ETW's Wyvern Gas Engine

[Jo]

Nice fix 

And I too like the GHT Universal pilar tool 

Jo

[vcutajar]

A really good save Rod.

Vince

[NickG]

Nicely done. Agree with Jo, that pillar tool looks the part.

[tangler]

Thanks guys.  The pillar tool is great.  I've not broken a tap since I made it.

Rod

[Don1966]

Nice save Rod and thanks for the experiments I learns a few things following you. I really need to get back to my pillar tool thread. Love to see it being used. You did a nice job on it.

Don

[tangler]

Now, where was I?  Oh yes, The cylinder head stud holes need facing and drilling so I spot faced in the mill




and then drilled through for 4BA tapping size on the pillar drill.  I decided it was best to drill the holes where they looked like they best fitted the castings.




I then used the cylinder head as a jig for drilling one hole in the cylinder jacket, the head is located by the cylinder liner which projects beyond the jacket - hence the parallels




 tapped this on the pillar tool, opened out the hole in the head to 4BA clearance, inserted a temporary screw and repeated the procedure for each hole in turn




A set of studs were then made and inserted




The head slid onto the studs very nicely with no shake and without having to ease the holes- testament I think to the pillar tool ensuring that the tapped holes were perpendicular.  The stud holes in the jacket seem to be in the right place



but the same can't really be said for the head.  No harm done, just not quite as neat as I would like



The job that I've been putting off is making the inlet and exhaust passages in the valve assemblies.  These were bolted in position and the cylinder head set up on the dividing head in the mill.  I don't have a 5/16" slot drill long enough to do this so had to use an end mill, which meant that I needed to put a smaller slot drill through first to do the centre cutting.  The tailstock is just providing a bit of steadying pressure.



It all seemed to work OK. 



Phew!

[Jo]

Nice to see some progress on this engine. (and more use of the UPT  )

That is a bummer with the stud breaking through on the outside on the under side of the head, it wasn't too hot on the top  ... Are you thinking of building it up with some JB weld or something?

Jo

[tangler]

Quite a bit of fettling will be required to make the head blend in with the the jacket.  I've got a spare head casting now.  The current plan is to see if I can get it the engine to run using the bodged head, as a test of the inserts, and then make a new head (properly this time).

cheers,

Rod

[tangler]

This is the  casting stick for the 2 rockers



The finished bosses protrude 1/8" on one side and 1/16" on the other.  A little bit of filing ensured that the arms sat level and firm on the 2 central bosses and the valve end.   I took the bosses down to 1/8", turned it over and milled the other side down to the total required thickness which was 5/16"



This demonstrates how the casting can make you look like an idiot.  The hole in the small boss (which will be tapped 4BA) clearly has to go in the middle of its boss and the pivot hole needs to be 1 1/8" from this, which of course isn't in the centre of that boss.



 I drilled the holes at the correct spacing and split the casting with a junior hacksaw
 


For aesthetic reasons the plan to leave the arms as cast had to go out of the window, so I turned up a stub mandrel to fit and machined the fulcrum bosses on both sides



This end of the rocker has a blind hole for a push rod and is supposed to be 1/4" diameter cylinder



There was just room to fasten a 1/4" filing button with an 8BA screw, the blind screw hole will be opened out later


3 hours filing later (which I rather enjoyed) and we have 2 reasonable rocker arms

[steamer]

Hey Rod,

Who's dividing head is that?...

Dave

[pgp001]

Its Rod's dividing head 

But seriously it looks like the Alan Timmins design to me.

Phil

[tangler]

Dave,

It's the Timmins design, originally published in Engineering in Miniature, the castings are available here http://www.blackgates.co.uk/.  It is available with either a 40:1 or 60:1 wheel.

I modified the design to use the plates and fingers from my GHT HDA.  I preferred the design to the VDH because it has a proper spindle with a Myford nose with 2MT socket and because in one orientation it sits at centre height on my Super 7 cross slide but rotate it through 90 degrees and it sits high enough on the milling machine to mount a decent sized chuck  (actually, the real reason I made it was because the casting came with the bits and bobs with my lathe) but it has always seemed to me to be a better design than the VDH for the Myford owner.

Aww Phil, I was going to use that joke

cheers,

Rod

[steamer]

Thanks Guys!....

I'd like a dividing head with a SB9 spindle nose and internal taper...for similar reasons...but will also be capable of mounting in my mill vise.

Dave

[Jo]

  I enjoyed it.

It looks like you have a pretty impressive workshop there Rod. I might just have to drop in one of these days if I find my way coming back from Reading to find out if you have any other desirables hiding away

Jo

[tangler]

Jo,

You're always welcome to pop in and see my desirables - although you might be disappointed by the size.

cheers,

Rod