Author Topic: A Robinson, in the " Making "  (Read 9931 times)

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
A Robinson, in the " Making "
« on: April 16, 2018, 04:30:25 PM »
Hello All.

A few weeks ago my two youngest sons and I attended the Spring opening event at the Anson Engine museum. We had the privilege of playing with one of Geoff's oldest toys! The engine is a Robinson type
" HA " that has recently been fully restored to working condition by Dave Allen, the man on the right in the video. This engine had seen some hard action and the crankshaft was so badly worn that a new one had to be made.

These engines were designed to run on Paraffin/Kerosene and employed a " permanent lamp " to keep both the ignition tube and vapouriser hot. They were listed as HA being up to 10 HP then the HB up to 20 HP, in different bore and stroke ratios.

At present this engine is a " sole survivor " and my sons suggested that a model should be made. A few cursory measurements were made, the flywheel in particular. It was a massive 27" in diameter, half scale, out of the question. But.... at 1/3 rd scale things started to gel, my " X " type flywheel is nearly 9" in diameter and is equally as chunky. Hmmm, a Robinson, in the " Making "

<a href="https://www.youtube.com/watch?v=nlpRdfHx1Vk" target="_blank">http://www.youtube.com/watch?v=nlpRdfHx1Vk</a>

Over the next few weeks I'll take you on a journey of how an engine is scaled, patterned, cast and machined and hopefully a finished working model.

Cheers Graham.


Online Jasonb

  • Full Member
  • *****
  • Posts: 9467
  • Surrey, UK
Re: A Robinson, in the " Making "
« Reply #1 on: April 16, 2018, 05:10:07 PM »
Looking forward to following this.

J

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6811
  • West Chester, PA, USA
Re: A Robinson, in the " Making "
« Reply #2 on: April 16, 2018, 06:19:57 PM »
That'll be an interesting journey.  :popcorn:

On the left side of the engine there is a cylinder looking thing hanging down. Is that just a weight?
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
Re: A Robinson, in the " Making "
« Reply #3 on: April 16, 2018, 06:43:04 PM »
Thanks Jason.   :ThumbsUp:

The Flywheel.

I've got a " thing " about flywheels. Always have....

Back before the days of printing things the flywheel pattern was quite a laborious process. My technique was to use good quality marine ply, 13 to the inch stuff.

I'd cut a disc or a square and proceed to machine the outer and inner rim profile to the correct size, not forgetting " shrinkage allowance " and depending on the job double shrinkage to allow for the wooden master to become an Aluminium master. By using plywood I could machine down to leave a single ply where I would be able to lay out the spokes. Before removing the blank I'd put a hole in the centre to take the hub spigot. Invariably my spokes would start out as cut lengths of " quadrant beading " the taper was arranged by using dress making pins at the small end and cocktail sticks at the hub end. Once the glue had set good old car body filler was used to fill and blend the gaps and create the curves.

The attached picture shows both a Robinson hot air and an R.L.E. " primary master " half. These patterns would then be moulded in sand, poured and cast twice. They were then " paired " together to fine finish and become the foundry " master pattern ".

The second picture is of the Robinson " X " type flywheel foundry master.

Cheers Graham.

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
Re: A Robinson, in the " Making "
« Reply #4 on: April 16, 2018, 06:47:30 PM »
That'll be an interesting journey.  :popcorn:

On the left side of the engine there is a cylinder looking thing hanging down. Is that just a weight?

Hi Zee.

Thanks for looking in, yes, it is in fact a " pendulum " governor. They are a rare sight and only work well if the engine is firmly anchored.

Cheers Graham.

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
Re: A Robinson, in the " Making "
« Reply #5 on: April 16, 2018, 07:17:22 PM »
WARNING

This engine will not be a true scale replica.... but a close facsimile, we can't have the full size one to play with!

Now a little more history.  The businesses of AE & H Robinson and L Gardner and sons were virtually at the opposite ends of the same street. Robinson were making engines before Gardner, in fact at that time Gardner's were general machinists, they made the parts like cranks and conrods for Robinson. Is it little wonder that Gardner's first engine a size 1 should look almost identical to a Robinson HA? Well, take a look at our modified Gardner size " 0 " base.   ;)

Cheers Graham.

Offline RayW

  • Full Member
  • ****
  • Posts: 735
Re: A Robinson, in the " Making "
« Reply #6 on: April 16, 2018, 07:20:14 PM »
Hi Graham,

I look forward to following this project with interest. Could there perhaps be a future kit in the making?

Regards

Ray
Ray

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
Re: A Robinson, in the " Making "
« Reply #7 on: April 17, 2018, 01:28:52 PM »
Hi Ray.

Let's wait and see.... ;)

Patterns, solid versus split.

There's probably a few readers wondering why we seem to make more work than necessary with regards to patterns.

A lot of parts that we need to make will need to use both halves of the moulding boxes. If we had a solid pattern the moulder would literally have to bury the item, turn the box over and then dig down to the centre. This is both messy and time consuming and the end results can be inconsistent.

