General Category > Chatterbox
More Fun with Castings -NOT
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 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 :ShakeHead: :ShakeHead: :ShakeHead:
Dave Otto:
Sad but true, fortunately all castings are not that bad, the castings for my pacific were an absolute dream to machine. I guess it boils down to the foundry and if they give a rip about the quality of their product.
The bad part is you really don't have any idea until after you plunk down your $$ and start cutting.
Dave
Jasonb:
In some ways I would rather not pay for such a comprehensive set of castings. The liner is just a tube so could have been left out and the builder supply some bar. The piston with a bit of a redesign of the internals could again have been done with bar so rather pay less for the casting set and buy sound bar myself.
The head would be harder for people to make so is one item that is better suited as a casting. It could probably be done as a steel fabrication silver soldered together or I would cut from a piece of CI bar.
Yes I've had some nice ones but it seems harder and harder to find foundries that will produce good castings
Jo:
That one seems to have a special coating ::)
Jo
Jasonb:
That is the full size original, takes a good 130yrs to perfect that coating :LittleDevil:
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