[SEL] Re: Alamo piston pattern update
Curt
curt at imc-group.com
Wed Feb 15 05:05:30 PST 2006
jbcast at charter.net wrote:
>
>> ---- Curt <curt at imc-group.com> wrote:
>> . The riser's purpose is to provide molten metal to
>>
>>> the casting as it cools and the metal shrinks. On your piston for
>>> example, you want to bring metal in at the crown. Once filled the
>>> casting should begin to solidify from the skirt moving toward the
>>> crown. The riser is attached to the largest section thickness thru a
>>> short gate. The gate and riser need to be sized such that they will
>>> freeze off last. This ensures molten metal can continue to flow into
>>> the crown as the rest of the piston cools and shrinks.
>>>
>>
>>
>> Curt, have you had any problems with shrinkage in the pin boss area?
>> I made a pattern and had some pistons cast, we had to add risers to
>> supply the pin boss, the first one sunk in on both sides of the
>> piston at the boss. J.B. Castagnos
>>
>>
>>
> JB,
> So far no troubles with this. But there may be a reason now that I
> think about it. In the core box photos you will see that there is a
> rib that runs under the crown of the piston and then down each side of
> the piston connecting to the boss area. I always thought this was a
> strengthening rib and admittedly I also thought it was overkill. But
> since you mention the shrinkage problem perhaps it has more to do with
> assuring a path for molten metal to continue feeding the boss areas
> while cooling.
> So far all of the piston patterns I've made have this rib going under
> the crown and connecting to the bosses. However, over the weekend I
> started on a pattern to make pistons for the 3HP Herc/Jaeger/Economy
> engines and that piston has the rib under the crown, but it does not
> have the rib extending down toward the bosses. I am planning on
> duplicating this exactly as Hercules did and will certainly let you
> know if this results in a shrinkage problem at the bosses. Very
> interesting thought you have brought up!
> Curt
>
>
>
>
>>
>>
>>
>>
>
>
More information about the sel
mailing list