hi fellas ... question about metal casting of aluminum motorcycleengine heads

I'm looking for a few web sites or blogs that tell individual accounts
of casting spare parts and engines.

I've looked, but maybe you know a good web page that isn't high in the
search rankings, or more obscure, etc.

Thanks jolly old lads.

ps. are the cooling fins different sizes at different latitudes?

 

I worked in foundries for many years.
It is next to impossible to make your own aluminium cast parts. Zinc
alloy or lead are possible, but aluminium has to be a lot hotter,
typically 750 deg. C +, as well as being scrupulously clean. Al oxides
easily when it is molten, so needs flux on its surface when molten,
de-gassing before pouring, and oxide filters in the mould.
Before you start, you need to get the right alloy. There are around 20
'common' alloys. LM25 is probably the best for engines cases. Use
anything else, and the strength and/or machining abilities will be poor.

Then you need your pattern to make the part. Al shrinks around 4% in the
mould. So an old part cannot be used to make a new one from. You need to
make a copy that is 4% bigger.
All in all, you can see why it is uneconomical to make new engine cases
etc.

No idea for 'modern' bikes, but old BSA cooling fins were all the same,
top to bottom.
Alan.

 

Fark yes. You should see the size of the fins on the Tropical Series
Yamaha made in the 70s. The extra metal nearly bankrupted them and plans
for a Sub-Saharan model were shelved as a result.

 

Look here:

http://www.realclassic.co.uk/techniques.html

Anything with "Humbernut" on it.

 

http://groups.google.co.uk/group/rec.aviation.homebuilt/browse_frm/thread/d2e10e13c2bda5e0/
"How To Make a Smelter
It's easy. YOU CAN DO IT."

Any activity in this field will be really hazardous. Lots
to go wrong and burn bits of your body off.

"if you drop it onto the ground any moisture that is present
will flash to steam instantly and explode the molten metal
into a hand grenade."

 

He's well worth reading, is Humbernut.

 

Rubbish. It will just splash like dropped milk.
The only time it will shoot out anywhere is where there is a sudden
expansion of gas, and the molten metal is stopping the gas exiting.
Quite common if a mould has not been vented, or the metal is poured in
too fast, but generally not particularly harmful if you have the
relevant safety gear on.
Alan.

 

What a load of fucking cock.

 

Come on then, explain how you can make decent castings in your garage.
No, it is not impossible, but to do a good job will be very difficult.
You cannot do it without considerable expense.
Alan.

 

It's a load of cock if you want porous castings that are about as
strong as a week old kitten but if you want decent quality castings
he's right in everything he said.

 

Didn't John Britten make his own castings, using wooden moulds, after he
discovered just how much the job would cost if a "professional" did it?

 

I wouldn't try to cast something as massive or complex as a full-size
cylinder head, or anything highly stressed for that matter, but I
don't think it's a case of 'considerable expense'. It certainly isn't
something you can do casually, though.

My own DIY attempts about fifteen years ago didn't go well, but in
retrospect I was over-ambitious.

Getting the heat isn't a problem: a furnace of firebricks, coke, and
an electric blower made out of a car radiator fan will (just) melt
steel - I tried it once. It didn't do the crucible any favours though.

You can, or at least used to be able to, buy all the stuff including
fluxes & degasser from model engineering foundry suppliers. Proper
crucibles weren't *that* expensive.

Unfortunately, over the years, the labels have all rubbed off the
various bags I've got, so I can't tell what's what, though I *think*
the big white tablet things are aluminium degasser. maybe.

Building another furnace is on the 'ToDo' list.

 

Utter fucking bilge. Plenty of people have made and are still doing good
quality backyard ally casting without needing massive amounts of
machinery and expensive workshops.

Jesus fucking christ, no wonder the country is going down the toilet
with the amount of nay-saying cunts around. What the **** happened to
the ones who just gave it a go?

 

On Sat, 16 May 2009 18:08:28 +0100, Grimly Curmudgeon

snip>

Stick to bodging things up in your back garden and leave proper
engineering to the experts.

 

Yah, like you'd know what one of them was like, you arsehole.

 

Tell us again exactly what it is you do for a living?

 

*nice*

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www.cuore-sportivo.co.uk

 

Angle grinders at dawn

 

I wouldn't disagree. If you want to make a list of genuine motorcycle
geniuses (not including riders), he'd be on mine.

Along with, er, Fabio Taglioni, Pops Yoshimura, Phil Vincent (or maybe
Phil Irving), Soichiro Honda, Carcano, and possibly Edward Turner.

Anyone like to diasgree or put up their own nominees?

 

Willie G?