quite simple, a hollowed out " doughnut " with a press fitted Brass disc with lots of holes. The trick is the gas/air mix...
Into the side of the burner ring is a passageway that connects to a proprietary made gas burner like Sievert etc. This ensures a perfect mix to burn from the ring !!

The side mounted exhaust valve chest is loosely based on the Robinson, but with twist, I decided to put the air/gas valve into the other end instead of a separate/different location.
This was my second freelance design so simplicity of build was still paramount. As we learned so we grew.

Cheers Graham.