With a split pattern the moulder simply lays down the first half on the board covers it with " virgin " facing sand then backs out the box with tempered older used sand. The box is turned over, top box placed and filled in the same fashion. For things like a flywheel the spokes will have excellent definition because the moulder didn't have to dig down, firm and part.

I'm hoping the above explains why we spend the extra time in making patterns in two halves rather than a more simple solid one?

Cheers Graham.

Online crueby

  • Full Member
  • *****
  • Posts: 18560
  • Rochester NY
Re: A Robinson, in the " Making "
« Reply #8 on: April 17, 2018, 06:37:34 PM »
Graham, great descriptions on how it all works, following along with interest!

 :popcorn: :popcorn: :popcorn:

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
Re: A Robinson, in the " Making "
« Reply #9 on: April 17, 2018, 08:00:06 PM »
Thank you crueby.

Cores, prints and boxes.

Almost all readers will know that to make a casting hollow a sand core is placed within the mould for the molten metal to run around. Once cooled the core is broken away leaving the cavity.

The attached picture shows the piston pattern and core box for my failed attempt at the quarter scale Hornsby Akroyd. Please note that the longer small diameter is the " print " and the larger diameter forms the piston casting proper. If you look carefully you can see the Hornsby part numbers faithfully reproduced using pattern makers letters. Also the bosses that create the bosses for the gudgeon pin.

There's many a material to make cores with these days Silicates, Resins etc. All that's required is a solid mass that'll stand up to the strain of the molten metal as it races around.

In the past I've actually used ordinary flour, water and Silica sand to make simple cores for Aluminium work.

Sometimes a pattern can be made to make its own core, in the same picture above the Aluminium is a Nylon pattern. This was used to make two halves of a hollow piston for my, now shelved Brayton ready motor. These type of patterns are called " self codding " but can only be used on shallow draughts because if pushed too far the bond can break.

I'm a little under the weather at the moment, slight chest infection but I've managed to find some nicely seasoned Ash ready to make our cylinder pattern from.

More to come, cheers Graham.

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
Re: A Robinson, in the " Making "
« Reply #10 on: April 17, 2018, 08:10:47 PM »
I've just remembered this video I did for Ray.

<a href="https://www.youtube.com/watch?v=L5wxf5x_oBs" target="_blank">http://www.youtube.com/watch?v=L5wxf5x_oBs</a>

It's been doing rather well in India and Pakistan....   :)

Cheers Graham.

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 1653
  • North Wales, Great Britain.
Re: A Robinson, in the " Making "
« Reply #11 on: April 27, 2018, 07:03:19 PM »
Not quite " Robinson " !!

It's amazing what can be done with time, patience and a few bits of seasoned Ash, glue and body filler!

Attached is a picture of the remake of two missing patterns for my Isaac F Allman engine.

Just some final detail finishing and a coat of Red Oxide primer before a trip to the foundry.

Cheers Graham.

Online Jasonb

  • Full Member
  • *****
  • Posts: 9467
  • Surrey, UK
Re: A Robinson, in the " Making "
« Reply #12 on: April 27, 2018, 07:16:57 PM »
They look good Graham and should save me some time if I'd had to carve from solid.

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15295
  • Hampshire, england.
Re: A Robinson, in the " Making "
« Reply #13 on: April 28, 2018, 07:03:05 AM »
They look good Graham and should save me some time if I'd had to carve from solid.

That's one of the main reasons we use castings  ::)

They also let you cast in cores that would be very difficult to machine unless you made the item by assembly and then you are forced to paint the item (or wait for the dirty black line when the silver solder tarnishes in years to come  :facepalm2: )

And sometimes it is cheaper to use castings than start from an expensive piece of barstock   ;)

Jo
Enjoyment is more important than achievement.

Online Jasonb

  • Full Member
  • *****
  • Posts: 9467
  • Surrey, UK
Re: A Robinson, in the " Making "
« Reply #14 on: April 28, 2018, 07:40:12 AM »
But using castings does take some of the enjoyment and satisfaction away from the process*, hardly exciting just facing off and drilling/boring a couple of holes in a piece like that. It also saves the issue of finding flaws in the casting and having to spend time making the outside look right where the two halves of the mould have shifted.

Tarnished solder joints tend to be more of an issue on fabricated brightwork when parts have been joined rather than cutting from a larger piece which would not normally have been supplied as a casting anyway. I do tend to paint the majority of "castings" anyway so that is not an issue for me, might be for those that don't get round to finishing and painting their engines.

Cost only really comes into it on larger parts. I've made six engines in that 24mm bore series now all about the size of a Stuart No 7 or No 8 and I would say they have cost me a 1/3 to a 1/4 of what one of those Stuarts would cost and that includes the barstock and fixings as well as materials to make the "castings" Even those large otto castings worked out about the same as using CI bar and 2 out of 3 columns were faulty.

J

*Unless you make your own patterns and maybe even do you own casting.
« Last Edit: April 28, 2018, 08:01:24 AM by Jasonb »

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal