Gerry's Beam Engine - Metric

[arnoldb]

Your engine runs a treat ;D - and thanks for the plans Ken Thm:

I would like to ask if you don't mind, where did you get those M2, M2.5 Hex Hd screws/bolts from?

Me too! ;D - I'm getting a little tired of making them!

And Welcome to HMEM Dave - we won't mention cricket; it seems to be a Northern Hemisphere thing at the moment... Beers out in SA and AUS to drown sorrows...

Kind regards, Arnold

 

[Ken I]

Dave H, those little M2 & M2.5 hex bolts were made from off the shelf stainless cheseheads - I silver soldered the slot closed - faced them off and ground the hex on my bench grinder - refer to earlier in the thread.

Regards,
Ken

 

[DaveH]

Ken I, Well they do look good.
Dave

 

[Ken I]

At the request of Smgraph an explaination of the valvegear.

The valve (sometimes called a "D" valve because it looks like a "D" in cross section) is moved up and down within the steamchest on the valve pin. To this end it should be a good fit between the valve and the pin in the direction of motion (we don't want a lot of lash) but a loose fit between the pin and the valve face on the cylinder.

Here it can float - it doesn't matter as the pressure within the steamchest keeps it firmly against the valve face of the cylinder.

Conversely you don't want any interference here or it will bind.

In the mid position all ports are covered, in the up position pressure can pass from the steamchest into the lower half of the cylinder and the exhaust from the opposite end via the underside cavity in the valve to the exhaust.

Obviously the stroke is fixed by the eccentric cam via the bellcrank etc. but it must be adjusted so that the full motion is equally spaced about the central (exhaust) port.

The valve is at the mid position when the piston is at the top or the bottom and at the fully open positions when the piston is midstroke - so the valvegear cycles about 90° out of synch with the piston.

I have attached a *.jpg and a *.dwg showing this in cross section - hope this helps.

Regards,
Keb

View attachment Dump.dwg

 

[smgraph]

Thanks Ken, That really helps. Steve

 

[Ken I]

This will be my last post on this engine and I have listed it under Finished Projects.

I have added a slip reversing gear which is in the updated plans and can be retrofitted to this (and most likely any similar engine).
I have posted the 2D ACAD drawing & *.dxf files in the uploads section.
The drawing has the various parts in different layers / colours - so by switching the layers on and off you can see where it goes relative to the rest.
There are detailed drawings of all the parts.

There are also a number of "doodles" wrt to manufacturing the chassis and the beam without a rotary table.

Here's the link :-
http://www.homemodelenginemachinist.com/index.php?action=tpmod;dl=item364]
I made a base for it, fitted the gland packings (thanks Tel) and added the slip reversing gear - cleaned it up and here it is.

Here the 180° slip reversing mechanism - you just rotate the flywheel in the direction you want it to rotate - this offsets the timing 180° and away you go.

Here's a video of it running :-

[ame=http://www.youtube.com/watch?v=3Dp5DApIwCk]http://www.youtube.com/watch?v=3Dp5DApIwCk[/ame]
While demonstrating the slip reverse, I hold the eccentric to stop it from rotating - this in order to speed things up rather than stopping, rotating the flywheel a couple of revs just to set it up etc. etc.

And finally a big thank you to Gerry Dykstra for posting the original plans for free use in the public domain - Gerry you got me started in this hobby and for that I shall always remain grateful.

Ken

 

[arnoldb]

Good going Ken :bow: ;D

I really like the addition of the slip eccentric Thm:

Kind regards, Arnold

 

[lazylathe]

Nice one Ken!!!! ;D
Looks like a great runner!

Love the idea of the slip clutch.
Will have to study the drawings to figure out how it works!

Andrew

 

[Gerry Sweetland]

:bow:
That is really cool, I love the sound it makes at slow rpm.
I can only hope that some day I can build at this level.
Another guy named Gerry

 

[Alec Ryals]

Hello, Beautiful Work, Just curious how you reverse the unit?
Thanks
Alec

 

[Ken I]

If you look at the photo above you can see the valve timing eccentric has a 180° annulus groove - driven via a pin in a hub attached to the crankshaft with a grub screw (other that the pin the eccentric can be rotated ±180°)
By holding the timing eccentric still and rotating the crank 180° in the direction you want it to run shifts the valve timing 180° and the motor then runs the other way.
The annulus must be correctly positioned (relative to the eccentric - refer to drawings) so that the pin drags it at the right position in the right direction. (imagine if the annulus was 180° out then the pin would rotate to the "wrong" end and end up stopping halfway - it just would not work.)

Regards,