Are all 69 cb750s sandcast models

[shinyribs]

If it's not diecast, and its not sandcast, then what is it?

Are you saying they used dies that were sandcast-constructed dies , which caused the rough texture to carry over, rather than smooth, machined dies?

I could see that being a possibility, thought it would be interesting to see a run of cases, all out of the same sandcast dies, that all shared the same surface "flaws".

[bernhard]

You have misunderstood my post, as I appear to have not made it abruptly clear- early ones are DIE-CAST as were they all. The early moulds were only good for making 4-5000 cases,  (which Happily coincided with the number of “sandcast” cases) whereupon Honda made a set of more robust & better moulds that didn’t leave this crackle effect as the latter moulds were of better quality –because they took longer to make.

[shinyribs]

I didn't misunderstand you, I was just curious of the "gray area" in your info that fee
Ll between diecasting and sandcasting.

Anyway, I did a little research and I think I may have a better idea of what you're talking about now.

When diecasting,manufacturers can inject the molten metal in to the molds under high pressure, or they can allow them to gravity- fill. Apparently, gravity-fill produces a coarse finish due to a remaining amount of trapped gasses. Whereas high pressure creates a smooth exterior finish, pore-free.

I can't say, but this does make sense now that you mention it. Sandcasting is very labor intensive and has a pretty decent chance of failing all together. You wouldn't think a company as "together" as Honda would be sandcasting in the late 60's. Interesting food for thought.

[Truck]

Everything I've read says Honda did sandcasting Because it was cheaper and they wanted to see how popular the bikes were before investing the money into better die's. Guess we all know they had nothing to worry about!

[shinyribs]

Sandcasting would definitely be cheaper for initial tooling, but the labor involved in sandcasting 7,000+ entire engine cases would be insane. Sand only makes sense on a really limited scale.

[TOOLS1]

Then why do all the car companies, and truck engine manufactures use sand molds to make their engines? I used to deliver sand to the International engine manufacturing plant.
TOOLS