Roy's Little Engine

[Alyn Foundry]

Hi Jason.

Yes, that's correct.

The wooden " primary " masters would be made with " double " shrinkage factored in, if making a true scale model like the Robinson or Gardner engine.

The R.L.E. however was my own design so this double shrinkage allowance wasn't nessessary. The cylindrical castings are for the piston with extra skirt for making the piston rings. The smaller diameter is called a " core print " made long so as to not require special fixing of the sand core.

Cheers Graham.

[Jo]

  Having found what I thought should be the centre of the hole on the cylinder casting I proceeded to drill through it using a long series drill. Before taking it out to size I gave the line up another check. Then drilled out to 4.76mm diameter and checked it lined up with the centre of the crank and the centre of the cam 


The bolt for the cam also acts as the governor arm pivot so that needed slotting and the pivot hole drilled. I was going to do the governor arm but that needs a bit more thinking about  So opted for the rocker arm   


The rocker started off as a piece of 16mm by 10ish which had a pivot point put in about the right place and the two sides taken down to leave 4.76mm in the middle where it goes through the rocker pivot arm. Then the two ends were cut down before a bit of initial shaping. Before going any further I decided it would be necessary to finish machining the rocker arm bracket first and it was getting late 

Jo

[Alyn Foundry]

You're getting there Jo.

The top photo made me smile....

It looks to me like my old company name has been used on a " new " range of cordless drills!   

Cheers Graham.

[Jo]

Thanks Graham 


Today was more rocker arm profiling. This included adding a bush in the arm so that it is running on the pivot pin rather than steel on steel. I added an adjuster for the end of the push rod but started getting concerned about the geometry  As the rod comes forward there is a tendency to push the rod from side to side as the ball end pushes inward  To over come this I have increased the diameter of the socket in the adjuster but maybe a completely different type of rod end would be better.

Moving down the engine I needed to know how long the push rod needed to be and that required that the cam was finished off. So mounting on a mandrel, with a washer on the top of the correct diameter for the root of the cam, the cam was machined to the artistic shape shown on the drawing 


I can now look to decide what to do at the end of the rod: It needs a big flat on the side of the push plate to work against the side of the gear to keep everything square on the round push rod and a trippy bit a little way along.  I probably should think about the governor arm while I am at it 

Jo

[Gas_mantle]

Looking good 

[Alyn Foundry]

Looking good 

Indeed....

Jo will have to consult the workshop manual for the " cold " exhaust valve tappet clearance!   

The inlet clearance is MASSIVE!

Cheers Graham.

[Jo]

Thank you Peter/Graham 

I am still thinking about the arrangement for the other end of the push rod and  I still have not worked out how the ignition points are going to be arranged. Ever since my op last year I have been struggling to think straight  I have even tried giving up   

Jo

[Alyn Foundry]

Good grief Jo!!

Not the  ....

A nice glass of Red has ended my day, every day since my heart do, good for you, you know!   

Well, as they say " up North " there's nowt wrong with simple, KISS.... The Brass half moon has lasted well over 30 years on my engine.

Being " old school " I favour simple points/condenser coil arrangements again KISS....

Ultimately though, it's your engine, do it your way.

Cheers Graham.

[Jasonb]

You could do away with the bracket that is fixed to the head and have a forked end to the rod, hole and pin in the rocker. with no bracket at the head end the small amount of sideways movement won't cause problems as the support near the timing gear is too far away. Or do you mean the cam follower end?

Have a look at the other RLE thread for position of hall sensor or contact points on the opposite side of the engine to the gears.

[Jo]

Jason: The motion of the rocker means the socket in the rod goes from side to side as the rocker is pushed.

I rather got lost trying to find anything in the other thread there are too many pictures of non RLE stuff in there 


For the other end of the push rod I decided to go for something like Graham's original drawing but simplified it to use a single bit of brass with a bit of gauge plate screwed on the side of the brass. Hardening gauge plate is easy but dropping a red hot bit of plate into a bucket of water that has been outside for a few days when it has been bitterly cold then trying to put your hand in the water to find it again is not to be advised 

Shaping up the brass was done by hand with the push rod hole drilled centrally using a square 5C collet by sticking the bit of brass in from the rear of the collet  The hole has been tapped 6BA for the screw.

The resulting follower can now be pushed on the end of the rod and can be later tapped to take the 6BA rod once the required rod length is better understood 

Jo

[Alyn Foundry]

Hi Jo.

What a novel approach, I like it!!   

Nice glass of  and some sleep works wonders.

Cheers Graham.

[Roger B]

Simple is usually best  Still following with interest     

[Jasonb]

Jason: The motion of the rocker means the socket in the rod goes from side to side as the rocker is pushed.
Jo

Yes I know that and it is why I said you could do away with the bracket at the head end as the small amount of sideways movement will be minimal where the rod passes through the hole in the cylinder flange so unlikely to make things go tight. Like this which runs OK



The other simple option is to have a slot in the end of the rocker for the clevis pin to fit into that way you can keep the bracket if you want to.Like this off the galloway



Or stick with the rounded rod end and socket on the rocker and just do away with the bracket. Just like the Gade which runs very well



Ignition contacts were actually in this thread, have a look from No 65 onwards. You can use a hall sensor as per that discussion or have an insulated contact on the moving part that had the hall sensor and a small metal contact on the moving part if you don't want to use a hall sensor. Your starting box will work with either arrangement.

[Jo]

Thank you Graham and Roger 


JB: The offset on the rod caused by the rocker movement varies from 0.15mm if the pivot is alongside the rocker pivot to 1.6mm where I have it 6.35mm back from the centre line. So to keep the RLE looking like Grahams son's original engine and to maximise the use of Grahams excellent castings  The simple answer surely is to is to make the hole in the arm into a slot 6.35mm by 4.76mm or slightly longer to allow for adjustment of the tappet gap and how the variation in position alters the sideways movement of the arm

Ignition contacts were actually in this thread, have a look from No 65 onwards.

That would account for me not being able to find them  I am still thinking about the ignition arrangements, I would like something more period But that is for later.

Jo

[michaelr]

Picture of the rocker and push rod on my RLE.   Mike