Author Topic: Roy's Little Engine  (Read 25698 times)

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11779
  • Hampshire, england.
Re: Roy's Little Engine
« Reply #15 on: November 29, 2017, 08:41:50 PM »
Having had Graham confirm I am allowed to post the drawings for this engine  :)

Here they are  :cartwheel:.

Jo
Usus est optimum magister

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 733
  • North Wales, Great Britain.
Re: Roy's Little Engine
« Reply #16 on: November 29, 2017, 08:56:12 PM »
It will run on petrol or liquid camping fuel such as Colmans as is or could have a modified carb so it can run on propane and probably the camping mixes as well.

And there was me thinking the name stood for Rusty little engine ;)

Graham, out of interest did you sell many of the air cooled versions as you don't see many of them about mostly all the hopper cooled variety.

J

Hi Jason.

Originally launched as an air cooled engine, nobody was tempted to buy castings. A good friend suggested the water hopper and " bingo " 300 plus kits were sold.

There might be 4 " out there " all together.

Here's one I built for a customer that recently sold through Cheffins.

Cheers Graham.

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11779
  • Hampshire, england.
Re: Roy's Little Engine
« Reply #17 on: December 04, 2017, 09:02:22 AM »
Sorry about the lack of posting yesterday I have internet access issues  :zap: Which may last for most of the week  :censored: In the mean time you will have to use your imagination and I will attach the photos later, if I remember  :old:

As Mr Silky spent Saturday doing the piston rings for the 5A and Swan he was already covered in Cast Iron dust so it seemed a good time to do the piston and rings for the little RLE. Graham when he designed this pattern clearly thought about it and made the skirt of the piston extra long so you can use it to make the rings.

To start with I had to machine the piston on the solid end of the casting. There is no dimensions on the ring grooves and they seem to be very close to the top of the piston  :headscratch: so I decided to machine the grooves 3.2mm down from the top and another 2.4mm down to the second ring slot. (As I was later to find out this would have made the internal bore to the piston a little close to the latter ring gap but I over came this by leaving the internal bore slightly undersize. )

Piston with rings turned this could then be used to hold the casting while I turned and cut the rings from the piston skirt. As you can see I managed to get 7 rings of the skirt. I still had another 2mm of spare piston skirt to machine off before the piston was to length. Leaving the boring for the internal gudgeon pin carrier and to tap it the required 3/8 whit.

I am pleased to report that the piston is a nice sliding fit in the bore. It probably does not need rings  :) All 7 of the rings are tucked in the end of the bore so that I can loose them  to stop me loosing them  ::)

Further updates when my internet access allows it  :rant:

Jo
« Last Edit: December 08, 2017, 04:59:06 PM by Jo »
Usus est optimum magister

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11779
  • Hampshire, england.
Re: Roy's Little Engine
« Reply #18 on: December 08, 2017, 05:03:08 PM »
The inner piston is screwed into the outer piston and provides the mounts for the gudgeon pin. It is threaded into the inside of the outer piston  ;)

I have tracked down the internet access problem   :killcomputer: windows  :rant: And it will continue to cause problems again :stickpoke: shortly  :rant: as it continues to fail to load the latest update (1709) :toilet_claw:  :ShakeHead:  :censored:  :censored:

Jo
Usus est optimum magister

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12421
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Roy's Little Engine
« Reply #19 on: December 08, 2017, 10:42:49 PM »
Sorry about the internet issues Jo. Kind of a catch 22...you need to update windows but can't do that without internet  :killcomputer:

Bill

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3541
  • Switzerland
Re: Roy's Little Engine
« Reply #20 on: December 09, 2017, 07:16:18 AM »
Another two piece piston  :headscratch:  I saw one on Deltatango's Mastiff build. Do they offer a significant advantage in weight saving or ease of construction?
Best regards

Roger

Online Jasonb

  • Full Member
  • *****
  • Posts: 6034
  • Surrey, UK
Re: Roy's Little Engine
« Reply #21 on: December 09, 2017, 07:40:20 AM »
I can't see them being any lighter than what you could machine with the same amount of effort, it's not hard to make a dog bone shaped slot and even under cut that to reduce weight.  I suppose it would allow you to play with compression ratio by making different inner parts without the need to make a whole piston but that would be more use to a one off design than a model that has been proven to run. Maybe Graham likes them as his CHUK range of engines have a similar arrangement

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11779
  • Hampshire, england.
Re: Roy's Little Engine
« Reply #22 on: December 09, 2017, 08:24:10 AM »
Another two piece piston  :headscratch:  I saw one on Deltatango's Mastiff build. Do they offer a significant advantage in weight saving or ease of construction?

