More Fun with Castings – NOT

[JasonBModerator @jasonb]

While putting the finishing touches to the latest engine and waiting for paint etc to dry I possibly foolishly in hindsight dug out a casting set to pass the time.

First I chucked up the cylinder liner approx 100mm long x 50mm diameter and proceeded to destroy 3 inserts. Both ends were so hard the carbide was just getting worn in seconds. Put it away thinking maybe I would heat treat it and have another go.

Next was the piston casting, decided to skim the skirt so I could hold it firmly to then machine the chucking spigot. Another insert bit the dust with the same problem of chill. Now starting to think about buying a foot of 50mm cast iron bar as heating may not work and even if it did the resulting iron was not going to be the nicest to machine for a parallel cylinder and close fitting piston.

Swapped over to the 4-jaw and thought I would have a go at the cylinder head. About 2mm of draft angle machined away reasonably well so I took a measurement and deduced that 4.5mm thickness still needed to come off the 58mm diameter flange. Started to hear an interrupted cut but pressed on even though I could see something getting bigger on the revolving machined surface. When I turned the lathe off this is what I found. The large hole goes almost to the ctr and is right where one of the three head bolts goes so little chance of getting a good head seal. As this is a hot tube engine with a lamp burning right under the head JBWeld is not going to be an option. I could CNC it from a 50mm long slice of 70mm cast iron bar but have started to loose interest with still other yet untouched castings to come.

Also if I did heat treat the other two castings what are my chances of finding holes in them if I do get under the skin?

Castings, don’t you just love them☹☹☹

[Speedy Builder5Participant @speedybuilder5]

Not that I wish you any ill feelings, but it is good to see that such an accomplished engineer as yourself experiences these difficulties now and again.  I hope the chunk of cast iron bar you purchase has a better integrity.

Bob

[noel shelleyParticipant @noelshelley55608]

I feel for you Jason ! Never mind the quality – feel the width. Noel.

[duncan webster 1Participant @duncanwebster1]

When I had some wheel castings with really hard spots the only thing that worked was brazed carbide with a big nose radius. Tips just crumbled quick time. I should have sent the castings back, but impatience ruled

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