"A Beginners Engine" From Model Engineer.

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sbwhart:

Oh - and where do I get a Wobbler Bar (used to center the Piston Valve ). Does it have another name ?

Hi Alex

I'm not sure if it has another name I think its one of those things that people sort of call it different things I've just always known it as a wobble bar.

Where you get them from:-

You can make one all you need is a length of 10mm ish diameter silver steel clock it up in the lathe so that its running as true as you can get it, you may get away with the three jaw if its a good un, if not use the independent four jaw, then put a female centre in the end with a centre drill, swap it round and clock the other end true then slew the compound over 30 deg and turn a cone on the end, you can use it as it is or you can harden the pointed end by heating it up to cherry and quenching.

Or:- you can use a solid morse taperd centre, check that it has a female centre in the end.

Her's a picture.

Hope this helps

Stew

ParCan:
More progress today.

Valve and Piston made. Body was easy enough, piston not so. Got it on the 3rd attempt.

Then I decided it was time for Small holes in Cast Iron time.
Centre punch did sweet nothing so I used a centre drill in the mill to mark each hole before drilling.
Drilled the Ports and used a small milling cutter for the Bore cutout.
Drilled the holes for the Valve. They both wondered a little so opened em out to 4mm.
The 8 X 1.6 mm holes were not fun, neither was the Tapping of said holes.
Just to note, I didn't have a suitable clamp, I Super Glued the Body to the Cylinder then spotted through with 2 mm and drilled 1.6 before removing the valve body and tapping the holes.
I'll leave you to guess where the rest of that tap is !

Piston rod is also done. I may do the piston later.

ParCan:
And more progress.

Brass Piston is made and attached to the piston rod. I turned the last bit with the piston mounted on the rod.
Lump of 35mm dia Brass arrived today so made the end caps. Still need to drill them for the mounting holes.
Piston almost runs freely in the bore. I'll knock a tiny bit off the locating 16mm dia.

I'm trying to work out the lesser of the evils for fixing the end caps.
I either drill 3mm all the way through the Cast Iron and mount the caps with studs.
OR I can drill and Tap M3 as per the drawings.
This lump of iron is darn hard in places..... Comments and ideas welcome.

NickG:
Alex, good progress there. Would be bit unorthodox drilling right through the cylinder but can see your point if you had a long enough drill and 3mm studding - Could get away with drilling only 4 holes rather than 8 and tapping 8 threads. Or if you could do with both covers clamped in place that's another 8 holes you don't have to drill!

ParCan:
After another day in the workshop, the assembled list now includes.

1 X Cylinder : Complete
2 X Cylinder end caps : Complete
1 X Piston Valve : Complete
4 X crosshead rails : Complete
I need to do cleaning and filing bits to make thing look nice.
A blow in the requisite hole moved the piston appropriately.

I decided to Drill & Tap the cylinder holes as per the standard method.
8 holes tapped with no breakage though some are rather shallow. I can't get 10mm long screws in at the moment.
I have nice screws for the final build but it's all gone together.

I Super Glued the End caps to the Cylinder and used the Mill to position the holes.
(8.5mm each way from centre seemed to be close enough to work)
I then centre drilled the end cap, Drilled 2.5mm for M3 then knocked the end cap off.
Turn it over and repeat for the other side.
I then drilled the end caps 1/8 " (3.2 mm) on the pillar drill.

I'm rather pleased with the outcome so far.

(edit) Um - I have just seen a problem in the photo's.
1 Brownie point to anyone else who can spot the mistake......

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