I asked this of Eric and he told me it was one of those design features people played with back in the 70's/80's, which allowed the inside of the piston to be closer to the correct profile but they are not light :ShakeHead: and I could have under cut under the gudgeon pin boss easy enough on the lathe.  In both the Mastiff and this one the pistons are ring carriers so they do not need to be a honed finish for running in the bore, although I would expect the fit of my piston to enable the engine to run without rings. Personally I will be making Ali pistons for my Mastiff.

Maybe Graham can say why he designed the piston this way on this engine.

Jo
Usus est optimum magister

Online Jasonb

  • Full Member
  • *****
  • Posts: 6034
  • Surrey, UK
Re: Roy's Little Engine
« Reply #23 on: December 09, 2017, 09:41:42 AM »

Maybe Graham can say why he designed the piston this way on this engine.


Easier pattern making maybe or the ability to make without a casting?

I suppose that what Eric said would have made machining easier when most hobbiests would have done their milling on a vertical slide so the two piece would be far easier than it is now.

Offline Ian S C

  • Full Member
  • ****
  • Posts: 1004
  • Stirling Engine Maker Darfield Canterbury N Z
Re: Roy's Little Engine
« Reply #24 on: December 09, 2017, 09:58:20 AM »
I didn't know that it had been a fashion of 40 years ago, it's the method I devised for constructing pistons for my hot air motors, I use much less metal in the inner yoke, and the piston usually has a skirt about .070" thick, and a crown about .150", light weight but no where to put a piston pin without the yoke screwed into the crown.
Ian S C
         

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 733
  • North Wales, Great Britain.
Re: Roy's Little Engine
« Reply #25 on: December 09, 2017, 11:35:24 AM »
Good morning.

That design feature goes way back, well beyond the 70’s back to the turn of the 19 th century. Many engine manufacturers chose this method of construction. And as Jason wrote, I do like it!

There are pros and cons, more weight but your gudgeon pin will never score your bore. As the R.L.E. was a freelance design the piston “ yoke “ allowed the constructor to “ play “ with the compression ratio a little.

You’re making nice progress Jo, eagerly waiting for the next stage.

Cheers Graham.

Online Jasonb

  • Full Member
  • *****
  • Posts: 6034
  • Surrey, UK
Re: Roy's Little Engine
« Reply #26 on: December 09, 2017, 01:14:39 PM »
Graham, have your sons made any progress with their ones? or do they work as fast as you do on the x-type ;)

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 733
  • North Wales, Great Britain.
Re: Roy's Little Engine
« Reply #27 on: December 09, 2017, 02:13:18 PM »
Jason, you cheeky monkey! :)

We have all been busy with things of a non model engineering nature recently, number 3 son is about a third of the way through with piston, cylinder head, cylinder, hopper, mainframe and base all machined. Number 2 son about a quarter. Mathew has posted some pictures on the Chester Machine tools forum also.

With the nasty weather now upon us I don't think there'll be much going on in the workshop for a little while. That's why I'm watching you folks....  ;)

Cheers Graham.

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11779
  • Hampshire, england.
Re: Roy's Little Engine
« Reply #28 on: December 09, 2017, 04:01:09 PM »
Well a little more has happened since I posted last. I started the flywheels and they must have moved as I reamed the holes in the centre and they came out tapered  :toilet_claw: They have been filled and re-reamed. They are over diameter but a bit thinner  :-\

I did learn that while trying to set up the flywheel for the repair that post-its are 0.1mm thick and grease proof paper is 0.05mm  :naughty:

Jo
Usus est optimum magister

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 733
  • North Wales, Great Britain.
Re: Roy's Little Engine
« Reply #29 on: December 09, 2017, 04:41:05 PM »
Hi Jo.

When you say tapered, what was ? The bore?

For thin shim I favour Steel drink cans as there's little to no " squish " as you apply pressure.

Cheers Graham.