# Machine from cast or get a billet and carve?



## great white (Jun 25, 2022)

I'm looking to make an upper triple clamp for a motorcycle:




The oem one is actually a cast unit, but I'm not sure if the same quality can be cast at home. I could whittle it out of a billet, but it woudl be pretty thick and that's not cheap these days. I've go lots of scraps of 6061 to melt and cast one and then machine it to final spec.

But again, the issue is the quality of the casting. I'm not sure if the factory just casts it, or if they work it post casting to harden it, or if they have tighter control of the pour itself which makes a different type of cast.


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## Larry$ (Jun 25, 2022)

Die cast? Likely a zinc alloy. If you have an electric kiln so you can keep away from the hydrogen embrittlement casting would be OK with the correct alloy.


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## markba633csi (Jun 25, 2022)

I wouldn't cast it


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## ps15toolroom (Jun 25, 2022)

Castings make poor clamps, they tend to be brittle. 100% mill that out.


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## benmychree (Jun 25, 2022)

It's your life at risk; seems obvious ---


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## markba633csi (Jun 25, 2022)

I'm guessing the factory part has to meet certain specs for strength, probably more than a milled billet-
but you won't know till it breaks


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## Chewy (Jun 25, 2022)

I wouldn't cast it either.  Just for the record, I read that casting aluminum is a different type from 6061 and not to use it.  I have been collecting cast aluminum pieces to use when I get a furnace setup. Can anybody shed some light on that?


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## Larry$ (Jun 26, 2022)

Chewy said:


> I have been collecting cast aluminum pieces to use when I get a furnace setup. Can anybody shed some light on that?


No expert but have made enough mistakes to shed some light. There are a lot of different alloys used in castings. Pistons usually have considerable silicone, Zinc is common in small mechanical parts. Magnesium is also common and I've wondered about it burning off??  Lots of other minor elements. Extrusions seem to be mostly just aluminum but that makes them kind of weak castings.   The problem for the home guy is keeping hydrogen bubbles out of it. They make castings brittle & weak. H2O provides hydrogen. To limit it, dry your metal before it goes into the furnace. I do that by laying it on top of the furnace while it is heating. I've tried some commercial products to ad to the molten metal but with little success. Air that is used for combustion caries humidity, water! The longer the melt is exposed to the fire the more hydrogen gets in from the humidity. So pour as soon as you can. Oxygen reacts with the molten aluminum and forms an oxide that floats on the surface as dross along with other contaminates. You need to keep that out of your pour. Skim just before the pour. Use a sprue that stays full the entire time you are pouring. Use a pouring basin that serves to skim as you pour and keep the sprue full. Provide a trash well at the bottom of the sprue for any stray sand the washes down. Provide a riser that is big enough to stay molten long enough to provide makeup metal as the casting shrinks as it solidifies.  
Alloy wheels  seem like OK material but are a pain to cutup. Manifolds, engine blocks etc. can be broken up with a sledge. Pop cans aren't worth the fuel to melt them and end up with lots of hydrogen bubbles. Avoid using steel or iron to melt in. It contaminates the casting. Crucibles are available online. 

An electric furnace eliminates much of the problem with hydrogen embrittlement. 

Olfoundryman videos are excellent. 

You can make your own casting sand with fine sand from Home Depot, Bentonite is carried by my local concrete company in 50# bags. Baby powder is often used to prevent the sand from sticking to the pattern. Sodium silicate is used for cores and CO2 to set it up. You can also use oil and bake the cores, I've never tried that. There is a lot of poor or outright dangerous YouTube stuff out there. Be careful molten metal will burn right through you. Boot covers, chaps, gloves, face shield and only leather or cotton clothing. 
Oil based casting sand can be purchased but shipping is a killer. You can make your own using a recipe online that uses auto transmission fluid for the oil. Lost foam or lost wax are other options. 

Casting is another of those giant rabbit holes!


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## matthewsx (Jun 26, 2022)

Super critical part, would like to think I have the skills to make one but for my project bike I spent the money and bought one.






						Cheney Engineering - Flat Track Racing Accessories
					

flat track racing motorcycle parts



					www.flattrackaccessories.com


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## Cadillac (Jun 26, 2022)

Chewy said:


> I wouldn't cast it either.  Just for the record, I read that casting aluminum is a different type from 6061 and not to use it.  I have been collecting cast aluminum pieces to use when I get a furnace setup. Can anybody shed some light on that?


Anything that’s been cast before will be a lot closer to the correct mix. My stash consist of small engine blocks, rims, heads, housings. 
 As for the above project I would buy a billet and widdle away at it.


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## MrWhoopee (Jun 26, 2022)

Even if you cast from 6061 scrap, it will not have the properties of 6061. Carve it from a billet and ride with confidence.


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## RJSakowski (Jun 26, 2022)

Chewy said:


> I wouldn't cast it either.  Just for the record, I read that casting aluminum is a different type from 6061 and not to use it.  I have been collecting cast aluminum pieces to use when I get a furnace setup. Can anybody shed some light on that?


I have cast aluminum in the past.  It tends to have internal micro pores but otherwise is suitable.  I have used sheet aluminum scraps for casting; not sure of the alloy though.  I collect aluminum small engine blocks and other castings for future use and probably have several hundred lbs.


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## Bi11Hudson (Jun 26, 2022)

Larry$ said:


> Likely a zinc alloy. If you have an electric kiln so you can keep away from the hydrogen embrittlement casting would be OK with the correct alloy.


I have not ridden for several years, since this last stroke put me in a chair. But after thousands of highway miles I will stand on the premise that either the upper or lower triple tree should only be a *salvaged OEM part*. If you cannot find the original part, be sure to change both the *upper and lower* for what you do find. I would not cast one, even using a local foundry, if he's even still in business, with my or his pattern. A triple tree is one of the primary stability parts of any bike. If you only chase trees, the stability and longevity of the machine still depends on the triple tree. Machined steel would be my choice there. The Al alloy is not a zink, ZAMAK, casting.

.


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## rwm (Jun 26, 2022)

People seem to forget that a lot of aluminum is also forged. That is stronger than cast. Many car wheels are actually forged. The alloy is different for forging (closer to an extrusion) and not ideal for casting. Could that triple tree be forged?


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## vtcnc (Jul 6, 2022)

rwm said:


> People seem to forget that a lot of aluminum is also forged. That is stronger than cast. Many car wheels are actually forged. The alloy is different for forging (closer to an extrusion) and not ideal for casting. Could that triple tree be forged?


I agree with this assessment. It looks forged and machined by my eye. It is hard to imagine Yamaha driving costs down and quality up by ignoring forging as a proven process.


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