Ridley's Half Beam

[tel]

OK - by popular demand ....

For some reason I'm never completely comfortable doing slide valves. Dunno why, perhaps it harks back to the days when I had to do 'em on a vertical slide in the lathe, because they are easy enough to do.

First, a look at the valve in question - my dimensions vary slightly from what is shown



The usual starting point is getting a piece of material, in this case a bit of 1/2" square brass, bung it in the vise and square one end.



With the end squared, the piece is already indicated for us - just raise the tool, crank along length + end mill diameter( in this case 1/2" + 3/8") and plough a groove thru the stock - this defines the length



Then I switched to a 3mm slot drill, and took the groove somewhat deeper. Now we have to indicate the end again, with the head of the RF30 set low enough for end mill cutting, it is a bit of a fiddle to fit in the wiggler, so back to basics - the good ol' moistened Tally Ho

 

[tel]

Now we crank along tool diameter + web thickness and set the l/h stop. Then shove in a bit of packing equal to the required travel and set the l/h stop. The fore and aft positions are a bit trickier - I worked to scribed lines.



... and milled out the cavity to the required depth (2mm)

 

[tel]

Now the height of the piece has to be reduced to 3/8" - again, I scribed a line, then put it back in the vise in the inverted position



Indicated the end again, and picked up the cut-off groove position. This time, take the groove somewhat deeper than the sribed line



Then mill away the excess material. Now locate the position of the spindle groove, and cut that to depth

 

[tel]

Now we indicate the front edge, and get the slot drill over the centre of the workpiece, and cut the slot for the nut



... and we should have something that looks like this

 

[tel]

Cut it off the stock, tidy it up a bit, and we have a valve!

 

[zeeprogrammer]

This is great stuff. I have to make a similar valve for the horizontal mill. The manual shows a different way to do it so I'm real happy to see this.

And a bonus juicy tip in there for us newbies...Tally Ho.

Tally Ho is cigarette paper.
Moisten it so it sticks to the metal.
Now tool can turn (without fingers in way) and you can move it until paper whips out.

I've seen the posts on measuring and using cigarette paper. I don't recall anyone mentioning 'moisture'. This little newbie isn't the sharpest (and therefore willing to point out what may be obvious to others) but I do know there's more of me out there. That's right...many more of me. :big:

Thanks tel.

 

[tel]

Yeah Zee - dry Tally Ho's don't stick real well to anything.

 

[vlmarshall]

Oh! Lick the PAPER and stick it to the METAL! Oops. ;D

 

[tel]

Gaskets drawn, printed and ready to cut out

 

[Maryak]

Yeah Zee - dry Tally Ho's don't stick real well to anything.

Except your lips; from which they remove half of the skin, if you forget to wet the end before your first drag

Ask me how I know. :

Best Regards
Bob

 

[tel]

Oooooh yes! We've all done that at some time or other. 'urts, don't it.

 

[zeeprogrammer]

My big problem was when I tried to take the cig out. Cig stuck to lips, fingers moved down. Fingers always ended up at the hot spot no matter the length of the cig. I don't smoke anymore.

 

[arnoldb]

Coming along well, Tel

What material are you using for the gaskets? - ordinary paper?

Oooooh yes! We've all done that at some time or other. 'urts, don't it.

Yep!
Regards, Arnold

 

[tel]

Yes Arnold, I always just use 90 gsm printer paper and oil 'em after they've been cut out

 

[Maryak]

Plain Brown Envelope or if you have them lying around, old marine charts make excellent gasket material, as tel says oil before use.

Best Regards
Bob

 

[arnoldb]

Thanks Tel & Bob

Kind Regards, Arnold

 

[tel]

SHE'S ALIVE!!!!

Ok, the flash has frozen the motion, but in the pic she's spinnin' over at about 300 rpm. Way too fast, I know, gonna need some tweaking.

 

[1Kenny]

That is a really nice looking engine, Tel.

Kenny

 

[tel]

Now we've got a bit of motion showing, and I've got it down to a more sedate 50 rpm